Abstract
Purpose: :
Corneal endothelial (CE) cell loss following corneal transplantation remains a strong risk factor causing graft failure.The present study tested the hypothesis that treatment of corneoscleral explants (explants) with CE cell autocrine vasoactive intestinal peptide (VIP)1-3 prior to their storage prevents loss from CE cells the α subunit of the receptor for the survival factor ciliary neurotrophic factor (CNTF)4, maintains higher levels of CE cell CNTF responsiveness, and promotes cell to Descemet’s membrane and cell-cell adhesions.
Methods: :
Paired explants (either fresh or in preservation in Optisol-GS) were incubated in 20 mM HEPES-buffered minimal essential medium (MEM) alone (OS) or that contained10 nM VIP (OD) (30 min; 37oC) before their storage in Optisol-GS. Following explant storage and using Western blot analysis, CE cell CNTFRα level was monitored, while the functionality of CNTFRα was determined by its effectiveness in transducing CNTF signal in inducing the gap junctional protein connexin-43 in CE cells4(37 oC, two days). Aalizarin red S (1% saturated solution in DPBS)-stained areas of damaged cell-cell adhesion and denuded Descemet’s membrane revealed in flat-mounted explants under a light microscope were quantified using the Adobe Photoshop computer software.
Results: :
CE cells in VIP-pretreated explants maintained higher levels of CNTFRα relative to those found in the control paired explants (142 +/-15% vs. 100%; p=0.014 in 7 pairs stored for 4-25 days) and that of CNTF responsiveness in inducing connexin-43 (174+/-23%, vs 100%;p=0.023 in 4 pairs stored for 9 days). Lower levels of cell-cell adhesion breakage and CE cell detachment were found in VIP-pretreated explants (100+/-16% vs 66+/-11%, p=0.039 in 3 pairs stored for 4 days). The beneficial effects of VIP pretreatment were potentiated by increased duration of storage.
Conclusions: :
CNTF is in abundance in the iris and ciliary body and is detected in the aqueous humor, preservation of the receptor for this survival factor in donor cornea is of significance. Our extensive studies of neurotrophic modulation of the corneal endothelium may provide some insights into means for enhancing corneal preservation, targeting at preventing CE cell loss following transplantation.1. Koh and Waschek. 2000. Invest. Ophthalmol. Vis. Sci. 41:4085-4092.2. Koh et al., 2008. Invest. Ophthalmol. Vis. Sci. 49:3491-3498.3. Koh et al., 2009a. J. Neurochem. 109:792-806.4. Koh et al., 2009b. Invest. Ophthalmol. Vis. Sci.50:1801-1807.
Keywords: cornea: storage • cornea: endothelium • cytokines/chemokines