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We assess studies on vector systems for delivery of transgenes to the cornea that have been published over the last year, and summarise new work on the identification of specific transgenes for corneal diseases. Recent findings Adeno-associated viral vectors (AAV) are increasingly being successfully applied to the cornea, although transgene expression requires corneal epithelial debridement, or intrastromal injection of the vector. Gene delivery platforms based on nanoparticles of chitosan or gold also show promise. Over-expression of vasoinhibin-1 or decorin, or siRNA-mediated blockade of the cannabinoid receptor CB1, can all reduce corneal neovascularization. Over-expression of decorin or matrix metalloproteinase 14 can reduce corneal fibrosis and haze, while over-expression of c-Met accelerates epithelial wound healing. Induction of corneal endothelial cell replication by over-expression of E2F2, p16 or p21 can maintain or even increase corneal endothelial cell density in eye bank corneas. Over-expression of the anti-apoptotic transgenes Bcl-xL or p35 significantly enhances corneal endothelial cell survival and reduces apoptosis in stored human corneas. Summary Despite a wealth of information on methods for the delivery of nucleic acids to the human cornea, and ever-increasing information transgenes with substantial therapeutic potential, gene therapy for corneal disorders has yet to reach the clinic., KAW is supported by the National Health & Medical Research Council of Australia.

Background Modification of a donor cornea by gene therapy ex vivo has potential to modulate irreversible rejection, the major cause of corneal graft failure. Our aim was to transfer the gene encoding mammalian IL-10 to ovine donor corneas and to determine subsequent orthotopic corneal allograft survival in an outbred sheep model. Methods The replicative capacity of ovine corneal endothelium was determined by autoradiography after deliberate injury. A replication-defective adenovirus was used to deliver the lacZ reporter gene to ovine corneas and transfected corneas were organ-cultured in vitro to allow transfection efficiency, duration of reporter gene expression, and toxicity attributable to the vector to be determined. A cDNA encoding full-length ovine IL-10 was cloned into an adenoviral vector that was used to transfect donor corneas ex vivo before transplantation. Orthotopic penetrating corneal transplantation was performed in outbred sheep. Results Sheep corneal endothelium was found to be essentially amitotic. Transfection of > 70% corneal endothelial cells was achieved with the viral vector and expression was maintained for 28 days in vitro. IL-10 mRNA was detectable in transfected, organ-cultured corneas for 21 days in vitro. Donor corneas transfected with cDNA encoding IL-10 showed significantly prolonged survival after penetrating keratoplasty (median 55 days, range 19 > or =300 days) compared with control corneas (median 20.5 days, range 18-32 days, P=0.011). Conclusion Local gene therapy-mediated expression of the immunomodulatory cytokine IL-10 has the potential to reduce the incidence of corneal graft rejection and to prolong corneal allograft survival.

Purpose To evaluate the effect of the location of the corneoscleral tunnel incision as well as preoperative and intraoperative parameters on total and localized endothelial cell loss. Setting Department of Ophthalmology, Humboldt-University of Berlin, Berlin, Germany. Methods Fifty consecutive patients scheduled for routine cataract surgery were selected prospectively for this clinical trial. Preoperatively, the axial length, anterior chamber depth, lens thickness, and astigmatism were measured. Phacoemulsification time and relative energy as well as total surgical time were recorded. With a specular microscope, endothelial cell counts were determined centrally, superiorly, and temporally preoperatively and 6 weeks and 6 and 12 months postoperatively. Results After 12 months, the mean overall central endothelial cell loss in all eyes was 8.5%. The mean endothelial cell loss was 11.9% in the lateral quadrant and 11.4% in the superior quadrant. There were no significant differences between superior and temporal surgical approaches in intraoperative parameters of phacoemulsification time, relative intensity of phacoemulsification, and surgical time. There were no significant differences in central endothelial cell loss or in the area localized in the quadrant of the positions of the corneal surgical site. The only risk factors found significant for higher endothelial cell loss were shorter axial length and longer phacoemulsification time. Conclusions The location of corneoscleral incisions for phacoemulsification can be chosen according to the preoperative astigmatism without inducing additional adverse effects on the corneal endothelium. Shorter eyes have a significantly higher risk for greater endothelial cell loss.