The vision of two patients suffering ‘wet’ age-related macular degeneration improved over the first year after receiving a transplanted ‘patch’ of retinal pigment epithelium grown from human embryonic stem cells, according to a study published online this week in Nature Biotechnology. A combination of cells and a synthetic scaffold, the patch is an engineered tissue derived from human embryonic stem cells. Transplantation of the patch did not cure the patients' macular degeneration, and its efficacy and safety for treating the disease will need to be determined in future, large-scale clinical trials.
The retinal pigment epithelium (RPE), a single layer of cells next to the light-sensing cells in the back of the retina, is essential to keeping the light-sensing cells healthy. In wet age-related macular degeneration, fluid leakage damages the RPE in the central retina, leading to the death of light-sensing cells and loss of central vision.
In previous research, RPE cells derived from human pluripotent stem cells were transplanted into the eyes of patients with macular degeneration as non-oriented cells in a liquid suspension or as an oriented layer on a matrix secreted by the cells themselves. In the new study, Lyndon da Cruz and colleagues grew RPE on a thin plastic scaffold that orients the cells and stabilizes the engineered tissue during and after the transplant.
The authors report survival of transplanted RPE cells in the two patients for one year and improvements in the patients’ visual acuity. Before surgery, for example, the patients could not read even with glasses, but could read afterwards with normal reading glasses, though slowly.
Further research is needed before this method could be considered for regulatory approval.