Glomerular endothelial cell heterogeneity in Alport syndrome

Glomerular endothelial cells (GEC) are a crucial component of the glomerular physiology and their damage contributes to the progression of chronic kidney diseases. How GEC affect the pathology of Alport syndrome (AS) however, is unclear. We characterized GEC from wild type (WT) and col4α5 knockout AS mice, a hereditary disorder characterized by progressive renal failure. We used endothelial-specific Tek-tdTomato reporter mice to isolate GEC by FACS and performed transcriptome analysis on them from WT and AS mice, followed by in vitro functional assays and confocal and intravital imaging studies. Biopsies from patients with chronic kidney disease, including AS were compared with our findings in mice. We identified two subpopulations of GEC (dim^tdT and bright^tdT) based on the fluorescence intensity of the Tek^tdT signal. In AS mice, the bright^tdT cell number increased and presented differential expression of endothelial markers compared to WT. RNA-seq analysis revealed differences in the immune and metabolic signaling pathways. In AS mice, dim^tdT and bright^tdT cells had different expression profiles of matrix-associated genes (Svep1, Itgβ6), metabolic activity (Apom, Pgc1α) and immune modulation (Apelin, Icam1) compared to WT mice. We confirmed a new pro-inflammatory role of Apelin in AS mice and in cultured human GEC. Gene modulations were identified comparable to the biopsies from patients with AS and focal segmental glomerulosclerosis, possibly indicating that the same mechanisms apply to humans. We report the presence of two GEC subpopulations that differ between AS and healthy mice or humans. This finding paves the way to a better understanding of the pathogenic role of GEC in AS progression and could lead to novel therapeutic targets.

SOX9+/PTF1A+ Cells Define the Tip Progenitor Cells of the Human Fetal Pancreas of the Second Trimester

Significant progress has been made in recent years in characterizing human multipotent progenitor cells (hMPCs) of the early pancreas; however, the identity and persistence of these cells during the second trimester, after the initiation of branching morphogenesis, remain elusive. Additionally, studies on hMPCs have been hindered by few isolation methods that allow for the recovery of live cells. Here, we investigated the tip progenitor domain in the branched epithelium of human fetal pancreas between 13.5 and 17.5 gestational weeks by immunohistological staining. We also used a novel RNA-based technology to isolate live cells followed by gene expression analyses. We identified cells co-expressing SOX9 and PTF1A, two transcription factors known to be important for pancreatic MPCs, within the tips of the epithelium and observed a decrease in their proportions over time. Pancreatic SOX9+/PTF1A+ cells were enriched for MPC markers, including MYC and GATA6. These cells were proliferative and appeared active in branching morphogenesis and matrix remodeling, as evidenced by gene set enrichment analysis. We identified a hub of genes pertaining to the expanding tip progenitor niche, such as FOXF1, GLI3, TBX3, FGFR1, TGFBR2, ITGAV, ITGA2, and ITGB3. YAP1 of the Hippo pathway emerged as a highly enriched component within the SOX9+/PTF1A+ cells. Single-cell RNA-sequencing further corroborated the findings by identifying a cluster of SOX9+/PTF1A+ cells with multipotent characteristics. Based on these results, we propose that the SOX9+/PTF1A+ cells in the human pancreas are uncommitted MPC-like cells that reside at the tips of the expanding pancreatic epithelium, directing self-renewal and inducing pancreatic organogenesis. Stem Cells Translational Medicine 2019;8:1249&1264.

Absence of Testicular Adrenal Rest Tumors in Newborns, Infants, and Toddlers with Classical Congenital Adrenal Hyperplasia

INTRODUCTION

Testicular adrenal rest tumors (TART) are a known consequence for males with classical congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. TART are associated with potential infertility in adults. However, little is known about TART in very young males with CAH.

OBJECTIVE

We assessed the presence of TART in newborn, infant, and toddler males with classical CAH via scrotal ultrasound.

METHODS

Males with CAH had scrotal ultrasounds during the first 4 years of life, evaluating testes for morphology, blood flow, and presence of TART. Newborn screen 17-hydroxyprogesterone (17-OHP) and serum 17-OHP at the time of ultrasound were recorded. Bone ages were considered very advanced if ≥2 SD above chronological age.

RESULTS

Thirty-one ultrasounds in 16 males were performed. An initial ultrasound was obtained in four newborns at diagnosis (6.8 ± 2.1 days), six infants (2.2 ± 0.9 months), and six toddlers (2.4 ± 0.9 years). Eleven males had at least one repeat ultrasound. A large proportion (11/16) were in poor hormonal control with an elevated 17-OHP (325 ± 298 nmol/L). One infant was in very poor hormonal control (17-OHP 447 nmol/L) at initial ultrasound, and two toddlers had advanced bone ages (+3.2 and +4.5 SD) representing exposure to postnatal androgens. However, no TART were detected in any subjects.

CONCLUSIONS

TART were not found by scrotal ultrasound in males up to 4 years of age with classical CAH despite settings with expected high ACTH drive. Further research into the occurrence of TART in CAH may elucidate factors that contribute to the detection and individual predisposition to TART.

Aberrant Activation of Notch Signaling Inhibits PROX1 Activity to Enhance the Malignant Behavior of Thyroid Cancer Cells

Papillary thyroid cancer (PTC) is one of the most common endocrine malignancies associated with significant morbidity and mortality. Although multiple studies have contributed to a better understanding of the genetic alterations underlying this frequently arising disease, the downstream molecular effectors that impact PTC pathogenesis remain to be further defined. Here, we report that the regulator of cell fate specification, PROX1, becomes inactivated in PTC through mRNA downregulation and cytoplasmic mislocalization. Expression studies in clinical specimens revealed that aberrantly activated NOTCH signaling promoted PROX1 downregulation and that cytoplasmic mislocalization significantly altered PROX1 protein stability. Importantly, restoration of PROX1 activity in thyroid carcinoma cells revealed that PROX1 not only enhanced Wnt/β-catenin signaling but also regulated several genes known to be associated with PTC, including thyroid cancer protein (TC)-1, SERPINA1, and FABP4. Furthermore, PROX1 reexpression suppressed the malignant phenotypes of thyroid carcinoma cells, such as proliferation, motility, adhesion, invasion, anchorage-independent growth, and polyploidy. Moreover, animal xenograft studies demonstrated that restoration of PROX1 severely impeded tumor formation and suppressed the invasiveness and the nuclear/cytoplasmic ratio of PTC cells. Taken together, our findings demonstrate that NOTCH-induced PROX1 inactivation significantly promotes the malignant behavior of thyroid carcinoma and suggest that PROX1 reactivation may represent a potential therapeutic strategy to attenuate disease progression.

Amniotic fluid stem cells prevent β-cell injury

BACKGROUND AIMS

The contribution of amniotic fluid stem cells (AFSC) to tissue protection and regeneration in models of acute and chronic kidney injuries and lung failure has been shown in recent years. In the present study, we used a chemically induced mouse model of type 1 diabetes to determine whether AFSC could play a role in modulating β-cell injury and restoring β-cell function.

METHODS

Streptozotocin-induced diabetic mice were given intracardial injection of AFSC; morphological and physiological parameters and gene expression profile for the insulin pathway were evaluated after cell transplantation.

RESULTS

AFSC injection resulted in protection from β-cell damage and increased β-cell regeneration in a subset of mice as indicated by glucose and insulin levels, increased islet mass and preservation of islet structure. Moreover, β-cell preservation/regeneration correlated with activation of the insulin receptor/Pi3K/Akt signaling pathway and vascular endothelial growth factor-A expression involved in maintaining β-cell mass and function.

CONCLUSIONS

Our results suggest a therapeutic role for AFSC in preserving and promoting endogenous β-cell functionality and proliferation. The protective role of AFSC is evident when stem cell transplantation is performed before severe hyperglycemia occurs, which suggests the importance of early intervention. The present study demonstrates the possible benefits of the application of a non-genetically engineered stem cell population derived from amniotic fluid for the treatment of type 1 diabetes mellitus and gives new insight on the mechanism by which the beneficial effect is achieved.

Shorter androgen receptor CAG repeat lengths associated with cryptorchidism risk among Hispanic white boys

CONTEXT

Cryptorchidism is the most frequent congenital malformation among males, the major established risk factor for testicular germ cell tumors, and a presumed infertility risk factor. Androgens are essential for testicular descent, and functional genetic polymorphisms in the androgen receptor gene (AR) are postulated to influence cryptorchidism risk.

OBJECTIVE

The aim of the study was to investigate whether the CAG repeat length polymorphism in exon 1 of the AR is associated with cryptorchidism risk.

DESIGN AND SETTING

We conducted a family-based genotype-risk association study employing the transmission disequilibrium test for genotypic variants transmitted on the X-chromosome at a university-affiliated regional children's hospital.

PARTICIPANTS

We studied 127 Hispanic boys with persistent cryptorchidism and comorbidities described in detail and their biological mothers.

INTERVENTION

Genotypes defined by number of CAG repeats were measured for each member of participating son-mother pairs.

MAIN OUTCOME MEASURE

Associations between CAG tract length genotype and cryptorchidism risk were estimated using matched-pairs logistic regression.

RESULTS

Cryptorchidism risk was significantly associated with shorter CAG repeats [CAG≤19 vs. CAG≥20, odds ratio (OR)=0.44; 95% confidence interval (CI), 0.23-0.88]. This association was restricted to cryptorchidism with accompanying comorbidities, which was primarily hernia [CAG≤19 vs. CAG≥20, OR=0.35 (95% CI, 0.16-0.78)], and was strongest for bilateral cryptorchidism [CAG≤19 vs. CAG≥20, OR=0.09 (95% CI, 0.010-0.78)].

CONCLUSIONS

Androgen receptor genotypes encoding moderate functional variation may influence cryptorchidism risk, particularly among boys with bilateral nondescent or congenital hernia, and may explain in part the elevated risk of testicular seminoma experienced by ex-cryptorchid boys. Mechanistic research is warranted to examine both classical and nonclassical mechanisms through which androgens may influence risk of cryptorchidism and related conditions.

Characterization of human amniotic fluid stem cells and their pluripotential capability

Over the past decade, there has been ever-increasing emphasis placed on stem cells and their potential role in regenerative medicine for reconstruction of bio-artificial tissues and organs. Scientists have looked at various sources for pluripotential cells ranging from embryonic stem cells to adult stem cells. Amniocentesis is a well-established technique for the collection of cells derived from the human embryo. In this chapter, we are going to describe how to isolate, maintain in culture, and characterize the pluripotential capabilities of stem cells derived from amniocentesis in an in vitro and in vivo system. Cell samples are obtained from human pregnancies, and the progenitor cells are isolated from male fetuses with a normal karyotype in order to confirm the absence of maternal admixed cells. Progenitor cells express embryonic-specific cell markers, they show a high self-renewal capacity with 350 population doublings, and normal ploidy is confirmed by cell-cycle analyses. They maintain their undifferentiated state, pluripotential ability, clonogenicity, and telomere length over the population doublings. The progenitor cells are inducible to different cell lineages (osteogenic, adipogenic, skeletal muscle, endothelial, neuronal, and hepatic cells) under specific growth conditions. The ability to induce cell-type-specific differentiation is confirmed by phenotypic changes, immunocytochemistry, gene expression, and functional analyses. In addition, we will describe an application of these cells in an ex vivo and in vivo system for potential in organ (renal) regeneration. The progenitor cells described in this chapter have a high potential for expansion, and may be a good source for research and therapeutic applications where large numbers of cells are needed. Progenitor cells isolated during gestation may be beneficial for fetuses diagnosed with malformations and could be cryopreserved for future self-use.

Ex vivo whole embryonic kidney culture: a novel method for research in development, regeneration and transplantation

PURPOSE

Whole metanephric organ culture represents a novel investigatory approach with potential application in many aspects of research in kidney regeneration and transplantation. We report the current status of embryonic kidney culture, discussing issues such as the appropriate culture conditions and methods, histological results, values of and limitations to the different techniques used today. To optimize this system in vitro for the benefit of future studies we focused our efforts on evaluating and developing a new durable 3-dimensional organ culture system using a uniquely modified approach.

MATERIALS AND METHODS

Metanephric kidneys were microdissected from the embryos of timed pregnant WT C57BL/C6 mice on days 12 to 16 of gestation (embryonic days 12 to 16). Novel perfusion channels were created in the harvested embryonic kidneys before placing them in culture. Embryonic kidneys were placed on a 0.4 microm pore size Transwell membrane, cultured in base medium at a medium gas interphase and incubated at 37C with fully humidified 5% CO2. Histological and immunocytochemical analysis was performed to evaluate for signs of necrosis, and the structural integrity and functionality of organs during culture.

RESULTS

We confirmed histologically that our organ culture system was capable of maintaining normal kidney structures significantly longer (mean 10 days) than previously reported standard protocols. Condensation and aggregation of the metanephric mesenchyma at the tips of the ureteral bud were observed, including the formation of well developed nephrons and glomeruli without evidence of necrosis. Organ maturation occurred in a developmentally appropriate centrifugal pattern and the expression of key regulatory factors was demonstrated.

CONCLUSIONS

Our in vitro model replicates closely the in vivo processes involved in normal kidney development. We also present what is to our knowledge the first demonstration of a durable 3-dimensional kidney culture system reported in the literature. This system may represent an uncomplicated method for in vitro kidney culture that we hope will serve as an effective adjunct to research focused on signaling pathways, development and regeneration as applied to the kidney.