UBC Theses and Dissertations
The role of fibroblast phenotype and pericellular matrix in wound healing Mah, Wesley Brandon
Scar formation as a result of wound healing in skin is associated with increased deposition of extracellular matrix (ECM) and reduced ECM turnover by fibroblasts. Remarkably, wound healing in the human oral mucosa results in scarless healing, while wound healing in the skin can often result in scarring. Therefore comparing fibroblast phenotype and interactions with their ECM niche in the gingiva and skin may provide novel information about the factors that regulate scar formation. To this end, a novel 3D cell culture model was utilized to yield a cellular microenvironment (niche) that closely mimics the in vivo situation and primary gingival (GFBL) and skin fibroblasts (SFBL) phenotype was characterized. Furthermore, fibroblasts were reseeded on cell-free 3D ECM derived from GFBL and SFBL and the effects of the 3D ECM on cell phenotype were analyzed. Interestingly, SFBL in 3D cultures had greater expression of ECM deposition associated genes, including collagens, matricellular proteins, SLRPs, TGF-β1 and CTGF, intracellular ECM degradation and myofibroblast differentiation and function-associated genes, while GFBL had a greater expression of matrix remodeling associated genes (MMPs). We also found that the 3D cultures showed a significant difference in expression of certain genes (MMPs and myofibroblast function-associated genes) between GFBL and SFBL compared to cells reseeded on the 3D ECM or 2D control substrate. Thus, the 3D culture conditions may differentially regulate expression of a subset of genes in these cells. Interestingly, SFBL had a greater expression of matrix deposition associated genes (collagens, SLRPs, tenascins) irrespective of the culture conditions, suggesting that expression of these genes is inherently distinct between GFBL and SFBL. This was associated with greater autogenous TGF-β expression and SMAD3 phosphorylation in SFBL than GFBL, which may partly explain the innate difference in gene expression. In addition, there was greater ERK1/2 phosphorylation in fibroblasts when seeded on 3D ECM compared to 2D substrate. Greater ERK1/2 phosphorylation may have promoted greater expression of AP-1-dependent MMPs seen in SFBL and GFBL on 3D ECM. In conclusion, reduced expression of matrix deposition associated genes and greater expression of matrix remodeling genes in GFBL may contribute to scarless healing in gingiva.
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