Corneal endothelial autocrine VIP enhances its integrity in stored human donor corneoscleral explant

To demonstrate corneal endothelial (CE) integrity enhanced during eye banking by a brief treatment of human donor corneoscleral explant (explant) with CE autocrine trophic factor vasoactive intestinal peptide (VIP).

Paired explants were used as control versus VIP (10 nM)-treated before storage in corneal storage medium (4°C). CE ciliary neurotrophic factor receptor (CNTFRα) and CNTF (0.83 nM) responsiveness in connexin 43 upregulation were monitored (Western blot analysis). CE damage in CNTF-modulated explants and corneal buttons from explants was quantified by analysis of panoramic and microscopic images of the alizarin red-stained corneal endothelium. CE cells scraped from the Descemet's membrane were counted. CE VIP receptor was demonstrated (Western blot analysis).

CE cells in every VIP-treated, freshly dissected explant demonstrated higher CNTFRα levels than controls (100% vs. 142% ± 15%; P = 0.014; 7 pairs stored for 4 to 25 days). Nine days after VIP treatment of previously preserved explants, CNTF responsiveness was 174% ± 23% (P = 0.023; 4 pairs) of controls. Panoramic images of explants and corneal buttons revealed that VIP treatment reduced CE damage to 75% ± 6% (P = 0.023; 4 pairs) and 71% ± 11% (P = 0.016; 9 pairs) of controls, respectively, whereas CE damage to 39% (2 pairs) and 23% ± 4% (P < 0.001; 7 pairs), respectively, was revealed in microscopic images. Twenty-one days after VIP treatment of previously preserved explants, CE cell retention was 206% ± 38% (P = 0.008; 14 pairs) of the control. CE cells from human donor corneas expressed VIP receptor VPAC1 (not VPAC2).

CE integrity during eye banking was enhanced by a brief treatment of the explant with the CE autocrine VIP.