Adipose-derived stem cells accelerate neovascularization in ischaemic diabetic skin flap via expression of hypoxia-inducible factor-1a

Skin flaps are frequently performed for diabetic patients in spite of countless detrimental effects of diabetes on flap survival, most of which may result from a defective response of the tissues to low oxygen tension. In this study, the authors explored the feasibility of applying human adipose-derived stem cells (ASCs) to increase the viability of random-patterned skin flaps in streptozotocin-induced diabetic mice. ASCs were isolated from the fresh human lipoaspirates and expanded ex vivo for three passages. After the elevation of caudally based random-patterned skin flaps (3 cm long and 1 cm wide), ASCs suspensions were then injected into the flap (group A). Media containing no ASCs were similarly injected as a control (group B), although nothing was injected into the flap base of mice in control group C. Flap assessments were carried out at post-operative day 7 for evaluation of flap viability. The flap survival rate of group A was significantly higher than those of groups B and C, whereas no difference was observed between groups B and C. Histological examination also demonstrated a statistically significant increase in capillary density in group A over both groups B and C. Furthermore, it was found that ASCs not only augmented the expression of vascular endothelial growth factor and hypoxia-inducible factor-1a (HIF-1a) in flap tissues from dermis of diabetes mice, but also promoted their expression in dermal fibroblasts from diabetic mice. Thus, ASCs could enhance the survival of random-patterned skin flaps in streptozotocin-induced diabetic mice via elevated expression of HIF-1a.