Initial assessment of gingival biotype as a potential source of variability in the migration, contraction and gene expression of fibroblasts

Gingival biotype refers to the clinical classification of gingiva based on the thickness of the tissue, with thick gingival tissues more resistant to trauma and recession than the thin variant. However, to date there has never been an analysis of whether fibroblasts isolated from different biotypes possess inherent phenotypic differences. We hypothesized that gingival fibroblasts from thick and thin biotype would exhibit differences in migration, contraction and gene expression in vitro in the presence of either transforming growth factor beta one (TGF-β1) or tumor necrosis factor alpha (TNFα), two major cytokines involved in wound repair.

Migration was quantified using closure of scratch wound assays, contraction was assessed using attached and detached collagen lattices and extracellular matrix related gene expression using Taqman Realtime polymerase chain reaction.

Human gingival fibroblasts isolated from both biotypes showed similar rates of closure of scratch wounds, which was not influenced by the addition of TGF-β1 or TNFα. Fibroblasts from both biotypes contracted detached, but not attached, collagen gels to 50 % of their original weight although this contraction was not associated with incorporation of α-smooth muscle actin into stressfibres under any tested culture condition. Analysis of gene expression showed that POSTN, and ACTA2 mRNA levels did not significantly change, but CCN2 and COL1A2 mRNA levels were significantly higher in thick compared to thin fibroblasts in response to TGF-β1.

While supra-cellular factors influence the healing, esthetic outcomes and recession in thin gingival biotypes, differences in gingival fibroblast gene expression in response to growth factors may also play a role and warrants further investigation.