[A novel system for minimally invasive transplantation of bone marrow derived stem cells as a thin layer in the subretina and extravascular spaces of the choroid--for treatment of retinal degeneration].

Abstract Incurable retinal degenerations affect millions worldwide. Stem cell transplantation rescued visual functions in animal models of retinal degeneration. In those studies, cells were transplanted in subretinal "blebs". A limited number of cells could be injected and photoreceptor rescue was restricted to areas in proximity to the injection sites. To develop a minimally-invasive surgical system for stem cell transplantation in the subretina and extravascular spaces of the choroid. A novel syringe with flexible needle and adjustable pin was developed. Human bone marrow mesenchymal stem cells [hBM-MSCs) were transplanted in the eyes of RCS rats and NZW rabbits through a longitudinal triangular scleral incision. No immunosuppressants were used. Retinal function was determined by electroretinogram analysis and retinal structure was determined by histological analysis and optical coherence tomography (OCT). Transplanted cells were identified as a thin layer across the subretina and extravascular spaces of the choroid. In RCS rats, cell transplantation delayed photoreceptor degeneration across the entire retina and significantly enhanced retinal functions. No changes in retinal functions were recorded in rabbits following transplantation. No retinal detachment or choroidal hemorrhages were observed. The novel syringe facilitates cell transplantation across the subretina and extravascular spaces of the choroid using a minimally-invasive procedure. Human BM-MSC transplantation using this system ameliorates retinal degeneration in the animal model. This new transplantation system may increase the therapeutic effect of other cell-based therapies and therapeutic agents. This study is expected to lead directly to phase I clinical trials for autologous hBM-MSCs transplantation in patients with retinal degeneration.