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Labeled CoRL acquire ultrastructural features of podocytes. To assess ultrastructural features labeled CoRL, immunoperoxidase staining for ZsGreen reporter was performed. A: image of immunoperoxidase staining for the ZsGreen reporter (brown) in the vascular smooth muscle compartment (indicated by arrow, positive control). B: immunoperoxidase staining for the ZsGreen reporter (black) on ultrathin section viewed by transmission electron microscopy (TEM) was detected in the vascular smooth muscle compartment, used as a positive control (arrows indicate examples). C: higher magnification image of reporter staining in the area indicated by the dashed square shown in B. D: immunoperoxidase staining for reporter (brown) in the intraglomerular compartment appears in a podocyte distribution (indicated by arrow). E: TEM image of podocyte with reporter staining (black) in both the cell body and within foot processes. F: higher magnification image of the area indicated by the dashed square shown in E. Arrows indicate staining in foot processes. G: even higher magnification image of the area indicated by the dashed square shown in F. Arrow indicates reporter staining in foot processes. H: lower magnification image of podocyte that lacked reporter staining in the cell body or within foot processes. I: higher magnification image of reporter staining (black) in the area indicated by the dashed square shown in H. Arrows indicate the lack of staining in foot processes. J: higher magnification image of the area indicated by the dashed square shown in I. Arrows indicate the lack of staining in foot processes.
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Aging nephropathy is characterized by podocyte depletion, accompanied by progressive glomerulosclerosis. Replacement of terminally differentiated podocytes by local stem/progenitor cells is likely a critical mechanism for their regeneration. Recent studies have shown that cells of renin lineage (CoRL), normally restricted to the kidney's extra-glom...
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... performed for ZsGreen with electron dense diaminobenzidine, and transmission electron microscopy was subsequently performed as previously described (2). As expected, immunoperoxidase staining viewed under light microscopy for Zsgreen was detected in the CoRL surrounding the arterioles outside the glomerulus, which was used as a positive control (Fig. 8A). Likewise, ultrathin sections viewed by transmission electron microscopy showed electron dense black staining in CoRL surrounding the arterioles outside the glomerulus (Fig. 8, B and C). The majority of podocytes lacked electron dense (black) staining in cell bodies and foot processes and represented native podocytes (Fig. 8, H-J). ...
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... staining viewed under light microscopy for Zsgreen was detected in the CoRL surrounding the arterioles outside the glomerulus, which was used as a positive control (Fig. 8A). Likewise, ultrathin sections viewed by transmission electron microscopy showed electron dense black staining in CoRL surrounding the arterioles outside the glomerulus (Fig. 8, B and C). The majority of podocytes lacked electron dense (black) staining in cell bodies and foot processes and represented native podocytes (Fig. 8, H-J). However, cells with reporter (ZsGreen) staining viewed under light microscopy were detected in the glomerulus (Fig. 8D) and clearly had electron dense black material within their ...
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... a positive control (Fig. 8A). Likewise, ultrathin sections viewed by transmission electron microscopy showed electron dense black staining in CoRL surrounding the arterioles outside the glomerulus (Fig. 8, B and C). The majority of podocytes lacked electron dense (black) staining in cell bodies and foot processes and represented native podocytes (Fig. 8, H-J). However, cells with reporter (ZsGreen) staining viewed under light microscopy were detected in the glomerulus (Fig. 8D) and clearly had electron dense black material within their cell bodies and within foot processes (Fig. 8, E-G). These results are consistent with a subset of CoRL within the glomerular tuft having ultrastructural ...
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... black staining in CoRL surrounding the arterioles outside the glomerulus (Fig. 8, B and C). The majority of podocytes lacked electron dense (black) staining in cell bodies and foot processes and represented native podocytes (Fig. 8, H-J). However, cells with reporter (ZsGreen) staining viewed under light microscopy were detected in the glomerulus (Fig. 8D) and clearly had electron dense black material within their cell bodies and within foot processes (Fig. 8, E-G). These results are consistent with a subset of CoRL within the glomerular tuft having ultrastructural features resembling ...
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... podocytes lacked electron dense (black) staining in cell bodies and foot processes and represented native podocytes (Fig. 8, H-J). However, cells with reporter (ZsGreen) staining viewed under light microscopy were detected in the glomerulus (Fig. 8D) and clearly had electron dense black material within their cell bodies and within foot processes (Fig. 8, E-G). These results are consistent with a subset of CoRL within the glomerular tuft having ultrastructural features resembling ...
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In the glomerulus, Bowman's space is formed by a continuum of glomerular epithelial cells. In focal segmental glomerulosclerosis (FSGS), glomeruli show segmental scarring, a result of activated PECs invading the glomerular tuft. The segmental scars interrupt the epithelial continuum. However, non-sclerotic segments seem to be preserved even in glom...
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Background:
Focal segmental glomerulosclerosis (FSGS) is a histologic pattern characterized by focal glomerular scarring, which often progresses to systemic and diffuse glomerulosclerosis. Previous studies have emphasized that the initiation of classic FSGS occurs in podocytes. The dysfunction and loss of podocytes have been associated with the de...
Citations
... They may represent latematuring podocytes that were not present at P21 or did not express the nuclear marker (p57) we used to identify postmitotic podocytes. Alternatively, these new podocytes may have been derived from parietal epithelial cells (Lasagni & Romagnani, 2010;Shankland et al., 2013) or cells or renin lineage (Kaverina et al., 2020;Pippin et al., 2014;Shankland et al., 2017). ...
Podocytes are terminally differentiated epithelial cells in glomeruli. Podocyte injury and loss are features of many diseases leading to chronic kidney disease (CKD). The developmental origins of health and disease hypothesis propose an adverse intrauterine environment can lead to CKD later in life, especially when a second postnatal challenge is experienced. The aim of this study was to examine whether a suboptimal maternal environment would result in reduced podocyte endowment, increasing susceptibility to diabetes-induced renal injury. Female C57BL/6 mice were fed a low protein diet (LPD) to induce growth restriction or a normal protein diet (NPD) from 3 weeks before mating until weaning (postnatal Day 21, P21) when nephron and podocyte endowment were assessed in one male and one female offspring per litter. Littermates were administered streptozotocin or vehicle at 6 weeks of age. Urinary albumin excretion, glomerular size, and podometrics were assessed following 18 weeks of hyperglycemia. LPD offspring were growth restricted and had lower nephron and podocyte number at P21. However, by 24 weeks the podocyte deficit was no longer evident and despite low nephron endowment neither albuminuria nor glomerulosclerosis were observed. Podocyte number was unaffected by 18 weeks of hyperglycemia in NPD and LPD offspring. Diabetes increased glomerular volume reducing podocyte density, with more pronounced effects in LPD offspring. LPD and NPD diabetic offspring developed mild albuminuria with LPD demonstrating an earlier onset. LPD offspring also developed glomerular pathology. These findings indicate that growth-restricted LPD offspring with low nephron number and normalized podocyte endowment were more susceptible to alterations in glomerular volume and podocyte density leading to more rapid onset of albuminuria and renal injury than NPD offspring.
... Our finding of a significant decrease in podocyte density with age in control mice confirms findings from previous studies (Kaverina et al. 2020;Pippin et al. 2014;Roeder et al. 2015;Schneider et al. 2017;Sweetwyne et al. 2017). A decrease in podocyte density can result from podocyte loss and/or glomerular hypertrophy. ...
Progressive podocyte loss is a feature of healthy ageing. While previous studies have reported age-related changes in podocyte number, density and size and associations with proteinuria and glomerulosclerosis, few studies have examined how the response of remaining podocytes to podocyte depletion changes with age. Mild podocyte depletion was induced in Pod Cre iDTR mice aged 1, 6, 12 and 18 months via intraperitoneal administration of diphtheria toxin. Control mice received intraperitoneal vehicle. Podometrics, proteinuria and glomerular pathology were assessed, together with podocyte expression of p-rp-S6, a phosphorylation target that represents activity of the mammalian target of rapamycin (mTOR). Podocyte number per glomerulus did not change in control mice in the 18-month time period examined. However, control mice at 18 months had the largest podocytes and the lowest podocyte density. Podocyte depletion at 1, 6 and 12 months resulted in mild albuminuria but no glomerulosclerosis, whereas similar levels of podocyte depletion at 18 months resulted in both albuminuria and glomerulosclerosis. Following podocyte depletion at 6 and 12 months, the number of p-rp-S6 positive podocytes increased significantly, and this was associated with an adaptive increase in podocyte volume. However, at 18 months of age, remaining podocytes were unable to further elevate mTOR expression or undergo hypertrophic adaptation in response to mild podocyte depletion, resulting in marked glomerular pathology. These findings demonstrate the importance of mTORC1-mediated podocyte hypertrophy in both physiological (ageing) and adaptive settings, highlighting a functional limit to podocyte hypertrophy reached under physiological conditions.
... Several lineage tracing studies have shed light on the source of renal progenitor cells, capable of supporting limited podocytes renewal in the postnatal kidney. These include the parietal epithelial cells (PECs) derived from the Bowman's capsule 5,6 , and cells of renin lineage (CoRL) located in the juxtaglomerular apparatus [7][8][9] . Although these lineage tracing studies demonstrate the kidney's modest capacity for intrinsic podocyte renewal, the filtration function of the kidney fails to fully recover in adult mice 10,11 . ...
Homeostatic renal filtration relies on the integrity of podocytes, which function in glomerular filtration. These highly specialized cells are damaged in 90% of chronic kidney disease, representing the leading cause of end-stage renal failure. Although modest podocyte renewal has been documented in adult mice, the mechanisms regulating this process remain largely unknown and controversial. Using a mouse model of Adriamycin-induced nephropathy, we find that the recovery of filtration function requires up-regulation of the endogenous telomerase component TERT. Previous work has shown that transient overexpression of catalytically inactive TERT (i-TERTci mouse model) has an unexpected role in triggering dramatic podocyte proliferation and renewal. We therefore used this model to conduct specific and stochastic lineage-tracing strategies in combination with high throughput sequencing methods. These experiments provide evidence that TERT drives the activation and clonal expansion of podocyte progenitor cells. Our findings demonstrate that the adult kidney bears intrinsic regenerative capabilities involving the protein component of telomerase, paving the way for innovative research toward the development of chronic kidney disease therapeutics.
... The number of senescence podocytes increases with aging. Moreover, these cells are reportedly unable to adequately proliferate to replace themselves and aggravate CKD [133,138]. Uremic toxins, including an extremely heterogeneous group of molecules, are the main source of oxidative metabolites in patients with CKD. They may forcefully initiate VC through inflammation, DNA damage, oxidative stress, and senescence [139]. ...
Chronic kidney disease is a devastating condition resulting from irreversible loss of nephron numbers and function and leading to end-stage renal disease and mineral disorders. Vascular calcification, an ectopic deposition of calcium-phosphate salts in blood vessel walls and heart valves, is an independent risk factor of cardiovascular morbidity and mortality in chronic kidney disease. Moreover, aging and related metabolic disorders are essential risk factors for chronic kidney disease and vascular calcification. Marked progress has been recently made in understanding and treating vascular calcification in chronic kidney disease. However, there is a paucity of systematic reviews summarizing this progress, and investigating unresolved issues is warranted. In this systematic review, we aimed to overview the underlying mechanisms of vascular calcification in chronic kidney diseases and discuss the impact of chronic kidney disease on the pathophysiology of vascular calcification. Additionally, we summarized potential clinical diagnostic biomarkers and therapeutic applications for vascular calcification with chronic kidney disease. This review may offer new insights into the pathogenesis, diagnosis, and therapeutic intervention of vascular calcification.
... However, we have shown that both sources of podocyte progenitors are adversely impacted by advancing age. For example, their numbers decrease with age leading to a reduced reservoir available to perform progenitor functions [19,29], they lose some of their characteristic markers, acquire phenotypic changes [19,30], and their expected responses to stimuli are reduced, such as the response of cells of renin lineage to RAAS blockade [31]. ...
Healthy aging is typified by a progressive and absolute loss of podocytes over the lifespan of animals and humans. To test the hypothesis that a subset of glomerular parietal epithelial cell (PEC) progenitors transition to a podocyte fate with aging, dual reporter PEC-rtTA|LC1|tdTomato|Nphs1-FLPo|FRT-EGFP mice were generated. PECs were inducibly labeled with a tdTomato reporter, and podocytes were constitutively labeled with an EGFP reporter. With advancing age (14 and 24 months) glomeruli in the juxta-medullary cortex (JMC) were more severely injured than those in the outer cortex (OC). In aged mice (24m), injured glomeruli with lower podocyte number (41% decrease), showed more PEC migration and differentiation to a podocyte fate than mildly injured or healthy glomeruli. PECs differentiated to a podocyte fate had ultrastructural features of podocytes and co-expressed the podocyte markers podocin, nephrin, p57 and VEGF164, but not markers of mesangial (Perlecan) or endothelial (ERG) cells. PECs differentiated to a podocyte fate did not express CD44, a marker of PEC activation. Taken together, we demonstrate that a subpopulation of PECs differentiate to a podocyte fate predominantly in injured glomeruli in mice of advanced age.
... Significant efforts have been undertaken to clarify the capacity of progenitors to replace lost podocytes (Pippin et al., 2014;Romoli et al., 2018). In individual cases, authors have successfully shown by lineage tracing studies that progenitor-derived fully developed podocytes intermingle with original resident podocytes. ...
This study presents a theoretical analysis of the problems related to the inability of podocytes to proliferate. The basis of these problems is the very high rate of glomerular filtration. Podocytes do not in general die by apoptosis or necrosis but are lost by detachment from the glomerular basement membrane (GBM) as viable cells. Podocytes situated on the outside of the filtration barrier and attached to the GBM only by their foot processes are permanently exposed to the flow dynamic forces of the high filtration rate tending to detach them from the GBM. The major challenge seems to consist of the high shear stresses on the foot processes within the filtration slits due to filtrate flow. Healthy podocytes are able to resist this challenge, injured podocytes are not, and may undergo foot process detachment, leading to a gap in the podocyte cover of the GBM. This represents a mortal event. Like a dam break, such a leak cannot be repaired. The ongoing exposure to filtrate flow prevents any attempt to close the gap, thus preventing any regeneration including cell proliferation. An improvement of this precarious situation consists of healing by scarring that may involve only one lobule of the glomerulus, permitting the remaining lobules to maintain filtration. An answer to the question of which waste product requires such a high filtration rate for its excretion may be in the huge quantity of circulating peptides, a problem that dates far back in evolution.
... Recent studies have shown that in addition to cells of renin lineage (CoRL) serving a major endocrine function, they likely also have a major biological role serving as progenitors for adult mesangial cells, podocytes, glomerular parietal epithelial cells and pericytes [23,[41][42][43][44]68]. Advanced aging is accompanied by reduced renin content in CoRL [3,10,74], and decreased CoRL number in aged mice [23]. ...
... Recent studies have shown that in addition to cells of renin lineage (CoRL) serving a major endocrine function, they likely also have a major biological role serving as progenitors for adult mesangial cells, podocytes, glomerular parietal epithelial cells and pericytes [23,[41][42][43][44]68]. Advanced aging is accompanied by reduced renin content in CoRL [3,10,74], and decreased CoRL number in aged mice [23]. In addition, CoRL proliferation in aged mice is blunted in response to ACEinhibitors [21]. ...
... Ren1cCre|ZsGreen mice as previously described [23] were bred and maintained in house and allowed to age for either 2 months (n = 5, 3M, 2F) or 27 months (n = 5, 3M, 2F) prior to sacrifice. These mice are the product of breeding the Ren1cCre mouse [77] with the ZsGreen mouse [78], and results in the constitutive and permanent labeling of all cells that have expressed renin. ...
Renin expressing cells in the kidney's juxta-glomeruluar compartment likely also serve as progenitors for adult glomerular cells in disease. Although these cells of renin lineage (CoRL) decrease in number with advancing kidney age, accompanied by less responsiveness to typical stimuli such as ACE-inhibition, mechanisms and the impact of sex as a biological variable with age are not known. Accordingly, labeled CoRL were sorted from individual young (2m) and aged (27m) male and female Ren1cCre|ZsGreen reporter mice, and their transcriptomic profiles analyzed by RNA seq. When both aged female and male mice were combined, there were 48 differentially expressed genes (DEG) compared to young mice. However, when compared to their young sex-matched mice, aged female and male mice had 159 and 503 DEGs respectively. In addition to marked differences in individual genes between aged female and male mice, gene ontology analysis showed major pathway differences by sex. The majority of DEGs in one sex did not significantly change or changed in the opposite direction in the other sex. These results show that in CoRL of advanced age, individual genes and gene ontologies change, but differ between female and male mice, highlighting sex related differences the aging process.
... More recently, other lines of evidence support the notion that renin lineage cells may enhance glomerular regeneration by functioning as progenitors of podocytes in a model of podocyte depletion using anti-podocyte antibody [19], although these cells also exhibit limited regenerative potential in aging mice [20]. To provide further evidence that remission of glomerular disease in mice with adriamycin nephropathy is associated with the generation of novel podocytes, pharmacological approach using glycogen synthase kinases 3-a and 3-b inhibitor increases podocyte regeneration and promotes glomerular disease remission [21]. ...
Kidney-derived c-Kit1cells exhibit progenitor/stem cell properties in vitro (self-renewal capacity, clonogenicity, and multipotential-ity). These cells can regenerate epithelial tubular cells following ischemia-reperfusion injury and accelerate foot processes efface-ment reversal in a model of acute proteinuria in rats. Several mechanisms are involved in kidney regeneration by kidney-derived c-Kit1cells, including cell engraftment and differentiation into renal-like structures, such as tubules, vessels, and podocytes. Moreover,paracrine mechanisms could also account for kidney regeneration, either by stimulating proliferation of surviving cells or modulatingautophagy and podocyte cytoskeleton rearrangement through mTOR-Raptor and -Rictor signaling, which ultimately lead to morpho-logical and functional improvement. To gain insights into the functional properties of c-Kit1cells during kidney development, home-ostasis, and disease, studies on lineage tracing using transgenic mice will unveil their fate. The results obtained from these studieswill set the basis for establishing further investigation on the therapeutic potential of c-Kit1cells for treatment of kidney disease inpreclinical and clinical studies.STEMCELLSTRANSLATIONALMEDICINE2018;7:317–32
... More recently, other lines of evidence support the notion that renin lineage cells may enhance glomerular regeneration by functioning as progenitors of podocytes in a model of podocyte depletion using anti-podocyte antibody [19], although these cells also exhibit limited regenerative potential in aging mice [20]. To provide further evidence that remission of glomerular disease in mice with adriamycin nephropathy is associated with the generation of novel podocytes, pharmacological approach using glycogen synthase kinases 3-a and 3-b inhibitor increases podocyte regeneration and promotes glomerular disease remission [21]. ...
Kidney-derived c-Kit+ cells exhibit progenitor/stem cell properties in vitro (self-renewal capacity, clonogenicity, and multipotentiality). These cells can regenerate epithelial tubular cells following ischemia-reperfusion injury and accelerate foot processes effacement reversal in a model of acute proteinuria in rats. Several mechanisms are involved in kidney regeneration by kidney-derived c-Kit+ cells, including cell engraftment and differentiation into renal-like structures, such as tubules, vessels, and podocytes. Moreover, paracrine mechanisms could also account for kidney regeneration, either by stimulating proliferation of surviving cells or modulating autophagy and podocyte cytoskeleton rearrangement through mTOR-Raptor and -Rictor signaling, which ultimately lead to morphological and functional improvement. To gain insights into the functional properties of c-Kit+ cells during kidney development, homeostasis, and disease, studies on lineage tracing using transgenic mice will unveil their fate. The results obtained from these studies will set the basis for establishing further investigation on the therapeutic potential of c-Kit+ cells for treatment of kidney disease in preclinical and clinical studies. Stem Cells Translational Medicine 2018;7:317-324.
... Studies have described healthy aging as a hyporeninemic state, based on lower plasma renin activity in humans (1, 7, 25, 26, 28 -30, 37, 45-49) and rats (5,6,13,17,23), reduced renin content in kidneys (5,6,13), and reduced responsiveness to certain stimuli known to increase renin (5,7,27,29,30,37,49). Although we recently reported that the number of cells of renin lineage was lower in middle-aged mice compared with a younger cohort (32), the majority of pioneering renin studies in aged kidneys were performed in the 1980s and 1990s when molecular and cellular biology methodologies were immature compared with today. Moreover, the mechanisms underlying these events are not well defined. ...
... AGING AND CELLS OF RENIN LINEAGE critical enzyme initiating the RAAS, which is essential for blood pressure control, regulation of glomerular hemodynamics, and electrolyte homeostasis through tubular sodium and potassium handling (42). More recently, studies have shown that CoRL also have additional biological functions where they serve as progenitors in experimental disease states for adult podocytes (19,24,(32)(33)(34), mesangial cells (24,43), glomerular parietal epithelial cells (24,34), and pericytes (33,44). In the current studies, we focused on changes in CoRL number and their responses under healthy aging conditions in mice. ...
... Second, the chronology of the decline in CoRL was not studied. That said, we have reported that mice aged 15 mo show reduced CoRL number (32). Third, although we did not study whether lowering blood pressure would have different impacts on CoRL responses, we deliberately chose doses of ACE inhibition and angiotensin receptor blockade that would not lower blood pressure, to mimic clinical practice in states of proteinuria. ...
Blocking the renin-angiotensin-aldosterone system (RAAS) remains a mainstay of therapy in hypertension and glomerular diseases. With the population aging, our understanding of renin producing cells in kidneys with advanced age is more critical than ever. Accordingly, we administered tamoxifen to Ren1cCreERxRs-tdTomato-R mice to permanently fate map cells of renin lineage (CoRL). The number of Td-tomato labeled CoRL decreased significantly in aged mice (24m of age) compared to young mice (3.5m of age), as did renin mRNA levels. To determine if aged CoRL responded less to RAAS blockade, enalapril and losartan were administered over 25d following uninephrectomy in young and aged mice. The number of CoRL increased in young mice in response to enalapril and losartan. However, this was significantly lower in aged mice compared to young mice due to limited proliferation, but not recruitment. Gene expression analysis of laser captured CoRL showed a substantial increase in mRNA levels for pro-apoptotic and pro-senescence genes, and an increase in a major pro-senescence protein on immunostaining. These results show that CoRL are lower in aged mice, and do not respond to RAAS inhibition to the same extent as young mice.
