Oral and Dermal Fibroblast Organotypic Co-cultures Show Differences in Phenotype

Oral wound healing results in the restoration of mucosal continuity with less visible scarring than equivalent dermal healing. It is recognized that a major element of this response is related to intrinsic phenotypic differences in the response of fibroblasts within these tissues. Furthermore, the onset of scarring is thought to occur with the appearance of myofibroblast phenotype and α-smooth muscle actin (α-SMA) expression. Harnessing this preferential phenotype for extra-oral healing regimes could improve the effectiveness of skin substitutes.

Objectives:

To investigate whether phenotypic differences exist between human oral (HOF) and dermal fibroblasts (HDF) when in organotypic co-culture

Methods:

Heterotypic oral and dermal organotypic models were constructed by seeding patient matched fibroblasts into a type I collagen. Lattices were overlaid a suspension of human dermal keratinocytes and raised to the air-liquid interface. Lattice contraction was measured daily. After a 3-week culture period mRNA expression of α-SMA, α_v integrin, uPA receptor and involucrin was studied using Real-Time RT-PCR.

Results:

Organotypic co-cultures appeared histologically normal. HOF contracted co-cultures faster than HDF, suggesting a greater efficiency at remodelling the extracellular matrix in vitro. Heterotypic models of oral mucosa had lower expression of α-SMA and related remodelling proteins, and higher involucrin expression than dermal counterparts. The faster contraction of these models may therefore be attributed to tractional movements rather than ‘activation' of these cells into myofibroblasts. Higher involucrin expression suggests greater differentiation of the epithelial layer.

Figure: Graphs show greater involucrin and lower α-SMA mRNA expression of oral organotypics compared to dermal counterparts in three patients (P<0.05).

Conclusion:

Oral fibroblasts encourage terminal differentiation of keratinocytes, remodelling the collagen matrices more efficiently with lower expression of α-SMA, when compared to their dermal counterparts. Thus, oral fibroblasts could be used in the dermal component of skin substitutes as alternatives to homotypic forms and also offer superior efficacy.