The multifaceted links between hearing loss and chronic kidney disease

Hearing loss affects nearly 1.6 billion people and is the third-leading cause of disability worldwide. Chronic kidney disease (CKD) is also a common condition that is associated with adverse clinical outcomes and high health-care costs. From a developmental perspective, the structures responsible for hearing have a common morphogenetic origin with the kidney, and genetic abnormalities that cause familial forms of hearing loss can also lead to kidney disease. On a cellular level, normal kidney and cochlea function both depend on cilial activities at the apical surface, and kidney tubular cells and sensory epithelial cells of the inner ear use similar transport mechanisms to modify luminal fluid. The two organs also share the same collagen IV basement membrane network. Thus, strong developmental and physiological links exist between hearing and kidney function. These theoretical considerations are supported by epidemiological data demonstrating that CKD is associated with a graded and independent excess risk of sensorineural hearing loss. In addition to developmental and physiological links between kidney and cochlear function, hearing loss in patients with CKD may be driven by specific medications or treatments, including haemodialysis. The associations between these two common conditions are not commonly appreciated, yet have important implications for research and clinical practice.

Hedgehog signalling in Foxd1+ embryonic kidney stromal progenitors controls nephron formation via Cxcl12 and Wnt5a

Congenital anomalies of the kidney and urinary tract (CAKUT) are characterised by a spectrum of structural and histologic abnormalities and are the major cause of childhood kidney failure. During kidney morphogenesis, the formation of a critical number of nephrons is an embryonic process supported, in part, by signalling between nephrogenic precursors and Foxd1-positive stromal progenitor cells. Low nephron number and abnormal patterning of the stroma are signature pathological features among CAKUT phenotypes with decreased kidney function. Despite their critical contribution to CAKUT pathogenesis, the mechanisms that underlie a low nephron number and the functional contribution of a disorganised renal stroma to nephron number are both poorly defined. Here, we identify a primary pathogenic role for increased Hedgehog signalling in embryonic renal stroma in the genesis of congenital low nephron number. Pharmacologic activation of Hedgehog (Hh) signalling in human kidney organoid tissue decreased the number of nephrons and generated excess stroma. The mechanisms underlying these pathogenic effects were delineated in genetic mouse models in which Hh signalling was constitutively activated in a cell lineage-specific manner. Cre-mediated excision of Ptch1 in Foxd1+ stromal progenitor cells, but not in Six2+ nephrogenic precursor cells, generated kidney malformation, identifying the stroma as a driver of low nephron number. Single-cell RNA sequencing analysis identified Cxcl12 and Wnt5a as downstream targets of increased stromal Hh signalling, findings supported by analysis in human kidney organoids. In vivo deficiency of Cxcl12 or Wnt5a in mice with increased stromal Hh signalling improved nephron endowment. These results demonstrate that dysregulated Hh signalling in embryonic renal stromal cells inhibits nephron formation in a manner dependent on Cxcl12 and Wnt5a. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Storytelling for impact: the creation of a storytelling program for patient partners in research

Storytelling is a powerful means to evoke empathy and understanding among people. When patient partners, which include patients, family members, caregivers and organ donors, share their stories with health professionals, this can prompt listeners to reflect on their practice and consider new ways of driving change in the healthcare system. However, a growing number of patient partners are asked to 'share their story' within health care and research settings without adequate support to do so. This may ultimately widen, rather than close, the gap between healthcare practitioners and people affected by chronic disease in this new era of patient and public involvement in research. To better support patient partners with storytelling in the context of a patient-oriented research network, Canadians Seeking Solutions and Innovations to Overcome Chronic Kidney Disease (Can-SOLVE CKD) Network adapted an existing in-person storytelling workshop for patient educators within a hospital setting. The result is a 6-week virtual program called Storytelling for Impact, which guides patients, family members, caregivers and organ donors in developing impactful stories and sharing them at health care and research events, e.g., conferences. The online series of synchronous workshops is co-facilitated by story coaches, who are program alumni and Can-SOLVE CKD staff with trained storytelling experience. Each story follows a structure that includes a call to action, which aims to positively impact the priority-setting and delivery of care and research in Canada. The program has been a transformational process for many who have completed it, and numerous other health organizations have expressed interest in sharing this tool with their own patient partners. As result, we have also created an asynchronous online program that can be used by other interested parties outside our network. Patient partners who share their stories can be powerful mediators for inspiring changes in the health care and research landscape, with adequate structured support. We describe two novel programs to support patient partners in impactful storytelling, which are applicable across all health research disciplines. Additional resources are required for sustainability and scale up of training, by having alumni train future storytellers.

Hedgehog-GLI mediated control of renal formation and malformation

CAKUT is the leading cause of end-stage kidney disease in children and comprises a broad spectrum of phenotypic abnormalities in kidney and ureter development. Molecular mechanisms underlying the pathogenesis of CAKUT have been elucidated in genetic models, predominantly in the mouse, a paradigm for human renal development. Hedgehog (Hh) signaling is critical to normal embryogenesis, including kidney development. Hh signaling mediates the physiological development of the ureter and stroma and has adverse pathophysiological effects on the metanephric mesenchyme, ureteric, and nephrogenic lineages. Further, disruption of Hh signaling is causative of numerous human developmental disorders associated with renal malformation; Pallister-Hall Syndrome (PHS) is characterized by a diverse spectrum of malformations including CAKUT and caused by truncating variants in the middle-third of the Hh signaling effector GLI3. Here, we outline the roles of Hh signaling in regulating murine kidney development, and review human variants in Hh signaling genes in patients with renal malformation.

Antenatally Diagnosed Kidney Anomalies

Congenital anomalies of the kidney and urinary tract encompass a broad spectrum of developmental conditions that together account for the majority of childhood chronic kidney diseases. Kidney abnormalities are the most commonly diagnosed congenital anomaly in children, and detection of this anomaly is increasing as a result of improved antenatal care and widespread access to more sensitive screening ultrasonography. Most paediatricians will encounter children with congenital kidney anomalies across a wide spectrum of disorders, and a broad understanding of the classification, investigation, and basis of management is important to appropriately direct their care.

Pallister-Hall syndrome, GLI3, and kidney malformation

Pallister-Hall syndrome (PHS) is a rare autosomal dominant disease diagnosed by the presence of hypothalamic hamartoma, mesoaxial polydactyly and a truncating variant in the middle third of the GLI-Kruppel family member 3 (GLI3) gene. PHS may also include a wide range of clinical phenotypes affecting multiple organ systems including congenital anomalies of the kidney and urinary tract (CAKUT). The observed clinical phenotypes are consistent with the essential role of GLI3, a transcriptional effector in the hedgehog (Hh) signaling pathway, in organogenesis. However, the mechanisms by which truncation of GLI3 in PHS results in such a variety of clinical phenotypes with variable severity, even within the same organ, remain unclear. In this study we focus on presentation of CAKUT in PHS. A systematic analysis of reported PHS patients (n = 78) revealed a prevalence of 26.9% (21/78) of CAKUT. Hypoplasia (± dysplasia) and agenesis were the two main types of CAKUT; bilateral and unilateral CAKUT were reported with equal frequency. Examination of clinical phenotypes with CAKUT revealed a significant association between CAKUT and craniofacial defects, bifid epiglottis and a Disorder of Sex Development, specifically affecting external genitalia. Lastly, we determined that PHS patients with CAKUT predominately had substitution type variants (as opposed to deletion type variants in non-CAKUT PHS patients) in the middle third of the GLI3 gene. These results provide a foundation for future work aimed at uncovering the molecular mechanisms by which variant GLI3 result in the wide range and severity of clinical features observed in PHS.

Program Report: Can-SOLVE CKD Network Presents an Inclusive Method for Developing Patient-Oriented Research Tools

Purpose of program:

Given the growing interest in patient-oriented research (POR) initiatives, there is a need to provide relevant training and education on how to engage with patients as partners on research teams.

Sources of information:

As part of its mandate to develop appropriate training materials, the patient-oriented renal research network, Canadians Seeking Solutions and Innovations to Overcome Chronic Kidney Disease (Can-SOLVE CKD), established a training and Mentorship Committee (TMC).

Methods:

The committee brings together a unique combination of Indigenous and non-Indigenous patient partners (including caregivers, family members, and living donors), researchers, as well as patient engagement and knowledge translation experts, combining a multitude of perspectives and expertise. Following an assessment of training needs within the network, the TMC undertook the co-development of 5 learning modules to address the identified gaps. Subsequently, the committee divided into working groups tasked with developing content using a consultive and iterative approach informed by the DoTTI framework for building web-based tools for patients. In addition, the TMC embodied the guiding principles of inclusiveness, support, mutual respect, and co-building as set out by the Patient Engagement Framework through the Strategy for Patient-Oriented Research (SPOR) of the Canadian Institutes of Health Research.

Key findings:

The 5 new modules include: A Patient Engagement Toolkit, Storytelling for Impact, Promoting Kidney Research in Canada (KidneyPRO), Wabishki Bizhiko Skaanj Learning Pathway, and Knowledge Translation. The TMC’s approach to developing these modules demonstrates how a diverse group of stakeholders working together can create tools to support high-quality POR. This also provides a roadmap for other health research entities interested in developing similar tools within their unique domains.

Limitations:

The landscape of patient engagement in research is constantly evolving. This underscores the need for sustained resources to keep POR tools and training relevant and up-to-date. Sustaining such resources may not be feasible for all research entities.

Implications:

Collaborative approaches integrating patients in the development of POR tools ensure the content is relevant and meaningful to patients. Broader adoption of such approaches has great potential to address existing gaps and enhance the Canadian POR landscape.

Heterogeneity of Diabetes: β-Cells, Phenotypes, and Precision Medicine: Proceedings of an International Symposium of the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases

One hundred years have passed since the discovery of insulin-an achievement that transformed diabetes from a fatal illness into a manageable chronic condition. The decades since that momentous achievement have brought ever more rapid innovation and advancement in diabetes research and clinical care. To celebrate the important work of the past century and help to chart a course for its continuation into the next, the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases recently held a joint international symposium, bringing together a cohort of researchers with diverse interests and backgrounds from both countries and beyond to discuss their collective quest to better understand the heterogeneity of diabetes and thus gain insights to inform new directions in diabetes treatment and prevention. This article summarizes the proceedings of that symposium, which spanned cutting-edge research into various aspects of islet biology, the heterogeneity of diabetic phenotypes, and the current state of and future prospects for precision medicine in diabetes.

Heterogeneity of Diabetes: β-Cells, Phenotypes, and Precision Medicine: Proceedings of an International Symposium of the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases

One hundred years have passed since the discovery of insulin-an achievement that transformed diabetes from a fatal illness into a manageable chronic condition. The decades since that momentous achievement have brought ever more rapid innovation and advancement in diabetes research and clinical care. To celebrate the important work of the past century and help to chart a course for its continuation into the next, the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases recently held a joint international symposium, bringing together a cohort of researchers with diverse interests and backgrounds from both countries and beyond to discuss their collective quest to better understand the heterogeneity of diabetes and thus gain insights to inform new directions in diabetes treatment and prevention. This article summarizes the proceedings of that symposium, which spanned cutting-edge research into various aspects of islet biology, the heterogeneity of diabetic phenotypes, and the current state of and future prospects for precision medicine in diabetes.

Heterogeneity of Diabetes: β-Cells, Phenotypes, and Precision Medicine: Proceedings of an International Symposium of the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases

One hundred years have passed since the discovery of insulin-an achievement that transformed diabetes from a fatal illness into a manageable chronic condition. The decades since that momentous achievement have brought ever more rapid innovation and advancement in diabetes research and clinical care. To celebrate the important work of the past century and help to chart a course for its continuation into the next, the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases recently held a joint international symposium, bringing together a cohort of researchers with diverse interests and backgrounds from both countries and beyond to discuss their collective quest to better understand the heterogeneity of diabetes and thus gain insights to inform new directions in diabetes treatment and prevention. This article summarizes the proceedings of that symposium, which spanned cutting-edge research into various aspects of islet biology, the heterogeneity of diabetic phenotypes, and the current state of and future prospects for precision medicine in diabetes.

Training Programs for Fundamental and Clinician-Scientists: Balanced Outcomes for Graduates by Gender

Background:

Women scientists are less likely to obtain Assistant Professorship and achieve promotion, and obtain less grant funding than men. Scientist/clinician-scientist training programs which provide salary awards as well as training and mentorship are a potential intervention to improve outcomes among women scientists. We hypothesized whether a programmatic approach to scientist/clinician-scientist training is associated with improved outcomes for women scientists in Canada when compared with salary awards alone. Trainees within the Kidney Research Scientist Core Education and National Training Program (KRESCENT), Canadian Child Health Clinician Scientist Program (CCHCSP), and the Canadian Institutes of Health Research (CIHR) salary award programs were evaluated.

Objective:

To examine whether the structured KRESCENT training program with salary support improves academic success for women scientists relative to salary awards alone.

Design:

Retrospective cohort study.

Setting:

Canadian national research scientist and clinician-scientist training programs and salary awards.

Participants:

KRESCENT cohort (n = 59, 2005-2017), CCHCSP cohort (n = 58, 2002-2015), and CIHR (n = 571, 2005-2015) Salary Awardees for postdoctoral fellows (PDF) and new investigators (NI).

Measurements:

National operating grant funding success, achieving an academic position as an Assistant Professor for PDF, or achieving promotion to Associate Professor for NI.

Methods:

The gender distribution of each cohort was determined using first name and NamepediA and was examined for PDF and NI, followed by a description of trainee outcomes by gender and training level.

Results:

KRESCENT and CIHR PDF were balanced (12/27, 44% men and 55/116, 47% women) while CCHCSP had a higher proportion of women (13/20, 65%). KRESCENT and CCHCSP NI retained women scientists (19/32, 59% and 22/38, 58% women), whereas CIHR NI had fewer women (165/455, 36% women vs 290/455, 64% men, P = 0.01). There was a high rate of NI operating grant success (91%-95%) with no gender differences in each cohort. There was a high proportion of CCHCSP PDF who achieved an Assistant Professorship (18/20, 90%) that may be due in part to a longer follow-up period (9.3 ± 3 years) compared with KRESCENT PDF (7/27, 26%, 0.88 ± 4.5 years), and these data were not available for CIHR PDF. Women KRESCENT NI showed increased promotion to Associate Professor (P = 0.02, 0.25 ± 3.2 years follow-up) and CCHCSP NI had high promotion rates (37/38, 97%, 6.9 ± 3.6 years follow-up) irrespective of gender. There was an overall trend toward more men pursuing biomedical research.

Limitations:

KRESCENT and CCHCSP training program cohort size and heterogeneity; assigning gender by first name may result in misclassification; lack of data on the respective applicant pools; and inability to examine intersectionality with gender, ethnicity, and sexual orientation.

Conclusion:

Overall trainee performance across programs is remarkable by community standards regardless of gender. KRESCENT and CCHCSP training programs demonstrated balanced success in their PDF and NI, whereas the CIHR awardees had reduced representation of women scientists from PDF to NI. This exploratory study highlights the utility of programmatic training approaches like the KRESCENT program as potential tools to support and retain women scientists in the academic pipeline during the challenging PDF to NI transition period.

Reducing Unnecessary Imaging in Children With Multicystic Dysplastic Kidney or Solitary Kidney

BACKGROUND AND OBJECTIVES

Children with isolated unilateral multicystic dysplastic kidney (MCDK) or congenital solitary kidney (CSK) undergo serial renal ultrasonography with variable frequency until they are transitioned to adult care. A growing body of literature suggests the value of frequent ultrasonography in this population is limited, providing no benefit to overall outcomes. Despite emerging evidence, ultrasound remains overused, resulting in avoidable health care expenditures and unnecessary use of resources. With our initiative, we aimed to improve quality of care by reducing avoidable ultrasounds in these children.

METHODS

This was a single-center, prospective, interrupted time series of children <18 years with ultrasound-confirmed isolated unilateral MCDK or CSK in the outpatient nephrology clinic to evaluate the effect of a decision-making algorithm on the proportion of children receiving an avoidable ultrasound. An algorithm depicting a consensus, evidence-based protocol for managing pediatric MCDK or CSK was refined through content expert feedback and usability testing to standardize frequency of ultrasonography. Ultrasounds were deemed necessary after birth, at 6 months, and at 2, 5, 10, and 15 years. Differences pre- and postintervention were determined by using a U chart and t and F tests for significance.

RESULTS

The algorithm resulted in a 47% reduction (P < .001) in the proportion of avoidable ultrasounds ordered in children with MCDK and CSK. This reduction was sustainable over a 6-month period and would result in at least $46 000 annual savings.

CONCLUSIONS

Introduction of a clinical decision-making algorithm was associated with a reduction in avoidable ultrasound testing. Improving adherence across providers may allow for an even more pronounced reduction.

Transforming growth factor beta signaling functions during mammalian kidney development

Aberrant transforming growth factor beta (TGFβ) signaling during embryogenesis is implicated in severe congenital abnormalities, including kidney malformations. However, the molecular mechanisms that underlie congenital kidney malformations related to TGFβ signaling remain poorly understood. Here, we review current understanding of the lineage-specific roles of TGFβ signaling during kidney development and how dysregulation of TGFβ signaling contributes to the pathogenesis of kidney malformation.

A Framework to Ensure Patient Partners Have Equal and Contributing Voices Throughout the Research Program Evaluation Process

PURPOSE OF PROGRAM

Traditionally, peer review was a closed process conducted only by individuals working in the research field. To establish a more integrated and patient-centered approach, one of Canada's largest kidney research networks (Can-SOLVE CKD) has created a Research Operations Committee (ROC) that includes patients as key members. The ROC represents one way for achieving meaningful patient-oriented research (POR).

SOURCE OF INFORMATION

Can-SOLVE CKD, a network created as part of the Canadian Institutes of Health Research (CIHR) Strategy for Patient-Oriented Research (SPOR).

METHODS

The ROC consists of patients, physicians, scientists, Indigenous partners, experts in research methodology, and a member of Can-SOLVE CKD's operational team. On an annual basis, Can-SOLVE CKD's research teams provide the ROC with a review package, which incorporates information from patient engagement check-in calls and surveys, the project's knowledge translation plan and products, and a progress report written by the project team. The ROC evaluates the review package and provides feedback and recommendations accordingly.

KEY FINDINGS

The transparent nature of the process, regular feedback and review, along with an overt accountability and scoring system, has been embraced by both patients and researchers. As a result of the ROC process, the number of patient leads for each project has grown over a 3-year period and more researchers have received POR and cultural sensitivity training.

LIMITATIONS

While anecdotal evidence suggests this approach is beneficial for achieving POR, formal mechanisms of evaluation are currently lacking.

IMPLICATIONS

This ROC framework ensures patients are active contributors throughout the research process and could be adopted by other organizations to achieve a more patient-centered approach to research.

COVID-19: a pandemic experience that illuminates potential reforms to health research

COVID‐19 has halted research around the globe and forced researchers out of their laboratories. Non‐emergency medical appointments were canceled. Ongoing clinical trials were challenged to create new modes of operation while public pressure mounted to find therapeutic options against COVID‐19. Yet, the inability to conduct research during COVID‐19 was overcome with cooperation, resource sharing, and compassion, which provides important lessons on how to improve health related research as we enter a new normal.

Precision Health Resource of Control iPSC Lines for Versatile Multilineage Differentiation

Induced pluripotent stem cells (iPSC) derived from healthy individuals are important controls for disease-modeling studies. Here we apply precision health to create a high-quality resource of control iPSCs. Footprint-free lines were reprogrammed from four volunteers of the Personal Genome Project Canada (PGPC). Multilineage-directed differentiation efficiently produced functional cortical neurons, cardiomyocytes and hepatocytes. Pilot users demonstrated versatility by generating kidney organoids, T lymphocytes, and sensory neurons. A frameshift knockout was introduced into MYBPC3 and these cardiomyocytes exhibited the expected hypertrophic phenotype. Whole-genome sequencing-based annotation of PGPC lines revealed on average 20 coding variants. Importantly, nearly all annotated PGPC and HipSci lines harbored at least one pre-existing or acquired variant with cardiac, neurological, or other disease associations. Overall, PGPC lines were efficiently differentiated by multiple users into cells from six tissues for disease modeling, and variant-preferred healthy control lines were identified for specific disease settings.

Suppressor of fused controls cerebellum granule cell proliferation by suppressing Fgf8 and spatially regulating Gli proteins

Cerebellar granule cell (GC) development relies on precise regulation of sonic hedgehog (Shh)-Gli signalling activity, failure of which is associated with motor disorders and medulloblastoma. Mutations in the pathway regulator suppressor of fused (Sufu), which modulates Gli activators and repressors, are linked to cerebellar dysfunction and tumourigenesis. The mechanism by which Sufu calibrates Shh signalling in GCs is unknown. Math1-Cre-mediated deletion of Sufu in mouse GC progenitors (GCPs) demonstrated that Sufu restricts GCP proliferation and promotes cell cycle exit, by promoting expression of Gli3R and suppressing Gli2 levels. Sufu is also required to promote a high threshold of pathway activity in GCPs. Remarkably, central cerebellar lobules are more deleteriously impacted by Sufu deletion, but are less sensitive to downstream genetic manipulations to reduce Gli2 expression or overexpress a Gli3R mimic, compared with anterior lobules. Transcriptome sequencing uncovered new Sufu targets, especially Fgf8, which is upregulated in Sufu-mutant GCPs. We demonstrate that Fgf8 is necessary and sufficient to drive Sufu-mutant GCP proliferation. This study reveals new insights into the spatial and temporal regulation of cerebellar Shh-Gli signalling, while uncovering new targets, such as Fgf8.

Critical Gaps in Understanding the Clinician-Scientist Workforce: Results of an International Expert Meeting

Clinician-scientists-health care professionals expert in research and clinical practice-can play a vital role in translating research outcomes to clinical practice. Concerns about the sustainability of the clinician-scientist workforce have been expressed in the literature for decades. Although many have made recommendations to increase the clinician-scientist workforce, there has been no substantial change. Therefore, an international expert meeting was held in March 2017 in Utrecht, the Netherlands, with the goal of discovering unidentified gaps in our understanding of challenges to the sustainability of the clinician-scientist workforce. Nineteen individuals (steering committee members; representatives from the AAMC, AFMC, and RCPSC; and physician-scientists, nurse-scientists, education scientists, deans, vice deans, undergraduate and postgraduate program directors, and a medical student) from Canada, the Netherlands, the United States, and Singapore participated in the meeting. The meeting identified 3 critical questions to be addressed: (1) What is the particular nature of the clinician-scientist role? (2) How are clinician-scientists to be recognized within the health and health research ecosystem? and (3) How can the value that clinician-scientists add to translational medicine and research be clarified to stakeholders and the public? The meeting participants identified a 3-fold agenda to address these questions: articulating the value proposition of clinician-scientists, supporting professionalization and professional identity development, and integrating clinical and research training. Addressing the 3 critical questions will likely contribute to a wider recognition of the value of clinician-scientists and be a first step in advancing from recommendations toward system-level changes to reinvigorate the clinician-scientist workforce.

Addressing the need for a new generation of young translational researchers that focuses on societal impact: The Apollo Toronto Story

Translational research (TR) is a multidirectional and multidisciplinary integration of basic research, patient-oriented research and population-based research, with the long-term goal of improving human health. Unfortunately, the current scientific training system does not adequately align with the goals of TR. To address this issue, an organization called Apollo Toronto was established at the University of Toronto in Toronto, Ontario. Apollo Toronto is a medical student-run international collaborative project between the Eureka Institute for Translational Medicine and the University of Toronto (one of Eureka Institute’s partner universities), and provides a general overview of TR to interested medical and graduate students. Through local and international initiatives, the various Apollo chapters (including Apollo Toronto) aim to establish a network of trainees equipped to address systemic issues that impede the translation of an ever-growing body of scientific literature into health solutions.

Building a Professional Identity and an Academic Career Track in Translational Medicine

Biomedical scientists aim to contribute to further understanding of disease pathogenesis and to develop new diagnostic and therapeutic tools that relieve disease burden. Yet the majority of biomedical scientists do not develop their academic career or professional identity as “translational scientists,” and are not actively involved in the continuum from scientific concept to development of new strategies that change medical practice. The collaborative nature of translational medicine and the lengthy process of bringing innovative findings from bench to bedside conflict with established pathways of building a career in academia. This collaborative approach also poses a problem for evaluating individual contributions and progress. The traditional evaluation of scientific success measured by the impact and number of publications and grants scientists achieve is inadequate when the product is a team effort that may take decades to complete. Further, where scientists are trained to be independent thinkers and to establish unique scientific niches, translational medicine depends on combining individual insights and strengths for the greater good. Training programs that are specifically geared to prepare scientists for a career in translational medicine are not widespread. In addition, the legal, regulatory, scientific and clinical infrastructure and support required for translational research is often underdeveloped in academic institutions and funding organizations, further discouraging the development and success of translational scientists in the academic setting. In this perspective we discuss challenges and potential solutions that could allow for physicians, physician scientists and basic scientists to develop a professional identity and a fruitful career in translational medicine.

The Integration of Clinical and Research Training: How and Why MD-PhD Programs Work

For over 60 years, MD-PhD programs have provided integrated clinical and research training to produce graduates primed for physician-scientist careers. Yet the nature of this integrated training is poorly characterized, with no program theory of MD-PhD training to guide program development or evaluation. The authors address this gap by proposing a program theory of integrated MD-PhD training applying constructs from cognitive psychology and medical education. The authors argue that integrated physician-scientist training requires development of at least three elements in trainees: cognitive synergy, sense of self, and professional capacity. First, integrated programs need to foster the cognitive ability to synergize and transfer knowledge between the clinical and research realms. Second, integrated programs need to facilitate development of a unique and emergent identity as a physician-scientist that is more than the sum of the individual roles of physician and scientist. Third, integrated programs should develop core competencies unique to physician-scientists in addition to those required of each independently. The authors describe how programs can promote development of these elements in trainees, summarized in a logic model. Activities and process measures are provided to assist institutions in enhancing integration. Specifically, programs can enact the proposed theory by providing tailored MD-PhD curricula, personal development planning, and a supportive community of practice. It is high time to establish a theory behind integrated MD-PhD training as the basis for designing interventions and evaluations to develop the foundations of physician-scientist expertise.

Impaired SIRT1 activity leads to diminution in glomerular endowment without accelerating age-associated GFR decline

Glomerular filtration rate (GFR) declines with age such that the prevalence of chronic kidney disease is much higher in the elderly. SIRT1 is the leading member of the sirtuin family of NAD+ -dependent lysine deacetylases that mediate the health span extending properties of caloric restriction. Since reduction in energy intake has also been shown to decrease age-related kidney disease in rodents, we hypothesized that a diminution in SIRT1 activity would accelerate the GFR decline and structural injury with age. To test this hypothesis, we compared changes in the kidney structure and function in control mice and mice that carry a point mutation at a conserved histidine (H355Y) of SIRT1 that renders the enzyme catalytically inactive. Taking advantage of this mouse model along with the disector/fractionator technique for glomerular counting and direct measurements of GFR by inulin clearance, we assessed the impact of SIRT1 inactivity on kidney aging. At 14 months of age, SIRT1 catalytically inactive (Sirt1Y/Y ) mice had lower GFRs and fewer glomeruli than their wild-type (Sirt1+/+ ) counterparts. This was not, however, due to either accelerated GFR decline or increased glomerulosclerosis and loss, but rather to reduced glomerular endowment in Sirt1Y/Y mice. Moreover, the compensatory glomerular hypertrophy and elevated single nephron GFR that customarily accompany reduction in nephron number were absent in Sirt1Y/Y mice. These findings suggest a role for SIRT1 not only in determining nephron endowment but also in orchestrating the response to it.

Preventing Translational Scientists From Extinction: The Long-Term Impact of a Personalized Training Program in Translational Medicine on the Careers of Translational Scientists

Far too much biomedical research is wasted and ends in the so called "Valley of Death": the gap that exists between biomedical research and its clinical application. While the translational process requires collaboration between many disciplines, current translational medicine focuses on single disciplines. Therefore, educational pathways that integrate clinical and research skills in interdisciplinary and interprofessional contexts are needed. The Eureka institute (http://www.eurekainstitute.org/) was founded to address these issues. The institute organizes an annual 1-week international certificate course to educate professionals in the domains of translational medicine. Study design: This study set out to investigate the impact of the Eureka certificate course on the alumni, focusing on their ability to engage in translational activities and thus become more proficient translational professionals. An explanatory, mixed-methods study was executed. Data collection: A questionnaire was distributed to collect quantitative data on the number of alumni who were able to apply what they learned during the Eureka course and engage in translational activities. Questionnaire data were also used to inform the semi-structured interviews that were conducted subsequently. Results: Fifty-one percent of the alumni reported that participating in the Eureka course played a role in their decision to change to a different job or in the way they were accomplishing their everyday work. Ten conditions for change that either hampered or supported the Eureka alumni's engagement in translational research activities were identified. Further, the learning outcomes of the Eureka course that impacted the alumni's professional activities were explored using Personal Professional Theory (PPT). The insight that alumni gained in the full translational spectrum and stakeholders involved stimulated reflection on their own role within that pathway. Further, according to the alumni, the course provided them with the skills and confidence to pursue a career as translational professional. These learning outcomes, in combination with conditions that supported alumni's engagement in translational activities, such as supportive professional partners, opportunities to network or collaborate, and a translational work environment, contributed to the large number of alumni that were able to engage in translational activities.

Hedgehog-GLI signaling in Foxd1-positive stromal cells promotes murine nephrogenesis via TGFβ signaling

Normal kidney function depends on the proper development of the nephron: the functional unit of the kidney. Reciprocal signaling interactions between the stroma and nephron progenitor compartment have been proposed to control nephron development. Here, we show that removal of hedgehog intracellular effector smoothened (Smo-deficient mutants) in the cortical stroma results in an abnormal renal capsule, and an expanded nephron progenitor domain with an accompanying decrease in nephron number via a block in epithelialization. We show that stromal-hedgehog-Smo signaling acts through a GLI3 repressor. Whole-kidney RNA sequencing and analysis of FACS-isolated stromal cells identified impaired TGFβ2 signaling in Smo-deficient mutants. We show that neutralization and knockdown of TGFβ2 in explants inhibited nephrogenesis. In addition, we demonstrate that concurrent deletion of Tgfbr2 in stromal and nephrogenic cells in vivo results in decreased nephron formation and an expanded nephrogenic precursor domain similar to that observed in Smo-deficient mutant mice. Together, our data suggest a mechanism whereby a stromal hedgehog-TGFβ2 signaling axis acts to control nephrogenesis.

Predictors of sustained research involvement among MD/PhD programme graduates

CONTEXT

MD/PhD programmes provide structured paths for physician-scientist training. However, considerable proportions of graduates of these programmes do not pursue careers in research consistent with their training.

OBJECTIVES

We sought to identify factors associated with sustained involvement in research after completion of all postgraduate training.

METHODS

Anonymised data from a national survey of Canadian MD/PhD programme graduates who had completed all physician-scientist training (n = 70) were analysed. Multivariable logistic regression was used to measure the associations between characteristics of graduates and five indicators of sustained research involvement following postgraduate training: (i) protected research time in the current appointment; (ii) percentage of time dedicated to research; (iii) planned future involvement in research; (iv) role as a principal investigator on a recent funded project, and (v) receipt of funding from a federal granting agency since graduation.

RESULTS

The majority of graduates were significantly involved in research on the basis of at least one outcome. Completion of a research fellowship, number of first-authored or co-authored manuscripts published during MD/PhD training, and duration of MD/PhD training were positively associated with continued research involvement. Completion of a Masters degree prior to MD/PhD training, female gender, debt greater than CAD$50 000 at completion of training, and pursuit of a clinical specialty other than internal medicine, paediatrics, neurology, pathology and the surgical specialties were negatively associated with sustained research involvement.

CONCLUSIONS

Most MD/PhD programme graduates remain significantly involved in research, but this involvement often does not correspond to traditional physician-scientist roles, in which a majority of time is dedicated to research. To minimise loss of investment in physician-scientist training, MD/PhD programmes should prioritise research productivity during training and the pursuit of additional research training during residency, and policymakers should establish stable sources of funding to reduce debt among graduates. Our data suggest further study is warranted to identify interventions to reduce attrition among female MD/PhD programme graduates.

Protein Kinase 2β Is Expressed in Neural Crest-Derived Urinary Pacemaker Cells and Required for Pyeloureteric Contraction

Nonobstructive hydronephrosis, defined as dilatation of the renal pelvis with or without dilatation of the ureter, is the most common antenatal abnormality detected by fetal ultrasound. Yet, the etiology of nonobstructive hydronephrosis is poorly defined. We previously demonstrated that defective development of urinary tract pacemaker cells (utPMCs) expressing hyperpolarization-activated cyclic nucleotide-gated channel 3 (HCN3) and the stem cell marker cKIT causes abnormal ureteric peristalsis and nonobstructive hydronephrosis. However, further investigation of utPMC development and function is limited by lack of knowledge regarding the embryonic derivation, development, and molecular apparatus of these cells. Here, we used lineage tracing in mice to identify cells that give rise to utPMCs. Neural crest cells (NCCs) indelibly labeled with tdTomato expressed HCN3 and cKIT. Furthermore, purified HCN3+ and cKIT+ utPMCs were enriched in Sox10 and Tfap-2α, markers of NCCs. Sequencing of purified RNA from HCN3+ cells revealed enrichment of a small subset of RNAs, including RNA encoding protein kinase 2β (PTK2β), a Ca²⁺-dependent tyrosine kinase that regulates ion channel activity in neurons. Immunofluorescence analysis in situ revealed PTK2β expression in NCCs as early as embryonic day 12.5 and in HCN3+ and cKIT+ utPMCs as early as embryonic day 15.5, with sustained expression in HCN3+ utPMCs until postnatal week 8. Pharmacologic inhibition of PTK2β in murine pyeloureteral tissue explants inhibited contraction frequency. Together, these results demonstrate that utPMCs are derived from NCCs, identify new markers of utPMCs, and demonstrate a functional contribution of PTK2β to utPMC function.

The Rising Challenge of Training Physician-Scientists: Recommendations From a Canadian National Consensus Conference

Physician-scientists are individuals who actively participate in patient care, have undergone additional research training, and devote the majority of their time to research. Physician-scientists are traditionally the primary catalysts in bridging the translational gap-that is, the failure to link fundamental new knowledge in the pathobiology of disease with advances in health care and health policy in a timely manner. However, there has been a shift away from training physician-scientists, and financial support for the physician-scientist is diminishing globally, causing the translational gap to grow. Given its socialized health care system and cultural and geographic diversity, Canada can serve as a unique case study in understanding how to address this phenomenon as a national priority. To this end, a Canadian national consensus conference was convened to develop recommendations for training programs and early-career supports for physician-scientists. Five recommendations were generated: (1) Establish an independent, national council whose mandate is to provide pan-Canadian oversight of physician-scientist training programs; (2) develop capacity for funding and mentorship support for physician-scientists; (3) develop coherent networks across a broad range of clinician-scientists, including physician-scientists, to reflect the unique cultural and geographic diversity of Canada and to reflect the interdisciplinarity of health research; (4) ensure that medical school curricula integrate, as a core curriculum feature, an understanding of the scientific basis of health care, including research methodologies; and (5) ensure that the funding of the physician-scientist trainee is viewed as portable and distinct from the operational funding provided to the training program itself.

Canadians Seeking Solutions and Innovations to Overcome Chronic Kidney Disease (Can-SOLVE CKD): Form and Function

PURPOSE OF REVIEW

This article serves to describe the Can-SOLVE CKD network, a program of research projects and infrastructure that has excited patients and given them hope that we can truly transform the care they receive.

ISSUE

Chronic kidney disease (CKD) is a complex disorder that affects more than 4 million Canadians and costs the Canadian health care system more than $40 billion per year. The evidence base for guiding care in CKD is small, and even in areas where evidence exists, uptake of evidence into clinical practice has been slow. Compounding these complexities are the variations in outcomes for patients with CKD and difficulties predicting who is most likely to develop complications over time. Clearly these gaps in our knowledge and understanding of CKD need to be filled, but the current state of CKD research is not where it needs to be. A culture of clinical trials and inquiry into the disease is lacking, and much of the existing evidence base addresses the concerns of the researchers but not necessarily those of the patients.

PROGRAM OVERVIEW

The Canadian Institutes of Health Research (CIHR) has launched the national Strategy for Patient-Oriented Research (SPOR), a coalition of federal, provincial, and territorial partners dedicated to integrating research into care. Canadians Seeking Solutions and Innovations to Overcome Chronic Kidney Disease (Can-SOLVE CKD) is one of five pan-Canadian chronic kidney disease networks supported through the SPOR. The vision of Can-SOLVE CKD is that by 2020 every Canadian with or at high risk for CKD will receive the best recommended care, experience optimal outcomes, and have the opportunity to participate in studies with novel therapies, regardless of age, sex, gender, location, or ethnicity.

PROGRAM OBJECTIVE

The overarching objective of Can-SOLVE CKD is to accelerate the translation of knowledge about CKD into clinical research and practice. By focusing on the patient's voice and implementing relevant findings in real time, Can-SOLVE CKD will transform the care that CKD patients receive, and will improve kidney health for future generations.

Activated Hedgehog-GLI Signaling Causes Congenital Ureteropelvic Junction Obstruction

Intrinsic ureteropelvic junction obstruction is the most common cause of congenital hydronephrosis, yet the underlying pathogenesis is undefined. Hedgehog proteins control morphogenesis by promoting GLI-dependent transcriptional activation and inhibiting the formation of the GLI3 transcriptional repressor. Hedgehog regulates differentiation and proliferation of ureteric smooth muscle progenitor cells during murine kidney-ureter development. Histopathologic findings of smooth muscle cell hypertrophy and stroma-like cells, consistently observed in obstructing tissue at the time of surgical correction, suggest that Hedgehog signaling is abnormally regulated during the genesis of congenital intrinsic ureteropelvic junction obstruction. Here, we demonstrate that constitutively active Hedgehog signaling in murine intermediate mesoderm-derived renal progenitors results in hydronephrosis and failure to develop a patent pelvic-ureteric junction. Tissue obstructing the ureteropelvic junction was marked as early as E13.5 by an ectopic population of cells expressing Ptch2, a Hedgehog signaling target. Constitutive expression of GLI3 repressor in Ptch1-deficient mice rescued ectopic Ptch2 expression and obstructive hydronephrosis. Whole transcriptome analysis of isolated Ptch2⁺ cells revealed coexpression of genes characteristic of stromal progenitor cells. Genetic lineage tracing indicated that stromal cells blocking the ureteropelvic junction were derived from intermediate mesoderm-derived renal progenitors and were distinct from the smooth muscle or epithelial lineages. Analysis of obstructive ureteric tissue resected from children with congenital intrinsic ureteropelvic junction obstruction revealed a molecular signature similar to that observed in Ptch1-deficient mice. Together, these results demonstrate a Hedgehog-dependent mechanism underlying mammalian intrinsic ureteropelvic junction obstruction.

Suppressor of fused controls cerebellar neuronal differentiation in a manner modulated by GLI3 repressor and Fgf15

BACKGROUND

Deficiency of Suppressor of Fused (SuFu), an intracellular mediator of Hedgehog signaling, in the murine mid-hindbrain disrupts cerebellar morphogenesis and cell differentiation in a manner that is rescued by constitutive expression of GLI3 transcriptional repressor (GLI3R). Here, we determined SuFu functions in cerebellar radial precursors following the stage of mid-hindbrain specification using a Blbp-Cre transgene.

RESULTS

SuFu-deficient cerebella were severely dysplastic, and characterized by laminar disorganization, and delayed differentiation of ventricular zone-derived precursors. In vitro analysis of cerebellar precursors isolated from control and mutant mice demonstrated an increased proportion of radial glial precursors vs. Tuj1-positive neurons in mutant cultures. Abnormal cell differentiation in SuFu-deficient precursors was rescued by a constitutively expressed GLI3R knock-in allele, albeit with variable penetrance. Using RNA expression analysis in control and SuFu-deficient cerebellar anlage, we identified up-regulation of Fgf15 in mutant tissue. Strikingly, exogenous hFGF19, a mFGF15 ortholog, inhibited neuronal differentiation in cultures of wild-type cerebellar precursors. Moreover, siRNA-mediated knockdown of Fgf15 in SuFu-deficient cerebellar precursors rescued their delayed differentiation to neurons.

CONCLUSIONS

Together, our results show that SuFu promotes cerebellar radial precursor differentiation to neurons. SuFu function is mediated in part by GLI3R and down-regulation of Fgf15 expression. Developmental Dynamics 247:156-169, 2018. © 2017 Wiley Periodicals, Inc.

Characteristics and outcomes of Canadian MD/PhD program graduates: a cross-sectional survey

BACKGROUND

Combined MD/PhD programs provide a structured path for physician-scientist training, but assessment of their success within Canada is limited by a lack of quantitative data. We collected outcomes data for graduates of Canadian MD/PhD programs.

METHODS

We developed and implemented a Web-based survey consisting of 41 questions designed to collect outcomes data for Canadian MD/PhD program alumni from 8 Canadian universities who had graduated before September 2015. Respondents were categorized into 2 groups according to whether they had or had not completed all training.

RESULTS

Of the 186 eligible alumni of MD/PhD programs, 139 (74.7%) completed the survey. A total of 136/138 respondents (98.6%) had completed or were currently completing residency training, and 66/80 (82%) had completed at least 1 postgraduate fellowship. Most (58 [83%]) of the 70 respondents who had completed all training were appointed as faculty at academic institutions, and 37 (53%) had been principal investigators on at least 1 recent funded project. Among the 58 respondents appointed at academic institutions, 44/57 (77%) dedicated at least 20% of their time to research, and 25/57 (44%) dedicated at least 50% to research. During their combined degree, 102/136 respondents (75.0%) published 3 or more first-author papers, and 133/136 (97.8%) matched with their first choice of specialty. The median length of physician-scientist training was 13.5 years. Most respondents graduated with debt despite having been supported by Canadian Institutes of Health Research MD/PhD studentships.

INTERPRETATION

Most Canadian MD/PhD program alumni pursued careers consistent with their physician-scientist training, which indicates that these programs are meeting their primary objective. Nevertheless, our findings highlight that a minority of these positions are research intensive; this finding warrants further study. Our data provide a baseline for future monitoring of the output of Canadian MD/PhD programs.

Origin and Function of the Renal Stroma in Health and Disease

The renal stroma is defined as a heterogeneous population of cells that serve both as a supportive framework and as a source of specialized cells in the renal capsule, glomerulus, vasculature, and interstitium. In this chapter, we review published evidence defining what, where, and why stromal cells are important. We describe the functions of the renal stroma andhow stromal derivatives are crucial for normal kidney function. Next, we review the specification of stromal cells from the Osr1+ intermediate mesoderm and T+ presomitic mesoderm during embryogenesis and stromal cell differentiation. We focus on stromal signaling mechanisms that act in both a cell and non-cell autonomous manner in communication with the nephron progenitor and ureteric lineages. To conclude, stromal cells and the contribution of stromal cells to renal fibrosis and chronic kidney disease are described.

Origin and Function of the Renal Stroma in Health and Disease

The renal stroma is defined as a heterogeneous population of cells that serve both as a supportive framework and as a source of specialized cells in the renal capsule, glomerulus, vasculature, and interstitium. In this chapter, we review published evidence defining what, where, and why stromal cells are important. We describe the functions of the renal stroma andhow stromal derivatives are crucial for normal kidney function. Next, we review the specification of stromal cells from the Osr1+ intermediate mesoderm and T+ presomitic mesoderm during embryogenesis and stromal cell differentiation. We focus on stromal signaling mechanisms that act in both a cell and non-cell autonomous manner in communication with the nephron progenitor and ureteric lineages. To conclude, stromal cells and the contribution of stromal cells to renal fibrosis and chronic kidney disease are described.

Professional Identity Formation and the Clinician-Scientist: A Paradigm for a Clinical Career Combining Two Distinct Disciplines

The clinician-scientist role is critical to the future of health care, and in 2010, the Carnegie Report on Educating Physicians focused attention on the professional identity of practicing clinicians. Although limited in number, published studies on the topic suggest that professional identity is likely a critical factor that determines career sustainability. In contrast to clinicians with a singular focus on clinical practice, clinician-scientists combine two major disciplines, clinical medicine and scientific research, to bridge discovery and clinical care. Despite its importance to advancing medical practice, the clinician-scientist career faced a variety of threats, which have been identified recently by the 2014 National Institutes of Health Physician Scientist Workforce. Yet, professional identity development in this career pathway is poorly understood. This Perspective focuses on the challenges to the clinician-scientist's professional identity and its development. First, the authors identify the particular challenges that arise from the different cultures of clinical care and science and the implications for clinician-scientist professional identity formation. Next, the authors synthesize insights about professional identity development within a dual-discipline career and apply their analysis to a discussion about the implications for clinician-scientist identity formation. Although not purposely developed to address identity formation, the authors highlight those elements within clinician-scientist training and career development programs that may implicitly support identity development. Finally, the authors highlight a need to identify empirically the elements that compose and determine clinician-scientist professional identity and the processes that shape its formation and sustainability.

Developing translational medicine professionals: the Marie Skłodowska-Curie action model

End goal of translational medicine is to combine disciplines and expertise to eventually promote improvement of the global healthcare system by delivering effective therapies to individuals and society. Well-trained experts of the translational medicine process endowed with profound knowledge of biomedical technology, ethical and clinical issues, as well as leadership and teamwork abilities are essential for the effective development of tangible therapeutic products for patients. In this article we focus on education and, in particular, we discuss how programs providing training on the broad spectrum of the translational medicine continuum have still a limited degree of diffusion and do not provide professional support and mentorship in the long-term, resulting in the lack of well established professionals of translational medicine (TMPs) in the scientific community. Here, we describe the Marie Skłodowska-Curie Actions program ITN-EUtrain (EUropean Translational tRaining for Autoimmunity & Immune manipulation Network) where training on the Translational Medicine machinery was integrated with education on professional and personal skills, mentoring, and a long-lasting network of TMPs.

The path ahead for MD/PhD programs in Canada Commentary on Jones et al

The paper by Jones and colleagues, published in this edition of Clinical Investigative Medicine, contributes to our understanding of Canadian MD/PhD Programs. While there has been little published on this subject by the Canadian programs, themselves, this paper is the most recent in a series by leaders of the Clinical Investigator Trainee Association of Canada (CITAC). The authors are to be commended for their efforts and productivity.

Research projects in the Surgeon-Scientist and Clinician-Investigator programs at the University of Toronto (1987-2016): a cohort study

BACKGROUND

Physicians have traditionally been at the forefront of medical research, bringing clinical questions to the laboratory and returning with ideas for treatment. However, we have anecdotally observed a decline in the popularity of basic science research among trainees. We hypothesized that fewer resident physicians have been pursuing basic science research training over time.

METHODS

We examined records from residents in the Surgeon-Scientist and Clinician-Investigator programs at the University of Toronto (1987-2016). Research by residents was categorized independently by 2 raters as basic science, clinical epidemiology or education-related based on the title of the project, the name of the supervisor and Pubmed searches. The study population was divided into quintiles of time, and the proportion pursuing basic science training in each quintile was calculated.

RESULTS

Agreement between the raters was 100%; the categorization of the research topic remained unclear in 9 cases. The proportion of trainees pursuing basic science training dropped by 60% from 1987 to 2016 (p = 0.005).

INTERPRETATION

Significantly fewer residents in the Surgeon-Scientist and Clinician-Investigator Programs at the University of Toronto are pursuing training in the basic sciences as compared with previous years.

Urogenital development in Pallister-Hall syndrome is disrupted in a cell-lineage-specific manner by constitutive expression of GLI3 repressor

Pallister-Hall syndrome (PHS) is a rare disorder caused by mutations in GLI3 that produce a transcriptional repressor (GLI3R). Individuals with PHS present with a variably penetrant variety of urogenital system malformations, including renal aplasia or hypoplasia, hydroureter, hydronephrosis or a common urogenital sinus. The embryologic mechanisms controlled by GLI3R that result in these pathologic phenotypes are undefined. We demonstrate that germline expression of GLI3R causes renal hypoplasia, associated with decreased nephron number, and hydroureter and hydronephrosis, caused by blind-ending ureters. Mice with obligate GLI3R expression also displayed duplication of the ureters that was caused by aberrant common nephric duct patterning and ureteric stalk outgrowth. These developmental abnormalities are associated with suppressed Hedgehog signaling activity in the cloaca and adjacent vesicular mesenchyme. Mice with conditional expression of GLI3R were utilized to identify lineage-specific effects of GLI3R. In the ureteric bud, GLI3R expression decreased branching morphogenesis. In Six2-positive nephrogenic progenitors, GLI3R decreased progenitor cell proliferation reducing the number of nephrogenic precursor structures. Using mutant mice with Gli3R and Gli3 null alleles, we demonstrate that urogenital system patterning and development is controlled by the levels of GLI3R and not by an absence of full-length GLI3. We conclude that the urogenital system phenotypes observed in PHS are caused by GLI3R-dependent perturbations in nephric duct patterning, renal branching morphogenesis and nephrogenic progenitor self-renewal.

Integrin-linked Kinase Controls Renal Branching Morphogenesis via Dual Specificity Phosphatase 8

Integrin-linked kinase (ILK) is an intracellular scaffold protein with critical cell-specific functions in the embryonic and mature mammalian kidney. Previously, we demonstrated a requirement for Ilk during ureteric branching and cell cycle regulation in collecting duct cells in vivo Although in vitro data indicate that ILK controls p38 mitogen-activated protein kinase (p38MAPK) activity, the contribution of ILK-p38MAPK signaling to branching morphogenesis in vivo is not defined. Here, we identified genes that are regulated by Ilk in ureteric cells using a whole-genome expression analysis of whole-kidney mRNA in mice with Ilk deficiency in the ureteric cell lineage. Six genes with expression in ureteric tip cells, including Wnt11, were downregulated, whereas the expression of dual-specificity phosphatase 8 (DUSP8) was upregulated. Phosphorylation of p38MAPK was decreased in kidney tissue with Ilk deficiency, but no significant decrease in the phosphorylation of other intracellular effectors previously shown to control renal morphogenesis was observed. Pharmacologic inhibition of p38MAPK activity in murine inner medullary collecting duct 3 (mIMCD3) cells decreased expression of Wnt11, Krt23, and Slo4c1 DUSP8 overexpression in mIMCD3 cells significantly inhibited p38MAPK activation and the expression of Wnt11 and Slo4c1. Adenovirus-mediated overexpression of DUSP8 in cultured embryonic murine kidneys decreased ureteric branching and p38MAPK activation. Together, these data demonstrate that Ilk controls branching morphogenesis by regulating the expression of DUSP8, which inhibits p38MAPK activity and decreases branching morphogenesis.

A New Grading System for the Management of Antenatal Hydronephrosis

BACKGROUND AND OBJECTIVES

Standard clinical assessments do not predict surgical intervention in patients with a moderate degree of upper tract hydronephrosis. This study investigated whether combined measures of renal calyceal dilation and anteroposterior diameter (APD) of the renal pelvis at the first postnatal ultrasound better predict surgical intervention beyond standard assessments of the APD or Society of Fetal Urology (SFU) grading system.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A retrospective cohort of 348 children with antenatal hydronephrosis followed from 2003 to 2013 were studied. Using Cox regression, the risk for surgery by APD, SFU, and combined grading on the basis of the first postnatal ultrasound was calculated. The predictive capability of each grading system for surgery was determined by calculating the positive likelihood ratio (LR+).

RESULTS

The combination of APD≥6-9 mm and diffuse caliectasis had a hazard ratio (HR) of 19.5 (95% confidence interval [95% CI], 3.94 to 96.9) versus 0.59 (95% CI, 0.05 to 6.53) for APD≥6-9 mm alone and a similar risk of 8.9 for SFU grade 3 (95% CI, 3.84 to 20.9). The combination of APD≥9-15 mm and diffuse caliectasis had an HR of 18.7 (95% CI, 4.36 to 80.4) versus 1.75 (95% CI, 0.29 to 10.5) for APD≥9-15 mm alone. The LR+ for surgery for diffuse caliectasis and APD≥6-9 mm was higher than for APD≥6-9 mm alone (HR=2.62; 95% CI, 0.87 to 7.94 versus HR=0.04; 95% CI, 0.01 to 0.32) and was higher for APD≥9-15 mm and diffuse caliectasis than APD≥9-15 mm alone (HR=2.0; 95% CI, 1.15 to 3.45 versus HR=0.14; 95% CI, 0.04 to 0.43). Both combined groups of moderate hydronephrosis (APD≥6-9 mm or ≥9-15 mm with diffuse caliectasis) had only slightly higher LR+ than SFU grade 3 (HR=1.89; 95% CI, 1.17 to 3.05).

CONCLUSIONS

These results suggest a grading system combining APD and diffuse caliectasis distinguishes those children with moderate degrees of upper tract hydronephrosis that are at higher risk of surgery.

Insights into the renal pathogenesis in Schimke immuno-osseous dysplasia: A renal histological characterization and expression analysis

Schimke immuno-osseous dysplasia (SIOD) is a pleiotropic disorder caused by mutations in the SWI/SNF2-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like-1 (SMARCAL1) gene, with multiple clinical features, notably end-stage renal disease. Here we characterize the renal pathology in SIOD patients. Our analysis of SIOD patient renal biopsies demonstrates the tip and collapsing variants of focal segmental glomerulosclerosis (FSGS). Additionally, electron microscopy revealed numerous glomerular abnormalities most notably in the podocyte and Bowman's capsule. To better understand the role of SMARCAL1 in the pathogenesis of FSGS, we defined SMARCAL1 expression in the developing and mature kidney. In the developing fetal kidney, SMARCAL1 is expressed in the ureteric epithelium, stroma, metanephric mesenchyme, and in all stages of the developing nephron, including the maturing glomerulus. In postnatal kidneys, SMARCAL1 expression is localized to epithelial tubules of the nephron, collecting ducts, and glomerulus (podocytes and endothelial cells). Interestingly, not all cells within the same lineage expressed SMARCAL1. In renal biopsies from SIOD patients, TUNEL analysis detected marked increases in DNA fragmentation. Our results highlight the cells that may contribute to the renal pathogenesis in SIOD. Further, we suggest that disruptions in genomic integrity during fetal kidney development contribute to the pathogenesis of FSGS in SIOD patients.

Challenges Facing Physician Scientist Trainees: a Survey of Trainees in Canada’s Largest Undergraduate and Postgraduate Programs in a Single Centre

Purpose: A number of indicators suggest that the physician scientist career track is threatened. As such, it is an opportune time to evaluate current training models. Perspectives on physician scientist education and career path were surveyed in trainees at the University of Toronto, home to Canada’s longest standing physician scientist training programs. Methods: Trainees from the Clinician Investigator Program (CIP) and MD/PhD Program at the University of Toronto were surveyed. Liekert-style closed-ended questions were used to assess future career goals, present and future perspectives and concerns about and beliefs on training. Demographic information was collected regarding year of study, graduate degree program and focus of clinical and health research. Statistical analysis included non-parametric tests for sub-group comparisons. Results: Both groups of trainees were motivated to pursue a career as a physician scientist. While confident in their decision to begin and complete physician scientist training, they expressed concerns about the level of integration between clinical and research training in the current programs. They also expressed concerns about career outlook, including the ability to find stable and sustainable careers in academic medicine. Trainees highlighted a number of factors, including career mentorship, as essential for career success. Conclusion: These findings indicate that while trainees at different stages consistently express career motivation, they identified concerns that are program- and training stage-specific. These concerns mirror those highlighted in the medical education literature regarding threats to the physician scientist career path. Understanding these different and changing perspectives and exploring those differences could form an important basis for trainee program improvements both nationally and internationally.

Renal branching morphogenesis: morphogenetic and signaling mechanisms

The human kidney is composed of an arborized network of collecting ducts, calyces and urinary pelvis that facilitate urine excretion and regulate urine composition. The renal collecting system is formed in utero, completed by the 34th week of gestation in humans, and dictates final nephron complement. The renal collecting system arises from the ureteric bud, a derivative of the intermediate-mesoderm derived nephric duct that responds to inductive signals from adjacent tissues via a process termed ureteric induction. The ureteric bud subsequently undergoes a series of iterative branching and remodeling events in a process called renal branching morphogenesis. Altered signaling that disrupts patterning of the nephric duct, ureteric induction, or renal branching morphogenesis leads to varied malformations of the renal collecting system collectively known as congenital anomalies of the kidney and urinary tract (CAKUT) and is the most frequently detected congenital renal aberration in infants. Here, we describe critical morphogenetic and cellular events that govern nephric duct specification, ureteric bud induction, renal branching morphogenesis, and cessation of renal branching morphogenesis. We also highlight salient molecular signaling pathways that govern these processes, and the investigative techniques used to interrogate them.

Urinary tract pacemaker cells: current knowledge and insights from nonrenal pacemaker cells provide a basis for future discovery

Coordinated ureteric peristalsis propels urine from the kidney to the bladder. Cells in the renal pelvis and ureter spontaneously generate and propagate electrical activity to control this process. Recently, c-kit tyrosine kinase and hyperpolarization-activated cyclic nucleotide-gated channel 3 (HCN3) were identified in the upper urinary tract. Both of these proteins are required for coordinated proximal to distal contractions in the ureter. Alterations in pacemaker cell expression are present in multiple congenital kidney diseases, suggesting a functional contribution by these cells to pathologic states. In contrast to gut and heart pacemaker cells, the developmental biology of ureteric pacemaker cells, including cell lineage and signaling mechanisms, is undefined. Here, we review pacemaker cell identify and function in the urinary pelvis and ureter and the control of pacemaker function by Hedgehog-GLI signaling. Next, we highlight current knowledge of gut and heart pacemaker cells that is likely to provide insight into developmental mechanisms that could control urinary pacemaker cells.

β-Catenin overexpression in the metanephric mesenchyme leads to renal dysplasia genesis via cell-autonomous and non-cell-autonomous mechanisms

Renal dysplasia, a developmental disorder characterized by defective ureteric branching morphogenesis and nephrogenesis, ranks as one of the major causes of renal failure among the pediatric population. Herein, we demonstrate that the levels of activated β-catenin are elevated in the nuclei of ureteric, stromal, and mesenchymal cells within dysplastic human kidney tissue. By using a conditional mouse model of mesenchymal β-catenin overexpression, we identify two novel signaling pathways mediated by β-catenin in the development of renal dysplasia. First, the overexpression of β-catenin within the metanephric mesenchyme leads to ectopic and disorganized branching morphogenesis caused by β-catenin directly binding Tcf/lef consensus binding sites in the Gdnf promoter and up-regulating Gdnf transcription. Second, β-catenin overexpression in the metanephric mesenchyme leads to elevated levels of transcriptionally active β-catenin in the ureteric epithelium. Interestingly, this increase of β-catenin-mediated transcription results from a novel Ret/β-catenin signaling pathway. Consistent with these findings, analysis of human dysplastic renal tissue demonstrates that undifferentiated mesenchymal cells expressing high levels of β-catenin also express increased GDNF. Furthermore, dysplastic ureteric tubules that were surrounded by high levels of GDNF also exhibited increased levels of activated β-catenin. Together, these data support a model in which the elevation of β-catenin in the metanephric mesenchyme results in cell-autonomous and non-cell-autonomous events that lead to the genesis of renal dysplasia.