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Keloids represent a pathological response to injury interrupting skin integrity, creating disfiguring scars with no definitive pathophysiology. Transforming growth factor- β1 (TGF-β1) has been regarded as one of the pathogenesis of keloids. The purpose of this study is to investigate the influence of keloid keratinocytes on TGF-β1 expression in co-culture system. Recent studies have highlighted the important concept of epithelial- mesenchymal interactions in normal skin biology, and applying this concept to keloids in vitro studies demonstrated significantly increased proliferation of fibroblasts and collagen production in keloid fibroblasts co-cultured with keloid-derived keratinocytes as compared with normal keratinocytes. In this study, normal or keloid fibroblasts in lower chamber were co-cultured with keratinocytes derived either from normal skin or keloid tissue in upper chamber, separated from lower chamber by permeable membrane. Results obtained by ELISA showed equal TGF-β1 expression when keloid fibroblasts were co- cultured with keloid keratinocytes, as compared with the normal keratinocytes at 24,48 hours, but significantly higher expression at 72 hours(p=0.0358). RT-PCR demonstrated that the TGF-β1 expression level was not significantly related to the level of mRNA encoding TGF-β1. These results suggest that overlying keloid keratinocytes play an important role in inducing high level of TGF-β1 expression in keloid by paracrine effect or epithelial-mesenchymal interaction.
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