Advances in gene therapy, synthetic biology, cancer genomics, and patient-derived cancer models have expanded the repertoire of strategies for targeting human cancers using viral vectors. Novel capsids, synthetic promoters, and therapeutic payloads are being developed and assessed through approaches such as rational design, pooled library screening, and directed evolution. Ultimately, the goal is to generate precision-engineered viruses that target different facets of tumor cell biology, without compromising normal tissue and organ function. In this study, we briefly review the opportunities for engineering cancer selectivity into viral vectors at both the cell extrinsic and intrinsic level. Such stringently tumor-targeted vectors can subsequently act as platforms for the delivery of potent therapeutic transgenes, including the exciting prospect of immunotherapeutic payloads. These have the potential to eradicate nontransduced cells through stimulation of systemic anticancer immune responses, thereby side-stepping the inherent challenge of achieving gene delivery to the entire cancer cell population. We discuss the importance of using advanced primary human cellular models, such as patient-derived cultures and organoids, to enable rapid screening and triage of novel candidates using disease-relevant models. We believe this combination of improved delivery and selectivity, through novel capsids and promoters, coupled with more potent choices for the combinations of immunotherapy-based payloads seems capable of finally delivering innovative new gene therapies for oncology. Many pieces of the puzzle of how to build a virus capable of targeting human cancers appear to be falling into place. Despite an array of improved surgical, chemotherapeutic, and radiotherapy interventions, options for cancer treatment remain inadequate to meet the needs of all patients. While new molecularly targeted therapies and immunotherapies have been successful in controlling certain tumor types, complete and durable remissions are often restricted to a disappointingly small subset of patients. Hence, cancer remains a leading global cause of death. There is an urgent need to establish innovative novel therapeutic strategies that are effective against tumors with the poorest survival rates. As a fundamentally genetic disorder, developing gene-based therapies for cancer has long been a seductive notion.e.g., a missing enzymatic activity). This can easily be achieved by means of viral-mediated gene transfer, including by vectors based on adeno-associated viruses (AAVs) and adenoviruses. These have been effective across a range of monogenic disorders with licensed therapies approved for treatment of monogenic disorders, including inherited retinal dystrophy (Luxturna™), spinal muscular atrophy (Zolgensma™), and hemophilia (Roctavian™). Nevertheless, the deaths of four patients in the recent Astellas AAV-based gene therapy clinical trial for X linked myotubular myopathy (XLMTM)1 serve as an unfortunate reminder that improvements in viral selectively are required for dosing within appropriate therapeutic windows.Thus far, the greatest accomplishments in the gene therapy field have come from the replacement or correction of single mutated genes to restore normal function in monogenic disorders. If the resulting protein operates through paracrine or systemic mechanisms, expression from only a subset of cells is needed to achieve meaningful clinical impact (2). Despite the appeal of this strategy, adopting a similar approach to deliver functional tumor suppressor genes or correct oncogenic driver mutations in cancer is plagued by two perennial issues: first, the heterogeneity of genetic disruptions in most aggressive solid tumors leads to plasticity and redundancy in oncogenic signaling pathways.Adopting a similar strategy to correct cancers by delivering wild-type tumor suppressor genes to tumors using a gene therapy approach has been the focus of a great deal of research. In 2003, a replication-deficient adenovirus expressing wild-type p53, Gendicine™, was approved in China for the treatment of cancer  to restore normal cellular behavior. Second is the delivery challenge, where prevention of tumor regrowth would only be accomplished if 100% of tumor cells we corrected. This is an impossible feat for even the most efficient methods of gene transfer. As such, despite decades of interest and exploration, development of gene-based therapies for cancer has lagged significantly behind those for monogenic disorders.Nevertheless, there is growing excitement and optimism that gene therapies have matured sufficiently to be harnessed in oncology. Success will most likely require the delivery of therapeutic transgenes that target different facets of tumor cell biology, rather than correction of underlying genetic driver mutations. Tumor-localized expression of therapeutic payloads that re-invigorate the anticancer immune response, inhibit angiogenesis, target the immunosuppressive tumor stroma, or convert prodrugs into their active cytotoxic form can target universal biological vulnerabilities of cancer cells. The remaining challenge is how best to deliver such potent payloads to tumor cells, while minimally impacting healthy tissue.Viruses are naturally pathogenic agents responsible for a broad spectrum of diseases and associated clinicopathological symptoms. Yet when harnessed appropriately, they enable highly efficient targeted delivery of nucleic acids, and hence have been the favored choice for the delivery of exogenous DNA transgenes to human tissues. The relative ease of genetic manipulation and capacity to be produced to high titers and degrees of purity further add to excitement regarding their potential application in cancer gene therapy.The range of oncolytic and viral gene therapy vectors being developed in the cancer field is diverse, encompassing both RNA and DNA viruses. In this review, we focus our discussion on examples from adenoviruses and AAV-based vectors. However, the strategies and challenges outlined are broadly applicable to other viral vectors.in situ amplification of the therapeutic agent.3 Viral progeny can spread through the tumor, causing further destruction of malignant tissue and release of tumor antigens. This results in a multipronged attack on tumors that can synergize with other immunotherapeutic cancer targeting strategies and offers a clear advantage over nonviral means of gene transfer.Adenoviruses drive robust, transient, high-level expression of transgenes, making them ideally suited to cancer gene therapy applications. Furthermore, recently, there has been renewed interest in oncolytic virotherapy, which utilizes replication-competent vectors such as conditionally replicating adenoviruses. A partially intact E1-gene enables intratumoral viral replication, resulting in direct oncolysis of transduced tumor cells, as well as 4). The physical size (∼25 nm) is smaller than adenovirus and may facilitate better biodistribution in certain tissues and there is evidence of good transduction from the natural serotypes across a range of cancer types, most likely due to the roles of heparan sulfate, integrins, proteoglycans, and RTK as receptors/co-receptors—expression of which is elevated in many solid tumors.By contrast, AAVs are ideally suited to long-term gene corrections strategies and form the platform of an ever-expanding number of licensed gene therapy products. In relation to cancer, AAVs offer the prospect of more durable gene expression that might be required for certain tumors to eliminate residual quiescent and dormant cells, since AAVs can transduce both dividing and nondividing cells and the viral genome persists as an episome. Use of AAVs has therefore been explored in both preclinical and clinical studies using a range of payloads .Some level of control can be achieved through astute selection of the route of delivery of the virotherapy into the patient. The route of administration has a direct bearing on the range and order of tissues that will be encountered and is therefore an important determinant of vector tropism. Systemic delivery, through the bloodstream following intravascular administration, necessitates trafficking of the vector to the tumor. Local delivery encompasses both direct intratumoral delivery and various site-specific injections that provide the vector near lesions at different anatomical locales , seroprevalence rates in specific geographical cohorts can be extremely high (up to 80–90%),8 potentially limiting the widespread effectiveness of systemically delivered therapeutics based on these viral backbones in specific populations. Other plasma factors can also be problematic; the clotting factor FX, for example, can promote rapid and efficient liver sequestration of intravenously delivered Ad5-based therapeutics through cross-linking to heparan sulfate proteoglycans (HSPGs) on hepatocytes.10Intratumoral injections are presently the most commonly relied upon approach for administering virotherapies to patients.Despite the advantages of local delivery, the ability to effectively administer virotherapies through intravenous injection remains a long-standing goal. Systemic delivery of virotherapies affords the opportunity of transducing the greatest number of tumor cells as intravenously injected viral vectors will travel through the bloodstream and can therefore potentially engage with all tumor cell populations, including disseminated metastatic or micro-metastatic lesions, which may not be detectable by conventional imaging methods. At a practical level, intravenous injection is facile, subverting the need for the complex surgical procedures that are required to access difficult-to-reach tumors for direct injection.11 Overcoming the systemic delivery challenge and identifying viral vectors that preferentially transduce tumor cells are therefore of the utmost importance; this will make trials easier and safer, as well as increasing the opportunity to eradicate all tumor cells.Furthermore, easily accessible tumors in noncritical organs are unlikely to benefit from intratumorally delivered virotherapies, since these are more amenable to conventional surgical resection—the preferred therapeutic stratagem. However, treating local tumors with oncolytic virotherapies may initiate immune priming and systemic abscopal effects.12 Those that have completed typically failed to demonstrate clear improvements in primary endpoints, likely reflecting the significant challenges posed by immune-clearance and off-target sequestration. Nevertheless, these challenges are not insurmountable, and improvements may be made through modification of the vector capsid surface to evade immune recognition and increase the selectivity over target-cell transduction. With the tools of modern synthetic biology, it has been possible to develop strategies that facilitate the development of viruses with genetically and chemically modified capsid proteins. Successes in rodent models, discussed below, point to the potential for highly tumor-selective viruses to be engineered for human applications.There have been a few studies investigating the clinical efficacy of intravenously delivered viral cancer therapy vectors.13 Adenoviruses are classically divided across seven different human adenoviral species from A to G; these engage diverse cell entry receptors, ranging from the tight junction localized coxsackie and adenovirus receptor (CAR) for species A, C, E, F, and (to a lesser extent) D, to CD46 and desmoglein-2 (DSG-2) for species B viruses, and sialic acid for certain members of species D.15 This variation can be capitalized upon for improved vector design by enabling the selection of serotypes that possess more favorable properties in the context of anticancer therapeutics.Human adenoviruses comprise a diverse phylogenetic tree containing 57 canonical serotypes. This diversification arises from natural selection pressures, resulting in viruses that differ in their tropism, cytotoxic capacity, and cellular infection kinetics.16 which do not bind FX in the blood.10Despite its prevalent use as a gene therapy vector, the species C adenovirus type 5 (HAdV-C5) has a broad tropism resulting from its reliance on CAR as a primary entry receptor, expression of which has further been shown to be downregulated on numerous cancer subtypes. The ability of the Ad5 hexon to bind FX protein and traffic to the liver, coupled with high seroprevalence rates in certain populations, make the investigation of alternative serotypes with lower seroprevalence rates and unstudied tropisms worthwhile for virotherapy applications. In this regard, species D adenoviruses  represent a relatively untapped pool of potential backbones with far lower seroprevalence rates,in vitro and in vivo).17 HAdV-D 26, 28, 45, and 48 have been shown to infect and replicate in several cancer cell lines, although cytotoxicity was lower than adenovirus 5-based vectors.18 Moreover, a replication-competent species B Ad11-derived vector was demonstrated to be capable of infecting and inducing oncolysis in colon cancer cell lines, which expressed high levels of the CD46 receptor.19 These studies highlight the feasibility of generating virotherapies from noncanonical human adenoviral serotypes.The species D adenovirus serotype 10  has recently been shown to form weak interactions with known adenoviral receptors, therefore providing a compelling starting point for engineering more cell type-selective infection and lysis of cells  alters primary receptor usage to render cellular infection CAR independent, with the resulting Ad5/3 pseudotype virus displaying enhanced transduction and oncolysis of ovarian carcinoma cell lines in vitro and in immunocompromised murine xenograft models23; this was due to cell entry through DSG-2, the primary receptor for the Ad3 virus.24This radically changes the receptors that can be engaged for cellular transduction.+ hematopoietic cells, gliomas, and various other tumor cell lines.25–27 The length of the adenovirus fiber has been shown to be important in impacting interaction with cell surface receptors and subsequent αv-integrin-mediated virus internalization.28 Care must therefore be taken to consider the impact of any alteration in fiber length when exchanging the entirety of this capsid protein. Nevertheless, the successful generation of several Ad5 fiber pseudotyped viruses demonstrates the feasibility of this approach.Pseudotyping the CD46-binding Ad35 fiber has also proved particularly promising, enabling enhanced gene delivery to human smooth muscle, CD3429 The reader is directed to Samulski and Muzyczka, for a comprehensive review of AAV biology, the history of its discovery, and its importance in gene therapy.30 It is relatively straightforward to engineer altered capsids  and produce recombinant AAV (rAAV) that can be tested with distinct genes of interest flanked by the common AAV-2 inverted terminal repeats (ITRs). The AAV capsid is responsible for the binding to various proteoglycans and both primary and secondary receptors. With improved knowledge of the key biochemical structural features required for receptor interactions, opportunities have opened for rational capsid engineering, often focusing on a specific region of the VP2 loop.31For AAV, there are around 13 different serotypes that are widely available, each with distinct capsid proteins that underpin their distinct tropisms. Natural serotypes have strikingly different cell type selectivity, for example, when comparing these in parallel in the primate CNS.A major limitation of relying on the natural viral variation to achieve cell extrinsic selectivity is that the array of receptors available is restricted to those naturally encountered and selected during viral evolution. Rational design may be a way to expand viral tropism usefully to enable targeting of transformed cells. As such, the extensive body of knowledge surrounding viral capsid structure and interaction with host receptors can be leveraged to generate precise tropism-modifying alterations that improve the tumor selectivity of vectors  or their receptors that are enriched in solid tumors, such as tenascin, LeX, or integrins.33 and poly-[N-(2-hydroxypropyl)methacrylamide] (pHPMA).34 These decorate the viral surface in a way that abrogates interaction with native receptors as well as plasma proteins, potentially enabling evasion of immune-mediated clearance by pre-existing antiviral antibodies. Targeting toward specific cellular subpopulations is subsequently achievable through coupling of the capsid to multivalent polymers, antibodies, peptides, or other high-affinity moieties that bind the receptor of interest.36Attempts have been made to nongenetically alter viral tropism such as through chemical coupling of capsid proteins to polymers, such as polyethylene glycol (PEG),37 bi-specific DARPins,38 and single-chain diabodies to simultaneously engage capsid proteins and cancer-associated receptors through opposite poles of the molecule.39 These nongenetic strategies have the limitation of an increased complexity associated with the manufacturing, quality controls, and delivery of such multicomponent systems. Furthermore, this retargeting strategy lacks heritability of tropism, which is of concern for replication-competent viral vectors where nontargeted daughter virions produced in situ could mediate off-target effects. As such, genetic modification of adenoviral tropism is a more desirable strategy.Other nongenetic targeting strategies utilize bi-specific adaptors such as Fab-based fragments, scFv diabodies,40 Binding can be abolished through two amino acid substitutions  in the Ad5 fiber knob AB loop,41 or a Y477A substitution and TAYT deletion in the FG loop.42 These have been widely incorporated into cancer-targeted adenoviral-based therapy vectors to prevent CAR-dependent cellular transduction in off-target healthy bystander tissues. Despite these tropism alterations, Alemany and Curiel showed that liver sequestration remains an issue.43Noteworthy for adenovirus has been the application of rational design to generate genetically targeted vectors that lack affinity for the ubiquitously expressed CAR receptor.44 These encompassed modification of the hexon hypervariable region 7 and an RGD to RGE mutation in the penton base. The resulting vector, Ad5NULL, is totally devoid of native means of uptake. Such vectors provide invaluable “blank canvases” on which further re-targeting modifications may be superimposed to generate precision-targeted virotherapies that are exquisitely tuned to cancer cell transduction.Further modifications within the remaining two major capsid proteins—the hexon and penton—eliminate the residual interactions with FX and αvβ3/5 integrins, respectively.46 fiber,47 and minor structural protein pIX of the adenovirus.48 Whilst the high copy number of the hexon and pIX proteins  makes these ostensibly appealing sites, conferring novel high affinity receptor interactions here may compromise the downstream virus release from endosomes following internalization.The site of insertion of targeting moieties must be carefully considered to avoid disruption of viral packaging and nuclear trafficking, while facilitating presentation to tumor-associated receptors of interest. Several capsid locales have been evaluated, including the hypervariable loops of the hexon,47 The surface-exposed HI loop of the HAdV-C5 fiber knob has been shown to be particularly tolerant of heterologous insertions, with peptides in excess of 100 amino acids being incorporated without detriment to viral fitness.50 Homology modeling has revealed the DG loop of the Species D adenoviruses 10 and 48 to be similarly permissive to insert engineering.52 The C-terminus of the HAdV-C5 knob domain has also previously been shown to enable virus re-targeting without compromising capsid assembly,53 while another approach has been to remove the fiber knob entirely and replace this with domains that facilitate incorporation of larger targeting molecules without structural clashing such as the T4 bacteriophage-derived fibritin protein.54By far, the most common site for rational insertion of targeting scaffolds has been the knob domain of the adenovirus fiber.NULL platform has been shown to facilitate tumor-restricted transduction and transgene expression in an immunocompromised mouse xenograft model.55 Similarly, DARPins for cancer-overexpressed receptors, such as HER2/neu, have also been demonstrated to facilitate cancer-specific delivery for AAV.56An extensive range of scaffold proteins with variable affinities have been rationally engineered into the adenoviral capsid structure to facilitate retargeting. These range from peptides, and scFvs, to T-cell receptors (TCRs), DARPins, and nanobodies. Of note are RGD motif-containing peptides that facilitate viral retargeting to integrins. Integrins are frequently overexpressed on aggressive carcinomas, while displaying relatively limited presence on healthy human tissues. This interaction could therefore be harnessed to achieve highly specific cancer targeting. Incorporation of the FMDV2 derived, αvβ6 integrin targeted A20 peptide into the HI loop of the fiber knob of the Ad5a priori knowledge of the underlying receptor-ligand interaction—although often do focus on specific structural regions. Highly diverse initial libraries are subjected to iterative rounds of in vitro or in vivo screening for transduction of cancer cells of interest with normal cell controls, to select for those virions that have improved transduction profiles and/or infection kinetics  into identified permissive capsid sites enables iterative rounds of screening and recovery of semi-rationally designed vectors, with mutagenesis by synthesis of random variants providing further diversification. By starting with a pool of initial viruses whose design was informed by pre-existing knowledge of structural biology and using protein sequences with anticipated activity, the likelihood of identifying a lead candidate vector for the desired purpose at the end of this process is greatly increased. This semirational approach has been adopted within the AAV field.58 However, increased complexities surrounding the generation of in-context adenoviral display libraries mean this approach is yet to produce significant breakthroughs for these vectors.59Inserting large libraries of diverse protein or peptide domains  underlying the activity.63 These studies nonetheless show the power of using sophisticated genetic screening strategies to recover desirable capsids.For AAV, an example of the power of screening random peptides to yield capsids with improved binding properties has been achieved in the nervous system, reviewed by Challis et al.Other innovative approaches for delivery, such as exosomes, nanoparticles, or synthetic cells, may emerge in coming decades. However, at present, these are unlikely to supersede engineered viruses. Discussion of these nonviral methods for delivery is beyond scope of this review. For the moment, evolution has resulted in very efficient gene delivery vehicles for human cells in the form of viruses; tapping into their vast potential for engineering selectivity remains a priority for the field.Following internalization, additional control can be exerted by regulating expression of payloads and/or critical viral replicative genes (for adenovirus) using promoters and enhancers that restrict their transcription to the malignant cellular compartment. Arguably, the selectivity that can be achieved through engineering of promoter/enhancers may far outstrip that which could ever be achieved through capsid engineering, since capsids are likely constrained by limitations inherent in the biology and biochemistry of available interactions. By contrast, modular regulatory elements and “tuning” of expression for specific cell types and states can be spectacularly selective as there is a combinatorial logic in the transcription factor (TF) “code,” which underpins the identity of many thousands of diverse cell types and states that make up human tissues.e.g., alphafetal protein for hepatocellular carcinoma64 or carcinoembryonic antigen [CEA] for colon cancer65) and (2) promoters/enhancers that are the endpoints in classic oncogenic signaling pathways  , cancer-specific mutations , or hypoxic elements.68 Other examples are oncogenic pathways, including the use of the oncogene-associated promoters. These genes and hence their associated promoters would display higher activity in cancer cells than surrounding tissues, providing therapeutic window.Historically, ubiquitous viral promoters have been favored for cancer gene therapies. These provide constitutive, high-level expression of the transgene. However, there are two broad choices that might give desirable selectivity by ensuring transcription in only tumor cells: (1) use of a tissue/developmental specific elements that are reactivated or highjacked in the tumor cells, but not normally present in adult tissues  through mapping of peaks for key TFs using ChIP-seq, enhancer chromatin markers such as H3K27 acetylation, or chromatin accessibility (ATAC-seq). This has resulted in thousands, or tens of thousands, of candidate cell type-specific regulatory elements that might be useful in adenoviral or AAV to provide selective expression.These early studies focused on proximal promoter regions; yet, for many cell type-specific genes, it is the long range cis-regulatory elements (enhancers) that provide the opportunity for selectivity.Moreover, advances in single-cell RNA-seq, DNA methylation, and chromatin accessibility profiling mean we will soon have a comprehensive atlas of diverse human cell types and cell states, with maps of their associated enhancers, including for tumor cells. Functional annotation of these regulatory elements alongside computational tools and machine learning strategies to identify the “rules” underlying their activity should transform our ability to rapid garner optimal synthetic promoters for gene therapy.70 these can be readily synthesized and screened (as they are often short sequences) for specific activity. Quicker, cheaper, and scalable methods to read, write, synthesize, and assemble DNA underpin the relatively new field of synthetic biology . Novel synthetic promoter and enhancers are therefore increasingly very easy to design, build, and test.As we learn more about the key TFs that define cell type identity, their specific motifs, and the grammar that leads to their selectivity,in vivo screening strategy searching for neuronal subtype enhancers revealed by scATAC-seq and identified those that can operate in AAV across species.72 Single-cell profiling technologies therefore not only provide the input set of candidate enhancers but also can be used to functionally annotate and rank these within their appropriate rAAV context.73Screening approaches for synthetic promoters and enhancers follow a similar strategy to capsids and involve similar steps: building complex libraries of DNA parts, designing strategies to identify the “winners,” and recovery of those regulatory sequences with desired activity using appropriate human cells or animal models. An example of what is possible is the screening in mice for 230 different enhancer sequences in AAV, which uncovered many novel elements that are specific for neuronal and glial cell subtypes. Furthermore, Mich et al demonstrated an elegant 74 This approach has been used to search for glioblastoma promoters using screening of libraries.75 However, this assumes that the key TFBMs are known and ignores the need for the appropriate “grammar” that will undermine either activity (strength) or selectivity. Future trends will likely combine the use of natural elements screened at scale that can be minimized , but combined in ways to rationally design cell state or type specific expression.Natural enhancers may have the wrong size, selectivity, or strength to be useful in gene therapy applications. For fully synthetic enhancers, most efforts initially have focused on transcription factor binding motifs  and concatemerization of these to gain stronger activity.Whilst replication-competent adenoviral-based therapies have some intrinsic anticancer activity through their oncolytic capacity, potency can be greatly potentiated by the incorporation of additional transgenes that confer novel therapeutic functionalities—effectively enabling them to act as Trojan horses that deliver anticancer payloads to the tumor cells. An array of different transgenes has been explored within the context of cancer virotherapy vectors , tumor-associated M2 polarized macrophage, and likely multiple other pathways. Hence, educating or unleashing the immune system through local tumor-specific immune modulators is an appealing strategy. The successes of immunotherapy for certain cancers and massive interest and investment in this area mean there is an ever-expanding collection of potential immuno-therapeutic payloads with which to arm virotherapies.Encoding such immune modulators within the framework of a cancer-selective virus can help to bypass some of the issues associated with their systemic application such as immune system hyperactivation, which in the worst cases can lead to systemic cytokine storms and ultimately death. Restricting the activated immune response to the tumor and its local microenvironment is one of the appealing prospects for viral gene therapies.76Proof of principle of the ability of immune transgenes to provide therapeutic efficacy when encoded as part of cancer virotherapies comes from the first oncolytic virus to be approved in the United States and Europe in the form of Talimogene laherparepvec (Imlygic™). This is an HSV-1-based virotherapy that incorporates a transgene encoding granulocyte macrophage colony-stimulating factor to promote the proliferation and differentiation of the bone marrow myeloid precursor cells that give rise to important immune effector subsets. Additional examples of immune-activating transgenes that have been encoded within the viral genome include checkpoint inhibitors, cytokines, chemokines, and bi- or tri-specific NK and T cell engagers.77 However, the use of IL-12 in a more restricted manner with viral delivery has shown some signs of success in glioblastoma.78Typically, the latter of these possess two scFv domains that enable them to engage with tumor-associated antigens at one end and the relevant immune cell subset at the other, thus bringing the two into proximity for immune cell activation and subsequent tumor clearance. IL-12 has previously been explored as a potential antitumor cytokine, with extremely promising preclinical studies that were subsequently undermined by toxicities when systemically delivered in clinical trials.79 Oncolytic activity in adenoviral constructs is commonly conferred by subtle changes in viral early genes that enable replication to proceed in tumor cells, yet attenuated in nontransformed cells. One such modification is the deletion of the adenoviral E1B protein, and this modification is the basis of Oncorine™, which has been licensed in China since 2005 for the treatment of nasopharyngeal carcinoma and head and neck cancers .Finally, viruses with oncolytic capacity, such as adenovirus, have the potential to provide particularly powerful synergies with immune-stimulating anticancer transgenes, since the immunogenic cell death that follows vector self-amplification and subsequent cell lysis releases damage-associated molecular patterns and tumor cell antigens that lead to recruitment and activation of immune effector cells, which potentiate the effects of any transgene.81 These patient-derived cancer models can provide improved in vivo models when orthotopically transplanted into mouse tissues (immunocompromised mice). These xenografts have more realistic histology and virus activity can therefore be explored through different delivery routes.Having designed precision-engineered viral vectors and armed them with therapeutic payloads for efficacy, screening and testing in appropriate models must be performed to identify the most promising candidates for clinical translation. A key concern of any screen or cell line/rodent-based studies for a human therapeutic agent is that the experimental model will reveal highly selective promoters or capsids that only operate in that specific model due to its unusual biology—and may have limited utility across species. The advent of primary human cancer models provides a timely experimental advance that can help address these limitations.82 Solid tumors, including patient-derived models, are now widely available and often are shared to the community and industry.83Patient-derived monolayers or organoids enable regulatory elements and viral vectors to be tested in the most relevant human disease context. Three-dimensional organoids that have the heterogeneity, hypoxic microenvironments, and diversity of differentiated states seen in primary tumors are a more realistic model for screening and head-to-head comparisons can be made with normal nontransformed tissue control organoids.There are of course caveats. Patient-derived cultures lack vasculature and immune cells; they are often not easy to scale up and engineer genetically. Furthermore, they may lack other features of the tumor biology such as appropriate extracellular matrices or structural features/mechanical forces. With long-term passage, there is the risk of genetic drift. However, as a complementary approach to murine studies, human primary cell cultures, organoids, and slice cultures should always be part of the triage process for identifying optimal engineered viruses for gene therapy.in vitro and in vivo, with normal matched tissue stem cell controls, should be harnessed in all discovery research to optimize and triage candidate lead products before entering the clinic. A major limitation, however, is the difficulty of modeling human immune interactions with the organoid-derived tumors. While strategies have been developed, these are often technically challenging, artificial, and costly; co-cultures of organoids with vascular cells and/or human immune cells may be more tractable.This ability to move back and forth between In conclusion, viral-mediated therapeutic gene delivery could achieve cancer-selective killing or cytostatic effects if the virus preferentially transduced cancer cells, only replicated within the cancer cells, or delivers payloads that are only expressed or active within the cancer cells (or a combination of these features). Over the past two decades, proof of concept for each of these different facets has been obtained and we now are armed with a wealth of new technologies and experimental models to develop these innovative therapeutics.Arguably, the vectors with greatest chance of success in the clinic will combine desirable features, from both cell extrinsic and intrinsic selectivity mechanisms, to generate advanced virotherapies that specifically seek out tumor cells, and only in these unleash their full potency through oncolysis and/or therapeutic transgene expression. The parts of the puzzle of how to build an exquisitely selective virotherapy are therefore emerging. This will surely ultimately guide us toward advanced and effective new gene-based therapies for cancer patients.


Higher rates of depression and anxiety are reported among women who belong to racial and ethnic minority groups, contributing to adverse birth outcomes, and remains a taboo topic within the global Muslim community. Non-pharmacological coping mechanisms such as prayer may be employed to reduce perinatal depression and anxiety, however the literature is sparse on the use of this intervention among pregnant Muslim women. Therefore, we aimed to conduct a scoping review examining the use of Muslim faith practices on anxiety and depression in perinatal period. Nine studies were identified that demonstrate that Muslim faith practices reduce perinatal anxiety and depression symptoms. These studies demonstrate that prayers and other faith-based practices, including reciting parts of the Quran, saying a Dua, and listening to audio recordings of prayers are all effective in decreasing anxiety, depression, stress, pain and fear in Muslim women during pregnancy, during childbirth, during an unexpected cesarean section, and when experiencing infant loss. Despite the scoping review's small sample size, findings confirm that incorporation of faith practices effectively reduces perinatal depression and anxiety among Muslim women and should be utilized in clinical settings for non-pharmacological management of perinatal mood disorders. Perinatal mental health disorders are experienced by 10% of pregnant women across the globe . It is wMuslim women are part of the fastest-growing religious group in the world, with 24%, 1.8 billion people, identifying as Muslim . The menIslamic faith practices are impactful in the daily lives of the Muslim community and vary among individuals but are always performed with intention for Allah, the Arabic word for God. Common Islamic faith practices include structured prayers and rituals, reciting the Qur'an, remembrance of Allah referred to as dhikr, and saying a Dua in which individuals request guidance, make a personal appeal or invocation “either on behalf of another or for oneself” . In IslaThis scoping review utilized Arksey and O'Malley's methodology to systematically review the literature pertinent to this topic . Eligibi* OR prenatal*) AND [TI (Muslim OR islam* OR Sunni OR Shia OR Quran) OR AB (Muslim OR Islam* OR Sunni OR Shia OR Quran) OR SU (Muslim OR islam* OR Sunni OR Shia OR Quran)]. Database searches were completed from July 2020 to September 2020. All peer-reviewed articles with publication dates through September 2020 were included for examination. The data collection and screening process began with a total of 249 abstracts and resulted in a total of 9 included peer-reviewed articles  AND  AND [Muslim(my) OR Muslim(tiab) OR Islam(mh) OR islam (tiab) OR Islamic (tiab) OR Sunni (tiab) OR Shia (tiab) OR Quran (tiab)]. Search strategy in all other databases utilized a combination of the following keywords:  AND  for the following inclusion criteria: (1) measurement of Islamic faith practices, (2) measurement of mood disorders, specifically anxiety and/or depression, including use of descriptive behaviors such as “anxious thoughts, worry, rumination, nerves” (3) population of pregnant women up until delivery, (4) original research study in peer-reviewed publication, (5) available in English. Discordant results for abstracts as well as “maybe” articles were reviewed in tandem by two perinatal mental health research scientists . For full text review, articles were obtained for all those which met the inclusion criteria. Full text reviews were conducted by SDS and KMT with no disagreements.Following completion of the scoping review, nine articles were included for synthesis on this research topic. In sum, 6 articles were quantitative in methodology while three were qualitative. The results of this scoping review are organized by methodological approach, first broadly describing quantitative findings followed by qualitative. Among the quantitative studies included in this scoping review, results are discussed in sum based upon the Muslim faith practice utilized as the intervention in the study design.Across the six quantitative studies examined in this scoping review examining the relationship between perinatal anxiety and depression and Muslim faith practices as non-pharmacological interventions, four studies were completed in Iran, with the remaining 2 studies conducted in Indonesia from 2016 to 2020 . All quaAmong the five intervention studies, including randomized control trials and quasi-experimental designs, various interventions were utilized including listening to Qur'an recitation recordings in three studies –21, and p < 0.01). Jabbari et al.'s (p < 0.001) with significant reduction in cortisol levels and time of labor as well (p < 0.001).There were various measures of anxiety, depression and stress present among these 6 studies including DASS-21, the Hamilton Anxiety Rating Scale, EPDS, STAI, PSS, the Beck anxiety and depression questionnaire, the Spielberger anxiety scale, and RAS-R. There were no two studies that utilized the same measure of mental health in pregnant women. Among the 5 intervention studies, all utilized pre-test post-test design with two or more measures for mental health throughout pregnancy. Across these 5 peer-reviewed intervention studies, results consistently reported significant reductions in mental health scores from the pre-intervention to post-intervention time points. Hamidiyanti and Pratiwi  intervenet al.'s  intervenp = 0.001). Mokhtaryan et al.'s (P ≤ 0.001).The two educational interventions around mindfulness, anxiety and Muslim faith reported similarly significant results. Aslami et al.'s  study ofet al.'s  study ofOne study included was cross-sectional in nature, with a sample size of 300, in which pregnant women completed the Islamic Lifestyle Questionnaire and DASS-21. Correlation analyses noted that a statistically significant inverse relationship between mental health scores and responses to the Islamic lifestyle questionnaire (r = −0.31) with regression analyses demonstrating that a “mean score of mental health measure decreases 0.09 per unit increase in Islamic lifestyle score” . This stQualitative results of the scoping review include three original research articles examining the relationship between Muslim faith practices and perinatal mood during the postpartum period . MutmainThis scoping review included nine quantitative and qualitative studies which consistently described the utility of faith practices in reducing perinatal anxiety and depression symptoms in a global sample of Muslim women. Specifically, the studies in this review, found overwhelmingly that prayers and other faith-based practices, including but not limited to reciting parts of the Quran, saying a Dua, or just the simple act of listening to prayers on a smart phone, aided in decreasing stress, pain, and fear in Muslim women before and during childbirth, when experiencing perinatal loss, and during an unexpected cesarean section surgery , 23.Prayer, as a healing practice for mood disorders, has been well-documented in many religious groups (Kirk) . LiteratResearch to date highlights the importance of investment in public health interventions paired with additional perinatal mental health services, to reduce mental health related maternal child morbidity and mortality . Non-phaIncreased cultural awareness around faith practices for diverse populations should be included in training for patient-facing members of healthcare organizations and public health systems including obstetricians and gynecologists, certified nurse midwives, nurses, social workers, public health providers and patient care support staff. Future research should consider testing the utility of audio or visual recordings of prayer, from different global faith traditions, in the reduction of perinatal anxiety and depression symptoms during in-patient hospital stays. Integration of faith practice recordings on hospital televisions would allow bedside clinicians and support staff to make this intervention readily available to those interested and enhance the utilization of this coping mechanism when preparing for birth or experiencing perinatal loss. Discussion of faith practices as public health screenings may increase a sense of community support around this issue, as faith-based multimedia is available for download directly onto individuals' personal mobile devices.Despite the number of strengths in this review, a potential limitation of this scoping review includes the limited number of studies to date, that discuss the correlation between perinatal mood disorders and faith-based practices used by Muslim women. Additionally, most studies included in this review paper take place in primarily Muslim countries. More research is needed to understand perinatal mood disorders in Muslim women who have moved and assimilated in new areas.Consideration of this study's findings should also include creating in-patient hospital environments that are respectful of women and their families during prayer. Supporting the utilization of faith practices in Muslim women, and others, during the intrapartum period may include thoughtfully allowing privacy during prayer, temporary removal of continuous monitoring devices, and asking if patients would like to request religious service support from the hospital directory of faith leaders. Acknowledging to antenatal and postpartum individuals that their faith practices are available to them as a resource and may be helpful in relieving perinatal mood symptoms may create an opportunity building trust and rapport with pregnant patients and their families.SDS, NQ, and KT conceived and designed the study. NQ and ZK performed the search strategy and abstract review process, with supervision by SDS and KT. SDS, NQ, ZK, and KT wrote the first draft and contributed to the final draft. SDS and NQ wrote the introduction and wrote the methods. SDS wrote the results. SDS, ZK, and KT wrote the discussion. All authors viewed and approved the final version.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.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Neurorehabilitation is a complex medical process which aims to aid recovery from a nervous system injury, and to minimize and/or compensate for any functional alterations resulting from nervous system injury disease. These diseases include stroke, spinal cord injury, cerebral palsy, Parkinson's disease, brain injury, and multiple sclerosis. Human-machine interface is a potential neuromodulation scheme for neurorehabilitation. To provide a platform for sharing the latest research findings in human machine interface-based neuromodulation for neurorehabilitation, we organized this Research Topic, in which 18 manuscripts have been accepted for publication, including 12 original research articles, four reviews, and two clinical trials. These articles stated that transcranial magnetic stimulation (TMS), brain–computer interface (BCI) and robots are the current advanced intervention techniques for the treatment of these diseases. In addition, the corresponding neural mechanisms were studied by healthy subjects using these intervention techniques. To a certain extent, these manuscripts have expanded the current understanding of diagnosis, treatment, and prognosis of such nervous system injury diseases.Cai et al. explored that brain network activity modulates corticospinal excitability in 32 healthy individuals by recording electroencephalography (EEG) and single TMS measurements. The results suggested that corticospinal excitability can be modulated by the power spectrum of sensorimotor regions and the overall efficiency of functional networks. Thus, EEG network analysis can provide a useful complement to study the relationship between EEG oscillations and corticospinal excitability.According to different TMS stimulation pulses, TMS can be divided into three stimulation modes: single TMS (sTMS), double pulse TMS (pTMS), and repetitive TMS (rTMS). A study by Yang, Cao, et al. and Xie Y.-l. et al. systemically evaluated the effect and safety of rTMS on recovery of dysphagia after stroke. They suggested that rTMS improved overall swallowing function and activity of daily living ability and reduced aspiration in post-stroke patients. Moreover, to explore the effect of 5 hz rTMS combined with wrist-ankle acupuncture on improving spasticity and motor function in children with spastic cerebral palsy by measuring electrophysiological parameters and behavior, 25 children with spastic cerebral palsy were enrolled in a single blind and randomized controlled trial. The authors found that wrist-ankle acupuncture combined with 5 Hz rTMS was the best for improving gross motor function and enhancing the conductivity of the corticospinal tract in children with cerebral palsy, but it could not highlight its clinical advantages in improving spasticity. Furthermore, executive dysfunction widely exists in a variety of neuropsychiatric diseases, and is closely related to the decline of daily living ability and function . Another study by Liu S. et al. analyzed the effect of low-frequency rTMS on executive function and its neural mechanism by using event-related potential (ERP). Thirty-one healthy subjects were randomly assigned to receive rTMS stimulations (1 Hz rTMS or sham rTMS) to the left dorsolateral prefrontal cortex (DLPFC) twice. They suggested that low-frequency rTMS of the left DLPFC can cause decline of cognitive flexibility in executive function, resulting in the change of N2 amplitude and the decrease of P3 and late positive component (LPC) components during task switching, which is of positive significance for the evaluation and treatment of executive function. In addition, MSA refers to a progressive neurodegenerative disease characterized by autonomic dysfunction, parkinsonism, cerebellar ataxia, as well as cognitive deficits. Zhang et al. systemically assessed the effects of Non-invasive brain stimulation (NIBS) on two subtypes of MSA: parkinsonian-type MSA (MSA-P) and cerebellar-type MSA (MSA-C). They found that NIBS can serve as a useful neurorehabilitation strategy to improve motor and cognitive function in MSA-P and MSA-C patients. However, they suggested that further high-quality articles are required to examine the underlying mechanisms and standardized protocol of rTMS as well as its long-term effect. Meanwhile, the effects of other NIBS subtypes on MSA still need further investigation.In addition to sTMS, rTMS technology is also widely used in the treatment of stroke, cerebral palsy, and multiple system atrophy (MSA). In studies focusing on recovery of dysphagia post-stroke, Ding et al. investigated the effects of iTBS on functional brain network through the resting-state EEG of stroke survivors. Thirty stroke survivors with upper limb motor dysfunction were studied. The authors provide evidence that iTBS modulates brain network functioning in stroke survivors. The acute increase in interhemispheric functional connectivity and overall efficiency after iTBS suggests that iTBS has the potential to normalize brain network function after stroke, which can be used for stroke rehabilitation. Furthermore, another study by Xie Y.-J. et al. explored the efficacy of cerebellar iTBS on the walking function of stroke patients. Thirty-six survivors with walking dysfunction who had suffered their first unilateral stroke were recruited. The authors found that applying iTBS over the contralesional cerebellum paired with physical therapy could improve walking performance in patients after stroke, suggesting that cerebellar iTBS intervention might be a non-invasive strategy to improve walking function for stroke survivors. Moreover, a study of Diao et al. investigated whether the individual level of GABA or NMDA receptor-mediated activity before stimulation is correlated with the after-effect in cortical excitability induced by iTBS. They found that that GABAA receptor-mediated activity measured before stimulation is negatively correlated with the after-effect of cortical excitability induced by iTBS. The short-interval intracortical inhibitory (SICI) might be a good predictor of iTBS-induced LTP-like plasticity for a period lasting 15 min following stimulation.Intermittent theta burst stimulation (iTBS) is a special form of repetitive transcranial magnetic stimulation (rTMS), which effectively increases cortical excitability and has been widely used as a neural modulation approach in stroke rehabilitation. A study by Yang, Zhang, et al. provided medical evidence-based support for BCI in the treatment of upper limb dysfunction after stroke by conducting a meta-analysis of relevant clinical studies. A total of 13 randomized controlled trials involving 258 subjects were retrieved. The authors demonstrated that BCI training can effectively promote the recovery of upper limb motor function in stroke survivors, and the effect size was moderate. Moreover, Liu L. et al. evaluated the efficacy of BCI training in chronic stroke patients with moderate or severe paresis. Eighteen hospitalized chronic stroke patients with moderate or severe motor deficits participated. They demonstrated that BCI-based rehabilitation can effectively intervene in the motor performance of post-stroke patients with moderate or severe upper limb paralysis and is a potential strategy for stroke neurorehabilitation. The results shown that the functional connectivity between ipsilesional primary motor cortex (M1) and frontal cortex might be enhanced after BCI training. Furthermore, Li X. et al. studied the effectiveness of a post-stroke hand rehabilitation system, which is the sensorimotor rhythm (SMR)-based BCI with audio-cue, motor observation and multisensory feedback. Twenty-four stroke survivors with severe upper limb motor deficits were studied. The authors found that the hand rehabilitation system combined with conventional therapy may promote long-lasting upper limb motor improvement. In addition to BCI training for stroke subjects, Lin et al. analyzed effects of frequency of motor imagery (MI) BCI training on the central nervous system. Sixteen young healthy subjects were randomly assigned to a high frequency group with performed MI-BCI training once per day and low frequency group which performed once every other day. The results revealed that compared to the low frequency group, the high frequency group presents more cortical activation and better BCI performance. Meanwhile, the authors suggested that 30 min per day for five consecutive days may be the lowest effective dose of MI-BCI training to activate modulation of cortical activation in healthy subjects, which can be extrapolated in the future to stroke patients. Similarly, another study by Qiu et al. used synchronous functional near infrared spectroscopy (fNIRS) to analyze whether mirror visual feedback (MVF) and a soft robotic bilateral hand rehabilitation system have synergistic effects on cortical activation. Twenty healthy subjects were recruited to perform four different visual feedback tasks with simultaneous fNIRS monitoring. Four different visual feedback tasks include the real visual feedback (RVF) task, mirror visual feedback (MVF) task, bilateral robotic movement (BRM) task, and MVF + BRM task. The results found that the synergistic gain effect on cortical activation from mirror visual feedback combined with a soft robotic bilateral hand rehabilitation system for the first time, which could be utilized to guide the clinical application and the future studies. Furthermore, Liu Y. et al. conducted 4-week BCI-controlled supernumerary robotic finger (SRF) training in 10 right-handed subjects to study the neuroplasticity mechanisms. The results shown that cerebellar compensatory and inhibitory mechanisms exist during BCI-controlled SRF training, and this result provides evidence for the neuroplasticity mechanism brought about by BCI-controlled motor-augmentation devices.A brain-computer interface (BCI) is a real-time communication system that connects the brain and external devices. The combination of BCI technology and hand rehabilitation robots is often used for motor function rehabilitation after stroke. In addition, some studies have explored cortical activation and neuroplasticity mechanisms in healthy subjects by BCI technology. Zhao et al. analyzed the performance of five methods for the extraction of spatial muscle synergy, namely, principal component analysis (PCA), independent component analysis (ICA), factor analysis (FA), non-negative matrix factorization (NMF), and AEs using simulated data and a publicly available database. The results showed that the performance of synergy extraction methods was affected by the noise and the number of channels, and classification algorithms were sensitive to the extraction methods. Moreover, the effect and mechanism of underlying enriched rehabilitation as a potentially effective strategy to improve gait and cognitive performance in patients with early Parkinson's disease (PD) were explored . The enriched rehabilitation represents that the enriched sensorimotor environmental stimulation paired with different types of sensory and motor exercises was applied to improve gait disorder and cognitive function in PD. The authors found that enriched rehabilitation could serve as a potentially effective therapy for early-stage PD for improving gait performance and cognitive function. The underlying mechanism based on functional magnetic resonance imaging (fMRI) involved strengthened resting-state functional connectivity (RSFC) between the left dorsolateral prefrontal cortex (DLPFC) and other brain regions.Muscle synergies have been largely used in many application fields, including motor control studies, prosthesis control, movement classification, rehabilitation, and clinical studies. After the analysis of 18 manuscripts in this Research Topic, we can draw the following conclusions. The rTMS could improve overall swallowing function and activity of daily living ability in post-stroke patients. Furthermore, rTMS can serve as a useful neurorehabilitation strategy to improve motor and cognitive function in MSA-P and MSA-C patients. However, further studies are performed to examine the underlying mechanisms and standardized protocol of rTMS as well as its long-term effect. The iTBS has the potential to normalize brain network function after stroke and also might be a noninvasive strategy to improve walking function for stroke survivors. The BCI-based rehabilitation can effectively intervene in the motor performance of post-stroke patients with moderate or severe upper limb paralysis and is a potential strategy for stroke neurorehabilitation.BS was responsible for drafting the manuscript. JW revised the manuscript. JZ and HY analyzed and discussed the results. All authors read and approved the final manuscript.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.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Sufficient bone volume is indispensable to achieve functional and aesthetic results in the fields of oral oncology, trauma, and implantology. Currently, guided bone regeneration (GBR) is widely used in reconstructing the alveolar ridge and repairing bone defects owing to its low technical sensitivity and considerable osteogenic effect. However, traditional barrier membranes such as collagen membranes or commercial titanium mesh cannot meet clinical requirements, such as lack of space-preserving ability, or may lead to more complications. With the development of digitalization and three-dimensional printing technology, the above problems can be addressed by employing customized barrier membranes to achieve space maintenance, precise predictability of bone graft, and optimization of patient-specific strategies. The article reviews the processes and advantages of three-dimensional computer-assisted surgery with GBR in maxillofacial reconstruction and alveolar bone augmentation; the properties of materials used in fabricating customized bone regeneration sheets; the promising bone regeneration potency of customized barrier membranes in clinical applications; and up-to-date achievements. This review aims to present a reference on the clinical aspects and future applications of customized barrier membranes. Sufficient bone volume is indispensable to achieve functional and aesthetic results in the fields of oral oncology, trauma, and implantology . The funl-lactide (uHA/PLLA) (In guided bone regeneration (GBR), one of the most predictable methods for reconstructing maxillofacial and alveolar bones, a membrane is used to isolate soft tissues and thereby promote bone regeneration. The application of barrier membranes is a key factor in the success of GBR . To dateHA/PLLA)  meshes tHA/PLLA) .This article outlines the basic workflow and advantages of modern 3D computer-aided surgery and critically analyzes materials , which combines 3D printing technology with 3D imaging techniques, has undergone remarkable developments in the past decades. As shown in According to the principle of “prosthetic guided regeneration,” alveolar bone defects can be divided into four classes, as shown in Barrier membranes in GBR act as protective films that maintain a stable bone regeneration environment, and an “ideal” barrier membrane is supposed to meet five basic principles : biocompA customized membrane should have sufficient stiffness to create and maintain a suitable space for the intended bone regeneration, which is mainly related to the thickness of the membrane . A stronThe thickness of Ti mesh commonly used ranges from 0.1 to 0.6 mm currently . For 3D The pores of barrier membranes are channels for nutrient and oxygen exchanges and are closely related to the blocking ability of cells. Nonporous barrier membranes can prevent fibroblasts from growing into bone defects, but insufficient blood supply may delay bone regeneration . A pore Surface properties, especially roughness, can be easily manipulated using post-production surface treatments, such as acid etching, sandblasting, and electropolishing, and directly affect the interactions of implant–cell interfaces, which play an important role in cell responses, including adhesion, adsorption, and differentiation . Smooth These studies suggest that a basic barrier membrane should possess abilities including biocompatibility, space preservation, selective permeability, host tissue integration, and clinical manipulation ability. The mechanical properties and biological performance of customized barrier membranes can be enhanced by optimizing their thickness, pore size, and roughness. Basic research is still needed as current research has not yet achieved a considerable balance between intrinsic properties and clinical needs.The customized Ti mesh has good mechanical and biological properties. The physical traits of a selective laser melting (SLM) Ti mesh should be tested by tensile test, mean elongation strength, proof stress, or micro Vickers hardness to ensure impact and fracture stability . Its higCustomized Ti devices are developed with two methods. One method is bending a commercial Ti mesh on a 3D printed augmented alveolar bone model . EI ChaaCiocca et al. used no screws to immobilize a customized Ti mesh and still achieved considerable bone augmentation following good fixation  minoDehiscence and mesh exposure can be prevented by properly managing soft tissues, and complete tension-free closure is indispensable during operation with single interrupted sutures and a deep mattress. Combination with collagen membranes does not reduce the exposure rate of a customized Ti mesh . AutologThese results indicate that a customized mesh is round and blunt and more suitable for alveolar bone morphology, and they show low exposure rates. Selecting an appropriate surgical procedure and combining autologous bioactive materials can promote wound healing and reduce Ti mesh exposure. When a Ti mesh is exposed, timely measures are needed to control infection and prevent bone graft failure.Apart from stabilizing graft material, creating enough space, and acting as a barrier membrane to guide bone regeneration in the same manner as a traditional Ti mesh does, patient-specific Ti, PEEK, and uHA/PLLA meshes have several benefits, as shown in Customized Ti, PEEK, and uHA/PLLA barrier membranes are designed with pores to receive nutrients and blood from the periosteum to promote bone healing. However, soft tissue-derived cells can grow through the pores into the osteogenic region and weaken the osteogenic effect. Therefore, using a customized barrier membrane alone cannot prevent soft tissue ingrowth and pseudo-periosteum formation. More research is needed to address this limitation.Customized Ti mesh also has its own disadvantages to address. Compared with traditional Ti mesh, customized Ti mesh can cause less membrane exposure because of its smooth round blunt shape. However, in some cases, the exposure rate of customized Ti mesh may reach an average of 20% or higher due to inherent stiffness . BesidesTo sum up, although customized Ti meshes are widely applied in GBR for alveolar bone augmentation and maxillofacial bone reconstruction, their inherent traits can lead to clinical complications and increase the complexity of treatment procedures. Relevant research should be directed towards increasing the antibacterial ability and osteogenic ability of Ti mesh to reduce membrane exposure and pseudo-periosteum formation.In vitro experiments found no evidence of the mutagenic or cytotoxic effects of PEEK  with PLLA . PLLA bein vivo. These results showed that the uHA-PLLA composite is highly biocompatible  combined use of customized membrane with collagen membrane; 2) using screws to fix the customized membrane to prevent micromovement between the bone graft and the membrane; 3) pore size and surface topography optimization; 4) surface modification of membrane materials; 5) development and application of Janus membranes. Besides, in order to obtain sufficient bone mass, excessive bone augmentation can avoid insufficient bone volume caused by soft tissue ingrowth and pseudo-periosteum formation.Thuy-Duong Thi Nguyen et al. coated Ti meshes with strontium-substituted calcium phosphate for surface modification and achieved better osseointegration compared with that in the untreated group in rat calvarial defect models (Zhao et al. found that porous chitosan gelatin doxycycline coatings on the Ti mesh exhibited antibacterial effects (Along with the progress of biomaterials, research for improving the bioactive properties of Ti alloys is advancing . Xu et at models . Zhao et effects . The impIn vitro tests showed that compared with pure PEEK, modified PEEK showed stronger osteogenic ability and could better promote the osteogenic differentiation of adipose-derived mesenchymal stem cells (The absence of osteogenesis and osseointegration ability limits the clinical application of PEEK , so numeem cells . It was em cells . OverallBiomaterials for tissue engineering are evolving from the first generation of metals and ceramics to the second generation of bioceramics  and polyDevelopments in digital modeling and 3D printing technologies have produced materials, such as Ti alloy, PEEK, and uHA/PLLA, with excellent mechanical properties and good biocompatibility, which are used in fabricating customized bone regeneration sheets for GBR. These materials are predictable and stable solutions for maxillofacial reconstruction and alveolar bone augmentation. By comparison, little research has been performed on customized PEEK and uHA-PLLA meshes, and a customized Ti mesh is the most mainstream protocol in GBR, although it needs to be removed in a second operation. In addition, improvement of material properties endows Ti and PEEK with high antibacterial and osteogenic properties, and the emergence of novel biological materials is developing towards biological absorption, enhanced osteogenesis, and reduced membrane exposure, which will promote the application of customized absorbable barrier membranes in GBR.


Virtual reality (VR) is a promising and cost-effective tool that has the potential to reduce the prevalence of falls and locomotor impairments in older adults. However, we believe that existing VR-based approaches to prevent falls do not mimic the full breadth of perceptual, cognitive, and motor demands that older adults encounter in daily life. Researchers have not yet fully leveraged VR to address affective factors related to fall risk, and how stressors such as anxiety influence older adult balance and real-world falls. In this perspective paper, we propose developing VR-based tools that replicate the affective demands of real-world falls  to enhance fall prevention diagnostics and interventions by capturing the underlying processes that influence everyday mobility. An effort to replicate realistic scenarios that precipitate falls in VR environments will inform evidence-based diagnostics and individualize interventions in a way that could reduce falls in older adults in daily life. Annually, 1 in 4 older adults are injured from falling  and resuWe argue that scientists currently using VR technology to evaluate and modify fall risk often overlook stressors such as anxiety or the “fear of falling” that are associated with higher prevalence of falls ,9. As weOur overarching interests are to establish early diagnostics that identify who is at greatest risk of falling and develop specific interventions that reduce the risk of falls in everyday life. In this perspective paper, we discuss leveraging the rising popularity of VR to develop meaningful protocols for diagnosing and treating the risk of falling in older adults. Specifically, we discuss how VR simulations can recreate the typical perceptual, cognitive, motor, and affective demands of daily life to facilitate diagnostics and interventions that reduce the risk of falling. The key points discussed in this paper are shown in Scientists should aim to better replicate the challenges that older adults experience during everyday walking to understand and prevent falls.We do not yet know if the experimental outcomes emerging from laboratory-based studies are representative of behavior in everyday life. However, virtual reality (VR) technology allows us to probe mobility-related affective responses with threats to stability and balance control.VR can simulate everyday situational demands and quantify responses with high resolution, thereby helping to bridge the gap between laboratory-based research outcomes and everyday fall risk.We propose a focus on scenarios where older individuals experience a fear of falling to identify associated deficits in perceptual, cognitive, and motor processes.To better detect everyday fall risk, scientists should incrementally challenge sensory, motor, and cognitive systems using a contextually appropriate VR-based stress test for fall risk.Using VR to address individual differences by measuring learning trajectories allows for tailored challenge points and appropriate difficulty levels that optimize learning.VR therapies successfully reduce anxiety in younger people; it is not hard to imagine a future where VR could help older adults overcome a fear of falling and cope with mobility-related anxiety.As a result of poor “balance confidence” or low “falls efficacy,” many older adults report a “fear of falling” and experience mobility-related anxiety during locomotion . We provScientists interested in the effects of anxiety on mobility have predominantly used VR to create controlled experiments that answer fundamental science questions. Unfortunately, often the experimental conditions induced have limited relation to situations encountered in daily life. For example, our previous work has shown that immersive VR can be used to increase mobility-related anxiety in healthy people by simulating standing on a wooden plank and raising the walkway approximately 15 meters above ground level ,28. AlthScientists have typically used VR to induce mobility-related anxiety by replicating laboratory-based studies that physically raise participants to elevated heights ,27,31. TAnother approach to study mobility-specific anxiety is to increase the difficulty of the locomotor task by walking on a narrow path. By increasing attentional demand and the energy cost of gait patterns ,41, a naVR-based tools can combine environmental and task-specific influences on mobility-related anxiety, emphasizing their potential to systematically examine the interactions between key perceptual, cognitive, and motor behaviors. Walking in VR on broad and narrow roads, and at low and high elevations, can reveal complex interactions between anxiety, cognition, and motor behavior in young and older adults . For insHowever, while VR has led to advances in understanding mobility-related anxiety and balance, there remains a disconnect between experimental manipulations of anxiety responses and the lived experience of older adults suffering from mobility-related anxiety in daily life. We propose that researchers use VR to simultaneously test the influence of task- and environmentally driven affective responses on locomotion, while working to develop generalizable applications. We envision VR could be used as a tool to generate outcomes that are experimentally controlled, while simultaneously being representative of everyday contexts that precipitate real-world falls.While our perspective details ways to enhance the application of VR for fall prevention, existing empirical evidence already supports the use of VR-based tools for preventing falls in older adults. We overview the current use of VR technology in fall-prevention research with reference to the following three general categories of current technology: (1) nonimmersive VR; (2) augmented reality (AR); and (3) immersive VR. We consider the advantages and disadvantages of each approach with regard to older adult fall prevention.The majority of published reports focusing on the benefits of VR-based tools in older adult fall prevention use nonimmersive devices that range in design and application -54. NoniAR, or mixed reality, is a unique technology with great potential to train balance and reduce falls using ecologically valid locomotor tasks. AR overlays 3D virtual illusions through interactive games within the individual’s real-world setting, typically using face-worn eyeglasses or goggles. Integrating the game into the real-world setting and feedback of oneself likely enhances the “task specificity” of AR-based tools for transferring performance to real-world balance and gait tasks . AR has Typically delivered via a head-worn virtual display, or head-mounted display (HMD), immersive VR replaces one’s current setting with an interactive 2D  or 3D  environment. By blocking out sensory feedback from the outside world, immersive VR presents an opportunity to stimulate sensory, and motor systems for fall prevention. Advances in graphic design and rendering capabilities have drastically improved the realism of immersive VR simulations and multiplied the potential experiences representative of daily life. Impaired older adults  can experience 2D images using an HMD , without negative side effects such as motion sickness . An HMD Rehabilitation scientists are limited in their ability to replicate complex everyday scenarios and elicit representative anxiety, hindering the ecological validity and translation of existing approaches. Simultaneously, we have yet to find a way to measure perceptual, cognitive, and motor processes in the real world without using disruptive and resource-heavy equipment. To address both limitations, VR can simulate everyday situational demands and quantify responses with high resolution, thereby helping to bridge the gap between laboratory-based research outcomes and everyday fall risk. As opposed to evaluating physical function in sterile clinical settings with clear hallways, using VR to challenge older adult mobility within an ecologically valid setting would better reveal real-world mobility deficits, thereby potentially leading to enhanced therapies to reduce fall risk.Crossing the street at night is an example of a locomotor context that elicits a specific mobility-related anxiety and requires effective perceptual , cognitive , and motor adaptations  to achieve safely. It may therefore be no surprise that older adults experience a higher prevalence of traffic-related injuries compared to younger pedestrians; a consequence attributed to a host of individual, task, and environmental factors , includiThe greater challenge is to capture behavior from fearful older adults during threatening walking scenarios and best use VR to quantify behaviors that perpetuate falls. We propose a focus on scenarios where older individuals experience a fear of falling, especially in settings leading to real-world falls such as stairwells, escalators, crowded sidewalks, shopping malls, or nighttime streets. Borrowing from the concepts developed from successful trauma-focused VR-based treatment of posttraumatic stress disorder (PTSD) in soldiers ,100, comVR environments that represent everyday situations associated with a fear of falling would allow clinicians to examine locomotor performance on a range of functional tasks in a fall risk "stress test". Such a virtual “stress test” was recently demonstrated in a functional VR game using an urban scenario designed for rehabilitating activities of daily living . The “UrA major advantage of VR is the capability to address individual differences due to its capacity to change the level of task difficulty and create appropriate “challenge points” or “desirable difficulties” . To bettThe individual differences in learning outcomes detected across challenge points in diagnostics can optimize VR-based interventions for each learner and lead to enhanced transfer of skills to the real world. VR lends itself to quantifying and adjusting training loads for individual responses to an intervention and augmenting training loads for learners . CommercPractitioners are already using VR with younger populations to rehabilitate those with anxiety-related disorders, pioneering a wider application of VR for “exposure therapy” to reduce anxiety . For exaThe use of VR-based approaches in conjunction with cognitive behavioral therapy could be effective in reducing fear of falling in older adults . VR-baseVR is an appealing and practical tool to enhance and maintain older adult mobility. We envision a future where realistic contexts for individualized VR-based fall-prevention diagnostics and interventions will reduce the risk of real-world falls in older adults. By incorporating the context of daily tasks into VR-based approaches, we can quantify movement within complex and realistic environments that better represent the demands that older adults navigate every day. Focusing on using VR to mimic the influence of affect on cognitive, perceptual, and motor behaviors should guide industry, researchers, and clinicians toward therapies that prevent everyday falls.


Three families of opioid peptides, beta-endorphin, enkephalins, and dynorphins, and three families of receptors, mu (MOR), delta (DOR), and kappa (KOR), constitute the endogenous opioid system. Opioid receptors are found throughout the central and peripheral nervous systems in both pre- and post-synaptic neurons modulating neurotransmitter release . Their di/G0), endogenous ligands or exogenous agonists that activate KOR receptors generally suppress neuronal activity or neurochemical release. A range of intracellular events mediate these inhibitory effects, which may include adenyl cyclase inhibition, reduced voltage-gated calcium channel opening, and potassium current stimulation through different channels, including G-protein inwardly rectifying potassium channels (GIRKs) (Being G-coupled inhibitory protein receptors (G (GIRKs) . Given tDalefield et al.; Leconte et al.). Unfortunately, KOR agonists clinical use has been hampered by their adverse effects, as dysphoria and psychotic symptoms, motor incoordination and sedation. It has been proposed that a mechanism involving the activation of intracellular β-arrestin/MAPK pathway mediates such unwanted effects . Further, Sturaro et al. present two novel agonists  confronting their properties to other well-known KOR ligands to classify each ligand action as full, partial, inverse agonist or neutral antagonists using a battery of assays. Of note, they designate Dyn A-palmitic as a new agonist biased towards G-protein signaling. Further studies are needed to elucidate if it exerts analgesic properties in vivo with no side effects.The KOR ligands synthetized so far have distinct pharmacological properties, as agonists, partial agonists, biased agonists, and antagonists . The most known KOR agonist effects are the antinociceptive and anti-pruritic ones, but they are not limited to them; this Research Topic actually includes two comprehensive analyses of the literature concerning the potential utility of KOR ligands as therapeutics . However, most of the knowledge we have accumulated so far on KOR blockade is based on studies employing drugs with unusually long duration of action and unclear pharmacokinetics. Despite this complicates both interpretation of results and translation of preclinical findings into the clinic, such long-acting KOR antagonists can still be useful tools to unravel the pharmacology of KOR. Indeed here, using norBNI, a study from the Neugebauer’s group provides new insights into the function of amygdalar KOR, demonstrating that KOR regulates rodent pain and aversive-like behaviors by inhibiting corticotropin releasing factor neurons of the central amygdala in a rat model of functional pain syndrome . A new generation of KOR antagonists with rapid onset and shorter duration of action can provide useful data that may be of interest for medication development. In this context, recent reports have shown that some novel short-acting KOR antagonists can attenuate or even block behaviors that are relevant to cocaine, nicotine and ethanol addiction in rats  can produce very rapid anti-immobility effect in an open space swim test as a model of acute stress exposure. Despite the large amount of preclinical evidence gathered to date and the fact that some molecules have already reached the clinical trial stage, no KOR antagonist has yet been approved for therapy. Thus, further research efforts are needed.KOR-mediated signaling regulates many aspects of the mesocorticolimbic dopamine system, contributing to the negative affective states occurring in a variety of neuropsychiatric disorders as well as in chronic pain . Both KO in rats . BaynardThe plethora of drugs synthetized that can modulate the KOR signaling is invaluable to unveil the complex pharmacology of this receptor and a further understanding of its molecular and behavioral pharmacology is essential. The collection of articles here presented perfectly fits this scope and contributes to advance the knowledge in the field.