Mucosal and dermal wounds show different patterns of collagen restoration and contain dissimilar levels of TGF‐B

Abstract

Compared to skin, wounds of the oral mucosa exhibit rapid healing and reduced scar formation. The mechanism behind the improved repair of mucosa has yet to be elucidated. One factor that might play a role is transforming growth factor ß (TGF-ß), a growth factor known to influence multiple stages of wound healing as well as scarring. Utilizing a murine model of identically sized oral and skin wounds; we first used transmission electron microscopy (TEM) to verify a reduction in scar formation in oral wounds. Analysis of collagen fibrils showed that fibril size is very heterogeneous in healing cutaneous wounds, with the majority of fibrils remaining smaller than normal for a prolonged period after injury. In oral wounds, however, collagen fibrils quickly reach a normal and uniform size. To determine if TGF-ß levels might contribute to the lack of scar formation in oral wounds scarring, we compared the expression and production of TGF-ß in oral and skin wounds. By RNase protection analysis (RPA), significantly lower levels of TGF-ß1 mRNA were observed in oral wounds compared to dermal wounds. ELISA analysis confirmed that oral wounds contained significantly lower levels of TGF-ß1 protein than dermal wounds, and exhibited a significant increase in the ratio of TGF-ß1 to TGF-ß3. These findings document reduced scar formation in oral wounds at the ultrastructural level, and suggest that altered TGF-ß production might contribute to superior healing of oral wounds. (NIH RO1 GM50875 to LAD)