effect of mesenchymal stem cells on doxorubicin-induced fibrosis

objective: the aim of this study was to test the effect of intravenous injection of mesenchymal stem cells (mscs) on doxorubicin (dox)-induced fibrosis in the heart. we investigated the mechanisms that possibly mediate this effect. materials and methods: in this experimental study, fibrosis in the myocardium of adult male wistar rats (weights 180-200 g, 9-10 weeks of age, total n=30) was created by dox administration. dox (2.5 mg/kg) was administered intraperitoneally 3 times a week, for a total dose of 15 mg/kg over a period of 2 weeks. mscs from wistar rats were separated and cultured in dulbecco’s modified eagle medium (dmem). the condition medium (cm) which contained factors secreted by mscs was also collected from mscs cultured in serum-free dmem. two weeks after the first injection of dox, mscs, cm and standard medium (sm) were transplanted via intravenous injection. four weeks after transplantation, histological (masson’s trichrome staining for fibrosis detection) and molecular [real-time polymerase chain reaction (rt-pcr)] analyses were conducted. in addition, insulin-like growth factor (igf-1) and hepatocyte growth factor (hgf) in the cm were measured with an enzyme-linked immunosorbent assay (elisa). for immunosuppressive treatment, cyclosporine a was given (intraperitoneally, 5 mg/kg/day) starting on the day of surgery until the end of study in all groups. fibrosis rate and relative gene expression were compared by analysis of variance (anova) and post-tukey’s test. hgf and (igf-1 in the cm were analyzed by independent sample t test. p<0.01 was considered statistically significant. results: our data demonstrated that intravenously transplanted mscs and cm significantly reduced fibrosis and significantly increased bcl-2 expression levels in the myocardium compared to the dox group (p<0.01). however, there was no significant difference between bax expression levels in these groups. in addition, secretion of hgf and igf-1 was detected in the cm (p<0.01). conclusion: we conclude that intravenous transplantation of mscs and cm can attenuate myocardial fibrosis and increase bcl-2 expression. this may be mediated by paracrine signaling from mscs via anti-fibrotic and anti-apoptotic factors such as hgf and igf-1.