Human Urine-Derived Renal Progenitors for Personalized Modeling of Genetic Kidney Disorders

Abstract

The critical role of genetic and epigenetic factors in the pathogenesis of kidney disorders is gradually becoming clear, and the need for disease models that recapitulate human kidney disorders in a personalized manner is paramount. In this study, we describe a method to select and amplify renal progenitor cultures from the urine of patients with kidney disorders. Urine-derived human renal progenitors exhibited phenotype and functional properties identical to those purified from kidney tissue, including the capacity to differentiate into tubular cells and podocytes, as demonstrated by confocal microscopy, Western blot analysis of podocyte-specific proteins, and scanning electron microscopy. Lineage tracing studies performed with conditional transgenic mice, in which podocytes are irreversibly tagged upon tamoxifen treatment (NPHS2.iCreER;mT/mG), that were subjected to doxorubicin nephropathy demonstrated that renal progenitors are the only urinary cell population that can be amplified in longterm culture. To validate the use of these cells for personalized modeling of kidney disorders, renal progenitors were obtained from (1) the urine of children with nephrotic syndrome and carrying potentially pathogenic mutations in genes encoding for podocyte proteins and (2) the urine of children without genetic alterations, as validated by next-generation sequencing. Renal progenitors obtained from patients carrying pathogenic mutations generated podocytes that exhibited an abnormal cytoskeleton structure and functional abnormalities compared with those obtained from patients with proteinuria but without genetic mutations. The results of this study demonstrate that urine-derived patient-specific renal progenitor cultures may be an innovative research tool for modeling of genetic kidney disorders. 26: 196126: -197426: , 201526: . doi: 10.1681 The incidence of AKI and CKD is rising and reaching epidemic proportions. 1 In patients with CKD, the progressive decline in renal function is multifactorial and attributable to a variety of mechanisms. 2 In particular, the critical role of genetic factors in the etiology, pathogenesis, and progression of many renal disorders is gradually becoming clear, especially in children. 3 Indeed, the advent of high-throughput sequencing techniques has fostered the identification of novel causative genes and allows the continuous discovery of genetic variants of unknown clinical significance, often raising the problem of the functional testing of their pathogenic role. 4 However, emerging evidence suggests that influence of the J Am Soc Nephrol

The use of lineage tracing to study kidney injury and regeneration

“…[20][21][22][23][24] Numerous studies have reported the existence of a putative population of tubular progenitors in the adult human kidney, characterized by the co-expression of CD133 and CD24 surface markers. 26,[34][35][36][37][38][39][40][41] Putative tubular progenitor cells co-express tubular markers, and reside scattered among differentiated tubular cells within the tubule. [25][26][27] The choice of a tubule differentiation marker as the promoter, therefore, might not allow the existence of tubularcommitted progenitors to be excluded as they would be genetically tagged in a similar pattern to differentiated tubular cells.…”

“…[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] The majority of these studies were performed in humans where lineage tracing cannot be performed; rather, stem cell identification and characterization relied on prospective isolation using specific markers followed by functional analyses, such as in vivo transplantation assays. [34][35][36][37][38][39][40][41] NCAM1 and ALDH1 (especially the ALDH1A2 paralogue) [42][43][44][45][46][47] have been suggested as stem and/or progenitor cell markers in the human foetal kidney and in Wilms' tumours during early nephrogenesis before nephron differentiation, and during mesenchymal-to-epithelial transition. [42][43][44][45][46][47] NCAM1 and ALDH1 allow the isolation and expansion of human nephron progenitor cells for the treatment of chronic kidney disease and are valuable therapeutic targets for Wilms' tumour eradication.…”

From Patient to Dish and Back Again

“…What does this mean in regard to the study of Lazzeri et al 1 ? The authors use the markers glyCD133, CD24, and CD106 to identify and define RPCs.…”

“…In this issue, Lazzeri et al 1 explore the use of exfoliated cells in the urine of children affected by proteinuric kidney diseases for diagnostic and therapeutic purposes (from patient-to-dish-topatient). The authors investigate whether the isolated cells represent putative renal progenitor cells (RPCs) and test whether they are similar to a previously isolated putative progenitor population.…”

“…In this issue of JASN, this latter strategy was explored by Lazzeri et al 1 The authors established cultures of rare exfoliated cells from the urine of children affected by different proteinuric disorders of the kidney. The authors noted that cultured cells expressed a certain combination of markers…”