Effect of insulin-like growth factor-1 on promoting healing of skin ulcers in diabetic rats.

To investigate the effect of exogenous insulin-like growth factor-1 (IGF-1) on the healing of skin ulcers in diabetic rats, male Sprague Dawleys (SD) rats with back skin ulcers were selected and divided into control group, model group and IGF-1 treatment group which received different doses of IGF-1 (0.5, 1.0, 1.5, and 2.0mg/L). The results showed that the healing speed of the skin ulcers was significantly affected by IGF-1, which reduced the size of wound (P less than 0.05). The expression of MMP-9 was enhanced while the expression of TIMP-1 was decreased in diabetic rats with skin ulcers. The IGF-1 treatment helped to re¬store the normal expression of both MMP-9 and TIMP-1 in diabetic rats with skin ulcers, and diabetic skin ulcers in the 1.5 mg/L IGF-1 group showed the best healing. Histological examination showed that after 20 days, fibroblasts in the IGF-1 experimental group with an appropriate concentration increased and the numbers of fibroblasts and capillaries were significantly higher than those of the other groups. Moreover, there were obvious wound surface contractions and re-epithelialization, and the new epithelium moved to the center of the wound faster. Therefore, it is concluded that an appropriate concentration of IGF-1 can significantly promote the healing of skin ulcers in diabetic rats.