Topical platelet-derived growth factor in patients enhances wound closure in the absence of wound contraction

Recombinant human platelet-derived growth factor (PDGF) is reported to promote wound closure in problem wounds. The mechanism of PDGF enhancement of wound closure is not clear. Does PDGF enhance wound contraction, or re-epithelialization, or both? In four patients undergoing elective surgery, a full excision 5 cm 2 punch wound was made behind each ear. The left post-articular wound received daily PDGF in a gel and each right post-articular wound received placebo-gel daily. The placebo-treated wounds closed in 19.8 days, while the PDGF-treated wounds closed significantly faster, in 15.6 days, p =0.002. At Day 20, all healed wounds were processed for histology. PDGF-treated wounds showed granulation tissue beneath an uninterrupted epidermis. A fine birefringence pattern, consistent with granulation tissue, was found by polarized light microscopy. The control closed-wounds had a smaller area of granulation tissue under an intact epidermis and polarized light microscopy showed mostly normal dermis. The presence of intact dermis within the closed-wound site is the hallmark of wound contraction. Topical PDGF limits the role of wound contraction in wound closure. Control wounds healed by wound contraction, while PDGF-treated wounds close by re-epithelialization and filling in with scar.