Book excerpt: This book discusses why specific diseases are being targeted for cell-based retinal therapy, what evidence exists that justifies optimism for this approach, and what challenges must be managed in order to bring this technology from the laboratory into routine clinical practice. There are a number of unanswered questions (e.g., surgical approach to cell delivery, management of immune response, optimum cell type to transplant) that very likely are not going to be answered until human trials are undertaken, but there is a certain amount of “de-risking” that can be done with preclinical experimentation. This book is essential reading for scientists, clinicians, and advanced students in stem cell research, cell biology, and ophthalmology.