The expression of transforming growth factor type beta in fetal and adult rabbit skin wounds.

Transforming growth factor, subtype beta (TGF-beta) exists in several isoforms and is known to have important roles in adult wound healing by promoting collagen and extracellular matrix component deposition. It is also believed that TGF-beta influences normal developmental processes during embryo-genesis. Immunolocalization of two isoforms, TGF-beta 1 and TGF-beta 2, in healing fetal and adult rabbit skin wounds shows distinctly different forms of expression of these molecules. TGF-beta 1 and TGF-beta 2 are both expressed within the developing fetal dermis, but no differential upregulation in the area of the healing wound is noted. In contrast, the expression of TGF-beta 1 and TGF-beta 2 is increased in adult wounds by day 7 after wounding, within macrophages that are abundant by this time. High levels of TGF-beta 1 and TGF-beta 2 within adult wounds might indicate that the relative paucity and differential distribution of these factors in fetal wounds are important in the production of scar in adults and the absence of scar in the fetus. Further, these patterns of expression suggest fundamental differences between fetal and adult tissues in accomplishing wound repair.