Augmentation of rat skin flap viability by relaxin‐expressing adenovirus

AbstractRelaxin (RLX) has multiple vascular actions, including vasodilation and angiogenesis, which occur via induction of vascular endothelial growth factor (VEGF) expression. We generated a RLX‐expressing (dE1‐RGD/lacZ/RLX) adenovirus and investigated whether it enhances skin flap survival. Thirty Sprague‐Dawley rats were divided into three groups: RLX‐expressing adenovirus group, control virus group, and phosphate‐buffered saline (PBS) group. Two days before surgery and immediately after flap elevation, the caudally based flap that was 3 × 9 cm in size was subdermally injected with the dE1‐RGD/lacZ/RLX virus (107 PFU), dE1‐RGD/lacZ virus (107 PFU), or PBS. The surviving area of the flap and the amount of blood flow were measured. On postoperative day 10, CD31‐positive vessels and VEGF protein expression were examined. We observed a significant increase in the survival area of the flap in the RLX group. Doppler measurement also showed significantly increased blood flow immediately after the operation and on postoperative days 7 and 10. CD31‐positive vessels and VEGF protein expression were significantly greater in the RLX group. Thus, administration of RLX‐expressing adenovirus into elevated skin flaps increased VEGF expression, the number of capillaries, and blood flow to the flap, thereby improving skin flap survival.