The effects of local injection of exosomes derived from BMSCs on random skin flap in rats.

Purpose: To determine if the viability of random pattern dorsal skin flaps in rats could be improved with local injection of exosomes derived from bone marrow mesenchymal stem cells (BMSCs). Methods: 30 adult male SD rats (weight 200-250 g) were randomly divided into experimental and control groups. Exosomes were isolated from the 4th generation of BMSCs. Experimental group were treated with local injection of exosomes suspension while control group were treated with saline solution in the same way. McFarlane-type flaps (9.0 × 3.0 cm) were then operated in the dorsum of all. On the seventh postoperative day, the percentage of viability area was measured and the blood flow was detected by laser doppler. Then rats were sacrificed and flaps were cut off for further check. Results: Compared with controls, the exosomes increased the area of survival (P<0.05). Hematoxylin and eosin (HE) staining of zone II showed higher microvascular density (P<0.05) and better angiogenesis (P<0.05) in the exosomes group. Similarly, the blood flow of exosomes was better than the control group according to laser doppler imaging (P<0.05). And the result of immunohistochemistry and western blot showed that the exosomes group had significantly higher VEGF and CD34 expression compared to the controls (P<0.05). Conclusions: Local injection of BMSCs exosomes was effective to attenuate necrosis of the McFarlane-type flaps in rats.