Necessary prone position time for human corneal endothelial precursor transplantation in a rabbit endothelial deficiency model

Purpose: We previously performed human corneal endothelial precursor cell transplantation into the anterior chamber and maintenance of the prone position for 24 hours in a bullous keratopathy model. This time, we investigated the necessary postoperative time in the prone position for clinical application of precursor cell transplantation. Methods: The sphere- forming assay was used to obtain precursors from cultured human corneal endothelial cells. Chloromethylbenzamidodialkylcarbocyanine ( CM- DiI)- labeled precursor cells were injected into the anterior chamber of the eye in rabbits with corneal endothelial defects, and the prone position was maintained for 0, 1, 6, or 24 hours to allow attachment to Descemet's membrane. Rabbits maintained in the prone position for 24 hours without precursor cell transplantation were the controls. Each group was observed for 28 days after surgery, followed by histological examination and fluorescence microscopy. Results: The mean corneal thickness of the rabbits kept in the prone position for 1, 6, or 24 hours after precursor cell transplantation was significantly less than that of the rabbits without adoption of the prone position after transplantation or the untransplanted rabbits at 14 days ( p < 0.005), 21 days ( p < 0.0001), and 28 days ( p < 0.0001) after surgery. And there was no significant differences in corneal thickness between the two groups kept in the prone position for 6 hours and 24 hours throughout the observation DiI- positive human corneal endothelial- like hexagonal cells were detected on Descemet's membrane in the rabbits kept in the prone position for 1, 6, or 24 hours, but not in the control groups. Three of the six corneas in the 1- hour group showed focal edema and incomplete coverage of the endothelial defects. Conclusions: Our findings demonstrated that transplantation of human corneal endothelial precursors into the anterior chamber with adoption of the prone position for 6 hours treated bullous keratopathy in rabbits with similar efficacy to maintenance of the prone position for 24 hours after surgery.