Figure 4.

Cell therapies for retinal degenerations. Allogeneic stem cell-based cell replacement strategies rely on induced pluripotent stem cells (iPSCs) or embryonic stem cells (ESCs) which can be differentiated into photoreceptor or RPE cell suspensions, sheets, or retinal organoids for transplantation. The donor cells or tissue replace lost photoreceptors and RPE in late stage IRDs. Subretinal injection of cell suspensions allows direct contact between donor cells and the surviving neuronal cells in the retina but can result in disorganised engraftment. Subretinal implantation of structured retinal sheet helps to retain anatomical organisation, which may facilitate appropriate cellular differentiation but is surgically challenging.