Adipose-derived stem cells improve erectile function partially through the secretion of IGF-1, bFGF, and VEGF in aged rats.

Adipose-derived stem cells (ADSCs) have recently been considered as a promising therapy for erectile dysfunction (ED). However, the mechanism of ADSC-based therapy is unclear. Insulin-like growth factor-1 (IGF-1), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) secreted by ADSCs were assessed in vitro. Sixteen 24-month-old male Sprague-Dawley rats were used for comparative analysis of 2-week treatment with labeled ADSCs or PBS. Eight additional 5-month-old rats were used as a young rat group. At 2 weeks post-transplantation, all rats were analyzed for erectile function, cavernous IGF-1, bFGF and VEGF levels, and penile histology. Conditioned medium and co-culture systems were used in cell experiments to detect how growth factors act on corpus cavernosum smooth muscle cells (CCSMCs) under oxidative stress conditions via crystal violet staining and immunofluorescence staining. We found that ADSCs secreted significantly higher IGF-1, bFGF, and VEGF levels in culture medium compared with basal medium. Compared with young rats, untreated aged rats had significantly lower Max ICP/MAP and ADSC treatment significantly increased the ratio. Immunofluorescence staining demonstrated a small number of labeled ADSCs in the corpus cavernosum. The untreated aged rats showed significantly decreased cavernous IGF-1, bFGF, and VEGF levels and significantly decreased contents of cavernous smooth muscle and endothelium compared with young rats. ADSC treatment partially normalized these alterations. In cell experiments, the groups receiving growth factor neutralizing antibody separately or combined had significantly decreased numbers of CCSMCs compared with control groups. These results indicated that ADSC treatment may improve aging-related ED partially through the secretion of IGF-1, bFGF, and VEGF.