Abstract
Purpose: :
The secreted protein, acidic and rich in cysteine (SPARC) is a protein involved in extracellular matrix (ECM) modification. Matrix metalloproteinases (MMPs) are secreted enzymes that can degrade the ECM to facilitate the migration of cells. The aim of this study is to investigate the molecular pathway induced by wounding which results in the increase in migration of conjunctival epithelial cells.
Methods: :
All experiments were performed on the IOBA-NHC cell line derived from normal human conjunctival epithelium. Scratch wound assay was used to determine the effect of exogenous SPARC and/or MMP inhibitors on cell migration. Expression of matrix metalloproteinases (MMPs) was examined by quantitative real-time PCR (qPCR). For multiple scrape wounds, monolayer cell cultures were wounded in a cross-hatched pattern with two perpendicular and two diagonal strokes of a multi-channel pipette fitted with five pipette tips. UV irradiation was performed by exposing the cells to UV at 20 mJ/cm2.
Results: :
Scratch wound assays demonstrated that IOBA-NHC cells migrate more rapidly when treated with exogenous SPARC. The SPARC-treated cells also showed an increase in MMP-3 expression as revealed by qPCR. Consistent with this observation, scratch wound assays in the presence of MMP inhibitors inhibited the increase in cell migration conferred by SPARC. Additionally, the upregulation of SPARC and MMP-3 is induced specifically by wounding and not by other environmental stimulation such as UV.
Conclusions: :
IOBA-NHC cells respond to wounding by increasing SPARC expression which in turn upregulates MMP-3 production. This results in an increase in cell migration to heal the wound. We therefore hypothesize that SPARC and MMP-3 are molecules integral to conjunctival epithelial wound repair.
Keywords: wound healing • extracellular matrix