Abstract
Purpose :
The microenvironment or “niche” plays an important role in regulating the fate of limbal stem cells. Our previous animal study showed that pigment epithelial derived factor (PEDF) accelerates the regeneration of limbal epithelium in limbal lesion created by partial limbal excision. The reconstruction of limbal niche in the process of limbal epithelial repair remains elusive. This study was to investigate the effect of PEDF-derived short peptide 29-mer on the renewal of limbal niche.
Methods :
New Zealand albino rabbits were used in this study. Limbal excision (180 degree) was performed surgically to remove complete limbal epithelium and partial limbal stroma. Topical 29-mer containing ointment once a day for 2 weeks was applied immediately after surgery. The repair of limbal niche at 2 weeks was assessed by immunofluorescence staining with antibodies for N-cadherin, CD90, CD105, c-kit, ABCG2. Corneal stromal stem cells (CSSC) were harvested from normal rabbit limbus and phenotypic evaluation was assessed by the expression of CD90. Inhibitors for morphogen pathways were used to investigate the cross-talk between morphogen pathways and PEDF signaling in regulating CSSC proliferation and markers.
Results :
Immunofluorescence analysis revealed that eyes treated with the 29-mer significantly increased the number of CD90, CD105, and N-cadherin positive cells in the anterior stroma of repaired limbus compared to vehicle treatment (P < 0.05). Interestingly, presence of c-kit, ABCG2 positive stromal cells were noted in 29-mer treated eyes but not in control eyes. This suggests that 29-mer may also mediate recruitment of BM-derived mesenchymal cells to the limbal wound. In cultured CSSC, western blotting showed upregulation of CD90 and cyclin D1 proliferation marker, and the effect was decreased after treated with the Inhibitors for Wnt and Hedgehog.
Conclusions :
PEDF facilitate limbal niche reconstruction with evidence of presenting CD90, CD105, c-kit ABCG2 and N-cadherin positive stromal cells. The beneficial effect of PEDF 29-mer on limbal niche cell may involve in morphogen pathways.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.