Prolongation of sheep corneal allograft survival by ex vivo transfer of the gene encoding interleukin-10

Background Modification of a donor cornea by gene therapy ex vivo has poten tial to modulate irreversible rejection, the major cause of corneal graft f ailure. Our aim was to transfer the gene encoding mammalian IL-10 to ovine donor corneas and to determine subsequent, orthotopic corneal allograft sur vival in an outbred sheep model. Methods. The replicative capacity of ovine corneal endothelium was determin ed by autoradiography after deliberate injury. A replication defective aden ovirus was used to deliver the lacZ reporter gene to ovine corneas and tran sfected corneas were organ-cultured in vitro to allow transfection efficien cy, 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, Tr ansfection of > 70% corneal endothelial cells was achieved with the viral v ector and expression was maintained for 28 days in vitro. IL-10 mRNA was de tectable in transfected, organ-cultured corneas for 21 days in vitro. Donor corneas transfected with cDNA encoding IL-10 showed significantly prolonge d survival after penetrating keratoplasty (median 55 days, range 19 greater than or equal to 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 r ejection and to prolong corneal allograft survival.