Endothelial–Stromal Communication in Murine and Human Corneas

The purpose of this study is to identify and characterize interactions of corneal endothelial cells with the posterior stroma. Corneal endothelial–stromal interactions were examined in developing postnatal day 3 (P3) and mature postnatal day 30 (P30) C57BL/6 mice and adult human corneas. Flat mounts and cross‐sections were studied using immunofluorescence microscopy. F‐actin was labeled with phalloidin to evaluate cell processes traversing Descemet's membrane (DM). Dynamic cell–cell communication was evaluated with fluorescence recovery after photobleaching (FRAP) using calcein acetoxymethyl dye. Endothelial–stromal interactions were observed across the whole cornea transversing DM during early postnatal development (P3), while these interactions became restricted to the periphery in the mature murine cornea (P30). In adult human corneas, endothelial extensions through the DM were observed in the peripheral cornea. The pattern of FRAP in both mature mice and human central corneas demonstrated endothelial–endothelial cell communication. In contrast, in the human cornea 2, distinct patterns were observed consistent with endothelial–endothelial and stromal–endothelial communication. Endothelial–stromal interactions were observed in the entire cornea during early postnatal mouse corneas. This evidence of endothelial–posterior stromal contact contradicts the hypothesis that corneal endothelial cells are isolated from the stroma by the DM and provides direct data to support endothelial–stromal comunication that may directly influence posterior corneal structure and function. Anat Rec, 2020. © 2020 American Association for Anatomy