Kerstin J. Rolfe

Differential gene expression in response to transforming growth factor-β1 by fetal and postnatal dermal fibroblasts

The multipotent growth factor transforming growth factor (TGF)‐β1 is consistently linked with fibrosis and scarring. The perfect (scarless) healing of cutaneous wounds in early gestational age fetuses is proposed to be due to this tissues predominance of the TGF‐β3 isoform over the profibrotic TGF‐β1 and 2. Nevertheless, TGF‐β1 is present during wound healing in the early fetus and recently we demonstrated that relevant intracellular signaling pathways are activated (albeit transiently) on TGF‐β1stimulation. This study aimed to determine whether TGF‐β1 has different effects on gene transcription in human fetal (<14 weeks) vs. human postnatal dermal fibroblasts, using real‐time polymerase chain reaction. The regulation pattern of a number of TGF‐β response genes differed dramatically between the two cell sources. The typical autocrine loop of TGF‐β1 autoinduction did not occur in fetal fibroblasts and genes that are normally up‐regulated, connective tissue growth factor and collagen type I were actually down‐regulated. Furthermore, other response genes responded in a delayed fashion (TGF‐β3) compared with that seen in the more developmentally mature postnatal fibroblasts. Finally, genes unaltered by TGF‐β stimulation in postnatal cells, TGF‐β2 and collagen III, were up‐regulated in fetal cells. These developmentally related differences in fibroblast response to TGF‐β1 may influence wound‐healing outcome, i.e., perfect regeneration or fibrosis.

Dermal fibroblasts derived from fetal and postnatal humans exhibit distinct responses to insulin like growth factors

BackgroundIt has been well established that human fetuses will heal cutaneous wounds with perfect regeneration. Insulin-like growth factors are pro-fibrotic fibroblast mitogens that have important roles in both adult wound healing and during development, although their relative contribution towards fetal wound healing is currently unknown. We have compared responses to IGF-I and -II in human dermal fibroblast strains derived from early gestational age fetal (<14 weeks) and developmentally mature postnatal skin to identify any differences that might relate to their respective wound healing responses of regeneration or fibrosis.ResultsWe have established that the mitogenic response of fetal cells to both IGF-I and -II is much lower than that seen in postnatal dermal fibroblasts. Further, unlike postnatal cells, fetal cells fail to synthesise collagen in response to IGF-I, whereas they do increase synthesis in response to IGF-II. This apparent developmentally regulated difference in response to these related growth factors is also reflected in changes in the tyrosine phosphorylation pattern of a number of proteins. Postnatal cells exhibit a significant increase in phosphorylation of ERK 1 (p44) in response to IGF-I and conversely the p46 isoform of Shc on IGF-II stimulation. Fetal cells however only show a significant increase in an unidentified 100 kDa tyrosine-phosphorylated protein on stimulation with IGF-II.ConclusionDermal fibroblasts exhibit different responses to the two forms of IGF depending on their developmental maturity. This may relate to the developmental transition in cutaneous wound healing from regeneration to fibrosis.

The effect of epigallocatechin-3-gallate, a constituent of green tea, on transforming growth factor-β1–stimulated wound contraction

Dermal fibrosis, or scarring, following surgical incisions, traumatic wounds and burns presents a major clinical burden. Transforming growth factor (TGF)‐β1 is a major factor known to stimulate fibroblast proliferation, collagen production, and the differentiation of fibroblast to myofibroblast promoting wound contraction. Furthermore, excessive or prolonged TGF‐β1 has been shown to be associated with scarring. Green tea contains high amounts of polyphenols with the major polyphenolic compound being epigallocatechin‐3‐gallate (EGCG). EGCG has been shown to be anti‐inflammatory, anti‐oxidant, and may improve wound healing and scarring, though its precise effect on TGF‐β1 remains unclear. This study aimed at determining the effect of EGCG on TGF‐β1 collagen contraction, gene expression and the differentiation of fibroblast to myofibroblast. EGCG appears to affect the role that TGF‐β1 plays in fibroblast populated collagen gel contraction and this seems to be through both myofibroblast differentiation and connective tissue growth factor gene expression and reduces the expression of collagen type I gene regulation.