Dermal αSMA+ myofibroblasts orchestrate skin wound repair via ß1 integrin and independent of type I collagen production.

Skin wound repair is essential for organismal survival and failure of which leads to non-healing wounds, a leading health issue worldwide. However, mechanistic understanding of chronic wounds remains a major challenge due to lack of appropriate genetic mouse models. αSMA+ myofibroblasts, a unique class of dermal fibroblasts, are associated with cutaneous wound healing but their precise function remains unknown. We demonstrate that genetic depletion of αSMA+ myofibroblasts leads to pleiotropic wound healing defects, including lack of reepithelialization and granulation, dampened angiogenesis, and heightened hypoxia, hallmarks of chronic non-healing wounds. Other wound-associated FAP+ and FSP1+ fibroblasts do not exhibit such dominant functions. While type I collagen (COL1) expressing cells play a role in the repair process, COL1 produced by αSMA+ myofibroblasts is surprisingly dispensable for wound repair. In contrast, we show that ß1 integrin from αSMA+ myofibroblasts, but not TGFßRII, is essential for wound healing, facilitating contractility, reepithelization, and vascularization. Collectively, our study provides evidence for the functions of myofibroblasts in ß1 integrin-mediated wound repair with potential implications for treating chronic non-healing wounds.

Both chloride-binding sites are required for KCC2-mediated transport.

The K+-Cl- cotransporter 2 (KCC2) plays an important role in inhibitory neurotransmission, and its impairment is associated with neurological and psychiatric disorders, including epilepsy, schizophrenia, and autism. Although KCCs transport K+ and Cl- in a 1:1 stoichiometry, two Cl- coordination sites were indicated via cryo-EM. In a comprehensive analysis, we analyzed the consequences of point mutations of residues coordinating Cl- in Cl1 and Cl2. Individual mutations of residues in Cl1 and Cl2 reduce or abolish KCC2WT function, indicating a crucial role of both Cl- coordination sites for KCC2 function. Structural changes in the extracellular loop 2 by inserting a 3xHA tag switches the K+ coordination site to another position. To investigate, whether the extension of the extracellular loop 2 with the 3xHA tag also affects the coordination of the two Cl- coordination sites, we carried out the analogous experiments for both Cl- coordinating sites in the KCC2HA construct. These analyses showed that most of the individual mutation of residues in Cl1 and Cl2 in the KCC2HA construct reduces or abolishes KCC2 function, indicating that the coordination of Cl- remains at the same position. However, the coupling of K+ and Cl- in Cl1 is still apparent in the KCC2HA construct, indicating a mutual dependence of both ions. In addition, the coordination residue Tyr569 in Cl2 shifted in KCC2HA. Thus, conformational changes in the extracellular domain affect K+ and Cl--binding sites. However, the effect on the Cl--binding sites is subtler.

Diagnostic leukapheresis reveals distinct phenotypes of NSCLC circulating tumor cells.

BACKGROUND: Circulating tumor cells (CTCs) hold immense promise for unraveling tumor heterogeneity and understanding treatment resistance. However, conventional methods, especially in cancers like non-small cell lung cancer (NSCLC), often yield low CTC numbers, hindering comprehensive analyses. This study addresses this limitation by employing diagnostic leukapheresis (DLA) to cancer patients, enabling the screening of larger blood volumes. To leverage DLA's full potential, this study introduces a novel approach for CTC enrichment from DLAs. METHODS: DLA was applied to six advanced stage NSCLC patients. For an unbiased CTC enrichment, a two-step approach based on negative depletion of hematopoietic cells was used. Single-cell (sc) whole-transcriptome sequencing was performed, and CTCs were identified based on gene signatures and inferred copy number variations. RESULTS: Remarkably, this innovative approach led to the identification of unprecedented 3,363 CTC transcriptomes. The extensive heterogeneity among CTCs was unveiled, highlighting distinct phenotypes related to the epithelial-mesenchymal transition (EMT) axis, stemness, immune responsiveness, and metabolism. Comparison with sc transcriptomes from primary NSCLC cells revealed that CTCs encapsulate the heterogeneity of their primary counterparts while maintaining unique CTC-specific phenotypes. CONCLUSIONS: In conclusion, this study pioneers a transformative method for enriching CTCs from DLA, resulting in a substantial increase in CTC numbers. This allowed the creation of the first-ever single-cell whole transcriptome in-depth characterization of the heterogeneity of over 3,300 NSCLC-CTCs. The findings not only confirm the diagnostic value of CTCs in monitoring tumor heterogeneity but also propose a CTC-specific signature that can be exploited for targeted CTC-directed therapies in the future. This comprehensive approach signifies a major leap forward, positioning CTCs as a key player in advancing our understanding of cancer dynamics and paving the way for tailored therapeutic interventions.

Endothelial cell plasticity at the single-cell level.

The vascular endothelium is characterized by a remarkable level of plasticity, which is the driving force not only of physiological repair/remodeling of adult tissues but also of pathological angiogenesis. The resulting heterogeneity of endothelial cells (ECs) makes targeting the endothelium challenging, no less because many EC phenotypes are yet to be identified and functionally inventorized. Efforts to map the vasculature at the single-cell level have been instrumental to capture the diversity of EC types and states at a remarkable depth in both normal and pathological states. Here, we discuss new EC subtypes and functions emerging from recent single-cell studies in health and disease. Interestingly, such studies revealed distinct metabolic gene signatures in different EC phenotypes, which deserve further consideration for therapy. We highlight how this metabolic targeting strategy could potentially be used to promote (for tissue repair) or block (in tumor) angiogenesis in a tissue or even vascular bed-specific manner.

Longitudinal analysis of pinnipeds in the northwest Atlantic provides insights on endemic circulation of phocine distemper virus.

Phocine distemper virus (PDV) is a morbillivirus that circulates within pinnipeds in the North Atlantic. PDV has caused two known unusual mortality events (UMEs) in western Europe (1988, 2002), and two UMEs in the northwest Atlantic (2006, 2018). Infrequent cross-species transmission and waning immunity are believed to contribute to periodic outbreaks with high mortality in western Europe. The viral ecology of PDV in the northwest Atlantic is less well defined and outbreaks have exhibited lower mortality than those in western Europe. This study sought to understand the molecular and ecological processes underlying PDV infection in eastern North America. We provide phylogenetic evidence that PDV was introduced into northwest Atlantic pinnipeds by a single lineage and is now endemic in local populations. Serological and viral screening of pinniped surveillance samples from 2006 onward suggest there is continued circulation of PDV outside of UMEs among multiple species with and without clinical signs. We report six full genome sequences and nine partial sequences derived from harbour and grey seals in the northwest Atlantic from 2011 through 2018, including a possible regional variant. Work presented here provides a framework towards greater understanding of how recovering populations and shifting species may impact disease transmission.

Prevalence of natural and acquired antibodies to amustaline/glutathione pathogen reduced red blood cells.

BACKGROUND: The INTERCEPT™ Blood System for Red Blood Cells (RBCs) utilizes amustaline (S-303) and glutathione (GSH) to inactivate pathogens and leukocytes in transfused RBCs. Treatment-emergent low titer non-hemolytic antibodies to amustaline/GSH RBC were detected in clinical trials using a prior version of the process. The amustaline/GSH process was re-formulated to decrease S-303 RBC adduct formation. STUDY DESIGN AND METHODS: A standard three-cell antibody screening panel was modified to include reagent red cells (RRC) with high (S-303H) or low (S-303L) S-303 adduct density as assessed by flow cytometry, representative of the original and current amustaline/GSH treatment processes, respectively. General hospital and RBC transfusion-dependent patients never exposed, and clinical trial subjects exposed to amustaline/GSH RBC were screened for antibodies to amustaline/GSH RBC using a standardized agglutination assay. RESULTS: Twelve (0.1%) of 10,721 general hospital and 5 (0.5%) of 998 repeatedly-transfused patients not previously exposed to amustaline/GSH RBCs expressed natural, low titer (2-32) IgM and/or IgG (non-IgG1 or IgG3 isotype) antibodies with acridine (a structural element of amustaline) (n = 14) or non-acridine (n = 3) specificity. 11 of 17 sera reacted with S-303L panel RRCs. In clinical studies 81 thalassemia and 25 cardiac surgery patients were transfused with a total of 1085 amustaline/GSH RBCs and no natural or treatment-emergent S-303 antibodies were detected. CONCLUSION: Standardized RRC screening panels are sensitive for the detection of natural and acquired S-303-specific antibodies. Natural low titer antibodies to amustaline/GSH RBC are present in 0.15% of naïve patients. The clinical relevance of these antibodies appears minimal but is under further investigation.

Partnership Between Japan and the United States for Early Development of Pediatric Medical Devices　- Harmonization By Doing for Children.

BACKGROUND: The Harmonization By Doing (HBD) program was established in 2003 as a partnership among stakeholders of academia, industry and regulatory agencies in Japan and the United States, with a primary focus on streamlining processes of global medical device development for cardiovascular medical devices. While HBD has traditionally focused on development of devices intended to treat conditions prevalent in adults, in 2016, HBD established the "HBD-for-Children" program, which focuses on the development of pediatric devices as the development of medical devices for pediatric use lags behind that of medical devices for adults in both countries.Methods and Results:Activities of the program have included: (1) conducting a survey with industry to better understand the challenges that constrain the development of pediatric medical devices; (2) categorizing pediatric medical devices into five categories based on global availability and exploring concrete solutions for the early application and regulatory approval in both geographies; and (3) facilitating global clinical trials of pediatric medical devices in both countries. CONCLUSIONS: The establishment of the HBD-for-Children program is significant because it represents a global initiative for the introduction of pediatric medical devices for patients in a timely manner. Through the program, academia, industry and regulatory agencies can work together to facilitate innovative pediatric device development from a multi-stakeholder perspective. This activity could also encourage industry partners to pursue the development of pediatric medical devices.

Sustained prognostic impact of circulating tumor cell status and kinetics upon further progression of metastatic breast cancer.

PURPOSE: Serial longitudinal enumeration of circulating tumor cells (CTCs) has shown its prognostic value on progression-free survival and overall survival (OS) in patients with stage IV breast cancer. This study prospectively evaluated the role of CTCs as a prognostic marker during further progression of metastatic breast cancer (MBC). METHODS: Among 476 MBC patients recruited between 2010 and 2015, the 103 patients with a known CTC status at baseline (CTCBL) and within 4 weeks of tumor progression (CTCPD) were included. Progressive disease (PD) was defined according to the Response Evaluation Criteria in Solid Tumors (RECIST, version 1.1). Using the CellSearch method, < 5 and ≥ 5 CTCs per 7.5 ml blood were determined as negative and positive, respectively. A shift in CTC status from baseline to progression ([Formula: see text] to [Formula: see text] and vice versa) was considered as alternating KineticsBL-PD. RESULTS: Median follow-up was 29.9 [21.2, 40.0] months. CTCPD positivity (37%, n = 38) was associated with a significantly shorter OS than CTCPD negativity (8.0 [5.1, 10.9] vs 22.6 [15.3, 39.8] months; P < 0.001). Alternating KineticsBL-PD was observed in 24% of the patients. This significantly changed the OS prediction of [Formula: see text] patients ([Formula: see text] vs [Formula: see text], 11.4 [9.7, not available (NA)] vs. 7.6 [4.4, 11.5] months; P = 0.044) and [Formula: see text] patients ([Formula: see text] vs. [Formula: see text], 8.4 [4.0, NA] vs. 22.6 [18.9, NA] months, respectively; P < 0.001). Prediction of survival was significantly improved (P = 0.002) by adding CTCPD status to clinicopathological characteristics and CTCBL status. CONCLUSIONS: CTC status upon further disease progression is a prognostic factor that could significantly improve well-established models. Thus, it represents a potential additional instrument supporting treatment decision.

Tonic B-cell receptor signaling in diffuse large B-cell lymphoma.

We used clustered regularly interspaced short palindromic repeats/Cas9-mediated genomic modification to investigate B-cell receptor (BCR) signaling in cell lines of diffuse large B-cell lymphoma (DLBCL). Three manipulations that altered BCR genes without affecting surface BCR levels showed that BCR signaling differs between the germinal center B-cell (GCB) subtype, which is insensitive to Bruton tyrosine kinase inhibition by ibrutinib, and the activated B-cell (ABC) subtype. Replacing antigen-binding BCR regions had no effect on BCR signaling in GCB-DLBCL lines, reflecting this subtype's exclusive use of tonic BCR signaling. Conversely, Y188F mutation in the immunoreceptor tyrosine-based activation motif of CD79A inhibited tonic BCR signaling in GCB-DLBCL lines but did not affect their calcium flux after BCR cross-linking or the proliferation of otherwise-unmodified ABC-DLBCL lines. CD79A-GFP fusion showed BCR clustering or diffuse distribution, respectively, in lines of ABC and GCB subtypes. Tonic BCR signaling acts principally to activate AKT, and forced activation of AKT rescued GCB-DLBCL lines from knockout (KO) of the BCR or 2 mediators of tonic BCR signaling, SYK and CD19. The magnitude and importance of tonic BCR signaling to proliferation and size of GCB-DLBCL lines, shown by the effect of BCR KO, was highly variable; in contrast, pan-AKT KO was uniformly toxic. This discrepancy was explained by finding that BCR KO-induced changes in AKT activity (measured by gene expression, CXCR4 level, and a fluorescent reporter) correlated with changes in proliferation and with baseline BCR surface density. PTEN protein expression and BCR surface density may influence clinical response to therapeutic inhibition of tonic BCR signaling in DLBCL.

Brains over brawn: experience overcomes a size disadvantage in fish social hierarchies.

Life experiences can alter cognitive abilities and subsequent behavior. Here we asked whether differences in experience could affect social status. In hierarchical animal societies, high-ranking males that typically win aggressive encounters gain territories and hence access to mates. To understand the relative contributions of social experience and physical environment on status, we used a highly territorial African cichlid fish species, Astatotilapia burtoni, that lives in a dynamic lek-like social hierarchy. Astatotilapia burtoni males are either dominant or submissive and can switch status rapidly depending on the local environment. Although dominant males are innately aggressive, we wondered whether they modulated their aggression based on experience. We hypothesized that as males mature they might hone their fighting tactics based on observation of other males fighting. We compared males of different ages and sizes in distinctly different physical environments and subsequently tested their fighting skills. We found that a size difference previously thought negligible (<10% body length) gave a significant advantage to the larger opponent. In contrast, we found no evidence that increasing environmental complexity affected status outcomes. Surprisingly, we found that males only a few days older than their opponents had a significant advantage during territorial disputes so that being older compensated for the disadvantage of being smaller. Moreover, the slightly older winners exploited a consistent fighting strategy, starting with lower levels of aggression on the first day that significantly increased on the second day, a pattern absent in younger winners. These data suggest that experience is an advantage during fights for status, and that social learning provides more relevant experience than the physical complexity of the territory.

Synthesis of uniform cyclodextrin thioethers to transport hydrophobic drugs.

Methyl and ethyl thioether groups were introduced at all primary positions of α-, ß-, and γ-cyclodextrin by nucleophilic displacement reactions starting from the corresponding per-(6-deoxy-6-bromo)cyclodextrins. Further modification of all 2-OH positions by etherification with iodo terminated triethylene glycol monomethyl ether (and tetraethylene glycol monomethyl ether, respectively) furnished water-soluble hosts. Especially the ß-cyclodextrin derivatives exhibit very high binding potentials towards the anaesthetic drugs sevoflurane and halothane. Since the resulting inclusion compounds are highly soluble in water at temperatures ≤37 °C they are good candidates for new aqueous dosage forms which would avoid inhalation anaesthesia.

Machine learning algorithms predict canine structural epilepsy with high accuracy.

Introduction: Clinical reasoning in veterinary medicine is often based on clinicians' personal experience in combination with information derived from publications describing cohorts of patients. Studies on the use of scientific methods for patient individual decision making are largely lacking. This applies to the prediction of the individual underlying pathology in seizuring dogs as well. The aim of this study was to apply machine learning to the prediction of the risk of structural epilepsy in dogs with seizures. Materials and methods: Dogs with a history of seizures were retrospectively as well as prospectively included. Data about clinical history, neurological examination, diagnostic tests performed as well as the final diagnosis were collected. For data analysis, the Bayesian Network and Random Forest algorithms were used. A total of 33 features for Random Forest and 17 for Bayesian Network were available for analysis. The following four feature selection methods were applied to select features for further analysis: Permutation Importance, Forward Selection, Random Selection and Expert Opinion. The two algorithms Bayesian Network and Random Forest were trained to predict structural epilepsy using the selected features. Results: A total of 328 dogs of 119 different breeds were identified retrospectively between January 2017 and June 2021, of which 33.2% were diagnosed with structural epilepsy. An overall of 89,848 models were trained. The Bayesian Network in combination with the Random feature selection performed best. It was able to predict structural epilepsy with an accuracy of 0.969 (sensitivity: 0.857, specificity: 1.000) among all dogs with seizures using the following features: age at first seizure, cluster seizures, seizure in last 24 h, seizure in last 6 month, and seizure in last year. Conclusion: Machine learning algorithms such as Bayesian Networks and Random Forests identify dogs with structural epilepsy with a high sensitivity and specificity. This information could provide some guidance to clinicians and pet owners in their clinical decision-making process.

Client's understanding of instructions for small animals in a veterinary neurological referral center.

BACKGROUND: It is not known how much information clients retrieve from discharge instructions. OBJECTIVE: To investigate client's understanding of discharge instructions and influencing factors. ANIMALS: Dogs and cats being hospitalized for neurological diseases. METHODS: Clients were presented questionnaires regarding their pet's disease, diagnostics, treatments, prognosis and discharge instructions at time of discharge and 2 weeks later. The same questions were answered by discharging veterinarians at time of discharge. Clients answered additional questions regarding the subjective feelings during discharge conversation. Data collected included: data describing discharging veterinarian (age, gender, years of clinical experience, specialist status), data describing the client (age, gender, educational status). Raw percentage of agreement (RPA) between answers of clinicians and clients as well as factors potentially influencing the RPA were evaluated. RESULTS: Of 230 clients being approached 151 (65.7%) and 70 (30.4%) clients responded to the first and second questionnaire, respectively (130 dog and 30 cat owners). The general RPA between clinician's and client's responses over all questions together was 68.9% and 66.8% at the 2 time points. Questions regarding adverse effects of medication (29.0%), residual clinical signs (35.8%), and confinement instructions (36.8%) had the lowest RPAs at the first time point. The age of clients (P = .008) negatively influenced RPAs, with clients older than 50 years having lower RPA. CONCLUSIONS AND CLINICAL IMPORTANCE: Clients can only partially reproduce information provided at discharge. Only clients' increasing age influenced recall of information. Instructions deemed to be important should be specifically stressed during discharge.

Social descent with territory loss causes rapid behavioral, endocrine and transcriptional changes in the brain.

In social species that form hierarchies where only dominant males reproduce, lower-ranking individuals may challenge higher-ranking ones, often resulting in changes in relative social status. How does a losing animal respond to loss of status? Here, using the African cichlid fish Astatotilapia burtoni, we manipulated the social environment, causing males to descend in rank, and then examined changes in behavior, circulating steroids and immediate early gene (IEG) expression (cfos, egr-1) in micro-dissected brain regions as a proxy for neuronal activation. In particular, we examined changes in the conserved 'social behavior network' (SBN), a collection of brain nuclei known to regulate social behaviors across vertebrates. Astatotilapia burtoni has rapidly reversible dominant-subordinate male phenotypes, so that within minutes, descending males lost their bright body coloration, switched to submissive behaviors and expressed higher plasma cortisol levels compared with non-descending and control males. Descending males had higher IEG expression throughout the SBN, but each brain region showed a distinct IEG-specific response in either cfos or egr-1 levels, but not both. Overall, SBN IEG patterns in descending males were distinctly different from the pattern observed in males ascending (subordinate to dominant) in social status. These results reveal that the SBN rapidly coordinates the perception of social cues about status that are of opposite valence, and translates them into appropriate phenotypic changes. This shows for the first time in a non-mammalian vertebrate that dropping in social rank rapidly activates specific socially relevant brain nuclei in a pattern that differs from when males rise to a higher status position.

Deciphering endothelial heterogeneity in health and disease at single-cell resolution: progress and perspectives.

Endothelial cells (ECs) constitute the inner lining of vascular beds in mammals and are crucial for homeostatic regulation of blood vessel physiology, but also play a key role in pathogenesis of many diseases, thereby representing realistic therapeutic targets. However, it has become evident that ECs are heterogeneous, encompassing several subtypes with distinct functions, which makes EC targeting and modulation in diseases challenging. The rise of the new single-cell era has led to an emergence of studies aimed at interrogating transcriptome diversity along the vascular tree, and has revolutionized our understanding of EC heterogeneity from both a physiological and pathophysiological context. Here, we discuss recent landmark studies aimed at teasing apart the heterogeneous nature of ECs. We cover driving (epi)genetic, transcriptomic, and metabolic forces underlying EC heterogeneity in health and disease, as well as current strategies used to combat disease-enriched EC phenotypes, and propose strategies to transcend largely descriptive heterogeneity towards prioritization and functional validation of therapeutically targetable drivers of EC diversity. Lastly, we provide an overview of the most recent advances and hurdles in single EC OMICs.

Detailed protocol for a corneal thermal cauterization-based (lymph-)angiogenesis assay in mice.

Angiogenesis and lymphangiogenesis, the formation of new blood or lymphatic vessels, respectively, from preexisting vasculature is essential during embryonic development, but also occurs during tissue repair and in pathological conditions (cancer; ocular disease; ischemic, infectious and inflammatory disorders), which are all characterized to a certain extent by inflammatory conditions. Hence, a rapid, inexpensive, feasible / technically easy, reliable assay of inflammation-induced (lymph-)angiogenesis is highly valuable. In this context, the corneal thermal cauterization assay in mice is a simple, low-cost, reproducible, insightful and labor-saving assay to gauge the role of inflammation in angiogenesis and lymphangiogenesis. However, to the best of our knowledge, there is no standardized protocol to perform this assay. Here, we provide a step-by-step description of the model's procedures, which include:•The thermal cauterization of the corneas,•Enucleation and dissection of the corneas,•Subsequent immunofluorescence staining of the neovasculature, and morphometric analysis. We also discuss ethical considerations and aspects related to animal welfare guidelines. Altogether, this paper will help to increase the reproducibility of the corneal thermal cauterization model and facilitate its use for angiogenesis and lymphangiogenesis research.

The pulmonary vasculature in lethal COVID-19 and idiopathic pulmonary fibrosis at single-cell resolution.

AIMS: Severe acute respiratory syndrome coronavirus-2 infection causes COVID-19, which in severe cases evokes life-threatening acute respiratory distress syndrome (ARDS). Transcriptome signatures and the functional relevance of non-vascular cell types (e.g. immune and epithelial cells) in COVID-19 are becoming increasingly evident. However, despite its known contribution to vascular inflammation, recruitment/invasion of immune cells, vascular leakage, and perturbed haemostasis in the lungs of severe COVID-19 patients, an in-depth interrogation of the endothelial cell (EC) compartment in lethal COVID-19 is lacking. Moreover, progressive fibrotic lung disease represents one of the complications of COVID-19 pneumonia and ARDS. Analogous features between idiopathic pulmonary fibrosis (IPF) and COVID-19 suggest partial similarities in their pathophysiology, yet, a head-to-head comparison of pulmonary cell transcriptomes between both conditions has not been implemented to date. METHODS AND RESULTS: We performed single-nucleus RNA-sequencing on frozen lungs from 7 deceased COVID-19 patients, 6 IPF explant lungs, and 12 controls. The vascular fraction, comprising 38 794 nuclei, could be subclustered into 14 distinct EC subtypes. Non-vascular cell types, comprising 137 746 nuclei, were subclustered and used for EC-interactome analyses. Pulmonary ECs of deceased COVID-19 patients showed an enrichment of genes involved in cellular stress, as well as signatures suggestive of dampened immunomodulation and impaired vessel wall integrity. In addition, increased abundance of a population of systemic capillary and venous ECs was identified in COVID-19 and IPF. COVID-19 systemic ECs closely resembled their IPF counterparts, and a set of 30 genes was found congruently enriched in systemic ECs across studies. Receptor-ligand interaction analysis of ECs with non-vascular cell types in the pulmonary micro-environment revealed numerous previously unknown interactions specifically enriched/depleted in COVID-19 and/or IPF. CONCLUSIONS: This study uncovered novel insights into the abundance, expression patterns, and interactomes of EC subtypes in COVID-19 and IPF, relevant for future investigations into the progression and treatment of both lethal conditions.

Development of a Formalized, Multifaceted Mentorship Program in Physical Medicine and Rehabilitation Residency Education.

ABSTRACT: Mentorship in medicine has long been a vital component to the training, development, and career advancement of physicians. Although optimal strategies for facilitating mentorship relationships are unknown, it is recognized that establishing a formalized mentorship program within residency training may augment mentor-mentee pairing, improve overall trainee experience, and enhance resident perception of strong mentoring relationships. A formalized mentorship program was successfully developed in a Canadian physical medicine and rehabilitation residency program, including innovations such as near-peer self-matching, a needs assessment survey, a speed dating event, formation of "link groups," and "fireside chats" with faculty members. This approach may serve as a guide for other medical education and residency programs seeking to implement a similar concept.

Tumor vessel co-option: The past & the future.

Tumor vessel co-option (VCO) is a non-angiogenic vascularization mechanism that is a possible cause of resistance to anti-angiogenic therapy (AAT). Multiple tumors are hypothesized to primarily rely on growth factor signaling-induced sprouting angiogenesis, which is often inhibited during AAT. During VCO however, tumors invade healthy tissues by hijacking pre-existing blood vessels of the host organ to secure their blood and nutrient supply. Although VCO has been described in the context of AAT resistance, the molecular mechanisms underlying this process and the profile and characteristics of co-opted vascular cell types (endothelial cells (ECs) and pericytes) remain poorly understood, resulting in the lack of therapeutic strategies to inhibit VCO (and to overcome AAT resistance). In the past few years, novel next-generation technologies (such as single-cell RNA sequencing) have emerged and revolutionized the way of analyzing and understanding cancer biology. While most studies utilizing single-cell RNA sequencing with focus on cancer vascularization have centered around ECs during sprouting angiogenesis, we propose that this and other novel technologies can be used in future investigations to shed light on tumor EC biology during VCO. In this review, we summarize the molecular mechanisms driving VCO known to date and introduce the models used to study this phenomenon to date. We highlight VCO studies that recently emerged using sequencing approaches and propose how these and other novel state-of-the-art methods can be used in the future to further explore ECs and other cell types in the VCO process and to identify potential vulnerabilities in tumors relying on VCO. A better understanding of VCO by using novel approaches could provide new answers to the many open questions, and thus pave the way to develop new strategies to control and target tumor vascularization.