Scar Prevention and Cosmetically Enhanced Wound Healing Using Relaxin

Relaxin has previously been tested in rodent wound healing models and been shown to promote angiogenesis and to speed healing. However, pigs have been shown to be a better model for human skin in dermatology studies, so juvenile pigs were selected for a study of scar reduction and cosmetic appearance. Twelve 20‐ by 6‐mm excisional wounds were created on the backs of all animals. Topical formulations of relaxin with 0, 0.5, or 2.5 mg/mL were applied twice daily for weeks 2–3 and then daily for weeks 3–6 in all animals. In addition, some animals received systemic relaxin, which was administered via infusion pumps at a rate of 125 μg/kg of body weight/day. Assessments of healing and cosmetic appearance were made by a dermatologist at weeks 2, 4, and 6. Wound sites were collected at 6 weeks and evaluated histologically for granulation tissue, inflammation, and collagen organization. Wounds in animals receiving systemic relaxin had an improved appearance with less redness, reduced granulation tissue, and lower amounts of inflammation. They showed a more‐well‐knit collagen structure compared to controls. Wounds treated with topical formulations did not show improvement over controls. The topical formulation used was found to have a short residence time, which likely limited penetration of relaxin. Reformulated relaxin preparations with improved penetration might be useful as a topical treatment for wounds to prevent or reduce scarring.