Bitter Melon Extract Promotes Granulation Tissue Growth and Angiogenesis in the Diabetic Wound

Bitter melon is a plant fruit that has been shown to exert a hypoglycemic effect when used systemically in patients with diabetes. This study was designed to investigate the topical effect of bitter melon on diabetic wounds using the wound chamber model in rats.

Two bilateral wound chambers were implanted subcutaneously in the thoracic-lumbar region of male Sprague-Dawley rats. Diabetes was induced with streptozotocin 7 days after implantation of wound chambers. After 24 hours of induction of diabetes, aqueous extract of bitter melon was injected into 1 wound chamber, and saline (0.9% sodium chloride solution) was injected into the contralateral chamber once daily for 3 days. Wound fluid was collected on day 4 for analysis, following which rats were euthanized. The granulation tissue encapsulating the wound chamber was removed and processed for histology. Controls included diabetic rats with wound chambers injected with saline (instead of bitter melon) and nondiabetic rats with wound chambers injected with bitter melon.

In rats with diabetes, wound granulation tissue treated with bitter melon was well formed, with distinct cellular layers, whereas the saline-treated granulation tissue showed a severe loss of tissue organization and blood vessels. Moreover, the bitter melon treatment increased angiogenesis in the diabetic granulation tissue, marked by abundant microvessels and large blood vessels. In nondiabetic rats, no differences in wound granulation tissues were observed between saline- and bitter melon-treated groups. Bitter melon treatment had no effect on systemic blood glucose levels or insulin receptor substrate 1, suggesting that its stimulatory effect on diabetic granulation tissue was not due to alteration of systemic blood glucose levels.

When applied locally to diabetic wounds, bitter melon extract prevents regression of granulation tissue and blood vessels, thus accelerating and improving wound healing.