Treatment of Central Retinal Vein Occlusion Using Stem Cells Study

The goal of this phase I/II prospective, randomized, sham-controlled, double-masked clinical trial is to determine whether intravitreal autologous CD34+ stem cell therapy is safe, feasible and potentially beneficial in eyes with vision loss from central retinal vein occlusion (CRVO). Retinal Vein Occlusion (RVO) is a leading retinal vascular cause of vision loss in the elderly. CD34+ stem cells in human bone marrow are mobilized into the circulation in response to tissue ischemia for tissue revascularization and repair. Since local delivery of CD34+ stem cells benefits ischemic tissue, intravitreal delivery of CD34+ stem cells may benefit vision and retinal ischemia in eyes with RVO. A pilot clinical trial has shown no major safety or feasibility concerns using intravitreal autologous CD34+ bone marrow stem cells. In this proposed expanded phase I/II study, 20 participants (20 eyes) with persistent vision loss from CRVO will be enrolled and followed for 1 year. Participants will be randomized 1:1 to immediate cell therapy/deferred sham therapy or immediate sham therapy/deferred cell therapy. At month 6, the cell treated eye will receive sham treatment and the sham treated eye will get cell therapy. The cellular therapy involves bone marrow aspiration, isolation of CD34+ cells from the aspirate under Good Manufacturing Practice (GMP) conditions, and intravitreal injection of isolated CD34+ cells. The sham therapy involves a sham bone marrow aspiration with penetration of the skin but no penetration of the bone and a sham intravitreal injection without penetrating the eye. The participant, examining ophthalmologist, visual acuity examiner, photographers and OCT, perimetry, and electroretinography (ERG) technicians will remain masked to study treatment assignment for study duration. A comprehensive eye examination with ETDRS best-corrected visual acuity, optical coherence tomography (OCT) and OCT angiography (OCTA), autofluorescence, fundus photography, fluorescein angiography, microperimetry, and electroretinography will be performed at baseline and serially. A subset of participants with good fixation on microperimetry and clear media on exam and commercial-grade OCTA and who give consent will have ultra-high resolution cellular retinal imaging using research-grade OCT and OCTA and adaptive optics-OCT at baseline. Participants with high quality images will have repeat imaging at 1 month after stem cell treatment, with at least 2 of the participants randomized to the deferred cellular therapy arm also having imaging 1 month after sham therapy. Post-release flow cytometry characterization will be performed to determine the composition of the CD34+ enriched final product in terms of hematopoietic versus angiogenic stem cells based on cell surface markers (i.e., CD133(+)/CD45(+)/CD34(+) vs CD31(+)/VEGFR-2(+)/CD45(-)/CD34(+)). The long-term objective is to determine whether intravitreal autologous CD34+ cell therapy can minimize, or reverse vision loss associated with retinal ischemia without compromising safety.