Bone Marrow‐Derived Cells Contribute to Podocyte Regeneration and Amelioration of Renal Disease in a Mouse Model of Alport Syndrome

Abstract

In a model of autosomally recessive Alport syndrome, mice that lack the ␣3 chain of collagen IV (Col4␣3 ؊/؊ ) develop progressive glomerular damage leading to renal failure. The proposed mechanism is that podocytes fail to synthesize normal glomerular basement membrane, so the collagen IV network is unstable and easily degraded. We used this model to study whether bone marrow (BM) transplantation can rectify this podocyte defect by correcting the deficiency in Col4␣3. Female C57BL/6 Col4␣3 ؊/؊ (-/-) mice were transplanted with whole BM from male wild-type (؉/؉) mice. Control female -/-mice received BM from male -/-littermates. Serum urea and creatinine levels were significantly lower in recipients of ؉/؉ BM compared with those of -/-BM 20 weeks post-transplant. Glomerular scarring and interstitial fibrosis were also significantly decreased. Donorderived cells were detected by in situ hybridization (ISH) for the Y chromosome, and fluorescence and confocal microscopy indicated that some showed an apparent podocyte phenotype in mice transplanted with ؉/؉ BM. Glomeruli of these mice showed small foci of staining for ␣3(IV) protein by immunofluorescence. ␣3(IV) mRNA was detectable by reverse transcription-polymerase chain reaction and ISH in some mice transplanted with ؉/؉ BM but not -/-BM. However, a single injection of mesenchymal stem cells from ؉/؉ mice to irradiated -/-recipients did not improve renal disease. Our data show that improved renal function in Col4␣3-/-mice results from BM transplantation from wildtype donors, and the mechanism by which this occurs may in part involve generation of podocytes without the gene defect.

Stem cell options for kidney disease

“…Nevertheless, BM transplantation can improve renal function. Whole BM transplantation has been reported to be able to improve renal function and reduce histological damage in the collagen4α3 defective model of Alport syndrome [24,25]. These authors reported that BM-derived cells transdifferentiated into podocytes and mesangial cells, accompanied by re-expression of the defective collagen chains and improved renal histology and function.…”

“…Furthermore, ex vivo manipulation of macrophages using specific cytokines confirmed that classically activated, M1 macrophages worsen chronic inflammatory adriamycin nephropathy, whereas alternatively activated M2 macrophages reduce histological disruption and functional injury [36]. Of note, in the heart Camargo et al [37] have [39] Glycerol-induced ARF (mouse) MSCs Enhanced tubular proliferation [68] IR (rat) Papilla LRCs Proliferation and incorporation [149] IR (mouse) Bone marrow No functional improvement, intrarenal cells are the main source of repopulating cell during repair [22] Folic acid-induced acute tubular injury (mouse) Bone marrow Intrinsic tubular cell proliferation accounts for repair after damage [150] Folic acid-induced acute tubular injury (mouse) Bone marrow 10% incorporation in tubules and G-CSF doubles this rate [151] IR (rat) MSCs Improved renal function and less injury [152] Cisplatin-induced renal failure (mouse) MSCs Accelerated tubular proliferation [153] UUO (mouse) Bone marrow macrophages Reduced renal fibrosis [41] IR (rat) MSCs Improved renal function, increased proliferation and decreased apoptosis [84] IR (rat) rKS56 (S3 segment outgrowth) Replace tubular and improve function [80] Glycerol-induced tubulonecrosis (mouse) Human CD133 + cells Homing and tubular integration [66] UUO (rat) Label-retaining cells (LRC) Proliferates, migrates and transdifferentiates into fibroblast-like cells [27] Cisplatin-induced renal failure (mouse) G-CSF ± M-CSF Improvement in renal function and prevention of renal tubular injury [154] Anti-Thy1.1 GN (rat) MSCs Increased glomerular proliferation and reduction in proteinuria [53] Col4α3 deficiency (mouse) MSCs Prevented loss of peritubular capillaries and reduced fibrosis but no increase in function or survival [24] Col4α3 deficiency (mouse) Bone marrow Partial restoration of expression of the type IV collagen α3 chain, improved histology and function [25] Col4α3 deficiency (mouse) MSCs Improved function and glomerular scarring and interstitial fibrosis reduced [155] UUO (mouse) BM Instertitial BM-derived cells do not contribute significantly to collagen synthesis after damage [74] Adriamycin-nephropathy (mouse) Renal side population Functional amprovement but very low rate of engraftment. [78] IR (rat) Multipotent renal progenitor cells In vivo epithelial differentiation, no difference on renal function [67] Cultured met...…”

“…There have been very few studies performed using animal models of chronic renal diseases, despite the plethora of experimental and genetic murine models of glomerulosclerosis or glomerulonephritis available. The utility of MSCs has been assessed in collagen4α3 [25,24] and 1α2 mutant mice [143] and streptozocin-induced type 1 diabetes [144,145], but no studies of stem cells in the db/db model of diabetic nephropathy have been reported and the only study in which stem cells have been examined in a model of end stage renal disease utilized human fetal kidney cells [146]. The diversity of pathology present in CKD may also mean that no one cellular therapy will be applicable to all conditions.…”

14S,21R-dihydroxy-docosahexaenoic Acid Treatment Enhances Mesenchymal Stem Cell Amelioration of Renal Ischemia/Reperfusion Injury

“…However, the mechanisms by which MSCs ameliorate I/R injury are not clear. Several studies have demonstrated the capacity of MSC to differentiate into kidney cells [11][12][13][14]. Controversial studies indicated that the grafted MSCs were not the predominant cellular components involved in the regeneration of injured tubuli [7,59], and it has been postulated that, rather than differentiation, cell fusion accounts for these cells [7,[59][60][61].…”

“…In particular, MSCs can ameliorate renal ischemia/ reperfusion (I/R) injury [5][6][7][8][9][10]. It has been reported that MSCs repair renal damage by differentiating into tubular epithelial cells [11], mesangial cells [12], endothelial cells [13], and podocytes [14], and by producing renotrophic cytokines and growth factors [15][16][17][18][19]. For example, MSCs can produce insulin growth factor-1 (IGF-1) and hepatocyte growth factor (HGF) [15], both of which are renal-protective or renotrophic factors [18,19].…”