Littérature scientifique sur le sujet « Tubular Progenitor »

Kidneys of mice, rats and humans possess progenitors that maintain daily homeostasis and take part in endogenous regenerative processes following injury, owing to their capacity to proliferate and differentiate. In the glomerular and tubular compartments of the nephron, consistent studies demonstrated that well-characterized, distinct populations of progenitor cells, localized in the parietal epithelium of Bowman capsule and scattered in the proximal and distal tubules, could generate segment-specific cells in physiological conditions and following tissue injury. However, defective or abnormal regenerative responses of these progenitors can contribute to pathologic conditions. The molecular characteristics of renal progenitors have been extensively studied, revealing that numerous classical and evolutionarily conserved pathways, such as Notch or Wnt/β-catenin, play a major role in cell regulation. Others, such as retinoic acid, renin-angiotensin-aldosterone system, TLR2 (Toll-like receptor 2) and leptin, are also important in this process. In this review, we summarize the plethora of molecular mechanisms directing renal progenitor responses during homeostasis and following kidney injury. Finally, we will explore how single-cell RNA sequencing could bring the characterization of renal progenitors to the next level, while knowing their molecular signature is gaining relevance in the clinic.

This study is aimed at characterizing medullary interstitial progenitor cells and to examine their capacity to induce tubular epithelial cell migration and proliferation. We have isolated a progenitor cell side population from a primary medullary interstitial cell line. We show that the medullary progenitor cells (MPCs) express CD24, CD44, CXCR7, CXCR4, nestin, and PAX7. MPCs are CD34 negative, which indicates that they are not bone marrow-derived stem cells. MPCs survive >50 passages, and when grown in epithelial differentiation medium develop phenotypic characteristics of epithelial cells. Inner medulla collecting duct (IMCD3) cells treated with conditioned medium from MPCs show significantly accelerated cell proliferation and migration. Conditioned medium from PGE2-treated MPCs induce tubule formation in IMCD3 cells grown in 3D Matrigel. Moreover, most of the MPCs express the pericyte marker PDGFR-b. Our study shows that the medullary interstitium harbors a side population of progenitor cells that can differentiate to epithelial cells and can stimulate tubular epithelial cell migration and proliferation. The findings of this study suggest that medullary pericyte/progenitor cells may play a critical role in collecting duct cell injury repair.

The prevalence of kidney dysfunction continues to increase worldwide, driving the need to develop transplantable renal tissues. The kidney develops from four major renal progenitor populations: nephron epithelial, ureteric epithelial, interstitial and endothelial progenitors. Methods have been developed to generate kidney organoids but few or dispersed tubular clusters within the organoids hamper its use in regenerative applications. Here, we describe a detailed protocol of asynchronous mixing of kidney progenitors using organotypic culture conditions to generate kidney organoids tightly packed with tubular clusters and major renal structures including endothelial network and functional proximal tubules. This protocol provides guidance in the culture of human embryonic stem cells from a National Institute of Health-approved line and their directed differentiation into kidney organoids. Our 18-day protocol provides a rapid method to generate kidney organoids that facilitate the study of different nephrological events including in vitro tissue development, disease modeling and chemical screening. However, further studies are required to optimize the protocol to generate additional renal-specific cell types, interconnected nephron segments and physiologically functional renal tissues.

Background Acute kidney injury (AKI) is a serious condition associated with chronic kidney disease, dialysis requirement and a high risk of death. However, there are specialized repair mechanisms for the nephron, and migrated committed progenitor cells are the key players. Previous work has described a positive association between renal recovery and the excretion of tubular progenitor cells in the urine of kidney transplant recipients. The aim of this work was to describe such structures in non-transplanted AKI patients and to focus on their differentiation. Methods Morning urine was obtained from four patients with AKI stage 3 and need for RRT on a consecutive basis. Urine sediment gene expression was performed to assess which part of the tubular or glomerular segment was affected by injury, along with measurement of neprilysin. Urine output and sediment morphology were monitored, viable hyperplastic tubular epithelial clusters were isolated and characterized by antibody or cultured in vitro. These cells were monitored by phase contrast microscopy, gene, and protein expression over 9 days by qPCR and confocal immunofluorescence. Furthermore, UMOD secretion into the supernatant was quantitatively measured. Results Urinary neprilysin decreased rapidly with increasing urinary volume in ischemic, toxic, nephritic, and infection-associated AKI, whereas the decrease in sCr required at least 2 weeks. While urine output increased, dead cells were present in the sediment along with debris followed by hyperplastic agglomerates. Monitoring of urine sediment for tubular cell-specific gene transcript levels NPHS2 (podocyte), AQP1 and AQP6 (proximal tubule), and SLC12A1 (distal tubule) by qPCR revealed different components depending on the cause of AKI. Confocal immunofluorescence staining confirmed the presence of intact nephron-specific epithelial cells, some of which appeared in clusters expressing AQP1 and PAX8 and were 53% positive for the stem cell marker PROM1. Isolated tubule epithelial progenitor cells were grown in vitro, expanded, and reached confluence within 5–7 days, while the expression of AQP1 and UMOD increased, whereas PROM1 and Ki67 decreased. This was accompanied by a change in cell morphology from a disproportionately high nuclear/cytoplasmic ratio at day 2–7 with mitotic figures. In contrast, an apoptotic morphology of approximately 30% was found at day 9 with the appearance of multinucleated cells that were associable with different regions of the nephron tubule by marker proteins. At the same time, UMOD was detected in the culture supernatant. Conclusion During renal recovery, a high replicatory potential of tubular epithelial progenitor cells is found in urine. In vitro expansion and gene expression show differentiation into tubular cells with marker proteins specific for different nephron regions.

Renal tubular epithelium has the capacity to regenerate, repair, and reepithelialize in response to a variety of insults. Previous studies with several kidney injury models demonstrated that various growth factors, transcription factors, and extracellular matrices are involved in this process. Surviving tubular cells actively proliferate, migrate, and differentiate in the kidney regeneration process after injury, and some cells express putative stem cell markers or possess stem cell properties. Using fate mapping techniques, bone marrow-derived cells and endothelial progenitor cells have been shown to transdifferentiate into tubular components in vivo or ex vivo. Similarly, it has been demonstrated that, during tubular cell regeneration, several inflammatory cell populations migrate, assemble around tubular cells, and interact with tubular cells during the repair of tubular epithelium. In this review, we describe recent advances in understanding the regeneration mechanisms of renal tubules, particularly the characteristics of various cell populations contributing to tubular regeneration, and highlight the targets for the development of regenerative medicine for treating kidney diseases in humans.

New and effective treatment for acute kidney injury remains a challenge. Here, we induced mouse hematopoietic stem and progenitor cells (HSPC) to differentiate into cells that partially resemble a renal cell phenotype and tested their therapeutic potential. We sequentially treated HSPC with a combination of protein factors for 1 wk to generate a large number of cells that expressed renal developmentally regulated genes and protein. Cell fate conversion was associated with increased histone acetylation on promoters of renal-related genes. Further treatment of the cells with a histone deacetylase inhibitor improved the efficiency of cell conversion by sixfold. Treated cells formed tubular structures in three-dimensional cultures and were integrated into tubules of embryonic kidney organ cultures. When injected under the renal capsule, they integrated into renal tubules of postischemic kidneys and expressed the epithelial marker E-cadherin. No teratoma formation was detected 2 and 6 mo after cell injection, supporting the safety of using these cells. Furthermore, intravenous injection of the cells into mice with renal ischemic injury improved kidney function and morphology by increasing endogenous renal repair and decreasing tubular cell death. The cells produced biologically effective concentrations of renotrophic factors including VEGF, IGF-1, and HGF to stimulate epithelial proliferation and tubular repair. Our study indicates that hematopoietic stem and progenitor cells can be converted to a large number of renal-like cells within a short period for potential treatment of acute kidney injury.

The characteristics of renal tubular progenitor/precursor cells and the role of renal tubule regeneration in the repair of remnant kidneys (RKs) after nephrectomy are not well known. In the present study of a murine model of subtotal nephrectomy, we used immunofluorescence (IF), immunoblot analysis, and in situ hybridization methods to demonstrate that nestin expression was transiently upregulated in tubule cells near the incision edges of RKs. The nestin-positive tubules were immature proximal tubules that colabeled with lotus tetragonolobus agglutinin but not with markers of mature tubules (aquaporin-1, Tamm-Horsfall protein, and aquaporin-2). In addition, many of the nestin-expressing tubule cells were actively proliferative cells, as indicated by colabeling with bromodeoxyuridine. Double-label IF and immunoblot analysis also showed that the upregulation of tubular nestin was associated with enhanced transforming growth factor-β1 (TGF-β1) expression in the incision edge of RKs but not α-smooth muscle actin, which is a marker of fibrosis. In cultured human kidney proximal tubule cells (HKC), immunoblot analysis indicated that TGF-β1 induced nestin expression and loss of E-cadherin expression, suggesting an association of nestin expression and cellular dedifferentiation. Knockdown of nestin expression by a short hairpin RNA-containing plasmid led to decreased migration of HKC cells that were induced by TGF-β1. Taken together, our results suggest that the tubule repair that occurs during the recovery process following nephrectomy may involve TGF-β1-induced nestin expression in immature renal proximal tubule cells and the promotion of renal cell migration.

During development, nephron progenitor cells (NPC) are induced to differentiate by WNT9b signals from the ureteric bud. Although nephrogenesis ends in the perinatal period, acute kidney injury (AKI) elicits repopulation of damaged nephrons. Interestingly, embryonic NPC infused into adult mice with AKI are incorporated into regenerating tubules. Since WNT/β-catenin signaling is crucial for primary nephrogenesis, we reasoned that it might also be needed for the endogenous repair mechanism and for integration of exogenous NPC. When we examined glycerol-induced AKI in adult mice bearing aβ-catenin/TCF reporter transgene, endogenous tubular cells reexpressed the NPC marker, CD24, and showed widespreadβ-catenin/TCF signaling. We isolated CD24+cells from E15 kidneys of mice with the canonical WNT signaling reporter. 40% of cells responded to WNT3ain vitroand when infused into glycerol-injured adult, the cells exhibitedβ-catenin/TCF reporter activity when integrated into damaged tubules. When embryonic CD24+cells were treated with aβ-catenin/TCF pathway inhibitor (IWR-1) prior to infusion into glycerol-injured mice, tubular integration of cells was sharply reduced. Thus, the endogenous canonicalβ-catenin/TCF pathway is reactivated during recovery from AKI and is required for integration of exogenous embryonic renal progenitor cells into damaged tubules. These events appear to recapitulate the WNT-dependent inductive process which drives primary nephrogenesis.

Diseases associated with impaired blood supply to the brain ranks second term of mortality in the world, losing the place only to coronary heart disease. The incidence of this disease in the world remains high and increasing significantly with the age. The recent years special attention has been paid to the search for new methods of therapy for ischemic diseases, such as study of angiogenic properties of stem cells and their conditioned medium. The aim of this work is studying the angiogenic properties of glial progenitor cells derived from human induced pluripotent stem cells. The study was carried out by testing the proliferative activity, mobility, migration of endothelial cells line EA.hy926 under the influence of glial progenitor cells and their conditioned medium. Also the research was conducted by ability to formation of the tubular and capillary-like structure by cells line EA.hy926 by modeling angiogenesis in the basement membrane matrix in vitro. The conditioned medium obtained by glial progenitor cells at concentrations of total protein 1 and 5 g/ml has a positive influence on the proliferative activity and mobility of the endothelial cells line EA.hy926. At the same time it does not accelerate the formation of the primary tubular and capillary-like structure by the modeling angiogenesis in the basement membrane matrix in vitro. But glial progenitor cells contribute to the formation of tubular and capillary-like structure due to contact-dependent signaling between the two cell types. The primary formed tubular structure had a long processes and large branch points under co cultivation with glial progenitor cells. Sprouting centers also had long and more convoluted processes and large cell clusters during the formation of a capillary-like structure. The glial progenitor cells and their conditioned medium had a positive effect on endothelial cell migration. This effect probably indicated by the production of substances by glial progenitor cells which was chemoattractants for endothelial cells line EA.hy926.

Nephrogenesis concludes by the 36th week of gestation in humans and by the third day of postnatal life in mice. Extending the nephrogenic period may reduce the onset of adult renal and cardiovascular disease associated with low nephron numbers. We conditionally deleted either Mtor or Tsc1 (coding for hamartin, an inhibitor of Mtor) in renal progenitor cells. Loss of one Mtor allele caused a reduction in nephron numbers; complete deletion led to severe paucity of glomeruli in the kidney resulting in early death after birth. By contrast, loss of one Tsc1 allele from renal progenitors resulted in a 25% increase in nephron endowment with no adverse effects. Increased progenitor engraftment rates ex vivo relative to controls correlated with prolonged nephrogenesis through the fourth postnatal day. Complete loss of both Tsc1 alleles in renal progenitors led to a lethal tubular lesion. The hamartin phenotypes are not dependent on the inhibitory effect of TSC on the Mtor complex but are dependent on Raptor.

Evaluation of tubular regenerative response in AKI-induced trasngenic rodent models. Discovered the existence of a progenitor population scattered in kidney tubule of adut mice devoted to tubular epithelium recovery after ischemic injury.

碩士
國立清華大學
分子醫學研究所
97
Angiogenesis not only play a critical role in embryonic development and tissue repair, but also is an important process for tumor growth and metastasis. Recent studies have shown that tumor cells could induce the mobilization of endothelial progenitor cell (EPC) and outgrowth endothelial cell (OEC) from bone marrow via many cytokines, such as GM-CSF、SDF-1 and VEGF. Furthermore, those EPC could migrate and invade to tumor micro-metastatic niche, and gradually differentiate into endothelial like-cell incorporate the growing vasculature. Using ex vitro culture-expanded EPC or OEC transplanted in to the tumor bearing mice, many researches suggest that EPC control the angiogenic switch and OEC facilitate the neoangiogenesis in the tumor progression. However, the underlying interaction mechanism of EPC/OEC and carcinoma cells in the progression of tumor cell remains unclear. Thus, the aim of the present study to elucidate the effect of tumor cell on differentiation, migration, invasion, and tubular structure formation of EPC and OEC, using in vitro co-cultured system. Firstly, we need to identified EPC and OEC derived from peripheral blood mononuclear cells. We found both of EPC and OEC displayed several commonly accepted EPC phenotypes, including spindle/cobblestone morphology, ac-LDL incorporation, UEA-1 binding, and CD31/KDR/Flt-1 reactivity. The previous clinical reports have indicated that hepatocellular carcinoma (HCC) is one of malignant tumor with rich neovascularization, which can be clearly observed in hepatic angiography. On the basis of co-culture transwell model and time-lapse video microscopy system, we show that migration and invasion capability of EPC was augmented by HCC, and also can induce EPC express higher intensity of endothelial markers to promote the differentiation of EPC. On the other hand, the migration, invasion and tubular structure formation of OEC was inhibited by HCC. In addition, HCC did not alter cell cycle of EPC, whereas they prevented OEC from entering S and G2/M phases and induce OEC cell cycle G0/G1 arrest. The present study suggests that the different effect of HCC on EPC and OEC may mediate their different contribution to tumor angiogenesis. Our findings may provide new insights into the interaction mechanism of EPC/OEC and HCC involve in the progression of angiogenesis.

Introduction: Breast cancer is the most common malignancy in women and represents a major obstacle to public health worldwide. The molecular diagnosis of this type of cancer is one of the main contemporary challenges in oncology, since it is hampered by a complex inheritance pattern, characterized by both genetic and environmental factors. Only a minority of breast cancers are explained by the presence of high penetrance gene mutations, such as those in the BRCA1 and BRCA2 genes, which together with mutations in intermediate penetrance genes explain only up to 25% of the risk. In fact, much of the genetic influence is elucidated by low penetrance variants. Mutations in the germline BRCA1 and BRCA2 are the most common alterations in cases of early onset or of family history of breast cancer. It is also important to acknowledge that BRCA2 mutations can increase the risk of developing other cancers. Some studies show a relation between BRCA2 mutations and the development of leukemia, especially acute myeloid leukemia (AML). Also, some of these mutations, when inherited from both parents, cause a rare form of Fanconi anemia, a syndrome associated with the development of AML. In addition, there are studies evaluating a higher risk of pancreatic and esophageal cancer in carriers of BRCA2 mutations. The risk of colorectal cancer is also increased in patients with BRCA1 mutations. However, there are also some authors who defend that BRCA2 mutations could also be related. The specific statistics are not well defined because of the lack of data focusing on the relationship with the aforecited types of cancers, demonstrating the need for further analysis. This study aims to report the case of a woman with breast cancer at an early age. Such malignancy is associated and was somehow induced by the rich family history, represented by the high prevalence of cancer in the ancestry. We report a 34-year-old woman with an extensive history of carcinoma in the family, who was diagnosed with breast cancer in July 2016. In order to confirm the diagnosis, it was required an ultrasound, which resulted in a 2.2×1.5 cm node on the right breast’s left superior quadrant, classified as BIRADS 4A. It also performed an ultrasound-guided biopsy that showed a tubular carcinoma on the right breast with the following characteristics: positive for estrogen and progesterone receptor, positive for KI 67 (5%), and negative for HER2, with staging of T1cN0M0. During anamnesis, the patient mentioned menarche at 12 years old, history of birth control pills use for 10 years, no pregnancy, and no breastfeeding. When it comes to family history, a great number of relatives were previously diagnosed with some type of cancer. Her paternal grandfather had rectum cancer at 42 years old and breast cancer at 62 years old. The paternal grandmother passed away because of a fast-progression leukemia at the age of 68. It is important to mention that her progenitors were first cousins. Furthermore, the patient’s dad was diagnosed with breast cancer at 62 years, alongside his three brothers who were also diagnosed with cancer: one with prostatic cancer at the age of 64 years and the other two with intestinal cancer at the ages of 64 and 68 years old. Considering such a family history, a genetic panel was performed, analyzing the genes related to hereditary cancer risk, and it identified mutations in the patient’s BRCA2 gene. Then, firstly, she performed a bilateral mastectomy in January 2017 with sentinel lymph node investigation, which was negative for neoplastic cells in the lymph nodes. Later, considering the BRCA2 mutation, in August 2017, the patient had to undergo prophylactic surgery: oophorectomy with salpingectomy.