The SARS-CoV-2 pandemic introduced the world to a new type of vaccine based on mRNA encapsulated in lipid nanoparticles (LNPs). Instead of delivering antigenic proteins directly, an mRNA-based vaccine relies on the host’s cells to manufacture protein immunogens which, in turn, are targets for antibody and cytotoxic T cell responses. mRNA-based vaccines have been the subject of research for over three decades as a platform to protect against or treat a variety of cancers, amyloidosis and infectious diseases. In this review, we discuss mRNA-based approaches for the generation of prophylactic and therapeutic vaccines to HIV. We examine the special immunological hurdles for a vaccine to elicit broadly neutralizing antibodies and effective T cell responses to HIV. Lastly, we outline an mRNA-based HIV vaccination strategy based on the immunobiology of broadly neutralizing antibody development. Since the first clinical observation of AIDS and the subsequent isolation of the causing retrovirus HIV in the early 1980s, the HIV/AIDS epidemic continues to be one of the major global health threats despite four decades of intense research . Current+ T cells would provide a secondary layer of defense, eliminating the earliest infected cells, preventing establishment of a latent reservoir of HIV-infected cells. Indeed, in the rhesus macaque Simian Immunodeficiency Virus (SIV) infection model, immunization with a modified rhesus cytomegalovirus vector expressing SIV genes induces potent CD8+ cytotoxic T cells that recognize SIV infected CD4+ T cells in the context of MHC-E and eliminates infected cells completely in 50% of macaques . A murine form of the TriMix-HTI mRNA vaccine induced systemic antigen-specific CTLs after direct injection into the lymph nodes of mice and the human version of the mRNA vaccine induced monocyte-derived DCs to mature and induce T cell proliferation and cytokines ex vivo . TriMix-Although ex vivo loading of DCs was the first to be evaluated in human clinical trials for HIV mRNA vaccine, this method involves working with autologous DCs, which requires much expertise in cell therapeutics and is laborious and expensive . The resEfforts to develop an effective HIV vaccine over the last forty years have largely served to reveal the roadblocks that a successful vaccine will need to overcome. Vaccines based on mRNA exhibit special properties that may be exploited for a new generation of HIV vaccines. Here, we summarize the immunological and viral challenges to HIV vaccination outlined in A key strategy to activating rare, possibly anergic, bnAb precursor B cells is providing well-folded, native-like immunogens in a manner that maximizes their activation and proliferation. Traditional subunit vaccines deliver immunogens as a bolus of protein that, immediately upon injection, is subject to degradation. In contrast, mRNA-based vaccines induce weeks-long production of immunogens in situ , increasStrategies that enhance immunogenicity of HIV Env antigens increase the chance that rare B cells bearing germline precursors with bnAb potential will be activated. One approach to increasing Env immunogenicity is to display Env immunogens on particulate arrays, such as nanoparticles or virus-like particles ,152. An As discussed earlier, an effective HIV vaccine may need to induce an immunological environment that is permissive for the development and maturation of auto/poly-reactive B cells with bnAb potential, a state akin to that occurring with chronic HIV infection. mRNA-based vaccines have the potential to transiently alter the host immunological milieu through the encoding of immunomodulatory factors. The capacity for an mRNA platform to generate bioactive molecules was demonstrated by Kariko et al., who injected mice with erythropoietin encoded as mRNAs and encapsulated in lipid nanoparticles and observed enhanced erythropoiesis . A varieA key feature of mRNA vaccines, particularly those delivered via cationic LNPs, is the induction of potent antibody responses via germinal centers. While the molecular basis for the robust induction of germinal centers with mRNA vaccines is still being unraveled, the generation of antigen-specific TFH cells is likely a paramount feature ,158. As Sequential immunization with optimized HIV Env immunogens represents a considerable jump in complexity compared to traditional vaccine regimens. On top of the biological complexities of identifying and testing a variety of immunogens is the pragmatic issue of producing them under Good Manufacturing Practices (GMP). In this area, mRNA-based vaccines have clear advantages over protein subunit or live/inactivated virus platforms. The mRNA manufacturing process is quicker and simpler than production systems based on mammalian cells or eggs, has high yield and purity and is scalable . Moreove+ T cell responses, vaccine researchers have typically relied on the delivery platform best suited for inducing a humoral vs. cellular immune response. For vaccines based on Env immunogens to elicit antibody responses, the protein subunit approach is most commonly employed: recombinant proteins are injected along with a suitable adjuvant, which favors the induction of TFH cells, germinal centers and antibodies. In contrast, studies of T cell vaccines have relied on delivery of HIV proteins or peptides via DNA plasmids and/or recombinant viruses, in which viral peptides are produced endogenously by host cells and loaded onto MHCI for presentation to CD8+ T cells [+ T cell response against tumor antigens, yet studies with these vaccines have rarely investigated the associated humoral response [+ T cell response is less clear [+ T cell response in humans [+ T cell activity [While an effective HIV vaccine will likely need to elicit both bnAb and CD8 T cells ,162. mRNresponse . Likewisss clear . Indeed,n humans ,164 but activity ,137. ThuWhile research innovations have driven rapid progress in the field of mRNA vaccines in the past few years, many unanswered questions and challenges remain in developing an mRNA HIV vaccine . First, An important component of any bnAb-inducing HIV vaccine will be well-folded, native-like Env immunogens in the pre-fusion conformation . For proAnother important consideration for HIV immunogen design for mRNA vaccination centers on the inescapable dependence on host cells to translate mRNA-encoded immunogens and apply post-translational modifications. For example, a recent study reported on the design of an Env immunogen targeting the purported germline precursor for a bnAb lineage that bound best when produced in a cell line lacking the glycosylation machinery to add complex carbohydrates . This tyFinally, with the recent rare anaphylactoid events to COVID-19 vaccine mRNA-LNP administration that have been attributed to possible sensitivity to polyethylene glycol 2000 in LNPs , it remaBecause of the biology of bnAb development, an effective HIV vaccine will likely be more complicated than current vaccines. We envision a series of Env-based immunogens that, when encoded and delivered as mRNAs, will guide B cell maturation from germline precursor to bnAb in germinal centers, through sequential immunization . Due to For broad coverage of potential T cell epitopes, the mRNA vaccine could also encode select regions of HIV Gag, Nef or Pol, either as full proteins, short peptides or mosaics. With proven efficacy and safety, immunomodulatory proteins could also be encoded as mRNA to transiently boost immune responses following vaccination. To achieve these goals, vaccine mRNA candidates will have to be designed and tested pre-clinically, produced under GMP and then evaluated iteratively in phase 1 clinical trials. We can imagine an mRNA HIV vaccine regimen targeting two different bnAb lineages with four sequential immunogens per lineage, plus two HIV potential T cell epitopes, encoded as mRNAs. The rapid manufacturing time of GMP mRNA could allow for multiple immunogens to be evaluated in human clinical trials concurrently ,170,171.


Data on barriers and facilitators to prenatal oral health care among low-income US women are lacking. The objective of this study was to understand barriers/facilitators and patient-centered mitigation strategies related to the use of prenatal oral health care among underserved US women.We used community-based participatory research to conduct two focus groups with eight pregnant/parenting women; ten individual in-depth interviews with medical providers, dental providers and community/social workers; and one community engagement studio with five representative community stakeholders in 2018–2019. Using an interpretive description research design, we conducted semi-structured interviews and focus groups which were audio-recorded, transcribed, and analyzed for thematic content.We identified individual and systemic barriers/facilitators to the utilization of prenatal oral health care by underserved US women. Strategies reported to improve utilization included healthcare system-wide changes to promote inter-professional collaborations, innovative educational programs to improve dissemination and implementation of prenatal oral health care guidelines, and specialized dental facilities providing prenatal oral health care to underserved women. Moreover, smartphones have the potential to be an innovative entry point to promote utilization of prenatal oral care at the individual level.Low-income women face multiple, addressable barriers to obtaining oral health care during pregnancy. Inter-professional collaboration holds strong promise for improving prenatal oral health care utilization. Despite the well-documented association between poor maternal oral health, preterm/low-birth-weight deliveries , 2 and iAt the patient level, demographic, socioeconomic, psychological, and behavioral factors affect utilization of prenatal dental care. Among women living in California, a population-based study found that the primary reason for not obtaining dental care was lack of perceived need, followed by financial barriers . A surveAt the clinician level, recommending prenatal oral health care utilization is not routinely practiced by maternity providers  , 19. A nData on barriers and facilitators to prenatal oral health care among low-income US women are lacking. Given differences in cultural beliefs, social environments, and health care systems, it is challenging to apply findings from other populations to women receiving care in underserved settings in the US. To address this gap, we used community-based participatory research (CBPR)  to assesWe examined a clinical phenomenon  to identify themes and patterns related to reported perceptions of oral health care among underserved women, medical/dental providers and community/social workers. We used the interpretive description  researchThis study was conducted in 2018–2019 in Rochester, NY. Rochester is the third most populous city in New York State, with a population of 208,046 residents. The University of Rochester Medical Center and Rochester Regional Health System are the two leading providers of comprehensive care for Rochester residents holding both private and state-supported medical insurance. Pregnant women whose income is equal to or lower than 138% of the Federal Poverty Threshold are eligible for NY State-supported dental insurance (Medicaid) which provides coverage for adult dental procedures including comprehensive oral examinations, extractions, and restorative/endodontic/periodontal procedures .We collaborated with two local organizations  on the development of the study design, participant recruitment, and data collection and interpretation. The University of Rochester provides obstetric services to more than 4000 pregnant women per year . Three-quarters of these pregnant women benefit from state-supported dental insurance that is provided to low-income groups (Medicaid). The Healthy Baby Network is a Rochester based non-profit social service organization dedicated to improving the health and well-being of mothers and babies by addressing systemic barriers that contribute to racial health disparities and that adversely impact healthy births. The Healthy Baby Network provides outreach services to over 200 low-income pregnant women per year.All study participants were 18 years of age or older. Five types of informants were included. Pregnant or parenting women (first group of informants) who participated needed to be pregnant or have at least one child < 2 years of age, be eligible for state-supported insurance . Medical providers (second group of informants), dental providers (third group of informants) and community/social workers (fourth group of informants) who participated in the study were required to be currently practicing. The fifth group of informants were community stakeholders purposefully selected by the community studio organizer (see below).Subjects who had decisional impairment or were incapable of making an informed decision about participation in the study were excluded. Recruitment was conducted face-to-face by two trained research coordinators, and study participants were consented prior to the beginning of study activities. Community stakeholders did not require formal consent in accordance with standard community studio practice.Two 2-h focus group sessions were conducted with eight pregnant or parenting women using a semi-structured interview guide  triangulation: we used different data collection methods detailed in the data collection methods, including individual interviews, focus groups, field notes and memos; (2) we applied principle of respect, reactivity , reflexiImportantly, we adopted the following strategies from Paterson : (1) expAudio recordings were initially transcribed by the Temi (USA) transcription service, and further verified by two trained researchers. Transcribed data were stored and analyzed using MAXQDA software . The data were coded by two trained coders with predetermined and later modified  open codes using a codebook with a description of the coding tree , and three dental providers (one hygienist and two community dentists). All participants were female, 34–63 years of age, with a mean age of 47.9 years. We did not encounter participants who refused to join the study or who dropped out. We reached data saturation by the end of the study, and after we were no longer receiving new information from additional interviewees.parenting woman: “I had issues with my gums, probably at mid pregnancy, it started swelling, bled and hurt. But I didn't go to the dentist. I just kind of dealt with it.”The focus group of pregnant and parenting women repeatedly reported experiencing dental problems during pregnancy. Many reported not knowing the importance of maintaining good oral health during pregnancy and described seeking dental care during pregnancy as “frustrating” and “did not know it is needed.” For example,Comments from all five types of informants were categorized as barriers, facilitators, and strategies or implications for policy-making. Table . Pregnant/parenting women reported that they could not get to their dental appointments due to lack of babysitting, lack of transportation, and priority of other life events.A commonly recognized barrier to medical care utilization, e.g., socioeconomic hardships and competing interests, also represented a barrier to utilization of prenatal oral health careAnother barrier was unawareness of the benefits and importance of prenatal oral health care among pregnant women. Many pregnant/parenting women reported lack of knowledge about the association between poor oral health and adverse birth outcomes, and the importance of maintaining good oral health during pregnancy.A unique barrier identified was unawareness of having dental coverage as a recipient of state provided medical insurance, e.g., Medicaid. A majority of medical providers, community/social workers, and pregnant/parenting women did not know about dental benefits associate with Medicaid. In addition, they were unaware of dental clinics that accepted Medicaid.Intriguingly, all participating medical providers, dental providers, community/social workers, and pregnant/parenting women recognized insufficient inter-professional collaboration in promoting prenatal oral health. A majority of informants felt that the initial introduction about the importance of prenatal oral health should be initiated by medical providers.We identified another system-level barrier: unawareness of the latest practice guidelines among medical and dental providers, and among community/social workers. Although some of them knew a few prenatal oral health guidelines, none of them were aware of the latest practice guidelines, including recommendations from professional organizations, such as the American College of Obstetricians and Gynecologists or the American Dental Association, both of which clearly state conditions that require immediate treatment, such as oral examinations, extractions, root canal treatment, and fillings are important and safe to perform at any time during pregnancy . Some OBBoth medical providers and community/social workers reported that they had referred their pregnant patients for oral health care but, unfortunately, some of their patients were denied dental care due to the pregnancy. Furthermore, the pregnant/parenting women expressed the notion that only a limited number of dental clinics accepted their State-supported insurance  and the long waiting list for care exacerbated their unwillingness to visit a dentist during pregnancy.A critical facilitator that pregnant/parenting women proposed was “constant reminders.” Participating women stressed that these reminders were important and should be introduced by their maternity health care team as early as their first pregnancy visit, and repeated at their follow-up pregnancy appointments.Pregnant/parenting women suggested raising community awareness via mass media as an essential facilitator to improve the use of prenatal oral health care. They recommended the use of commercials, informational campaigns, bus stop banners, health fairs, and community events.Strengthening interprofessional collaboration was proposed as a strong facilitator to promote the use of prenatal oral health care. Medical and dental providers, and community/social workers specifically commented on several pivotal points that are crucial to a sustainable interprofessional collaboration, including merging the medical and dental electronic record systems, shortening physical distance between prenatal medical and dental offices, creating billable prenatal oral health counseling services, and enhancing collaborations with social service groups.Parenting woman: “Nowadays, most people will use smartphones. Smartphones will be a good way for patients to get oral health information. For example, if they are pregnant or breastfeeding, they can download an app with a professional dental knowledge plugin at every different stage. When they are reviewing pregnancy or breastfeeding related information, noticeable pictures and videos will provide better oral health education, not only for moms, but also for young children.”Parenting woman: “It should be a commercial somewhere, whether it's Facebook and it could be played between a popular show that everyone is watching.”OBGYN: “Many of our moms are members of online support groups. I think Text-for-Baby is one that connects moms with knowledge they need to know during pregnancy.”Through this study, we further mapped the elements of both the real and virtual communities that women interacted with during pregnancy; these are demonstrated in Fig. In recent years, federal agencies and professional organizations have mounted a substantial effort to address an increasingly recognized public health problem, poor prenatal oral health, which has serious implications for maternal and child health. Yet, prenatal oral health care is significantly underutilized in the US (and worldwide), especially among underserved groups, many of whom lack access to care.This study used a community based participatory research (CBPR) strategy to engage a hard-to-reach, priority population of underserved pregnant women, and clarified barriers and facilitators to their use of prenatal oral health care. We applied the principle of respect, reactivity, and reflexivity to build a trusting relationship between study participants and study personnel. In addition, we used rigorous qualitative methods to promote validity, in particular triangulation across different data collection methods and different stakeholders. Finally, we identified barriers and facilitators that led to the identification of several innovative strategies and indications for potential policy-making regarding prenatal utilization of oral health care in the community.Create healthcare system-wide changes to promote inter-professional collaborationIncorporate dental care into the medical care setting. To address the historical problem of inadequate communication between medical and dental providers, collaboration could be facilitated through shared facilities and particularly electronic record systems. Referrals, reminders, and feedback that could be easily communicated on a shared platform would significantly improve the rate of follow-through for recommended prenatal oral health care.Promote prenatal oral health counseling by non-MDs. Within the scope of prenatal oral health, the professionals who could make significant impactful changes include non-MD providers, e.g., midwives [midwives , nurse pmidwives  and mediImprove collaboration with social benefit programs, e.g., Women, Infant and Children (WIC). Use innovative mediators to promote prenatal oral health, such as community/social workers, peer counselors and doulas. In Klamath County, Oregon, Milgrom et al. [m et al.  demonstrIntroduce innovative educational programs to improve dissemination and implementation of prenatal oral health care guidelines.A majority of the medical/dental providers and community social worker participants were unaware of the current prenatal oral health care guidelines, therefore the first step should be to increase the awareness of guidelines. Lee et al.  investigDevelop specialized dental facilities to provide prenatal oral health care to underserved groups.Use a Hub-Spoke model; highly specialized dental facilities that are dedicated to underserved pregnant women could serve as the hub to meet regional patients’ needs and educate staff at satellite facilities. The University of Rochester Eastman Institute for Oral Health (EIOH) has robust clinical services with a strong community orientation. The most significant recent change to the current prenatal oral care services in Rochester has been the new EIOH Pregnancy and Infant Dental clinic, which is dedicated to underserved pregnant women and their infants.Use social media and smartphones to promote prenatal oral health education and oral health care utilization.Smartphone health care products have been successfully applied to manage individual behaviors and health conditions , such asBased on our study, we share below four recommendations that have potential to improve prenatal oral health care utilization in underserved US women.Despite the strengths of this study, our findings should to be cautiously interpreted. First, all study participants, including medical and dental providers, and community/social workers were female, which precludes generalization of our findings to male clinicians or community/social workers. Second, the study was conducted in only one city. In the US, despite the extended Medicaid health insurance coverage for pregnant women through public programs, adult dental benefits are optional for states to offer among Medicaid services. In 2014, seven states provided no dental benefits and only 17 states provided comprehensive adult dental benefits, including New York State . As of 2Low-income women face multiple, addressable barriers to obtaining oral health care during pregnancy. Inter-professional collaboration holds strong promise for improving prenatal oral health care utilization. System-wide policy changes to improve such inter-professional collaboration should include explicit recommendations for prenatal oral health care from obstetrical/medical providers, effective mediation by community/social workers, and implementation of recommended universal practice guidelines for community dental providers. Furthermore, use of smartphones and social media offers an innovative entry point to promote prenatal oral care utilization at the individual level. We plan to test the effectiveness of these innovative strategies  in our future studies. The CBPR process has strengthened local research capacity and has formed ongoing relationships among study investigators, local liaisons, and the community that will be essential for the next phase of program design and policy development for future implementation.


The clinical and radiological presentation of chronic obstructive pulmonary disease (COPD) is heterogenous depending on the characterized sources of inflammation. This study aimed to evaluate COPD phenotypes associated with specific dust exposure.This study was designed to compare the characteristics, clinical outcomes and radiological findings between two prospective COPD cohorts representing two distinguishing regions in the Republic of Korea; COPD in Dusty Area (CODA) and the Korean Obstructive Lung Disease (KOLD) cohort. A total of 733 participants  were included finally. A multivariate analysis to compare lung function and computed tomography (CT) measurements of both cohort studies after adjusting for age, sex, education, body mass index, smoking status, and pack-year, Charlson comorbidity index, and frequency of exacerbation were performed by entering the level of FEV1(%), biomass exposure and COPD medication into the model in stepwise.The mean wall area  became significantly lower in COPD patients in KOLD from urban and metropolitan area than those in CODA cohort from cement dust area  after including FEV1 in the model. COPD subjects in KOLD cohort had higher CT-emphysema index . The difference in the EI (%) was consistently significant even after further adjustment of FEV1 . However, there was no difference in the ratio of mean lung density (MLD) between the two cohorts (p = 0.077). Additional adjustment for biomass parameters and medication for COPD did not alter the statistical significance after entering into the analysis with COPD medication.Higher MWA and lower EI were observed in COPD patients from the region with dust exposure. These results suggest that the imaging phenotype of COPD is influenced by specific environmental exposure. Chronic obstructive pulmonary disease (COPD) is defined as progressive airway obstruction with parenchymal lung destruction and airway inflammation. The prevalence of COPD is increasing and COPD is predicted to become the 3rd leading cause of death worldwide by 2030 , 2. The The clinical and radiological presentations of COPD have proposed heterogeneity. Inflammation, characterized by COPD, can differ by smoking, air pollutants, biomass, or genetic factors leading to diverse clinical or radiological findings. Heterogeneity of COPD on computed tomography (CT) findings have been broadly characterized as either; emphysema-predominant or airway-predominant type , 4. BronTo evaluate COPD phenotypes for specific exposure, it is necessary to compare radiologic findings between patients who reside in regions representing specific dust exposure and non-residents. In this study, we investigated whether there is a difference in structural findings in CT by evaluating the characteristic of patients with COPD who lived in two functional areas; urban areas where mainly composed of metropolitan regions with residential areas, without large industrial emissions and rural areas, where large cement plants are located nearby expecting exposure to different composition of dust.This study was designed to compare characteristics and clinical outcomes using radiological findings between two prospective COPD cohorts representing distinguishing regions in the Republic of Korea; COPD in Dusty Area (CODA) and the Korean Obstructive Lung Disease (KOLD) cohorts. The CODA cohort was prospectively recruited from 2012 to 2015 to observe the clinical outcomes of Korean COPD patients from rural area living near cement plants . This coThe study design and methods were approved by the Institutional Review Board (IRB) of Kangwon National University Hospital (IRB No. KNUH 2012-06-007) and the study was conducted following the tenets of the Declaration of Helsinki.Spirometry tests were performed using standardized equipment by qualified technicians following the ATS/ERS guidelines . SpiromeIn this study, we asked previous biomass exposure which was also known to influence the phenotype of COPD by questionnaire . The queVolumetric CT scans were taken at full inspiration and expiration, using a first-generation dual-source CT system  in CODA and 16-multidetector CT scanners produced by three different manufacturers  in KOLD based on their reports of both the CODA and KOLD studies . Scan paThe baseline characteristics of the patients were reported as mean ± standard deviation (SD). The distribution of each variable was tested by Kolmogorov–Smirnov (K–S) and Shapiro–Wilk test. Normal distribution parameters were analyzed using an independent sample t-test, and non-normal distribution data, such as the EI and hs-CRP, were analyzed using the Mann–Whitney U-test. As EI was not in normal distribution, it was analyzed by log-transformed value. Multivariate analysis of the means of clinical and CT variables were estimated using the least squares mean of the generalized linear model. Age, body mass index (BMI), and post-bronchodilator FEV1 (% of predicted) were included in the model in stepwise as these variables were associated with the extent of emphysema in smokers with COPD , 19. In Table Multivariate analysis for the comparison of lung function and CT measurements of both cohorts after adjusting for age, gender, educational attainment, BMI, smoking status, pack-years of their smoking among smokers, CCI, and COPD exacerbation showed higher EI in KOLD cohorts than in the CODA cohort . This significant difference was consistent even after further adjustment for FEV1  , MWA by CT measurements was significantly higher in the CODA cohorts which represented a rural area near cement plants. These results were consistent, even after adjusting for age, gender, educational attainment, BMI, smoking habits, CCI, spirometry parameters, history of COPD exacerbation, medication they used and biomass. Patients with COPD living in rural area showed higher incidence and events of COPD exacerbation in previous studies , 21. HowIn this study, we measured the MWA and EI by CT scan within the two cohorts. In previous studies, CT findings showed various patterns and phenotypes for several conditions and causal materials including biomass, smoking, occupational chemicals and combustion. For instance, non-smoker and female patients with COPD had less emphysema and air-trapping, as detected by HRCT, thicker basement membranes and greater endobronchial pigmentation . Non-smoParticipants in the CODA cohort, who lived near cement plants and were exposed to cement dust, had increased wall thickening on chest CT. In a previous study, exposure to cement dust by living or working near cement plants was associated with a higher prevalence and hospitalization of patients with COPD and who also experienced more respiratory symptoms , 25. RecStructural changes represented by wall thickness in CT have been reported in studies of other types of dust. Individuals with low FVC who were occupationally exposed to the World Trade Center disaster showed higher WA% representing proximal airway inflammation. However, there was no difference in the measurement of distal airway and emphysema compared to persons with normal spirometry . The carOccupational factors according to regional distinction have also influenced COPD incidence or exacerbations in previous studies. Agricultural workers who are often exposed to dust and vapors that can cause or aggravate underlying lung diseases are the most prevalent rural occupation , 34. It Biomass exposure is another cause of COPD development which had been studied in non-smoker and female subjects , 39. BioTo our knowledge, this study is the first to provide a direct comparison of the phenotype of CT findings between patients with COPD from rural and urban areas. This study could explain the different clinical characteristics of patients with COPD from a rural area. Despite the strengths of this study, there were several limitations. First, this study had a cross-sectional design, so there was no chronologic information for changes in these results due to the nature of this study design. The findings of longitudinal CT images of further studies should be followed to confirm the characteristics revealed in this study. Second, we compared two distinguished cohorts representing patients with COPD living in rural and urban areas which might have less comparability while exploring the effect of various exposures. We could not distinguish occupational exposure from regional exposure of individuals who lived within the same district. Despite this limitation, we included almost all possible confounders mediating the COPD phenotype by stepwise multivariable analysis. In addition, the intensity, duration and type of biomass which are well-known COPD phenotype factors between the two cohorts, were not compared in this study. However, as far as we included household biomass exposure, we found consistent results. Further studies regarding quantitative data of individual environmental, occupational or biomass exposure are still needed concerning their effect on CT findings, or their biological effects on COPD. Third, quantitative analysis in COPD is influenced by the CT scanner and scan parameters such as reconstruction algorithm, radiation dose, section thickness . Scan paHigher MWA and lower EI were observed in the dust exposure region. These results suggest that the imaging phenotype of COPD is influenced by environmental exposure.


Alveolar hypoxia is the most prominent feature of high altitude environment with well-known consequences for the cardio-pulmonary system, including development of pulmonary hypertension. Pulmonary hypertension due to an exaggerated hypoxic pulmonary vasoconstriction contributes to high altitude pulmonary edema (HAPE), a life-threatening disorder, occurring at high altitudes in non-acclimatized healthy individuals. Despite a strong physiologic rationale for using vasodilators for prevention and treatment of HAPE, no systematic studies of their efficacy have been conducted to date. Calcium-channel blockers are currently recommended for drug prophylaxis in high-risk individuals with a clear history of recurrent HAPE based on the extensive clinical experience with nifedipine in HAPE prevention in susceptible individuals. Chronic exposure to hypoxia induces pulmonary vascular remodeling and development of pulmonary hypertension, which places an increased pressure load on the right ventricle leading to right heart failure. Further, pulmonary hypertension along with excessive erythrocytosis may complicate chronic mountain sickness, another high altitude maladaptation disorder. Importantly, other causes than hypoxia may potentially underlie and/or contribute to pulmonary hypertension at high altitude, such as chronic heart and lung diseases, thrombotic or embolic diseases. Extensive clinical experience with drugs in patients with pulmonary arterial hypertension suggests their potential for treatment of high altitude pulmonary hypertension. Small studies have demonstrated their efficacy in reducing pulmonary artery pressure in high altitude residents. However, no drugs have been approved to date for the therapy of chronic high altitude pulmonary hypertension. This work provides a literature review on the role of pulmonary hypertension in the pathogenesis of acute and chronic high altitude maladaptation disorders and summarizes current knowledge regarding potential treatment options. A large portion of human population has inhabited high altitude settings, such as the mountainous geographic locations of the Andes, Tibet, Ethiopian highlands, Pamir, and Tian-Shan. In addition, the number of people traveling to high altitudes in connection with economic or recreational purposes has been constantly increasing during last decades . High alHPV is a unique response of the pulmonary circulation to alveolar hypoxia. Acute HPV is considered as an adaptive response of the pulmonary circulation to a regional alveolar hypoxia, which optimizes ventilation-perfusion matching and gas exchange by diverting blood flow from poorly ventilated to optimally ventilated lung segments ,7. LocalThe exact underlying mechanisms of HPV have not been fully elucidated yet . NeverthIn isolated buffer-perfused lungs and isolated pulmonary artery rings, hypoxia elicits a biphasic response consisting of a transient vasoconstriction lasting about 10–15 min, followed by a sustained constriction that develops more gradually to reach a plateau after 30–40 min . InteresFor most mammals, including humans, the ascent to high altitude is associated with an increase in PAP. Acute HPV is responsible for the initial PAP elevation on exposure to high altitude hypoxia . BreathiSeveral factors have been identified that modulate the magnitude of the HPV in lowlanders . ChildreThere is evidence that continuous or intermittent altitude preexposure can reduce acute mountain sickness and improve physical performance at high altitude . In thisIron bioavailability is another factor that can influence the magnitude of the hypoxic pulmonary vascular pressure response. Iron deficiency can lead to increased pulmonary vascular resistance  and poteHAPE is a potentially life-threatening form of noncardiogenic pulmonary edema that may develop in otherwise healthy individuals during the first days after rapid ascent to high altitudes . Risk faExaggerated hypoxic pulmonary hypertension is a hallmark of HAPE. Early studies with invasive hemodynamic measurements documented the presence of an abnormally high PAP in HAPE patients ,59,60. FIn experimental studies, the nonhomogeneous nature of HPV has been demonstrated ,74. FurtAlthough most of the HAPE-susceptible subjects exhibit abnormal pulmonary vascular responses to hypoxia ,86, someThe most efficient approach to prevent or reduce HAPE severity is a properly organized acclimatization process. Most important is the sleeping altitude and not the highest elevation achieved during the day . It is rFor successful acclimatization, a slow staged ascent is recommended with the first sleep at an altitude below 2400 m. Prospective studies demonstrated reduced incidence and severity of acute mountain sickness during slow staged ascent ,99. FurtOne of the key biologically active mediators regulating vascular tone is nitric oxide. Nitric oxide is produced by the enzyme nitric oxide synthase, located in the endothelial vascular cells and epithelial cells of the airways. Local generation of nitric oxide (NO) contributes to blood distribution from poorly ventilated regions to well aerated ones, thus maintaining normal ventilation-perfusion matching. There is experimental evidence of hypoxia-induced suppression of NO synthase activity ,102,103.In HAPE-susceptible subjects, acute hypoxia leads to decreased exhaled NO levels , and higSeveral randomized double-blind placebo-controlled cross-over studies clearly demonstrated attenuation of hypoxic PAP elevation in healthy volunteers at rest and during exercise by a single dose of the phosphodiestherase-5 inhibitor sildenafil ,115,116.Endothelin-1 is one of the most potent vasoconstrictor agents . EndotheEndothelin-1 binds two types of receptors, A and B. The former is located on endothelial cells; the latter is expressed by endothelial cells and smooth muscle cells. Activation of both receptors on smooth muscle cells induces vasoconstrictor and mitogenic effects of endothelin-1, whereas stimulation of the receptors on endothelial cells contributes to endothelin-1 clearance and nitric oxide and prostacyclin release. Randomized double-blind placebo-controlled cross-over studies demonstrated that a single dose of 250 mg bosentan, a dual endothelin receptor antagonist, significantly attenuated hypoxia-induced PAP rise in healthy volunteers  and in iSeveral other drugs have been demonstrated to reduce the elevated PAP at high altitude. In a randomized double-blind placebo-controlled study, nifedipine has been shown to reduce PAP and prevent HAPE in HAPE-susceptible mountaineers . In anotAcetazolamide, a carbonic anhydrase inhibitor, has long been successfully used for the prevention and treatment of acute mountain sickness . The undThus, a potential role in PAP reduction and HAPE prevention has been demonstrated for a number of drugs targeting various signaling pathways. However, only calcium-channel blockers are currently recommended for drug prophylaxis in high-risk individuals with a clear history of recurrent HAPE due to extensive clinical experience with nifedipine in HAPE prevention in susceptible individuals . FurtherTargets of potential pharmacological agents to prevent or reverse HPV are summarized in Any delay in treatment initiation can lead to fatal consequences. In mild cases, bed rest and supplemental oxygen might be sufficient ,156. HowGiven the important role of HPV and pulmonary hypertension in HAPE pathogenesis, it seems rational to use vasodilators for HAPE treatment. Nitric oxide is one of the potent endogenous vasodilators, which is synthesized by endothelial nitric oxide synthase. Local production of nitric oxide contributes to the maintenance of the normal ventilation-perfusion matching by redistributing blood to the better ventilated lung areas. Indeed, nitric oxide inhalation has been demonstrated to selectively inhibit acute HPV in healthy humans without causing systemic hypotension . MoreoveThe calcium channel antagonist nifedipine has been demonstrated to improve symptoms and radiological evidence of alveolar edema in HAPE patients, which were associated with improved arterial oxygenation and reduction of the alveolar-arterial gradient and PAP in a nonrandomized, unblinded study . In contAlthough there is no clear recommendation for vasodilator therapy, in field settings, nifedipine should be used as an adjunct to descent, supplemental oxygen, or portable hyperbaric therapy or as primary therapy if none of these other measures are available . If nifeProlonged exposure to alveolar hypoxia leads to remodeling of pulmonary vessels, resulting in sustained pulmonary hypertension. However, most of the studies investigated relatively short periods of high altitude acclimatization in the range of several days to weeks. In Operation Everest II, simulated ascent in a hypobaric chamber of sea level residents for several weeks resulted in a stable rise of PAP, which was partially responsive to oxygen . LikewisInvasive PAP measurements have demonstrated that prolonged altitude exposure during a four-week sojourn at 3454 m leads to a persistent elevation in PAP in healthy sea level residents . In mostIn some temporary high altitude residents, clinically significant pulmonary hypertension may develop. Pulmonary hypertension may persist following the resolution of HAPE . HoweverAbout three decades ago, a syndrome characterized by severe pulmonary hypertension and right heart failure was initially described in infants of Han origin who were born in lowlands and subsequently brought to live at altitudes above 3000 m . In the In 10–20% of acclimatized sea level residents, prolonged exposure (>3 months) to extreme altitudes of 5800–6700 m is associated with development of subacute adult mountain sickness ,180. ThiEarly studies revealed PAP elevation in permanent high altitude dwellers ,184,185.Invasive pulmonary hemodynamic measurements in a small number of native Andeans revealed a very close correlation between PAP values and the altitude level of birthplace . This deAlthough the average PAP levels in the high altitude populations are higher than those in sea level residents, there is marked variability in PAP values among highlanders ,197,198,Interestingly, large studies with non-invasive estimation of PAP did not reveal any difference in systolic PAP levels between Han Chinese and Tibetan children aged 0–14 years permanently residing at 3700 m . SimilarAlthough elevation of PAP in most high altitude dwellers is modest, some individuals may develop severe pulmonary hypertension . PulmonaHypoxia inducible factors (HIFs) play an essential role in oxygen homeostasis by facilitating oxygen supply to the tissues under hypoxic conditions. HIFs coordinate intracellular signaling in response to oxygen deficiency by regulating transcription of hundreds of hypoxia-controlled genes . HIFs arAt sea level, individuals with various mutations impairing HIF signaling display a phenotype similar to that seen in lowlanders acclimatized to high altitude hypoxia. Activating HIF2α gene mutations are associated with elevated resting PAP values ,227 and There is compelling evidence from experimental models implicating the HIF pathway in hypoxic pulmonary hypertension ,244. ImpSeveral genome-wide selection studies provided evidence of natural selection for gene variants encoding proteins in the HIF signaling pathway, EPAS1 (encodes HIF2a), and EGNL1 (encodes PHD2) in high altitude populations ,258. IdeThe severity of pulmonary hypertension at high altitude is characterized by an interindividual variability, which may result from differences in hypoxic stimulus intensity and/or intrinsic strength of the pulmonary vascular response. The interspecies and intraspecies variability of acute HPV is well recognized ,7,15. InExposure to high altitude hypoxia stimulates erythrocytes production in an attempt to improve tissue oxygenation. Long-term high altitude residence can be complicated in some individuals by development of excessive erythrocytosis and chronic mountain sickness . ErythroSeveral studies have demonstrated that adverse oxygenation during perinatal and late fetal life is associated with higher PAP levels in young, high altitude residents ,281. TheSeveral studies demonstrated that manipulation of iron bioavailability can modulate responses of the pulmonary circulation to acute hypoxia ,41,43. IPulmonary hypertension can develop as a complication of a diverse range of medical conditions, including chronic lung diseases, pulmonary embolism, cardiovascular diseases, and many others. Pulmonary hypertension due to hypoxia is classified as group 3 pulmonary hypertension ,287. HowA recent study retrospectively analyzed etiologies of pulmonary hypertension in patients admitted over five years to the Qinghai Red Cross Hospital, located at 2200 m . InteresLarge epidemiological studies have demonstrated high prevalence of congenital heart disease at high altitudes ,297,298.Pulmonary hypertension is a common complication of mitral valve disease and may affect more than 70% of patients depending on disease severity . Mitral High altitude populations are traditionally characterized by their less exposure to risk factors for coronary artery disease, such as sedentary lifestyle, smoking, high-fat diet, and stress . HoweverHigh altitude hypoxia is associated with an increased thrombotic risk . In highThus, other common causes of secondary pulmonary hypertension in lowlanders may underlie and/or contribute to pulmonary hypertension in high altitude residents. The challenges of detection of the underlying causes of pulmonary hypertension in high altitude residents are related to the asymptomatic course of the disease, low educational level of highlanders, limited access to facilities for diagnosis, and high rates of unawareness and low index of suspicion by local physicians .Prevention of common causes of secondary pulmonary hypertension can prevent development of pulmonary hypertension in high altitude dwellers. Early diagnosis and timely treatment of a bacterial sore throat can help prevent rheumatic fever and subsequently pulmonary hypertension due to rheumatic heart disease. Implementing preventive screening programs for congenital heart disease and rheumatic heart disease using echocardiography can facilitate early detection and treatment of these diseases.The goal of the management of pulmonary hypertension is primary therapy of the underlying cause. Before treatment initiation, all efforts should be made to diagnose the underlying condition that may be responsible for pulmonary hypertension in a given case. Therefore, the awareness of local physicians of other clinical forms of pulmonary hypertension is very important in order to consider all the potential causes of pulmonary hypertension in every patient using the classic diagnostic tools, including careful clinical history taking and physical examination complemented by laboratory and imaging methods.Given the important role of hypoxia in the pathogenesis of hypoxic pulmonary hypertension, relocation of the place of residence to lower altitudes may improve pulmonary hypertension and probably cure the disease. Earlier studies have demonstrated a reduction of PAP in healthy highlanders after two years of relocation to low altitude ,317. LikDescent to low altitudes may not be acceptable to high altitude dwellers for various reasons, necessitating administration of pharmacological therapies. However, no drugs have been approved to date for the therapy of chronic high altitude pulmonary hypertension. Extensive clinical experience with vasodilator drugs in patients with pulmonary arterial hypertension suggests their potential for the treatment of high altitude pulmonary hypertension. However, only few studies have investigated the effects of drug therapy on pulmonary hypertension in high altitude dwellers. Small studies have demonstrated efficacy of single doses of nifedipine  and boseSince most high altitude populations live in resource-limited countries, access to the currently approved pulmonary arterial hypertension pharmacologic therapies may be limited by their availability and their cost ,321. TheAcetazolamide is a carbonic anhydrase inhibitor that is used in the prevention of acute mountain sickness. Experimental studies demonstrated that acetazolamide prevented hematocrit elevation and pulmonary vascular resistance increase in chronically hypoxic rats . ImportaCompelling experimental evidence suggests an important role Rho-kinase in the pathogenesis of pulmonary hypertension . FasudilExperimental studies using hypoxia-induced pulmonary hypertension models help in identifying new targets for development of novel drugs, including growth factors, transcription factors, and inflammation and metabolic remodeling .Among numerous growth factors, an important role in the pathogenesis of hypoxic pulmonary hypertension has been demonstrated for the platelet-derived growth factor ,339,340,Hypoxia activates various transcription factors and the hypoxia-inducible factor is the most prominent among them ,356. OthAccumulating evidence suggests a role of inflammation and oxidative stress in hypoxic pulmonary hypertension ,367,368.Hypoxic pulmonary hypertension plays an important role in the pathogenesis of HAPE. Drugs that increase nitric oxide bioavailability or attenuate endothelin-1 signaling have shown potential to blunt PAP increase in response to acute hypoxia or at high altitude in healthy individuals. Currently, due to extensive clinical experience with nifedipine in HAPE prevention in susceptible individuals, only calcium-channel blockers are recommended for drug prophylaxis in high-risk individuals with a clear history of recurrent HAPE. Further controlled studies are necessary to evaluate the efficacy of the vasodilator therapy in HAPE treatment in susceptible individuals.While in most altitude dwellers elevation of PAP is mild-to-moderate, some of the highlanders develop pulmonary hypertension. Pulmonary vascular disease in high altitude residents may be due to the effects of hypobaric hypoxia and/or may have other underlying causes, such as congenital heart disease, rheumatic heart disease, chronic lung diseases, left heart diseases, and others. Several small studies have investigated the potential of drug therapy of pulmonary hypertension in high altitude dwellers and have had positive results. However, no drugs have been approved for the therapy of chronic high altitude pulmonary hypertension yet. Preclinical studies provide new insights into the role of various signaling pathways involved in the pathogenesis of hypoxic pulmonary hypertension, which may serve as promising therapeutic targets.


Some dogs do not make a full recovery following medical or surgical management of acute canine intervertebral disc herniation (IVDH), highlighting the limits of currently available treatment options. The multitude of difficulties in treating severe spinal cord injury are well-recognized, and they have spurred intense laboratory research, resulting in a broad range of strategies that might have value in treating spinal cord-injured dogs. These include interventions that aim to directly repair the spinal cord lesion, promote axonal sparing or regeneration, mitigate secondary injury through neuroprotective mechanisms, or facilitate functional compensation. Despite initial promise in experimental models, many of these techniques have failed or shown mild efficacy in clinical trials in humans and dogs, although high quality evidence is lacking for many of these interventions. However, the continued introduction of new options to the veterinary clinic remains important for expanding our understanding of the mechanisms of injury and repair and for development of novel and combined strategies for severely affected dogs. This review outlines adjunctive or emerging therapies that have been proposed as treatment options for dogs with acute IVDH, including discussion of local or lesion-based approaches as well as systemically applied treatments in both acute and subacute-to-chronic settings. These interventions include low-level laser therapy, electromagnetic fields or oscillating electrical fields, adjunctive surgical techniques (myelotomy or durotomy), systemically or locally-applied hypothermia, neuroprotective chemicals, physical rehabilitation, hyperbaric oxygen therapy, electroacupuncture, electrical stimulation of the spinal cord or specific peripheral nerves, nerve grafting strategies, 4-aminopyridine, chondroitinase ABC, and cell transplantation. Current treatment for acute canine intervertebral disc herniation (IVDH) can be divided into medical/conservative or surgical management. The decision as to which to pursue depends largely on the severity of neurologic signs. These might be due to either reversible or irreversible damage to the spinal cord itself, with some resulting from tissue ischemia that is difficult to counteract and others resulting from spinal cord compression that are easily reversible. Medical management commonly consists of activity restriction, pain, and anti-inflammatory medications. The goals are: (i) to avoid further disc herniation to minimize additional damage to the spinal cord; (ii) provide pain relief; (iii) allow the extruded disc material to gradually dissipate by phagocytosis over time; (iv) and leave the ruptured disc annulus to seal by fibrosis over time. Surgical intervention is used to alleviate persistent spinal cord compression. The reader is directed to the article, “Current approaches to the management of acute thoracolumbar disc extrusion in dogs” for more information regarding the evidence for the commonly applied treatment options.Neither medical nor surgical management currently aim to repair the damaged intervertebral disc, nor heal the injured spinal cord, and there are limits to the recovery that can be attained. Severe injuries still result in incomplete recovery and unsatisfactory functional status. Although largely understandable, with restoration of function to spinal cord injured individuals recognized as a holy grail for centuries, this failure has prompted a vast effort in neuroscience research. The aim is to develop strategies that directly target the injury within the spinal cord, limit the extent of secondary injury, facilitate regeneration of axons, or increase compensatory plasticity of the surviving tissue. Many neuroprotective and neuro-regenerative therapies have shown promise in pre-clinical experimental models but few have made it beyond this phase and when they have, repeatedly failed to successfully translate to humans or dogs with naturally-occurring spinal cord injury (SCI) , 2. In fThis review will summarize adjunctive or emerging therapies that have been proposed as treatment options for dogs with acute IVDH. We will focus on data available from companion dogs with naturally-occurring SCI but also include data on experimental dogs where relevant. This is the information that we hope will be most useful to veterinary clinicians and might soon be applicable in the neurology clinic. We will focus on therapies that can be applied following acute SCI (within 1 month of injury) but also discuss therapies that might aid in repairing the spinal cord or restoring function in the subacute to chronic patient (> 1 month from injury). We have divided treatments in those delivered at or close to the injury site and those delivered systemically.in lieu of, decompressive surgery. These include laser therapy, application of electromagnetic fields or oscillating electrical fields, adjunctive surgical techniques, locally-applied spinal cord hypothermia, and cell transplantation. Cell transplantation strategies will be discussed in the subacute to chronic section in the second part of this review.A variety of locally administered interventions have been proposed in the treatment of SCI that are applied directly to the lesion site in addition to, or Low-level laser therapy or photobiomodulation has been a reported therapy for various injuries, including SCI. In the nervous system, it has been proposed to enhance neuronal metabolism and sprouting and to decrease glial scar formation and the immune response , 6. WhilWhile application of a pulsed electromagnetic field (PEMF) device to the site of injury has been most widely studied in pain and wound repair, PEMF therapy has been reported to reduce back and neck pain in people and possibly improve recovery from SCI in an experimental model in cats –13. The Oscillating electrical field therapy, which is suggested to enhance axonal regrowth and improve functional recovery, has been applied to spinal cord-injured animals . In paraLocally-applied spinal cord hypothermia has been rarely reported as a treatment for SCI in dogs in experimental studies –20. HypoThe role and indications for decompressive surgery as well as fenestration as a standalone technique for acute IVDH are outlined in the companion article in this issue, “Current approaches to the management of acute thoracolumbar disc extrusion in dogs.” Adjunctive surgical techniques of durotomy and myelotomy are summarized below.Durotomy has been investigated as a means to decompress a swollen spinal cord, to improve spinal cord blood flow and oxygen delivery and to evaluate for gross myelomalacia as a prognostic indicator –27. Duron = 65) or hemilaminectomy plus durotomy (n = 51)  . A large(n = 51) . Of the (n = 51) . No adveDorsal midline myelotomy has been reported as a treatment for SCI to decrease intramedullary pressure, increase the oxygen interface, remove necrotic debris, and release noxious vasoactive substances trapped in the spinal cord post-injury , 32. In A variety of systemic or “whole dog” interventions have been applied to treat dogs with IVDH. Administration of some type of systemic medication or chemical as a neuroprotective strategy for the treatment of acute IVDH has been reported to be recommended by up to a quarter of specialist veterinarians . This vaCorticosteroids are a commonly administered adjunctive therapy for the treatment of IVDH in dogs. Methylprednisolone (MPSS) at so-called “shock doses” has received the most attention and been most extensively examined but dexamethasone has also been investigated in dogs , 36–43. Polyethylene glycol (PEG) a hydrophilic polymer capable of fusing cell membranes has been infrequently investigated as a treatment for acute SCI with inconsistent results. In an acute canine spinal cord transection model, immediate application of PEG at the site of injury was determined to be beneficial and to re-establish anatomic continuity . In a stn = 81), DMSO alone (n = 84), placebo (n = 41), or received no treatment (n = 20). Transient injection site reactions were common in the GM6001 treated dogs (which could have compromised the blinding) and a subset (n = 6) developed self-limiting musculoskeletal signs, but it was otherwise well-tolerated. Treatment with GM6001 with DMSO resulted in improved neurologic recovery compared to placebo but was not different compared to DMSO alone. While efficacy for treatment with this MMP inhibitor was not demonstrated with regard to sensorimotor recovery, it did increased long-term bladder compliance.Matrix metalloproteinases (MMPs) are released by cells to degrade the extracellular matrix. MMPs, specifically MMP-9 and MMP-12, have been shown to be upregulated following SCI and are implicated in the deleterious secondary injury cascade. In two prospective studies, Levine et al. evaluated a broad-spectrum MMP inhibitor, GM6001, in dogs treated surgically for IVDH resulting in acute (<48 h) non-ambulatory paraparesis or paraplegia , 52. AllDimethyl sulfoxide (DMSO) is most often used as a vehicle to improve drug solubility but has been uncommonly investigated as an intervention for brain and SCI , 52. ItsN-acetylcysteine (NAC) is a precursor of glutathione with potent antioxidant as well as anti-inflammatory and neuronal protective properties that has been proposed as a treatment for acute SCI . In a coThere are other rarely reported interventions with limited, mostly experimental evidence in dogs. Analogs of the hypothalamic hormone, thyrotropin releasing hormone (TRH), have been reported to inconsistently improve outcomes after SCI in humans and experimental models . In a piVarious systemic, non-medication-based therapies have been advocated for the treatment of acute SCI in dogs including physical rehabilitation, hyperbaric oxygen therapy, and electroacupuncture.Physical rehabilitation in dogs recovering from surgery due to IVDH is being increasingly utilized, recommended by 58% of board-certified surgeons and neurologists surveyed , 63. WhiFor details on the currently available evidence regarding the role of physical rehabilitation in dogs recovering from IVDH, the reader is referred to the companion article “Current approaches to the management of acute thoracolumbar disc extrusion in dogs” in this issue. While there have been relatively few studies performed in this population and the results have been mixed, early post-operative initiation of rehabilitation has been determined to be safe with no associated adverse events or increased post-operative pain , 65–70. Hyperbaric oxygen therapy has been uncommonly reported as a treatment for acute SCI. The proposed mechanism is to increase the tissue partial pressure of oxygen and counteract the adverse effects of spinal cord hypoxia associated with injury . There iElectroacupuncture has been occasionally reported as a therapy for acute SCI in dogs , 74. ItsTreatment strategies are also being explored for dogs with permanent impairment following acute SCI. These are typically applied in the subacute-to-chronic stage (> 1 month from the time of injury) and include spinal cord radiation, electrical stimulation of the spinal cord or specific nerves below the injury, nerve grafting, 4-aminopyridine, chondroitinase ABC delivery, and cell transplantation.Spinal cord radiation has been evaluated in rodents and in an experimental model in Beagles . RadiatiFunctional electrical stimulation has not yet been reported in dogs, but a wearable device is being developed that might be useful in dogs with incomplete recovery from acute IVDH . Short-tGrafting of peripheral nerves from above the injury level  into the distal portion of experimentally transected spinal cord has also been performed in dogs with the goal of harnessing the regenerative potential of the peripheral nervous system –87. NervAdditional compounds that have been investigated in chronically impaired dogs include 4-aminopyridine (4AP) and chondroitinase ABC. 4-aminopyridine is a potassium channel antagonist that has been shown to restore hind limb motor function in some dogs with chronic thoracolumbar SCI , 96. ThiChondroitinase ABC is an enzyme that degrades chondroitin sulfate proteoglycans which are key components of the glial scar and inhibitors of axonal regeneration following SCI . This haTransplantation of cells into the spinal cord has been investigated in dogs either after creating an experimental spinal cord lesion or after naturally-occurring SCI. This involves predominantly stem cell therapies such as mesenchymal stem cells of various origin, neural stem cells, or bone marrow-derived mononuclear cells but other fully differentiated cells have been used such as olfactory glial cells, olfactory mucosal cells, Schwann cells, or macrophages. Most commonly, the cell transplants are administered via intraparenchymal or intrathecal injection but intravenous delivery has also been reported.Placement and inflation of a ventral epidural balloon has been used to produce experimental compression and contusion of the dog spinal cord , 104. DeA canine hemisection model in which a gel seeded with human neural stem cells was placed immediately into the hemisected spinal cord gap , 121 shoA canine transection model has been reported from groups in China recently, testing the effect of collagen-based biomaterial loaded with human umbilical cord-derived mesenchymal stem cells , human pA group from Egypt described a compression/contusion model using a “clip” placed on the spinal cord at the L4 spinal cord segment; neural-induced bone marrow derived stem cells were then injected intrathecally by lumbar puncture 2 weeks after the injury by a blinded investigator . The injIn summary, there is a growing number of transplantation experiments originating primarily from Korea and China which have generally low power and follow the same experimental pattern with varying cell types. One group in Korea translated their experiment to the clinic by transplanting adipose-derived stem cells  to 9 comOne of the best known cell type studied in dogs is olfactory ensheathing cells, which are not stem cells but fully differentiated cells located within the olfactory mucosa and olfactory bulb, forming an interface between the peripheral and central nervous systems –133. OlfIn the last decade, there has been an increasing number of publications from Japan, Brazil, Turkey, and India testing different cell transplants in dogs with naturally-occurring injury. First in Japan, two groups reported that autologous bone marrow stromal or mononuclear cell transplants were safe in 7  and 1 1 dogs witSince 2014, institutions in Brazil have reported seven trials testing safety or efficacy of various cell transplants  in small series of companion dogs, sometimes with concomitant spinal cord decompression, or in association with other alternative therapies such as electroacupuncture  or low-iThe follow-up duration in these studies was usually of several months. Taken together, the results suggest an improvement of locomotor function, based on an increase in locomotor scores. However, these cases rarely achieved scores suggesting unassisted ambulation and for those that did walk again, they remained deep pain negative suggesting that the locomotion could have been independent of the therapeutic intervention . Interestingly, in some dogs, there was reported recovery of deep pain , 148 butIn Turkey, Besalti et al. transplanted intramedullary neurogenically-induced bone marrow-derived mesenchymal stem cells 42 days after the initial injury . They coAltogether, the results of various cell transplantation studies in dogs are encouraging, although most studies remain of low power and preliminary. They have proven safety, but the recovery is always limited to a proportion of studied dogs and recovery of one function at a time, either locomotion, continence, or pain perception. This perhaps suggests that other factors than the actual treatment led to the change in function and highlights the severity of lesions and difficulties in repairing them. A consensus on which intervention holds the greatest promise would be useful to then apply in large multicenter trials in dogs, where evaluation of efficacy could be investigated with greater power.In conclusion, we have outlined a variety of therapeutic strategies that have been applied to dogs with SCI in both the acute as well as subacute-to-chronic settings. These range from those applied to the spinal cord directly to systemic treatments and with variable goals from repair to compensation. While some techniques are more promising than others, they all serve to highlight the challenges in treating severe SCI and in developing successful treatment options for a heterogeneous clinical population. Moving forward, multimodal approaches to therapy building on conventional treatment options will likely be most successful.ML, NG, and NJ participated in manuscript conception, preparation, and editing with the first two (ML and NG) contributing equally. The additional members of the CANSORT-SCI consortium contributed to manuscript conception, editing, and review.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


As the world population has grown, new demands on the production of foods have been met by increased efficiencies in production, from planting and harvesting to processing, packaging and distribution to retail locations. These efficiencies enable rapid intranational and global dissemination of foods, providing longer “face time” for products on retail shelves and allowing consumers to make healthy dietary choices year-round. However, our food production capabilities have outpaced the capacity of traditional detection methods to ensure our foods are safe. Traditional methods for culture-based detection and characterization of microorganisms are time-, labor- and, in some instances, space- and infrastructure-intensive, and are therefore not compatible with current (or future) production and processing realities. New and versatile detection methods requiring fewer overall resources  are needed to transform the throughput and safety dimensions of the food industry. Access to new, user-friendly, and point-of-care testing technologies may help expand the use and ease of testing, allowing stakeholders to leverage the data obtained to reduce their operating risk and health risks to the public. The papers in this Special Issue on “Advances in Foodborne Pathogen Analysis” address critical issues in rapid pathogen analysis, including preanalytical sample preparation, portable and field-capable test methods, the prevalence of antibiotic resistance in zoonotic pathogens and non-bacterial pathogens, such as viruses and protozoa. Traditional enrichment culture combined with differential and selective plating serves as gold standards for the detection and identification of foodborne bacterial pathogens. Although accurate and sensitive, culture-based methods are labor-intensive and time consuming with the results often taking from days to weeks. There is a desire to replace these methods with “rapid methods” that typically employ highly sensitive and fast biosensor-based analysis . HoweverNoroviruses: Human noroviruses (HuNoVs) are the leading cause of acute gastroenteritis globally and, in the U.S., sicken ~685 million people annually [annually . Despiteannually  provide Preanalytical Sample Preparation: Two papers in this issue address the issue of preanalytical sample preparation (“sample prep”), the various physical, chemical or other treatments needed to make a sample amenable to analysis. Quality of input into a detection step is critical to the overall success of the assay. While many papers may investigate individual sample prep methods, those that compare different approaches within the same study have a unique value. Armstrong et al. [Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes) was also examined to evaluate the value of these methods within the context of foodborne pathogen detection. Data from the multifactorial analysis not only delineated the particle size ranges but also defined the unique compositional profiles and quantified the bacterial retention. The three filtration membranes allowed for the passage of bacteria with minimal loss while CFC concentrated the inoculated bacteria. In addition, the deposition and therefore concentration of food matrix observed with CFC was considerably higher for meat samples than for spinach. However, filtration with glass wool prior to CFC helped clarify meat samples, which led to considerably lower amounts of post-processing solids in the CFC vessel and increased recovery of bacteria. Overall, these authors provide a framework for the deductive selection of appropriate sample preparation techniques, empowering the research community with knowledge of compatible sample prep/detection method pairings.g et al.  applied Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella, and also explored the use of hydrolytic enzymes for digestive detachment of these biofilms for downstream analysis. The authors found that trypsin was the most effective enzyme for biofilm detachment. Trypsin is routinely used for detachment of mammalian cells from culture vessel surfaces, suggesting its utility for biofilm detachment. Trypsin is used in volume in the pharmaceutical, silk and leather industries and is therefore widely available and relatively inexpensive. The work done here provides tools and knowledge that will help promote further understanding of mixed bacterial biofilms, including information relevant to their detection and inactivation.Biofilms, complex assemblages of microorganisms, polysaccharides, extracellular DNA and other environmental detritus, represent a special challenge for sample preparation and detection. Although most laboratories study bacteria in the free-swimming, planktonic form, biofilms are the dominant format for microbial life in nature. However, the inherent genotypic and physiological complexities of biofilms are barriers to their effective study and their presence on or within food processing equipment can serve as a recurrent source of product contamination. Aryal et al.  developeNucleic Acid-Based Methods: Nucleic acid-based methods for microbial detection and characterization have demonstrated their value over the past few decades. Despite a fairly long lag period between the invention of the polymerase chain reaction (PCR) in 1983 and its adoption by the food industry, it is now a firmly established and commercially supported method for the detection of foodborne pathogens. Resendiz-Nava and colleagues describe a nested PCR method for the detection of the protozoan pathogen Cyclospora cayetanensis in fresh berries and berry farm soils. Pushing the utility of this method beyond simple detection, the authors used Sanger sequencing of the resulting PCR products to enable phylogenetic analysis and attribution of geographical origin for C. cayetanensis isolates detected with the assay [he assay . While PCR depends on temperature cycling, not all nucleic acid amplification methods do. Isothermal amplification methods belong to a broad family of nucleic acid amplification methods that do not depend on temperature cycling, but instead are carried out using static reaction temperatures. Independence from cycling obviates the need for expensive and potentially bulky thermal cycling instrumentation and potentially enhances the portability of isothermal methods. It is clear that the cells in our own bodies do not constantly cycle between extremes of 55 and 95 °C in order to replicate their DNA—this is done at body temperature, using enzymes to “melt” DNA and taking advantage of the reagent-rich milieu of the cytoplasmic gel architecture. Some isothermal amplification methods, such as Recombinase Polymerase Amplification (RPA), mimic the enzymatic processes, physical compartmentation and molecular crowding found in cellular DNA synthesis, with reaction optima of 37–42 °C—essentially “body temperature”. This latter property has practical implications for portability and utility under austere field conditions, allowing the use of simple heating equipment (including USB or solar sources), exothermic chemical reactions or the body’s own warmth to carry out reactions .Salmonella fimbrial gene fimY, using a lateral flow (LF) readout for detection [Salmonella in pure culture was 12 CFU/mL after a 10 min reaction time at 37 °C, and it could detect as low as 1.29 × 102 CFU/mL in artificially contaminated vegetable samples. The assay was evaluated in parallel with the FDA-BAM method for Salmonella and a TaqMan-based qPCR assay developed in-house targeting the fimY gene, showing equivalence between the methods for naturally contaminated samples  after enrichment.Two papers from the same author group used Recombinase Polymerase Amplification (RPA) for the detection of pathogens in foods. In the first paper, Li et al. developed an RPA assay targeting the conserved etection . AlthougSalmonella assay into a triplex Staphylococcus aureus/Vibrio parahaemolyticus/Salmonella test  and demonstrated its sensitivity, specificity and utility for screening natural samples processed according to the BAM methods for these pathogens [In the second paper, Ma et al. expanded the athogens .Zoonotic Dissemination of Antimicrobial Resistance (AMR): Enterococcus spp. are ubiquitous in nature, and although foodborne transmission is rare, their intrinsic antibiotic resistance and their prevalence in the feedlot, beef processing, urban or surface water and clinical environments raises concern for the dissemination of AMR via horizontal gene transfer among these interactive biospheres [Enterococcus spp. are needed, especially those with the potential to be applied across the farm-to-fork-to-physician continuum. Anders and Bisha [Enterococcus spp. are recognized opportunistic pathogens, commonly found in gastrointestinal tracts of mammalian and avian species, which rapidly evolve to develop AMR genotypes and phenotypes, transferable to other bacteria, including several major bacterial pathogens. Wildlife are increasingly receiving attention as potential reservoirs of AMR bacteria and serve and vectors facilitating the dissemination of AMR. MALDI-TOF MS successfully identified 658 Enterococcus spp. isolates out of 718 presumptive isolates collected from gastrointestinal tracts of European starlings, which were captured near livestock operations in Colorado, Iowa, Kansas, Missouri, and Texas; antimicrobial susceptibility testing was then performed using 13 clinically significant antibiotics. While isolation and identification of target bacteria from the fecal material of wildlife is notoriously difficult, this work by Anders and Bisha provides ample evidence that MALDI-TOF MS can serve as a useful tool for high-throughput detection of enterococci in these types of samples.ospheres . New appnd Bisha  evaluateIn summary, this Special Issue on “Advances in Foodborne Pathogen Analysis” compiles eight papers addressing critical issues in rapid pathogen analysis, ranging from preanalytical sample preparation to new developments in nucleic acid-based testing, high-throughput screening across the production-to-consumption-to-disease continuum and studies related to non-bacterial pathogens, including viruses and protozoa. We thank the authors for their valuable contributions to this issue.


This method highlighted, in particular, variants in the genes involved in the respiratory chain providing a direct indication of the cell-specific damage within the mitochondrial genome as predictor of the oocyte quality.Mitochondrial DNA (mtDNA) plays a key role in the development of a competent oocyte. Mutations of the mitochondrial genome lead to an altered energetic metabolism with negative effects on oocyte developmental competence. In this study, mtDNA heteroplasmy at an intra-oocyte level and between the different analyzed human oocytes ( Defects of the mitochondrial DNA (mtDNA) cause an altered energetic metabolism with negative effects on oocyte competence  protocol allowed to sequence the entire mitochondrial genome of a single oocyte  were collected, after providing written informed consents, from three healthy women aged <35 years with normal BMI undergoing in vitro fertilization (IVF) for tubal disease. The entire mtDNA was amplified by using the REPLI-g Mitochondrial DNA Kit . The mtDNA genome sequencing of each oocyte was performed in single end using an Ion Torrent™ PGM platform . The mtDNA was depleted during analysis. Raw reads were uploaded on the Orione platform . To the best of our knowledge, this is the first study that has investigated the whole mtDNA and heteroplasmy in individual human oocytes using NGS. It is important to realize the full potential of high-throughput sequencing that could be confidently applied for the advancement of mitochondrial research related to oocyte quality.The mitochondrial DNA sequences were submitted to GenBank under the accession numbers KX061446, KX061447, KX061448, KX061449, KX061450, KX061451, KX061452, KX061453, KX061454, KX061455, KX061456, and KX061457.


This Research Topic focuses on small molecule therapy to various macromolecule storage disorders. Apart from nucleic acids, all macromolecular building blocks of cells—proteins, lipids, and glycans—are prone to aggregation upon chemical modification or imbalance between their synthesis and breakdown. Unmanaged, this aggregation and often ensuing precipitation can lead to cell stress and pathology. Different treatment strategies, ranging from immunotherapy to pharmacological and gene therapy, have been applied to clear these pathogenic macromolecular aggregates. In particular, the elimination of precipitated misfolded proteins by molecular chaperones has been thoroughly investigated. Lipids and glycans also precipitate into lipofuscins and polyglucosans. However, these inclusions also include oxidation-prone proteins. This Research Topic deals with pharmacological interventions aimed at countering the detrimental effects of macromolecular aggregates. Through illustrating the beneficiary or even toxic effects of different small molecules and pharmacological agents, the selected articles provide a comprehensive picture of interventional and innate means of curative aggregate clearance.Parets et al. paper introduces a novel therapeutic approach for Alzheimer's disease (AD): Instead of targeting the amyloid cascade, according to which proteolysis of the integral membrane protein amyloid precursor protein (APP) by γ-secretase is the culprit of AD  on amyloid synthesis and degradation. The approach presented is based on targeting the aggregates, rather than the cellular pathways which generate or disintegrate them. Interestingly, the review shows that through specific interaction with the misfolded form of various amyloidogenic proteins and with deposited amyloid fibrils, NQTrp can respectively inhibit the formation or disaggregate toxic amyloids.The more direct, classical, approach to amyloids as AD culprit is presented by Lahiani-Cohen et al. is the only paper in this Topic which addresses the pathogenic, rather than the therapeutic, value of small molecules. Tau proteins regulate microtubule-dependent processes in neurons, such as neurite outgrowth and axonal transport. However, hyperphosphorylated Tau form pathological and insoluble neurofilament tangles implicated in AD, Parkinson's disease (PD) and dementia. Lahiani-Cohen et al. show that mitochondrially-generated oxidative stress induced by the small molecule 3-nitropropionic acid (3NP) can cause hyperphosphorylation and consequent neurotoxic tangle formation in both Tauopathy-modeling and wild type mice. This paper demonstrates the link between mitochondrial oxidative stress and toxic neurological aggregates and further shows that the oxidative stress-aggregopathgy axis can be facilitated by natural small molecule toxins such as 3NP.The research paper by Castellano et al. show that nutraceutical and dietary lipids can systemically regulate transport and deposition of lipids. Small lipid molecules such as phytosterols, carotenoids, terpenoids, and tocopherols are involved in triacylglycerol absorption and fatty acid mobilization and storage in adipocytes. Consequently these naturally occurring lipids are pivotal systemic metabolic regulators. Moreover, through controlling lipid peroxidation, these natural lipids can act as strong antioxidants and restrict adipocyte-mediated inflammation. While this review doesn't address aggregate handling, it well demonstrates lipid involvement in all aspects of metabolic regulation.Metabolic dysregulation can cause lipids to aggregate, chiefly in atherosclerotic plaques and sphinglolipid lysosomal deposits. Han et al.'s review. This review reveals that the lysosomal glycosphinglolipid hydrolase glucocerebrosidase also interacts with α-synuclein monomers. Therefore, glucocerebrosidase deficiency leads to aggregation of both Gaucher disease-associated glucocerbrosides and PD-associated α-synuclein oligomers. Furthermore, the latter can bind and further inhibit glucocerebrosidase in a positive feedback causing overaccumulation of α-synuclein aggregates (Lewy bodies) and glucocerbrosides  are lysosomal storage disorders caused by faulty degradation of glycosaminoglycans. In their mechanistic study Palhegyi et al. present a biomedical view of autophagy as a modulator of macromolecule storage disorders. This review shows that autophagy is involved in clearing protein, lipid and glycan aggregates. The review discusses innate and pharmacological regulators of autophagy, importantly stressing not only how autophagy can clear pathogenic aggregates, but also how mutant proteins causing aggregopathies can impair autophagic protection thus exacerbating pathology—for instance, inhibition of phagophore formation and autophagosome maturation by mutated huntingtin and glucocerebrosidase, respectively. The review also presents the beneficiary effect of pharmacological inducers of autophagy for treating various storage disorders.Lastly, In conclusion, this Research Topic demonstrates the importance of small molecules for the mechanistic understanding of aggregate pathogenicity. Moreover, based on examples from different storage diseases, this Topic warrants the use of small molecules as a leading therapeutic intervention for treating storage disorders.All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


RNA interference (RNAi) is an efficient post-transcriptional gene modulation strategy mediated by small interfering RNAs (siRNAs) and microRNAs (miRNAs). Since its discovery, RNAi has been utilized extensively to diagnose and treat diseases at both the cellular and molecular levels. However, the application of RNAi therapies in bone regeneration has not progressed to clinical trials. One of the major challenges for RNAi therapies is the lack of efficient and safe delivery vehicles that can actualize sustained release of RNA molecules at the target bone defect site and in surrounding cells. One promising approach to achieve these requirements is encapsulating RNAi molecules into hydrogels for delivery, which enables the nucleic acids to be delivered as RNA conjugates or within nanoparticles. Herein, we reviewed recent investigations into RNAi therapies for bone regeneration where RNA delivery was performed by hydrogels. RNA interference (RNAi), first observed in the late 1980s by in vitro or in vivo for treating various diseases , play important roles in inducing osteoblast differentiation and bone growth . BMPs haThe bone microstructure is composed of mineralized extracellular matrix and bone remodeling units. The balance of osteoclasts and osteoblasts consistently helps to maintain bone hemostasis . OsteocyBone is continuously turning over and remodeling through the actions of bone-resorbing osteoclasts and bone-forming osteoblasts, which originate from hematopoietic and mesenchymal lineages, respectively. The activity of these two types of cells is regulated by several key signaling pathways , includiAs a single gene can modulate bone formation or bone resorption extensively, gene therapy is particularly applicable to bone tissue regeneration, and upregulating Runt-related transcription factor 2 (Runx2) or BMP expression levels may induce extensive new bone regeneration . To prommiRNAs are the most studied non-coding RNAs related to bone diseases and bone metabolism. miRNAs are single-stranded RNA molecules composed of 20–24 nucleotides, and they function by silencing the expression of mRNA through binding to complementary sequences in the 3′ untranslated region (UTR) of target mRNAs. Approximately 1,800 miRNAs are encoded by the human genome, and each miRNA is predicted to regulate several target genes . It has To date, a large number of miRNAs have been identified that are involved in the regulation of bone metabolism and serve as specific therapeutic targets for diagnosis and bone disease treatment . Runx2 iShort interfering RNAs (siRNAs) are used in a subset of RNAi-based approaches and have been increasingly investigated for therapeutic purposes. Similar to miRNA mimics, artificially synthesized siRNAs can lead to gene silencing. siRNAs are double-stranded RNA molecules that can exert gene silencing against a complementary mRNA target after the transfection of the siRNA, which is performed by a method similar to that used for miRNA mimics. However, while miRNAs may target a number of genes at the same time through partial complementarity, siRNAs can only target one specific gene with full complementarity .RNAi methods represent very powerful tools for elucidating gene function, but there are inevitable challenges that need to be overcome to achieve clinical translation. In 2010, unmodified siRNAs were used for the first time in clinical trials, resulting in questionable RNAi effects and immune-related toxicities . Later, Transportation of RNAi molecules into specific organs or cells is the main obstacle to RNAi therapeutic development. Naked RNAi molecules are vulnerable when directly injected into tissues or blood and will further cause off-site bioactivities. When transported through cell membranes, RNAi molecules can be repelled because of their like-charged physiochemical property, as miRNA and siRNA have a negatively charged phosphate backbone . During A successful delivering system should protect RNAi molecules from cellular barriers, target RNAi to a specific type of cells or tissues, and achieve sustained release of RNAi molecules into the cytoplasm. To date, although the delivering method undergoes a rapid development, scaffolds obtain both advantages and limitations in the use of RNAi delivering for bone regeneration, as we discussed in A range of biomaterials have been investigated as molecular RNAi carriers for bone tissue engineering, including nanoparticles , bioactiTo improve RNAi uptake from hydrogels and protect the RNA molecules from enzymatic hydrolysis, numerous strategies have been investigated, including inclusion within nanoliposomes to produce lipophilic nanoparticles or ionic complexation with cationic polymers, such as polyethyleneimine (PEI) . To datein vivo local bone induction, Gsk-3β and activate the Gsk-3β/β-catenin signaling pathway in osteoblasts, which promoted osteogenic differentiation and bone regeneration. This study indicated that hydrogels could be a promising platform for controlling miRNA delivery.For in situ 8-arm PEG hydrogel loaded with siRNA/PEI nanocomplexes. The siRNA release profile indicated that sustained delivery was obtained, and siRNA remained bioactive over a prolonged period. In vitro experiments showed that sustained delivery of siNoggin and siNoggin/miRNA-20a augmented hMSC osteogenic differentiation in hydrogel 3D cultivation (In vivo osteogenesis experiments demonstrated that sustained release enhanced miRNA-26a expression at both the defect and the surrounding tissue, which promoted vascularization and bone formation. in vitro and in vivo.tivation . Similartivation . Bone isWith the approval of patisiran, liver-targeted RNAi systemic therapy has become a clinical reality. The therapeutic effect of delivering RNAi to non-liver and non-kidney tissues has become viable in the experimental setting. For bone tissue regeneration, a range of investigations have identified the potential of hydrogels to deliver RNAi molecules to specific bone defect sites and achieve sustained gene silencing. Emerging modification methods have been carried out with hydrogel delivery systems for accelerating bone tissue regeneration, and they have shown efficacy in preclinical animal models. However, translation to the clinic is still ongoing.The unique properties of hydrogels, such as their high water content, help to improve cell adhesion and tissue response. Their mechanical, chemical, and physical properties can also be modulated for specific clinical applications. Moreover, for drug delivery, hydrogels are an ideal platform for assisting in retention and promoting sustained drug release.While hydrogels are a promising platform for RNAi delivery, the improvement of RNAi molecular release and uptake from hydrogels is still needed. The structure and size of nanoparticles may need more exploration to facilitate hydrogel-based delivery methods. Micro- or nanopatterning can also be used to study and understand the cellular responses to RNAi . FurtherTY and YZ collected the literature and wrote the manuscript. BH and XW conceived and revised the content of manuscript. HW collected the literature and revised the manuscript. All authors approved the final version of the manuscript for publication.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.