ENDOTHELIAL DYSFUNCTION

The development of cultured endothelial cell therapy for eyes with bullous keratopathy is a work-in-progress for Shigeru Kinoshita MD, PhD, and colleagues. Speaking at the 6th EuCornea Congress in Barcelona, Spain, Dr Kinoshita gave a brief history of the project that began in 2003 and entered a clinical research phase in 2013. So far, there are promising results in a limited number of eyes injected with cultured human corneal endothelial cells (cHCECs). More work needs to be done, however, before this “advanced cell therapy” can move into a larger clinical trial. The ultimate goal of corneal transplantation for endothelial dysfunction is to obtain a cornea with a high endothelial cell density and long-lasting, good physiological function, said Dr Kinoshita, Professor and Chairman of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan. “Endothelial transplantation with cHCECs has several possible advantages compared with grafting tissue from donor eyes. Using a single young donor cornea, we could obtain master cells with good longevity and physiological function and conceptually treat many patients, perhaps more than 100 or 1000, in a procedure that is minimally invasive,” he said. The work began in a monkey model with cultivation and transfer of a corneal endothelial cell sheet. Achieving only partial success, that approach was abandoned in favour of a technique based on injecting a suspension of cultured cells, and corneal endothelial recovery was achieved in rabbit and monkey models. Culturing of HCECs suitable for transplantation in human eyes proved more difficult, but Dr Kinoshita and colleagues developed a successful protocol that incorporates a rho-kinase inhibitor, mesenchymal stem cell-derived conditioned medium, and TGF-beta signalling inhibition. Having found that the cHCECs represent heterogenous subpopulations, they have also characterised markers to identify the well-differentiated cells that are desired for injection. Dr Kinoshita presented a case of a 58-year-old patient injected with cHCECs for treatment of Fuchs’ corneal dystrophy. After five months, the patient’s central corneal thickness had decreased from 725 microns to 543 microns and best corrected visual acuity improved from 0.06 to 1.0. In preparation for a larger clinical trial, ongoing work is focusing on quality-control issues to assure the cultivated product is safe and stable. With safety in mind, another recent study investigated whether injected cells exiting the eye into the peripheral circulation might accumulate or proliferate ectopically. Assessments of tissue from numerous organ systems in monkeys undergoing anterior chamber cHCEC injection showed no abnormalities by histological evaluation or evidence of human DNA using polymerase chain reaction assays. Shigeru Kinoshita: shigeruk@koto.kpu-m.ac.jp