AIM: To investigate whether fetal kidney stem cells(f KSC) ameliorate cisplatin induced acute renal failure(ARF) in rats and promote renal angiogenesis.METHODS: The f KSC were isolated from rat fetuses of gestation day 16 and expanded in vitro up to 3rd passage. They were characterized for the expression of mesenchymal and renal progenitor markers by flow cytometry and immunocytochemistry, respectively. The in vitro differentiation of f KSC towards epithelial lineage was evaluated by the treatment with specific induction medium and their angiogenic potential by matrigel induced tube formation assay. To study the effect of f KSC in ARF, f KSC labeled with PKH26 were infused in rats with cisplatin induced ARF and, the blood and renal tissues of the rats were collected at different time points. Blood biochemical parameters were studied to evaluate renal function. Renal tissues were evaluated for renal architecture, renal cell proliferation and angiogenesis by immunohistochemistry, renal cell apoptosis by terminal deoxynucleotidyl transferase nickend labeling assay and early expression of angiogenic molecules viz. vascular endothelial growth factor(VEGF), hypoxia-inducible factor(HIF)-1α and endothelial nitric oxide synthase(eN OS) by western blot.RESULTS: The fK SC expressed mesenchymal markers viz. CD29, CD44, CD73, CD90 and CD105 as well asrenal progenitor markers viz. Wt1, Pax2 and Six2. They exhibited a potential to form CD31 and Von Willebrand factor expressing capillary-like structures and could be differentiated into cytokeratin(CK)18 and CK19 positive epithelial cells. Administration of fK SC in rats with ARF as compared to administration of saline alone, resulted in a significant improvement in renal function and histology on day 3(2.33 ± 0.33 vs 3.50 ± 0.34, P < 0.05) and on day 7(0.83 ± 0.16 vs 2.00 ± 0.25, P < 0.05). The infused PKH26 labeled fK SC were observed to engraft in damaged renal tubules and showed increased proliferation and reduced apoptosis(P < 0.05) of renal cells. The kidneys of fK SC as compared to saline treated rats had a higher capillary density on day 3 [13.30 ± 1.54 vs 7.10 ± 1.29, capillaries/high-power fields(HPF), P < 0.05], and on day 7(21.10 ± 1.46 vs 15.00 ± 1.30, capillaries/HPF, P < 0.05). In addition, kidneys of fK SC treated rats had an upregulation of angiogenic proteins hypoxia-inducible factor-1α, VEGF and eN OS on day 3(P < 0.05).CONCLUSION: Our study shows that fK SC ameliorate cisplatin induced ARF in rats and promote renal angiogenesis, which may be an important therapeutic mechanism of these stem cells in the disease. AIM: To investigate whether fetal kidney stem cells (f KSC) ameliorate cisplatin induced acute renal failure (ARF) in rats and promote renal angiogenesis. METHODS: The f KSC were isolated from rat fetuses of gestation day 16 and expanded in vitro up to 3rd passage. They were characterized for the expression of mesenchymal and renal progenitor markers by flow cytometry and immunocytochemistry, respectively. The in vitro differentiation of f KSC towards epithelial lineage was evaluated by the treatment with specific induction medium and their angiogenic potential by matrigel induced tube formation To study the effect of f KSC in ARF, f KSC labeled with PKH26 were infused in rats with cisplatin induced ARF and, the blood and renal tissues of the rats were collected at different time points. Blood biochemical parameters were studied to evaluate renal function. Renal tissues were evaluated for renal architecture, renal cell proliferation and angiogenesis by immunohistochemistry, renal c ell apoptosis by terminal deoxynucleotidyl transferase nickend labeling assay and early expression of angiogenic molecules viz. vascular endothelial growth factor (VEGF), hypoxia-inducible factor (HIF) -1α and endothelial nitric oxide synthase (eN OS) by western blot.RESULTS: The fK SC expressed mesenchymal markers viz. CD29, CD44, CD73, CD90 and CD105 as well as human progenitor markers viz. Wt1, Pax2 and Six2. They showed a CD31 and Von Willebrand factor expressing capillary-like structures and could be differentiated into Administration of fK SC in rats with ARF as compared to administration of saline alone, resulted in a significant improvement in renal function and histology on day 3 (2.33 ± 0.33 vs. 3.50 ± 0.34, P <0.05) and on day 7 (0.83 ± 0.16 vs 2.00 ± 0.25, P <0.05). The infused PKH26 labeled fK SC were observed to engraft in damaged renal tubules and showed increased proliferation and reduced apoptosi s (P <0.05) of renal cells. The kidneys of fK SC as compared to saline treated rats had a higher capillary density on day 3 [13.30 ± 1.54 vs 7.10 ± 1.29, capillaries / high-power fields (HPF), P <0.05], and on day 7 (21.10 ± 1.46 vs 15.00 ± 1.30, capillaries / HPF, P <0.05). In addition, kidneys of fK SC treated rats had an upregulation of angiogenic proteins hypoxia-inducible factor-1α, VEGF and eNOS on day 3 (P <0.05). CONCLUSION: Our study shows that fK SC ameliorate cisplatin induced ARF in rats and promote renal angiogenesis, which may be an important therapeutic mechanism of these stem cells in the disease.