Stem Cell Therapies for Reversing Vision Loss

Current clinical trials that evaluate human pluripotent stem cell (hPSC)-based therapies predominantly target treating macular degeneration of the eyes because the eye is an isolated tissue that is naturally weakly immunogenic. Here, we discuss current bioengineering approaches and biomaterial usage in combination with stem cell therapy for macular degeneration disease treatment. Retinal pigment epithelium (RPE) differentiated from hPSCs is typically used in most clinical trials for treating patients, whereas bone marrow mononuclear cells (BMNCs) or mesenchymal stem cells (MSCs) are intravitreally transplanted, undifferentiated, into patient eyes. We also discuss reported negative effects of stem cell therapy, such as patients becoming blind following transplantation of adipose-derived stem cells, which are increasingly used by ‘stem-cell clinics’. Current clinical trials using hPSC-based therapy predominantly target treatment of macular degeneration of the eyes. Transplants of autologous human induced PSC (iPSC)-derived RPE cell sheets are currently safe and feasible for treating patients with age-related macular degeneration. Cells differentiated into progenitors or mature differentiated cells from hPSCs are transplanted into patients’ eyes, whereas adult and fetal stem cells are directly transplanted into the patients’ eyes without differentiation. An hPSC-derived RPE patch with a supporting polymeric layer appears to be more valuable than injecting a single hPSC-derived RPE cell suspension, which is currently performed in most clinical trials. Biocompatible polymeric membranes that support hPSC-derived RPE should have appropriate pore size and thickness to act as an artificial Bruch's membrane that allows the free transport of water and small molecules.