Objective To investigate the protective role of bone marrow-derived stem cells (BMDSCs) in progressive glomerulosclerosis rats,and to observe whether BMDSCs promote glomenlar repair and regeneration.Methods Progressive glomerulosclerosis was induced in enhanced green fluorescent protein (EGFP) bone marrow chimeric rats by injecting with anti-Thy1.1 antibody,followed by unilateral nephrectomy.Subsequently,these rats were treated with either BMDSCs infusion (treatment group,10 rats) or phosphate-buffered saline (untreated group,1O rats).Renal function and histological alterations were examined at week 12 after Thy1.1 antibody injection.Repair and regeneration of glomerular endothelial cells was detected by immunofluorescence.Results Only 3 rats survived in untreated group,other 7 rats died at week 2,7,9,11 after antibody injection.In treatment group,9 rats survived at week 12,only 1rat died at week 10.The BUN and Scr were significantly lower in treatment group as compared to untreated group [BUN(43.55±29.06) vs (76.58±66.19) mmol/L,Scr (138.79±75.14) vs (233.38±164.43) μmol/L].Proteinuria was not significantly different between two groups at day 3,7,14 and 28,while it was significantly decreased at day 42,56 and 84 in treatment group compared with untreated group.Light microscopy showed that there was severe diffuse mesangial cell proliferation,mesangial matrix expansion and glomerulosclerosis in untreated group,and such changes were ameliorated in treatment group.The mesangial expansion index and glomerular sclerosis index in untreated group was significantly higher than those in treatment group.More BMDCs were recruited into the glomeruli and differentiated into glomerular endothelial cells in treatment group as compared with untreated group.Double immunofluorescence stain also demonstrated that BMDSCs infusion promoted glomerular capillary repair and regeneration.Conclusion BMDSCs infusion can improve renal function and histological changes,and promote the repair and regeneration of glomerular capillary.