Substratum Topography Modulates SMA Expression in Corneal Stromal Cells

Abstract

Purpose: : TGFβ is known to be important in regulating corneal fibroblast differentiation to the myofibroblast phenotype and plays an important role in normal and dysregulated wound healing. Myofibroblasts are generally located at the normal and wound tissue interface suggesting that the tissue provides cues that may modify TGFβ signaling. The purpose of this study was to determine the effect of topographic cues on TGFβ-induced myofibroblast differentiation of rabbit corneal stromal cells.

Methods: : Rabbit corneal fibroblasts were plated on nanopatterned surfaces having topographic features of varying pitch (pitch=groove width + ridge width). Cells were cultured with TGFβ at concentrations of 0.0 ng/ml, 0.1ng/ml, 1ng/ml or 10ng/ml. 72 hours later RNA was collected from the surfaces and analyzed for SMA by quantitative real time PCR.

Results: : Cells grown on a planar surface expressed negligible levels of SMA at 0.0 and 0.1ng/ml TGFβ. A 3 fold increase was observed at 1ng/ml and a 23 fold increase at 10ng/ml. Cells grown on all topographically patterned surfaces demonstrated significantly reduced levels of SMA (p<0.002) when exposed to at least 1ng/ml of TGFβ. Cells on the 1400nm pitch surface expressed the lowest levels of SMA, expressing 30% less than those on planar surfaces at 1ng/ml TGFβ and 90% less SMA at 10ng/ml TGFβ.

Conclusions: : These data suggest that nanoscale topographic features modulate TGFβ-induced myofibroblast differentiation and the expression of SMA. We propose that in the wound environment the native nanotopographic cues likely assist in stabilizing the keratocyte/fibroblast phenotype while pathologic alterations of the topographic environment may be permissive for myofibroblast differentiation and the development of fibrosis and corneal haze.

Keywords: cornea: stroma and keratocytes • wound healing