Injury induced expression of TGF-beta 1 mRNA is enhanced by exogenously applied TGF-beta S

We have analysed and compared, by in situ hybridisation, the effects of exogenously applied TGF-beta s on expression of endogenous TGF-beta mRNAs in partial thickness thermal wounds in old and young mice. Although injury induced the expression of TGF-beta 1 mRNA in the epidermis and dermis at the wound margins, expression of TGF-beta 2- or TGF-beta 3-mRNA was not detected. Biopsies taken 24 hours following injury revealed a focally clustered distribution of TGF-beta 1 hybridisation signals in the dermis, the number of positive cells and expression levels being reduced in old mice. Topical application of all three TGF-beta isoforms enhanced TGF-beta 1 mRNA expression in the dermis of old and young mice. In biopsies taken three days following injury, TGF-beta 1 hybridisation signals were most prominent in the regenerating epidermis although at this timepoint differences in expression levels between treated and non-treated animals were less pronounced.