Clinical effect of bioengineered cornea and in vivo confocal microscopy observation after human lamellar keraplasty

Background Xenotransplantation is arousing more attention of researchers because of the lack of corneal donors. Biological corneal scaffolds constructed by porcine corneal acellular stroma appears to have an acceptable biocompatibility. However, its clinical effects and the histomorphological features in the corneal tissue of receipts' are still unclear. Objective This study was to evaluate the viability of bioengineered corneas as a new material of human lamellar keratoplasty and observe the in vivo biological features after human keratoplasty under the laser confocal microscope. Methods A prospective serial cases observational study was carried out. Fifteen eyes of 15 patients with infectious keratitis were enrolled in Henan Eye Hospital from February to August 2014 under the approval of Ethic Committee of Henan Eye Hospital and informed consent of each patient, including 4 eyes of fungal keratitis, 1 eye of bacterial keratitis, 9 eyes of mixed infectious keratitis and 1 eye of leucoma. Corneal lamellar transplantation was performed on the eyes with the bioengineered corneas as grafts and the follow-up time was one year. The survival of grafts was assessed and scored, and the indices including corneal transparency, neovascularization, graft lysis or inflammatory recurrence and visual acuity (logMAR) were evaluated. The morphology and density of corneal epithelial cells and endothelial cells, corneal stroma and subepithelial neural fibers were examined by laser confocal microscope 3, 6, 9 and 12 months after surgery. Results Postoperative inflammatory response was seen 3 days and disappeared 7 days after surgery. The grafts were clear 1 month after surgery, and no corneal dissolution was found during the follow-up duration. Glaucoma occurred in 1 eye at 6 months and graft rejection occurred in another eye 12 months after surgery. The logMAR, corneal transparency scores and corneal neovascularization scores improved after surgery in comparison with before surgery, with a significant difference among various time points (χ2=92.63, 59.37, 10.50, all at P<0.05). Complete epithelization of grafts was seen. Compared with the contralateral eyes, the morphology of epithelial cells was similar and endothelial cells were enlarged in the operated eyes. In addition, no stromal cell structure was seen in the corneal stroma in the operative eyes. Subepithelial nerve fibers appeared in 8 eyes at 6 months, but the fiber density was lower in the operated eyes than that in the contralateral eyes. Significant difference was found in epithelial cell density among different time points (F=1.48, P=0.22). The endothelial cell densities were (2 542±119), (1 895±129), (1 869±135), (1 854±101) and (1 844±103)/mm2 before surgery and 3, 6, 9 and 12 months after surgery, showing significant differences between preoperation and postoperative time points (all at P<0.05). The subepithelial nerve fibers densities were (1.26±0.13), (3.62±0.81) and (5.98±0.44) mm/mm2 at 6, 9 and 12 months after surgery, with significant differences between adjacent two time points (t'=-8.16, -7.24; both at P=0.00). Conclusions Bioengineered corneal grafts survive well in human eye after lamellar transplantation, which can reconstruct ocular surface and improve the visual acuity. Biological cornea can replace human corneal materials. Key words: [Key words] Corneal transplantation; Transplantation, heterologous; Graft survival/immunology; Microscopy, confocal; Humans; Bioengineered corneas; Porcine corneal acellular stroma