Abstract
Uncontrolled fibrosis via excess deposition of extracellular matrix (ECM) is a hallmark of hypertrophic scars and keloids. A decellularized ECM biomaterial from porcine small intestinal submucosa (SIS; Biodesign or BioD, Cook Biotech, Inc.) is widely used in clinical applications for tissue repair. The objective of the current study was to test the effects of BioD scaffolds, as compared with collagen constructs, on normal human skin (nFB) and keloid fibroblasts (kFBs). Immortalized human dermal fibroblasts (hFBs) and human keloid fibroblasts (hKFs) were utilized for all experiments. Cells were cultured either on BioD membranes or on collagen gel (used as a control). To investigate pro-fibrotic signaling pathways, real-time quantitative PCR (qPCR), ELISA, and gene knockdown studies were conducted on cultured cells. ECM gene expression array revealed that BioD significantly attenuated (p < 0.05) the expression of thrombospondin-1 and fibronectin-1, two drivers of fibrosis in nFB as well as kFB. BioD-repressed thrombospondin-1 and fibronectin-1 gene expression manifested as significant downregulation (n = 5-6; p < 0.05) of both proteins in nFB and kFB. The levels of latent transforming-growth factor (LAP-TGFβ-1) were markedly reduced (n = 5; p < 0.05) in both nFB and kFB cultured on BioD, but not the other constructs. Knockdown of FN1 using siRNA significantly attenuated (n = 5, p < 0.05) pro-fibrotic responses, including expression of Col1A1 and the levels of LAP-TGFβ-1 in nFB, suggesting that downregulation of FN1 by BioD is one of the primary underlying mechanisms of attenuated pro-fibrotic responses in keloid fibroblasts. This study reports that a decellularized ECM scaffold may significantly attenuate pro-fibrotic responses in both normal and keloid fibroblasts via TSP1 and FN1-dependent mechanisms.