Trophic effect of PACAP on human corneal endothelium

Cornea's posterior surface includes endothelium maintaining stromal hydration and clarity. Due to their limited proliferative capability, the loss of endothelial cells can outcome in permanent opacity. In the last years, different studies have demonstrated the protective effect of pituitary adenylate cyclase-activating polypeptide (PACAP) in different ocular diseases. However, its role on human corneal endothelial cells (HCECs) has not been investigated, yet. Here, we have developed a culture protocol to differentiate HCECs from donor's cornea. PACAP treatment prevented damage induced by growth factors deprivation of cells grown on transwell supports as revealed by TERR measurements. Moreover, this peptide significantly increased tight junction proteins expression by conferring resistance to endothelial barrier. This effect is also related to promotion of cell viability as demonstrated by MTT assay. Furthermore, PACAP stimulated repairing of corneal endothelium lesion as shown by wound healing analysis. In conclusion, our data suggest that this peptide could represent an important trophic factor in maintaining functionality of human corneal endothelium.