Multiple sclerosis (MS) is the inflammatory demyelinating and neurodegenerative disease of the central nervous system (CNS) that affects approximately 2.8 million people worldwide. In the last decade, a new era was heralded in by a new phenotypic classification, a new diagnostic protocol and the first ever therapeutic guideline, making personalized medicine the aim of MS management. However, despite this great evolution, there are still many aspects of the disease that are unknown and need to be further researched. A hallmark of these research are molecular biomarkers that could help in the diagnosis, differential diagnosis, therapy and prognosis of the disease. Proteomics, a rapidly evolving discipline of molecular biology may fulfill this dire need for the discovery of molecular biomarkers. In this review, we aimed to give a comprehensive summary on the utility of proteomics in the field of MS research. We reviewed the published results of the method in case of the pathogenesis of the disease and for biomarkers of diagnosis, differential diagnosis, conversion of disease courses, disease activity, progression and immunological therapy. We found proteomics to be a highly effective emerging tool that has been providing important findings in the research of MS. Multiple sclerosis (MS) is a chronic, inflammatory, neurodegenerative disease of the central nervous system (CNS). It mainly affects young adults 20–45 years), it is predisposed toward women , it is more common in the Caucasian race and it shows a north–south gradient  5 years, ,7,8,9. IHowever, the significance of MS goes beyond the mere number of patients. Among the affected young adult/middle aged population, MS is the most common neurological cause of disability after epilepsy ,12. The The aforementioned make it clear that early diagnosis, estimating the rate of aggression of the disease at the beginning and the earliest adequate therapy is of utmost importance. Thus, the identification of biomarkers  regarding either the pathogenesis, the activity, the progression of the disease or the monitoring of therapeutic effectivity is the hallmark in MS research.In this comprehensive review, after the short summary of the pathogenesis, diagnosis and therapeutic considerations of the disease, we aim to present the usefulness of proteomics in the research of and the latest data on biomarkers identified by this method regarding MS, from the clinician’s point of view.There is no complete consensus on the pathological processes leading to MS due to conflicting data; however, the disease is considered to be a two-staged entity by most researchers. The more accepted view states that it begins with an autoimmune inflammatory response primarily against the oligodendrocytes in the CNS, leading to demyelination (inflammation), and, after a while, when the regenerative capacity of the oligodendrocytes is exhausted, the inflammatory processes are directed against the neurons themselves, leading to the permanent injury and dysfunction of the CNS (neurodegeneration) .During the earlier inflammatory stage, two different  processes can be identified. The first begins in the periphery when autoreactive lymphocytes enter the CNS through the damaged blood–brain barrier (BBB), recognizing antigens and initiating an inflammatory cascade by producing proinflammatory cytokines and recruiting more immune cells to the site . These lRegarding the second inflammatory process, the key players are the CD20+ B cells. These cells can be found in the connective tissue in the CNS as well, mainly in the meninges and the Virchow-Robin spaces forming inflammatory aggregates, so-called “ectopic germinal centers”, there ,29,30. T2+-overload, resulting in neuronal death [Through these inflammatory responses—mainly microglia being the source of the oxidative stress—the autoimmune process will inevitably lead to axonal dissection in the white matter and cortical and subcortical neuronal injury in the grey matter, evidently from the very beginning of the disease . The mosal death . Despiteal death .However, this view on the “primacy” of autoimmune inflammation has been challenged recently. Some promising data emerged implying that oligodendrocyte apoptosis and axonal damage, thus neurodegeneration, is the first step in the evolution of MS. This process reveals previously hidden antigens and activates the immune system, which leads to a secondary autoimmune response, initiating the whole “vicious circle” ,37,38,39Whichever hypothesis is ultimately true, there are still many unanswered questions regarding the pathological processes leading to MS. If the disease is primarily an immune condition, what can be the initiator of the inflammatory response ? Why and how does the BBB get damaged and become unable to halt the invasion of the immune cells? What are the targeted antigens of the process? If the second hypothesis is true, what process leads to the oligodendrocyte apoptosis, and how and why does that happen? Again, how will the BBB be damaged to make the secondary immune response possible? Many more data are needed to give satisfactory answers to these questions. However, as new and new results accumulate, our understanding of the pathological processes behind the disease grows, and this will lead to further answers.Since the publication of the new phenotypic classification of the disease in 2014, the clinical courses of MS can be categorized into two basic types: the relapsing and progressive disease courses . The relBoth basic clinical types can be further classified. In the case of the relapsing subtype, the disease can be active or not active, based on the clinical (new relapse) and radiological (new or enlarging T2 or T1 lesions on MRI) signs of activity . ProgresAt least one T2 hyperintense lesion in 2 ≤ predilecting  regions;Two or more T2-hyperintense lesions in the spinal cord;OGP in the CSF.The accurate diagnosis of MS is based on proving that the disease is disseminated in space (DIS) and time (DIT) as well. Since the implementation of the new McDonald diagnostic criteria in 2017, the diagnosis has become faster without sacrificing any sensitivity or specificity . Apart fIn 2018, the first ever therapeutic guideline in MS was implemented by the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) and the European Academy of Neurology (EAN) in Europe ,46. ThisAll these summarized data show that today, MS can be diagnosed earlier than before with good accuracy, the clinical course can be clearly defined and there is a clear guideline for the appropriate treatment on the clinical basis. However, there are still many aspects in which our knowledge is lacking. There are still many CIS or isolated optic neuritis cases, where an initial biomarker showing the potential conversion to CDMS would be invaluable. Moreover, there is no specific biomarker for the diagnosis of MS, which would greatly enhance the differential diagnostic potential. The diagnosis of SPMS is very difficult and is often retrospective as the clear boundary between RRMS and SPMS is undefined, thus, a biomarker for the conversion to SPMS would be extremely useful. Despite several attributes that set PPMS apart from relapsing MS, the diagnosis can only be made after at least 1 year of progression. Thus, patients would benefit greatly from a potential biomarker suggestive of PPMS at the very beginning of the disease. Last but not least, despite being able to give a good estimation on disease activity at the onset, highly accurate biomarkers would be very important for predicting the change in disease activity in the future. All in all, identifying specific molecular biomarkers for the aspects of MS are highly important and are considered hot topics in the current research. Proteomics, as a method, could be very effective in reaching these goals and providing us with these extremely important tools in the near future.Since the beginning of the new millennia, biomedical sciences have taken a tremendous leap in progress. It began with the in-depth analysis of the human genome  that provided detailed data about the structure, expression and function of genes, which gave birth to the science of genomics . HoweverClinical proteomics: The discipline that analyzes the role of proteins as potential biomarkers in a given disease.Structural proteomics: This discipline aims to evaluate the three-dimensional structure of a protein in connection with its function in the cell.Functional proteomics: The main goal of this discipline is to analyze the interactions of a given protein with other proteins or other types of molecules in connection with its role in the complex (patho)physiological processes.Proteomics is the branch of biomedical studies that specifically analyzes the whole protein content, their functions and interactions in a cell or a whole organism . DespiteA plethora of technologies are in use under the umbrella-term proteomics such as the conventional analytical approaches, including chromatography-based techniques or enzyme-linked immunosorbent assay (ELISA), and the new, advanced technologies including mass spectrometry or the gel electrophoresis techniques. However, it is most practical to summarize these technologies based on their everyday application in research .To purify biological samples, several chromatography-based techniques, such as ion exchange chromatography (IEC), size exclusion chromatography (SEC) and affinity chromatography, can be utilized ,52. The Biomarkers were defined by the World Health Organization as “any substance, structure, or process that can be measured in the body or its products and influence or predict the incidence of outcome or disease” . This brNowadays, there are two basic approaches for the quantitative proteomic analysis in neurological conditions . The firAs was mentioned above, identifying biomarkers in the case of neurological diseases may have more difficulties than in other conditions due to the isolated and sensitive nature of the CNS. Despite this, the number of researches aiming to identify biomarkers for neurological conditions has exponentially grown in the last two decades. One of the key moments in this process is to choose the right type of sample for the analysis . Here, wBlood (both the plasma and the serum) is the single most “popular” biosample for molecular biomarker research in any medical discipline. It is easily collected by minimally invasive means and can be repeated as often as needed without causing any potential harm to the patient. It is abundant in different proteins and cells, including CNS specific molecules, thus makes an ideal sample for biomarker research ,73. Desp3) and the ion concentration differs from the plasma [The CSF is the special bodily fluid that provides mechanical and immunological protection to the CNS and plays an important role in its homeostasis. It is produced by the choroid plexus of the ventricles, circulates through the subarachnoid space and the ventricular system and is absorbed into the venous blood through the arachnoid granulations . There ie plasma ,78,79.Due to its proximity to the CNS, its circulation and special composition, it may diffusely contain pathological proteins in the case of neurologic disorders and do so in relatively high concentration. Some of the proteins may only be found in the CSF due to its isolated nature. Moreover, due to its relatively lower concentration of albumin and other highly abundant proteins, proteins, even in small quantities, may not be masked in the CSF in contrast to blood samples . All theSaliva is the special fluid produced by multiple salivatory glands  and is the first digestive fluid of the gastrointestinal tract . It has Tear is another alternative bodily fluid sample for proteomics research as its composition not only reflects the ocular tissue but the CNS as well. It is easily collectable by non-invasive means and repeated sampling poses no difficulties . HoweverUrine has been more extensively studied than saliva or tear in the case of neurological disorders. It has some undeniable advantages, including easy, cheap and non-invasive sample collecting in large amounts that can be repeated any time . MoreoveBrain or spinal cord tissue samples are natural choices for biomarker research when we consider CNS disorders. The direct and methodical analysis of the affected tissue from the affected site yields far more diverse and detailed results than other samples. However, for everyday utility, its viability is extremely limited. Sampling is extremely invasive and dangerous, making it a last resort effort in almost any disease, while repeated sampling is unthinkable in human subjects. The only way for performing routine evaluation is by post-mortem examinations in humans and dissection in animals. Thus, its utility, despite being highly important, is limited to animal models and basic research in the case of neurological disorders  .There are several attributes of proteomics that make it a better choice for biomarker research than other methods. Despite great advances in DNA sequencing and genetics as a whole, it was found that almost 40% of protein-coding genes lack experimental evidence at the protein level . MoreoveWe have elaborated on the several hardships in the identification of candidate protein biomarkers above—low abundance in easily collectable samples, the masking effect of resident proteins or their fast degradation by protease enzymes after sample collection, to name a few. However, new technologies are continuously being developed with success at overcoming these issues. For example, Luchini et al. reported the development of “smart” nanoparticles that can be immediately mixed with the collected sample and may perform chromatography and sequester the proteins in question away from albumin at the same time . DespiteThe first proteomic studies were undertaken in the early 2000s; since then, their numbers have increased exponentially. These assessments encompass a wide range of strategic goals. Studies dedicated to the understanding of the pathological mechanism behind the development of the disease are probably the most abundant and were undertaken on both the classical animal models  and cuprizone models) of MS and on human tissue samples. However, a plethora of assessments were aimed at finding molecular biomarkers for several aspects of the disease: diagnosis and differential diagnosis, forecasting disease activity and progression at the beginning of the disease, predicting conversion from one clinical course to another and also monitoring the therapeutic effect of different DMTs. In the following sections, we try to give an up-to-date summary on the results of these research.bis-cyclohexanone oxaldihydrazone (aka cuprizone) which leads to demyelination [Despite MS being exclusively a human condition, a number of animal models have been developed for the disease. The two most often utilized such models are the EAE and the cuprizone model. In the case of EAE, an inflammatory demyelination is induced in the CNS of the murine by either subjecting the animal to immunization with myelin antigens or by the direct transfer of myelin-specific T-lymphocytes . The cuplination . Howeverlination . These mIn the past two decades, several proteomics studies were conducted utilizing these animal models aiming to shed light on the pathological processes leading to MS. In 2010, Fazeli et al. assessed brain tissue samples from EAE mice compared to a control group . They deAs animal models are only able to mimic the pathological processes leading to MS, studies on the pathogenesis of the disease naturally need to utilize human tissues. Of these, CNS samples would provide the most direct source for analysis; however, due to the insurmountable limitations of sampling on which we elaborated above, obtaining direct CNS samples is only confined to autopsies and very rare biopsies. Thus, the bulk of the data originate from research conducted on the CSF, blood and other alternative fluid samples, with all their limitations.The rare studies using direct CNS sampling identified several candidate proteins in the pathogenesis of MS. In a pivotal proteomics study from 2008, several hundred proteins were identified that were unique to different pathological subtype of MS lesions as compared to healthy controls; however, no comparison was performed with normal-appearing white matter . FurtherEvaluations conducted on the CSF add to the above mentioned results. One such study from 2016 identified seven proteins potentially involved in the pathogenesis of MS, of which secretogranin-1 (Scg1) levels were elevated at the onset of MS as compared to healthy controls and RRMS patients . AnotherIn the case of serum/plasma or alternative fluid markers, an early study established that the pre-symptomatic MS cohort differed from the control group in 22 proteins’ expression . AnotherAll the reviewed data, whether from animal models or human subjects, point to a mechanism behind the pathogenesis of MS that is far more diverse than we already know. Apart from the long-time suspected and (partly) proven role of immune cells and inflammatory pathways, several other key players were identified. The role of astrocytes, the molecular pathways involved in coagulation, mitochondrial functions, redox reactions, glial and neuronal differentiation, etc., all seem to be important in the development of the disease; thus, their further analysis is required for us to understand the whole picture. These studies have already marked several peptides as possible players for further in-depth reproduced analysis on large samples.Despite the fact that having an understanding of the pathogenic mechanism behind the development of MS would be a tremendously important achievement, in everyday clinical practice, the diagnosis, differential diagnosis and the prognosis drive the therapeutic decisions of the neurologist. Thus, the identification of any potential biomarker that can aid a faster and more accurate diagnosis and differential diagnosis, the early accurate measurement of the temporal prognosis and the potential to monitor therapeutic effects could be considered a “holy grail” from the clinician’s point of view. In this section we try to summarize the results in biomarker studies aiming to find these candidate biomarkers that utilized proteomics.Molecular biomarkers for the diagnosis of MS have long been of great interest to researchers. If we consider the diagnostic criteria of MS, we can realize, however, one such biomarker has been in use for many decades: OGP. Despite being sensitive yet not at all specific to MS, the presence of oligoclonal bands in the CSF have several attributes of importance: (a) it proves the presence of chronic inflammation in CNS; (b) it proves that the disease is disseminated in time; (c) its absence may aid in differential diagnosis ). Despite these, the sensitivity and specificity prevents it from becoming more than a very helpful additional tool. Thus, molecular biomarkers are constantly researched and mainly involve the plasma/serum, the CSF and, in a smaller number of instances, other alternative fluids .One of the first evaluations dedicated to molecular biomarkers for the diagnosis of MS was conducted in a pediatric population. This is not surprising as pediatric MS is quite rare and the other acquired forms of demyelination are more common than in adults, making differential diagnosis sometimes complicated . This evSeveral assessments were carried out on the adult population as well as searching for possible markers differentiating between MS and non-MS patients. Hassan et al. analyzed the CSF of MS patients and control subjects. They identified α-1-antichymotrypsin (SERPINA3), prostaglandin-H2 D-isomerase, desmoplakin and hornerin to be constantly upregulated in MS patients . In 2012Biomarkers that can differentiate between the different clinical courses at the very beginning of the disease are also of special interest. The number of these types of evaluations is also rising. One of the first evaluations on this topic is from 2009 by Linker et al. They assessed both the animal model (EAE) in the later stages and compared the CSF of SPMS patients with RRMS and controls. They found GFAP levels to be upregulated in the spinal cord of EAE mice in the later stages of the disease and an increased level of GFAP specifically in the CSF of SPMS patients compared to both RRMS and the controls . In 2010The last important role of diagnostic biomarkers would be their capacity to differentiate MS from other inflammatory, CNS or systemic disease that may mimic it. There are not many researches dedicated to this topic—we were able to identify only six, albeit their findings are highly important. The most important differential diagnostic problems are usually the so-called “related disorders” to MS: other acquired CNS demyelinating disease that can present similarly to MS, namely, NMOSD, Leber’s Hereditary Optic Neuropathy (LHON) and acute disseminated encephalomyelitis (ADEM). Other, systemic inflammatory conditions, such as Sjögren’s disease or systemic lupus erythematosus (SLE), may mimic MS as well, albeit for them to present as an isolated white matter neurological condition is considered extremely rare; thus, usually, the differential diagnosis causes fewer problems than in the case of NMOSD or LHON. Sometimes other non-inflammatory white matter diseases can present quite similarly to MS at the beginning; however, either the clinical or the radiological (or combined) presentations of these disorders usually have specific distinguishing markers that can help the diagnosis, not to mention the absence of evidence for inflammatory activity. All in all, it is not surprising that the bulk of the few researches on this topic deal with the differences between MS and NMOSD. The first evaluation on this topic using proteomics analysis is from 2012 conducted by Komori et al. . They coAll in all, a high number of potential biomarkers for the diagnosis and the differential diagnosis of MS have been found to date, but most of them are yet to be validated on any level. The biomarker candidates with the greatest potential identified by proteomics, however, seem to be GFAP, CHI3L proteins and SERPINA3 at the moment, based on the reviewed literature.Aside from the pathogenesis and the diagnosis of MS, another aspect has become important: to find biomarkers that can potentially either predict, or at least pinpoint, the time of conversion from one clinical course to another. Data on these type of biological markers evaluated with proteomics are scarce however. Here, we summarize their results.The first proteomic analysis dedicated to identifying biomarkers of conversion from CIS to RRMS is from 2009. In this research, the authors compared the CSF of eight originally CIS patients who remained CIS after 2 years to eight patients who converted into RRMS during that period. They found one protein to be upregulated (serin peptidase inhibitor) and eight proteins to be downregulated  in patients who converted into RRMS as compared to those who remained in the CIS stage . HoweverAn interesting assessment from 2017 identified four neuro-axonal proteins  to be far less abundant in the CSF of patients during their first demyelinating attack than those of the control group . HoweverIn the case of conversion to SPMS, data obtained via proteomics are lacking. The only study we were able to identify regarding the subject is from 2020 by Huang et al. They found Eotaxin-1 (CCL11) to be increased in both the CSF and the plasma of SPMS patients as compared to RRMS patients . It was Naturally, many more studies are needed for further validations; however, there are already a couple of good candidate biomarkers that could predict conversion from CIS to RRMS. Among these, CHI3L1 has the most robust backing data, elevating it to be the best candidate for a biomarker of CIS to RRMS conversion. In the case of conversion to SPMS, however, data are sporadic at best, necessitating further research.Biomarkers that can potentially measure or predict the activity or aggression of the disease would be invaluable in clinical practice. This kind of biomarker could have a direct influence on therapeutic decision making helping to choose the most appropriate therapy for the patient at the onset of MS.However desirable these biomarkers would be, data available on the topic are quite scarce, as we were able to identify only four articles. In 2010 Sawai et al. analyzed the sera of 31 RRMS patients. They found in their assessment the complement C4a fragment to be elevated during relapses and decreased in remission, thus representing activity of the disease . In 2011Despite the scarcity of evaluations, three out of four assessments identified peptides of the complement system, the C4 protein in particular, to be associated with a more severe disease course in both the CSF and sera of the patients. These results suggest C4 to be a good candidate for being a biomarker of disease activity; however, further studies on a larger population are needed for validation.As well as disease activity, the other hallmark process defining MS is progression: the accumulation of disability over time as measured by the EDSS score. Similarly to activity, any biomarker predicting or monitoring progression would be of utmost importance in therapeutic decision making and for the prognosis of the individual patient.Again, similarly to disease activity, research using proteomic analysis to discover biomarkers for MS progression is scarce; however, their results are encouraging. In 2015, Kroksveen et al. found secretogranin-1 to be elevated in the CSF of CIS patients as compared to RRMS and controls as was reviewed above. However, when this result is combined with an earlier study on patients with an average disease course of 16 years that found secretogranin-1 levels to be decreased in that population, this suggests secretogranin-1 to also be a possible marker of disease progression in RRMS ,179. In An interesting subset of research should be noted here as well, albeit concerning disease progression in a looser sense. There are some interesting epidemiological studies implying that ischemic events are more prevalent and result in a higher risk of mortality of MS patients, mainly in the progressive phases of the disease ,190,191.All in all, despite the growing amount of evidence, there is only an enlarging number of candidate molecules for MS progression and no definitive markers so far. However, these promising results show the capability of proteomics in finding new and new possible biomarkers in this field.The regular clinical and radiological follow-up of MS patients is of utmost importance and the core step in the quality management of the disease. However, despite these tools, we can usually only predict the effectiveness of the chosen DMT with a certain level of confidence at initiation, and we are unable to monitor it during treatment aside from radiological and clinical measures, which, by definition, mean there is a new clinical attack, confirmed progression or new MRI lesions, all of which we aim to avoid. Thus, molecular biomarkers that can predict at the beginning or prove during the course of treatment the effectivity of the chosen therapy would be of tremendous help to the clinicians in everyday practice.Research using proteomics are not widespread in this topic either. However, there are some promising data that have emerged showing candidate markers to monitor our existing DMTs more precisely than we are able today. The first such investigation dates back to 2007 and concerns IFN-β treatment. Alexander et al. found 14-3-3, metavinculin, myosin-9, plasminogen, reticulocalbin-2 and-3, ribonuclease/angiogenin inhibitor 1, annexin A1, tropomyosin and Ras-related protein Rap-1A to be elevated in endothelial cells exposed to RRMS sera, and that the level of these proteins may decrease after IFN-β treatment . In 2013There is another important aspect of MS not yet elaborated on in this article. Apart from the pathogenesis and the diagnostic or prognostic markers of the disease, proteomics may be used to uncover potential new targets for therapy.In 2008, Han et al. assessed the brain tissue of deceased MS patients, analyzing the different type of plaques . Their analysis identified tissue factor and protein C inhibitor, both members of the coagulation cascade, are dysregulated in chronic active plaques. After that, they treated EAE mice with hirudin or recombinant activated protein C, that resulted in the decrease in proliferation and inhibition of Th1 and Th17 cytokines in the mice . In 2015Despite there being only a few assessments regarding the identification of new therapeutic targets for MS using the proteomic approach, their results point toward new and exciting pathways and molecular targets to consider. They also prove that proteomics may be a highly effective method for undertaking such research.In the last decade, the management of the disease has been rapidly evolving, and as of today we have reached the state where our  aim is the implementation of personalized medicine. The latest diagnostic guideline and the new phenotypic classification helps us in the fast and sensitive diagnosis of the disease and the identification of the clinical courses, while the therapeutic guideline gives clear recommendations for the use of available DMTs and the criteria of an MS center has already been defined ,46,202. However fast evolving the knowledge about MS is, there are still many aspects of the disease that are in need of new discoveries and innovations. The pathogenesis of the disease is thus far largely unknown, and there are still many aspects of the disease that we are only able to identify or monitor retrospectively  or by the re-appearing clinical or MRI activity, which we would like to avoid. Therefore, from the clinical neurologist’s point of view, there is a dire and growing need for validated biomarkers by which we can predict and effectively monitor the disease in the long term. Thence, methods that can help to identify such markers will always be in the focus of research.Proteomics is a continuously developing discipline of molecular sciences that greatly enhances the possibility of identifying proteins relevant in the neurological sciences, thus meeting the above mentioned requirements. It has been producing more and more data that have led to important new discoveries in the pathogenesis of MS and yielded candidate biomarkers—some with already robust possibility for clinical utility in the future—for many aspects of the disease (summarized in In our review, we aimed to give a summary of the importance of this methodology and a comprehensive review on its results that are, or may be relevant, to the everyday clinical practice in the near future, highlighting the more promising or surprising findings. As this field is under constant exponential evolution, we believe that many more data will emerge in the near future that will further support the findings reviewed here and herald a new and exciting era of personalized medicine in MS.


The invitation for analysis and discussion of these relevant issues was made to me by theAssociação Brasileira de Residentes em Cirurgia Cardiovascular (ABRECCV).With 39 years of experience as a preceptor and 27 years as coordinator of the commissionto prepare the teaching and training programs of the Sociedade Brasileira de CirurgiaCardiovascular (SBCCV), I accepted this honorable mission.. In the past, wesailed in calm waters, operating on patients with various structural heart diseases withsurgical indication established by medical science and contained in current guidelines,when new facts appeared with great potential for changing directions. Cardiologists,stimulated by technological advances in their field, have moved from diagnosis tointerventions, taking on a new role as interventional cardiologists. With the mastery ofthese skills, they invested in the treatment of ischemic heart disease, treating somelesions of the coronary arteries using angioplasty and intraluminal stents. They startedto defend these methods with the concept of being less invasive compared to the greaterexposure of conventional surgery. Several structured studies comparing the twoapproaches provoked different interpretations by the groups involved. At the end of thestudies, the analysis of primary outcomes maintained the surgery with the bestprognosis, even treating patients with higher risk scores and multi-vessel and morecomplex lesions, and the systematic use of anastomosis of the left internal thoracicartery in the anterior interventricular artery. Even though these results are includedin all guidelines of the main specialty societies, interventional cardiology continuesto treat a significant portion of these patients. These facts, continued, provoked a huge reduction in surgicalprocedures of myocardial revascularization, the most frequent surgical procedure in ourspecialty. The SBCCV’s MRPin Cardiovascular Surgery was developed in accordance with Resolution 1785/2006 of theConselho Federal de Medicina (CFM) of the Associação MédicaBrasileira (AMB) and the Comissão Nacional de Residência Médica(CNRM) of the Ministério da Educação (MEC). In that same year, thiscommission, through Resolution number 2 (of 05/17/2006), admitted it as a NationalMedical Residency Program in Cardiovascular Surgery, but with two years of prerequisitein general surgery, making the training period extremely long. The immediate reflectionof these decisions was the alarming drop in candidates for training in the specialty,occupying only 24.2% of the 323 vacancies offered each year, and it became urgent toreverse this disastrous situation. We had a previous successful experience, whichcontinues to this day, with SBCCV’s Teaching and Training Centers, which have alwaysbeen of direct access and with a significant number of candidates, proving the negativeimpact of the inclusion of the prerequisite[4,. Then, a wave ofinnovation using new technologies introduced a series of procedures with less invasivepotential, via mini-access and percutaneous catheters, occupying an important space inthe treatment of valvular, aortic, and congenital heart diseases, implants of mechanicalcirculatory assistance devices, and in the treatment of arrhythmias. In other words,they reached the full spectrum of our performance. It has become urgent to acquireexpertise in these new forms of treatment. Experienced surgeons with a broad vision of the future encouragedtheir peers to acquire skills in catheter procedures[7,. With thesupport of large international institutions, including Brazil, they developed a set ofnew minimally invasive techniques increasing the therapeutic arsenal of surgerybenefiting a significant number of patients[9-. Thereformulation of the CNRM collegiate, assuming the surgeon Rosane Leite de Melo asexecutive secretary, accepted the SBCCV’s arguments, approving the direct access programexcluding the prerequisite of general surgery and establishing five years for completionof the residency in the specialty.The president of SBCCV from 2016 to 2017, professor Fábio Jatene, with dedicationand pertinacity led this important and decisive mission, assisted by Professors HenriqueMurad, Renato Kalil, and Rui Almeida, members of its board, and Doctor Rosane Leite deMelo, executive secretary of MEC’s CNRM, who played an effective role in this outcome.It was a big and decisive step, because, immediately, the interest in attending ourresidency was renewed, translated by the expressive increase of candidates. Braziliancardiovascular surgery is recognized by the international community for the skill andcreativity of its surgeons, and for the contributions of new surgical techniquesroutinely used by surgeons around the world. This far-reaching legacy initiated by ourpioneers is kept alive by the dedicated work of new and creative actors.The SBCCV’s medical residency program (MRP) is a living organism that has a past,present, and future, and is modified by the incorporation of advances in the specialty.The first step in changing a training program is to identify why this was necessary.This task is essential, so we don’t make mistakes, and it necessarily leads us to knowthe past, and whoever doesn’t will be giving up having the present and thefuture. The new format opened up agenerous space for mastering the essential procedures to compete proficiently in thecompetitive job market. The strong emphasis on programmed internships in Cardiology,Hemodynamics, Thoracic Surgery, and Vascular Surgery, repeated in the initial fouryears, plays a powerful role in acquiring new skills and competences. So, we have anexcellent program whose integrality of execution will only be possible in hospitalservices that have, in addition to basic cardiovascular surgery, the full spectrumof subspecialties. This profile includes surgery for congenital heart diseases,heart transplantation, implantation of circulatory assist devices, valve andcoronary surgery using video-assisted or robotic mini-access, and endovasculartreatment of diseases of the aorta and its branches using percutaneousendoprostheses. Forthis to be possible, the institution must have qualified professionals,state-of-the-art imaging equipment, hybrid rooms, multidisciplinary teams, andpreceptors with full mastery of these technologies, with a satisfactory volume ofcases. We have fewinstitutions with this profile in Brazil. The new program, sensitive to these facts,offers alternatives to solve this scenario through an academic mobility process,which allows and encourages the resident to seek new skills and competences wherethey are available, during their training period or in additional years of training.In Brazil, training in basic cardiovascular surgery, without considering all theadvances of new procedures, is performed with a good level of proficiency in allservices with accredited residency programs. Residents from these services have areasonable job market, as all surgeons, including here those who will seek newskills, and they need this essential basic training. After all, not every patient isa candidate for mini-invasive techniques due to various anatomical factors, amongother impediments. The distribution of the workload covering various activities isan important factor that facilitates the performance of residents. This programcomplies with the regulations issued by the CNRM, which requires 2888 hours peryear, including 10% to 20% for theoretical activities and 80% to 90% for in-servicetraining. The SBCCV’s commission, in an innovative process, redistributed these14,440 hours over five years, placing emphasis on tutored teaching in the operatingroom, allocating 60% (8640 hours), and 5% (720 hours) in the operative techniquelaboratory for training in simulators. Although all the activities of the programare very useful and necessary, none surpasses in importance the operative act in theoperating room with the supervision of the mentor.The pedagogical structure of this new teaching and training program assimilated thesetransformative innovations with the aim of producing a new model of cardiovascularsurgeon. It comprehensively includes all theoretical and practical cognitiveframework from diagnosis to surgical treatment by mini-invasive and conventionaltechniques. With a clear description of the primary and secondary objectives and acareful selection of skills, it has become a powerful instrument for permanentconsultation, guiding the performance desired by the resident. The first year has been completely restructured,the resident is exposed to the fundamentals of cardiovascular surgery throughrotations with an emphasis on diagnostic methods in clinical cardiology,hemodynamics, imaging methods, vascular surgery, thoracic surgery, general surgery,extracorporeal circulation, and intensive care unit. The objective of studying theseareas is to provide a basic and general view of the universe of the diagnostic andtherapeutic arsenal available for the management of patients. From the second to thefourth year, the primary objective is to offer, in a sequential and progressive way,the deepening of the cognitive domain of cardiovascular diseases and the forms ofconventional and mini-invasive surgical treatment. I identify that there is a highconcentration of theoretical content, which to be assimilated will require extrahours of study invading the moments destined for rest and leisure. The fourth andfifth years were planned by placing a strong emphasis on the field of practicalwork, becoming the engine that enshrines know-how. The offer in the second semesterof these years for the resident to study full-time in an area of interest, aiming toconsolidate or acquire new skills, constitutes an effective tool to seekproficiency, signaling one of the great novelties of this program. This performancewill only be possible with the effective implementation of a robust mobility system,through scheduled rotations between the services enabled by the SBCCV or the CNRM.At the end of five years of training, some areas of complex procedures will requirean additional year or two of training to acquire proficiency in their completedomain. In our view, they can be carried out through fellowship courses in Brazil orat international centers certified through agreements signed with theSBCCV. The opinion ofresidents who complete the five regimental years and of the preceptors of this newprogram will be a valuable tool to correct the trajectory, considering what isfeasible and where are the difficulties and failures of its pedagogical structure.The individual performance evaluation system is well structured; however, I think itcould take place every six months, simplifying the process. It would maintain thestated virtues, allowing the resident to correct directions when necessary. Thelevel of proficiency of the graduates of the program, working in the community, willgive us the answer we want to know, if we were able to produce a new model ofcardiovascular surgeon.The sum of hours spent by residents in this activity is one of the most expressivemarkers of the program’s quality. Mastery of theoretical cognitive content enablesresidents to know how to say and mastery of practical content enables them to knowhow to do. The curriculum of this new program indicates all these steps in order toprepare cardiovascular surgeons in these areas. The competence matrix set out foreach year of residency, defining the general and specific objectives, constitutes apowerful instrument of the expected performance at each stage. Observing carefully,they will identify that each year from the first to the fifth has a pedagogicallogic of progressivity with greater exposure both in the offer of theoreticalcontent and in the levels of practical activities[17,. In recent data from the SBCCV,it was found that 55% of Brazilian cardiovascular surgeons in activity are over 60years of age. With rare exceptions, most of them will continue to competentlyperform conventional surgery that covers the entire spectrum of cardiovasculardiseases. Younger surgeons who are proficient in the new procedures will have ampleworkspace. Other options are to invest in subspecialties where there is a chronicshortage of surgeons and high demand from patients, such as in the treatment ofcongenital heart diseases where the waiting list is immense. In Brazil, around 80%of the 27 thousand children with heart disease that are born each year should betreated, but only half are operated on, the rest increase the waiting list with highmortality. In our country, there are 68 services that treat these patients, and itis imperative to double the number of surgeons in this important subspecialty.Another sensitive areas with a shortage of services and surgeons is the treatment ofadvanced heart failure through heart transplantation and implantation of circulatorysupport devices and the treatment of arrhythmias through the implantation ofmulti-site pacemakers and cardioverter/defibrillators. So, there is a wide field ofwork for surgeons with mastery in the treatment of these patients. But only thosequalified to know how to do it will compete for this important work space.The Brazilian population shows a substantial increase in the age group of people over65 years of age, where ischemic, valvular, and vascular degenerative cardiovasculardiseases are more prevalent, more complex, and at greater risk for invasiveinterventions. These patients are special candidates for the use of less invasiveprocedures performed by multidisciplinary teams through mini-access or percutaneouscatheters guided by imaging equipment in hybrid rooms with a significant reductionin operative risk. This scenario is no longer future, it is happening now and withsolid signs of growth and application also in cases of medium risk in youngerpatients (below 60 years of age) with promising results. New technologies in fulldevelopment are signaling the need for surgeons with a new trainingprofile.An important law of life determines that survival is not the preserve of thestrongest, but of those who have the greatest capacity to adapt. It will beessential to become competent in the execution of these new procedures based on newtechnologies[18,. This will require more trainingtime of one to two years invested in the subspecialties of cardiovascular surgeryafter completion of residency.The universe of this scenario no longer allows one to be a specialist in severalareas of the specialty, the volume of new information and new techniques changesevery three months and requires in-depth, very high competence, and absolute masteryof the procedures of the chosen sub area. It is necessary to be part of a Heart Team not as anexpendable sidekick but as an essential member in decision making. In the managementof high-risk patients by a multidisciplinary team, performed in hybrid rooms, it isnecessary to be one of the main actors respected for their competence and totalmastery of the surgical act and not seen as a secondary professional in theprocess. New surgeonsshould maintain the habit of permanent study and use the continuing medicaleducation courses provided by medical societies, industry, and institutions as anupdating tool. Also, includesystematic training in very high-fidelity simulators to maintain a high level ofproficiency, especially when technical variants in their area of expertisearise. Finally, do notforget that by training they are the only professional in this scenario qualified totreat complications that require conversion to the open method. Those qualified for theseprocedures will have a broad and heated job market, due to assimilation intotraditional service teams, due to a significant increase in demand, and due to thechoice and preference of patients.The first challenge is to accept the paradigms that have transformed the specialty byembracing and understanding the changes. It is not easy to radically change fromthoracotomy and suture techniques to mini-access or percutaneous procedures withguides, catheters, and imagesI conclude this text by thanking all preceptors and mentors that for many years withtotal dedication, competence, and sense of responsibility continue to trainBrazilian surgeons.


Large skull defects present a reconstructive challenge. Conventional cranioplasty options include autologous bone grafts, vascularized bone, metals, synthetic ceramics, and polymers. Autologous options are affected by resorption and residual contour deformities. Synthetic materials may be customized via digital planning and 3D printing, but they all carry a risk of implant exposure, failure, and infection, which increases when the defect is large. These complications can be a threat to life. Without reconstruction, patients with cranial defects may experience headaches and stigmatization. The protection of the brain necessitates lifelong helmet use, which is also stigmatizing.Our clinical trial will formally study a hybridized technique's capacity to reconstruct large calvarial defects.A hybridized technique that draws on the benefits of autologous and synthetic materials has been developed by the research team. This involves wrapping a biodegradable, ultrastructured, 3D-printed scaffold made of medical-grade polycaprolactone and tricalcium phosphate in a vascularized, autotransplanted periosteum to exploit the capacity of vascularized periostea to regenerate bone. In vitro, the scaffold system supports cell attachment, migration, and proliferation with slow but sustained degradation to permit host tissue regeneration and the replacement of the scaffold. The in vivo compatibility of this scaffold system is robust—the base material has been used clinically as a resorbable suture material for decades. The importance of scaffold vascularization, which is inextricably linked to bone regeneration, is underappreciated. A variety of methods have been described to address this, including scaffold prelamination and axial vascularization via arteriovenous loops and autotransplanted flaps. However, none of these directly promote bone regeneration.We expect to have results before the end of 2023. As of December 2020, we have enrolled 3 participants for the study.regenerative matching axial vascularization technique). This technique may be used to reconstruct skull bone defects that were previously thought to be unreconstructable, reduce the risk of implant-related complications, and achieve consistent outcomes in cranioplasty. This must now be tested in prospective clinical trials.The regenerative matching axial vascularization technique may be an alternative method of reconstruction for large calvarial defects. It involves performing a vascularized free tissue transfer and using a bioresorbable, 3D-printed scaffold to promote and support bone regeneration (termed the Australian New Zealand Clinical Trials Registry ACTRN12620001171909; https://tinyurl.com/4rakccb3DERR1-10.2196/36111 Cranioplasty, as a procedure for reconstructing cranial defects, has been around for thousands of years. Despite significant advances in technology and extensive research into bone biology, the reconstruction of the calvarium still poses a significant challenge for surgeons ,2. SinceThese issues with autologous bone grafts have prompted research into suitable synthetic alternatives; metals, synthetic ceramics, and polymers are all advantageous in different ways but have significant fallbacks that relate to infection, malleability, and in situ inflammatory or exothermic reactions ,9. A bioThe success of these cellular impregnation techniques for promoting acceptable osteogenesis has been shown to be directly linked with the vascularity of the constructs used ,18. The Throughout the literature, there is a clear consensus that an ideal cranioplasty graft should have the following: (1) long-term mechanical protection for the brain and meninges until the host bone regenerates, (2) acceptable cosmetic contouring, and (3) graft materials that promote bone growth through osteoconductive and osteoinductive mechanisms that are governed by degradation kinetics and biological interactions. Moreover, if the prosthesis remains, it should not cause undue complications or patient inconveniences.The composite PCL-TCP scaffold acts as a synthetic analogue of two major bone constituents—hydroxyapatite and collagen. As cranioplasty materials, PCL-TCP fulfill the above criteria by retaining strength and promoting osteoconduction over extended remodeling periods via consistent degradation mechanics and with minimal adverse effects. As a consequence of advancements in tissue engineering, the demand for customizable implants is understandably intensifying. This case highlights the potential of harnessing emerging biomedical technologies and 3D tailoring to meet individual and specific clinical needs.In a case report published by Yogishwarappa et al  in 2016,Osteoinduction and, as a consequence, osteogenesis are intricately linked to angiogenesis in normal fracture healing . CorticoInvestigations into periosteal flaps as sources of axial vascularization are well documented in animal models. Nau et al  comparedThe research by our group at the Centre for Regenerative Medicine  has focused on the reconstruction of critical-sized bone defects for more than 1 decade ,17,27. IAlthough osteoinductive scaffolds have been trialed clinically by a number of authors -35, limiThe regenerative capacity of vascularized corticoperiosteal tissue is well recognized ,37. It hBetween 2016 and 2018, we undertook a preclinical study that evaluated the concept of RMAV by using a corticoperiosteal flap from a sheep’s hind limb and a 3D-printed mPCL-TCP scaffold to reconstruct 6- and 3-cm intercalary defects of the tibia . This woGiven these successes in preclinical research and our first-in-human case, we feel that the logical next step for the emerging RMAV technique should be a robust feasibility clinical trial examining the behavior of the mPCL-TCP implant and postimplantation bone healing. Once appropriate outcome measures are clearly defined, it may then be appropriate to proceed to a randomized clinical trial in which RMAV is compared to other clinical techniques for a given bone defect.The use of an mPCL-TCP scaffold, in conjunction with a corticoperiosteal tissue transfer, is a safe and effective approach to reconstructing critical-sized bone defects in the calvarium.The primary objectives of our trial are to (1) determine the feasibility and efficacy of using an mPCL-TCP scaffold, in conjunction with a vascularized corticoperiosteal tissue transfer, for the reconstruction of calvarial bone and (2) determine the clinically relevant functional outcomes that follow the reconstruction of an acquired calvarial defect by using an mPCL-TCP scaffold in conjunction with a vascularized corticoperiosteal tissue transfer.The secondary objective is to collect data to allow for the later evaluation of the cost-effectiveness of this approach and a view of its applications across a broader range of clinical situations.Our study will be a single-arm feasibility trial that evaluates the outcomes of using an mPCL-TCP scaffold, in conjunction with a vascularized corticoperiosteal tissue, in participants with acquired defects of the calvarial bones of the skull resulting from trauma, malignancy, or infection. The study will capture data that will be used to inform the design of future clinical trials in this area.polycaprolactone, which is bioabsorbable, is malleable, is slow to degrade, and possesses mechanical strength that is similar to that of trabecular bone. The product will be manufactured by using 3D printing technology that is precise and allows for the customization of shape and geometry. The unique, 3D-printed, biomimetic microarchitecture of the 3D scaffolding, which is contained within Osteopore products, allows for the infiltration of cells and blood vessels, of which both play a key role in wound healing and tissue repair.The mPCL-TCP scaffold that will be used in the study will be manufactured by the trial sponsor—Osteopore International Pte Ltd (Singapore). Osteopore products are made of a US Food and Drug Administration–approved polymer (K051093) called The study will be an open-label, single-arm feasibility trial that will be jointly coordinated by the investigators at the Princess Alexandra Hospital (PAH) in Woolloongabba , the Herston Biofabrication Institute, the Australian Centre for Complex Integrated Surgical Solutions at the Translational Research Institute , and the Centre for Regenerative Medicine at the Institute of Health and Biomedical Innovation in Kelvin Grove . With the aim of calvarial reconstruction, the study population will include any patient with a calvarial defect that is amenable to reconstructive approaches that involve using the Osteopore implant, following discussions by the multidisciplinary team (MDT) of investigators.Our inclusion criteria are as follows:Acquired defect of the calvarium that is suitable for reconstruction by using a PCL-TCP scaffold system and performing a corticoperiosteal tissue transferPatients aged >18 years and <55 yearsPatients aged >55 years may still be eligible for the trial after an assessment by and at the discretion of the investigators, and documentation to this effect will be provided by the clinic for the trial documents pertaining to such patientsPatients who are willing and able to comply with the study requirementsPatients who are eligible for undergoing magnetic resonance imaging Patients or their guardians are capable of providing valid informed consentOur exclusion criteria are as follows:Active infection at the time of study inclusion Patients or their guardians are unwilling or unable to provide fully informed consentPatients with a known history of immunodeficiency, including a history of HIV, concomitant systemic corticosteroid therapy, chemotherapy, synchronous hematological malignancy, or other causes of a secondary or primary immunodeficiencyPatients with a known severe concurrent or intercurrent illness  that would, in the opinion of the primary investigator, compromise their safety or compliance or interfere with the interpretation of study resultsWomen who are currently pregnant, are breastfeeding, or are planning to become pregnant within 2 years after the reconstruction surgeryWomen of childbearing potential who are not using an appropriate contraceptive methodPatients who are ineligible for undergoing MRIPatients with a life expectancy of <36 months.Patients who are unable or unwilling to comply with the study requirementsThis feasibility trial will recruit a total of 10 patients.As a part of their clinical management, patients with acquired calvarial defects from the neurosurgery clinic or the skull base/head and neck clinic at the PAH will be reviewed as candidates for cranial reconstruction via the Osteopore implant by the MDT. Referrals to this process will be accepted from throughout Queensland via standard pathways, and national out-of-catchment referrals will be considered for special circumstances in which the PAH has unique expertise. The specific conditions assessed may include acute and subacute pathologies  or chronic pathologies .The relevant specialties that will be involved in the MDT review and decision-making process include infectious diseases, plastic and reconstructive surgery, neurosurgery, infectious diseases, and engineering. The MDT will determine the best treatment option for each patient. Should cranial reconstruction by using an Osteopore implant be recommended by the MDT, the patient’s treating specialist will discuss the case with the coordinating principal investigator, and the extent to which the potential participant satisfies the trial’s inclusion and exclusion criteria will be determined collaboratively. Written informed consent will be obtained following the MDT’s decision and prior to the conduct of the cranioplasty. Informed consent must be completed prior to any study-related activities.Patients will be followed up for at least 24 months from the time of initial reconstruction. Given that the PAH collectively sees around 5 patients per year with significant bone defects, the recruitment phase will take place over 2 to 3 years to recruit a total of 10 patients for the feasibility analysis.In addition to the prospective recruitment pathway detailed above, patients who have undergone cranioplasty via the Osteopore implant may also be recruited into the study at the discretion of the sponsor and coordinating principal investigator.Prior to deciding on a treatment pathway, medical imaging will be conducted as a part of each patient’s standard clinical management, which may include CT and/or MRI scans of the head and neck, as well as white cell–labeled, whole-body bone scans. The imaging results will inform the clinical assessment performed by the neurosurgeon or the skull base/head and neck surgeon involved in the care of the patients and inform the MDT review. Clinical notes, including medical histories, will also be generated as a part of the clinical care process of patients during their clinical management. Imaging data and clinical notes that relate to the defects among patients and are collected prior to informed consent will be made available to the study participants as a part of the informed consent process.A description of the patient journey is summarized in The trial-related interventions will focus on capturing defined functional outcomes and, consequently, will require the collection of data at specific time points. CT and/or MRI scans of the head and neck will be used to identify complications and establish clinical and radiological evidence of union at 1, 12, and 24 months after surgery. As performing 2 CT scans in the first year during the postoperative follow-up period is standard clinical practice, the amount of ionizing radiation to which the participants are exposed will not exceed the amount of radiation that patients typically receive during standard clinical care. Additional CT and MRI scans may be performed during the follow-up period in accordance with patients’ clinical needs.The other research-related functional assessments will include the administration of the Quality of Life After Brain Injury (QOLIBRI) and 36-item Short Form Quality of Life (SF-36) questionnaires at prereconstruction and at 1, 12, and 24 months after surgery.The key primary end points for evaluation in our single-arm study are the time to the formation of stable, regenerated bone that is sufficient for protecting the brain  and patient-reported outcomes. These primary end points serve as surrogate markers for satisfactory bone healing but, more importantly, are clinically useful for and relevant to the study goal and overarching purpose of the intervention. Functional outcomes are more difficult to measure reliably and are therefore secondary outcomes, which will be measured with the QOLIBRI and the SF-36 questionnaires . The schThe statistical analysis of the data will be undertaken by the Queensland Facility of Advanced Bioinformatics (QFAB). QFAB personnel will use REDCap (Research Electronic Data Capture) software (Vanderbilt University) to design and validate an electronic data capture system for use in the trial. Deidentified data will be entered into the REDCap-based electronic data capture system by a member of the research team after the coordinating principal investigator or delegate has certified each case report form (CRF). The database will contain validation ranges for each variable to minimize the chance of data entry errors. An audit trail will be created to maintain a record of the initial entries and changes made, the reasons for changes, the times and dates of entries, and the usernames of the people who made the changes. Data queries will be raised, and missing data or suspected errors will be resolved prior to locking the database and performing the analysis.All patients who are registered for the trial will be accounted for in the (intention-to-treat) analysis. For retrospectively recruited patients, all data points may not be available for all assessments, or data collection may have occurred outside of the trial-specific window . In such cases, these subjects will not be evaluated for a particular analysis unless the number of data points required for the analysis is enough, or a trend can be extrapolated from the data that were collected outside of the trial-specified window.A quantitative analysis that relates to the evaluation of the cost-effectiveness of this approach will not be undertaken as a part of this study, as the data set will most likely be too small to achieve statistical significance. Instead, the outcome measures that have an impact on the financial burden for treating patients will be combined with data from other similar trials that are conducted in the future, and the analysis of health economics data will be undertaken at that point.P<.05. Data will be analyzed by using SPSS for Windows version 22 (IBM Corporation).Statistical analyses of descriptive statistics for the demographic, primary, and secondary outcomes at each time point will be conducted. A comparison analysis of the questionnaire results at each time point and a univariate Cox regression analysis of the time to weight-bearing for the affected limbs will be performed due to the small sample size. Statistical significance will be defined as The study represents a high-quality clinical study in which bias will be kept to an absolute minimum. The study will be heavily controlled with the well-defined inclusion and exclusion criteria that will ensure that the number of patients with confounding features will be reduced, thereby effectively minimizing sources of selection bias and increasing the homogeneity of the cohort under investigation.The follow-up period is 24 months. Generally, we would expect to see sufficient bone regeneration for most extensive defects by this time. Ongoing care will be provided in accordance with the recommendations of the treating surgeons and other members with relevant specialties, as appropriate.The trial will be conducted in accordance with the principles of the Declaration of Helsinki, Notes for Guidance on Good Clinical Practice (CPMP/ICH/135/95), as adopted by the Australian Therapeutic Goods Administration in 2000, and in accordance with the National Health and Medical Research Council’s National Statement on Ethical Conduct in Research Involving Humans . A copy It is the responsibility of the investigator to obtain written informed consent from each individual who participates in the study after an adequate explanation (in lay terms) of the aims; methods; objectives; and potential discomforts, risks, and benefits of the study is given. The investigator must also explain to the subjects that they are completely free to refuse to enter the study or withdraw, without prejudice, from the study at any time. Before enrollment into the study, each prospective candidate will be given a full explanation of the study. Individuals who are eligible and wish to participate will be provided the trial’s participant information and consent form (PICF) prior to participation. The PICF details all of the relevant aspects of the trial procedures. Potential participants will be given time to read through the information and ask any questions. The formal consent process will be undertaken by the principal investigator or the associate investigator and will be documented by the trial coordinator. The PICF will be submitted for approval to the Human Research Ethics Committee of the PAH. Participants will be provided with a copy of their signed PICF.As of December 2020, we have enrolled 3 participants for the study. We expect to have results before the end of 2023.We aim to evaluate the potential of tissue engineering with a bioresorbable, 3D-printed scaffold and autologous vascularized tissue transfer in the reconstruction of acquired calvarial defects. It is essential to undertake a prospective feasibility trial that formally explores this technique to establish its safety and efficacy. This trial will offer critical baseline data against which current and future implants can be compared. Tissue regeneration could be enhanced via scaffold refinements, including additives such as growth factors, osteoprogenitor cells, and vascular networks -39. HoweThe project, as a whole, has a number of benefits for both individuals and society at large. It is expected that the results of our open-label feasibility trial will provide additional evidence on the effectiveness of the RMAV treatment approach for patients with calvarial defects for which contemporary surgical management may have a greater risk of failure or complications ,43.regenerative matching axial vascularization technique). This technique may be used to reconstruct skull bone defects that were previously thought to be unreconstructable, reduce the risk of implant-related complications, and achieve consistent outcomes in cranioplasty. This must now be tested in prospective clinical trials.The RMAV technique may be an alternative method of reconstruction for large calvarial defects. It involves performing a vascularized free tissue transfer and using a bioresorbable, 3D-printed scaffold to promote and support bone regeneration (termed the


Digital health is a promising tool to support people with an elevated risk for atherosclerotic cardiovascular disease (ASCVD) and patients with an established disease to improve cardiovascular outcomes. Many digital health initiatives have been developed and employed. However, barriers to their large-scale implementation have remained.This paper focuses on these barriers and presents solutions as proposed by the Dutch CARRIER  consortium. We will focus in 4 sections on the following: (1) the development process of an eHealth solution that will include design thinking and cocreation with relevant stakeholders; (2) the modeling approach for two clinical prediction models (CPMs) to identify people at risk of developing ASCVD and to guide interventions; (3) description of a federated data infrastructure to train the CPMs and to provide the eHealth solution with relevant data; and (4) discussion of an ethical and legal framework for responsible data handling in health care.The Dutch CARRIER consortium consists of a collaboration between experts in the fields of eHealth development, ASCVD, public health, big data, as well as ethics and law. The consortium focuses on reducing the burden of ASCVD. We believe the future of health care is data driven and supported by digital health. Therefore, we hope that our research will not only facilitate CARRIER consortium but may also facilitate other future health care initiatives. Atherosclerotic cardiovascular disease (ASCVD) remains one of the leading causes of death worldwide  and is aHowever, a recent survey from EUROASPIRE V investigators showed that “a large majority of patients at high [AS]CVD risk fail to achieve lifestyle, blood pressure, lipid, and glycemic targets” . The limeHealth has the potential to reach a wide audience of people at risk and support patients to adopt a healthy lifestyle and reduce their cardiovascular risk -7. NeverOne of the barriers to eHealth implementation is a mismatch between the end product and the needs of its end users -10. It iIn addition to cocreation with relevant stakeholders, implementation also depends on availability and communicability of data between stakeholders involved in the prevention of ASCVD. The availability of data is essential for innovative clinical prediction models (CPMs) for the early identification of people at risk, accurate risk estimation, and guiding interventions .Unfortunately, data are scattered among the stakeholders, and thus, not readily available. Therefore, a mature data infrastructure connecting the stakeholders needs to be developed. A federated data infrastructure using the Personal health Train  is a proFinally, successful implementation of digital health interventions requires consideration of ethical and legal demands for the aforementioned data infrastructure. Therefore, an ethical and legal framework for responsible data handling in health care needs to be instigated.The Dutch CARRIER  consortium  consistsIn this paper, we will discuss the aforementioned barriers and propose the following practical solutions for the implementation of digital health to reduce the burden of ASCVD: (1) description of the development process of an eHealth application using cocreation with relevant stakeholders, which enhances the adoption of the end product by its end users; (2) presentation of the modeling approach for two innovative CPMs for the early identification of people at risk of developing ASCVD, accurate risk estimation, and guiding interventions; (3) description of a federated data infrastructure using the Personal Health Train to connect relevant stakeholders; and (4) discussion of an ethical and legal framework for responsible data handling in health care.To increase the likelihood of successful adoption of the end product by its end users, the user-centered design approach—“design thinking”—will be applied ,15. DesiWithin the first 2 phases , we used cocreation to describe our ideal digital health solution for ASCVD. Essential elements of this solution are as follows: a CPM for risk estimation, personalized risk communication, personalized treatment goals, individualized eHealth modules to guide and monitor treatment and outcomes, and the use of a federated data infrastructure to connect different organizations involved . These eIntegration of CPMs in a digital health solution enables the use of relevant and readily available data from different organizations to identify people at risk. After calculating the risk, this will be visualized and communicated according to the preferences and level of understanding of the individual. This information supports the patient and health care professional to set tailored goals using shared decision-making. The optimal format and visualization for risk communication is further examined and is therefore part of the objectives of CARRIER.As different subgroups of people have a different adherence to lifestyle interventions, eHealth modules need to be adapted toward a personalized approach . When ineHealth modules that support patients in achieving their goals will be available within the eHealth solution for cardiovascular risk factors, such as smoking, hypertension, diabetes, and hypercholesterolemia, and additionally, for medication adherence, a healthy diet, physical activity, and stress reduction. The modules should also provide the possibility to monitor the effect of the interventions by (automatic) collection of relevant data. Activity trackers, for example, can be used to obtain insight into the physical activity of the patient. The modules should provide personalized feedback to the patients and their health care professionals. Monitoring of the goals can assist the patient and health care professional to guide the timing and frequency of medical follow-up. Relevant outcomes should be collected and used to improve the content of the eHealth modules and the risk estimation of the CPMs. Besides the first 2 steps  of the design thinking process, the other 3 steps include the following: ideate, prototype, and testing. The testing phase will include an evaluation with the involvement of end users. Thereby, the testing phase provides feedback and may lead to reevaluation of the proposed solution. To ensure maximal implementation, the eHealth solution needs to be integrated into the workflow of care pathways .The early identification of people at risk for ASCVD can be supported by CPMs. However, current CPMs, such as Framingham or SCORE, only use conventional patient characteristics for their risk estimation . To imprTwo CPMs will be constructed in CARRIER. The first model aims to identify people at risk to develop ASCVD. The second model aims to guide interventions for those at a high risk or with an established ASCVD. We will refer to the first model as the screening model and to the second model as the intervention model.Consensus on which conventional and nonconventional risk factors should be included in the models will be reached through a Delphi study  by experThe screening model will be based on federated learning (explained in the next section) using data from three different organizations: hospitals, general practices, and the national office for statistics . Data from the hospitals and general practices include electronic health record (EHR) data from individual patients. EHR data are not systematically gathered, resulting in many possible sources of bias  , which wRegarding the intervention model, we plan to make use of data of a regional observational cohort study in which clinical and lifestyle data are being collected . These dIn terms of statistical modelling techniques, we plan to use (1) regression models; (2) Bayesian networks, which suit well to causal graphs and provide an intuitive and explainable framework where data can be combined with expert knowledge ; and (3)When implementing the screening and intervention model, we anticipate a deterioration of the models’ performance over time due to shifting data distributions . TherefoThe two main issues of using medical data for prediction modelling are poor quality and scattering across different organizations. CARRIER aims to tackle these problems by following the Findable, Accessible, Interoperable, and Reusable (FAIR) data principles  and by dTo develop our screening model, we need to combine data from different organizations. Currently, relevant and potentially privacy-sensitive data from different organizations need to be shared to a central database before they can be analyzed. However, growing awareness of privacy and data ownership–related ethical issues have led to growing legal restrictions on data sharing. This is noticeable under the current legal regimens (more details are provided in the next section).In the last few years, federated learning has risen to prominence to analyze distributed data, for example, to train machine learning models ,37. AlthData from hospitals, general practices, and SN will be used to develop the screening model for ASCVD. Hence, data on each individual are distributed across different organizations. This is termed ‘vertically partitioned’ (or ‘heterogeneous’). Federated learning on vertically partitioned data presents a unique set of challenges. The first is privacy-preserving record linkage, that is, linking records that correspond to the same individual across different data sets, without revealing any sensitive information . Given tAfter matching the individual records, the main challenge is to perform data analysis on different sources without each party revealing their data to the other parties. Secure multiparty computation (SMC) is a subfield of cryptography that allows a set of parties (or organizations) to perform calculations with their private data without revealing these data to the other parties . A technAfter requested analyses are performed within the federated data infrastructure, the degree of privacy sensitivity of an analysis can be represented by ε-differential privacy . This caIn summary, in CARRIER, we are developing a federated, FAIR data infrastructure. This infrastructure allows us to train models on vertically partitioned data and ensures that our analyses preserve privacy by means of SMC techniques and ε-differential privacy.CARRIER concerns the processing of different medical, lifestyle, and other personal data, held by different organizations, that relate to citizens. These data are collected for a range of different purposes, but the processing for CARRIER involves the processing of newly gathered data as well as the processing of already gathered data for the prevention and treatment of ASCVD. This means that the processing relies on the manner in which the data have been gathered in the first place and how the different applicable legal regimes impact upon that processing.CARRIER is a project primarily taking place in the Netherlands. Therefore, it is subject to the European Union General Data Protection Regulation (GDPR), which has direct effect in European Union Member States’ law and the national law implementing the GDPR. The implementing law enables the Netherlands to make choices in relation to discretions contained in the GDPR. Alongside the personal data protection laws, the law relating to medical devices must be taken into consideration, as CARRIER seeks to create a digital health solution. SN is a partner in the project and holds one of the data sets that is key to the development of the project. The rules under which personal data held by SN can be accessed or processed by third party partners is strictly governed under the SN act. Finally, besides legal considerations, there are ethical considerations, particularly in relation to ‘nudging’ people to adopt particular behaviors , and more broadly, about the ethics of individuality and solidarity in relation to the use of personal data for developing novel CPMs for ASCVD.Federated learning, as is explained previously, enables communication of pseudonymized data from different organizations. Federated learning might therefore provide safeguards and techniques that enable the sharing of nonidentifiable answers to questions asked of the data between the stakeholders, thereby contributing to public health while respecting individuals’ privacy. However, how this federated data infrastructure can be organized and accepted within the requirements of law and ethics is one of the goals of CARRIER.In order to make this assessment, CARRIER follows 3 broad phases. First, it ensures that the research undertaken—particularly in relation to the development of CPMs using already gathered data—conforms to the law as it is currently understood. Second, it identifies alternative interpretations sustainable in the law to ensure the future operation of the digital health solution and the continuing research. this part acknowledges that GDPR  presents a number of options for, for example, processing data in the public interest. Further, the operation of informed consent is far from clear in GDPR. Given that there are legitimate options available for the interpretation of GDPR, CARRIER is exploring how those interpretations of the law can work in relation to the work of the project. One aspect of this exploration is to present to different publics  the dilemma that citizens want both new and effective treatments that are dependent upon big data processing techniques, and at the same time, they want control of their privacy. This public engagement produces a set of answers that feeds into the last phase. Last, it engages with regulatory authorities, whereby CARRIER will present to the European Data Protection Board and the Dutch Supervisory Authority the findings of the second phase of the work. The aim is to produce a dialogue around the interpretation of GDPR that is open to different understandings of the central dilemma (as explained above), and the interpretation of autonomy and solidarity in the use of personal data in (big data) research.Digital health is a promising tool for the prevention and treatment of ASCVD. In recent years, many digital health solutions have been developed, but barriers, as described by the Society of Cardiology e-Cardiology working group, exist for a successful large-scale implementation. In this paper, we presented solutions as proposed by the CARRIER consortium.We described the development process of a digital health solution, employing design thinking and cocreation with relevant stakeholders. Using cocreation, we ensure that the digital health solution meets the needs and vision of future end users. Personalization of the eHealth solution can improve adherence to the intervention. This enhances the eHealth implementation in care pathways for ASCVD.We also described the modeling approach for a screening model to identify people at high risk for ASCVD. CPMs that can make use of conventional and nonconventional risk factors from different organization create the opportunity for early identification and guiding interventions, even without the need for medical testing.However, a data infrastructure connecting these different organizations is currently not available. We described the possibilities and characteristics of a federated data infrastructure that enables the connection of these organizations. The Personal Health Train allows for federated data analysis while keeping data owners in control of their data. As this federated data infrastructure raises ethical and legal questions, we also described the development of a framework that ensures responsible data handling in health care.We believe the future of health care is data driven and supported by eHealth. Therefore, our research on a mature and sustainable federated data infrastructure and ethical and legal aspects will not only facilitate CARRIER but may also facilitate other future health care initiatives.