Abstract
Purpose: :
We have investigated the role of TGFβ concentration in fibroblast migration and corneal wound healing as a means to enhance stromal repopulation and improve corneal stromal wound healing after LASIK.
Methods: :
Human corneal fibroblasts (HCFs) were cultured on collagen in supplemented serum-free media (SSFM). Cell migration was assessed by a scratch-wound assay and results were quantified using T-Scratch software. Immunocytochemistry was used to evaluate SMAD 2/3 localization and α-SMA expression. Active TGFβ was quantified by co-culturing HCFs with TMLC cells containing the PAI-1 promoter linked to the luciferase gene. Wounding in vivo was performed by creating a corneal flap of 8mm in diameter and 200µm in depth with a FlapMaker Disposable Microkeratome in New Zealand White rabbits (2.5-3.0kg). At 0 and 24 hours, corneas were excised and embedded for histological examination to measure wound closure and α-SMA expression. The contralateral eyes served as unoperated controls.
Results: :
We demonstrated that endogenous levels of active TGFβ1 (0.01ng/ml) stimulated cell migration in vitro since neutralizing antibody to TGFβ1 inhibited cell migration by 3.6-fold compared to IgG control, which had no effect. Addition of 1.0 ng/ml TGFβ1 (100-fold higher than endogenous levels) also reduced cell migration by 3.2-fold, and promoted fibrotic markers: SMAD 2/3 nuclear translocalization and myofibroblast differentiation. Similarly after corneal wounding in rabbits in vivo, application of 0.01ng/ml TGFβ1 significantly increased the rate of wound closure with reduced α-SMA expression compared to 1.0 ng/ml TGFβ1.
Conclusions: :
These in vitro and in vivo data suggest that low levels of TGFβ1 (0.01ng/ml) promote cell migration and wound closure with a reduced fibrotic response. Thus controlling but not eliminating TGFβ may be a key to promoting regenerative healing in the cornea.
Keywords: cornea: stroma and keratocytes • wound healing • cornea: basic science