Differential collagen I gene expression in fetal fibroblasts

Abstract

Purpose: Fetal wound healing is characterized by the regeneration of normal dermis and the absence of scar. Transforming growth factor beta-1 (TGF-β1) is a ubiquitous cytokine with potent fibrogenic effects in both postnatal and fetal wounds. Supplementing fetal wounds with TGF-β1 results in increased fibrosis consisting primarily of collagen I. We hypothesized that the lack of scar formation in fetal wounds may be caused by differential collagen I gene (COL1A1) expression. The authors examined basal collagen la gene expression in human fetal, newborn, and adult dermal fibroblasts after stimulation with exogenous TGF-β1. Methods: Subconfluent human dermal fibroblasts from fetal, newborn, and adult cell lines were incubated for 24 hours, then stimulated by incubation for 4 hours with 1 ng/mL of human recombinant TGF-β1, or with media alone for basal collagen gene expression, and then placed in guanidium isothyocyanate buffer. To quantitate COL1A1 gene expression, total cellular RNA was extracted and subjected to northern and slot blot hybridization analysis with Diglabeled COL1A1 probes. The membrane was exposed to x-ray film for 15 minutes and developed. Results: Scant COL1A1 gene transcript was detected in control fetal fibroblasts. Brief stimulation with of TGF-β1 upregulated the COL1A1 gene transcription in fetal fibroblasts. Gene expression for COL1A1 in both postnatal cell lines appeared similar in treated and untreated cells. Housekeeping control (GAPDH) confirmed no difference in total amount of RNA at the start or end of the experiment. Conclusion: COL1A1 gene expression is notably absent in unstimulated fetal fibroblasts, but is upregulated by TGF-β1. In contrast, postnatal fibroblasts demonstrate significant constitutive COL1A1 gene expression at baseline and unchanged after TGF-β1 stimulation. This differential regulation may contribute to the ability of fetal wounds to regenerate without scar and explain the effect of exogenous TGF-β1 to increase fibroplasia in fetal dermal incisional wounds.