Compared with gene therapy, stem cell treatment is more widely used for all kinds of gene mutation types of RP. Therefore, the research and development costs are more affordable in China. Stem cell treatment is just like we cannot cure hypertension, but we can manage the blood pressure and prevent stroke and other cardiovascular accidents via effective medication.
Eyes are immune privilege organ, stem cells will not be rejected when it’s inside the eyes. We can track where the stem cell goes with our current technology. The mechanism of stem cell treatment includes :
1. Stem cell can replace the damaged cells.
2. Stem cell secretes nutritional factors.
3. Control immune response, stimulate regeneration of the optic nerve, promote the material exchange of the stem cell and the recipient cells.
Till 2021, the summary of the stem cell clinical trials for retinal diseases is as followed:
1, Retinal precursor stem cells derived from embryonic tissue to treat RP. The stem cell is implanted through subretinal injection. We’ve done 3 years of follow-up, the treatment is of high security, vision improvement remained one year for middle-stage RP patients. The defect is, it’s impossible for industrialization since it’s hard to get a big amount of eligible embryonic stem cells.
2, Intravenous infusion of umbilical cord mesenchymal stem cells for late-stage RP. These candidates’ vision function has been restored for one or two years. Need to be repeated.
3, Bone marrow stem cells for diabetic retinopathy.
4, Retinal pigment epithelial cells derived from embryonic stem cells for age-related macular degeneration.
5, Now we are using three-dimensional culture, cultivating embryonic stem cells into retinal organoid, that is, cultivating them into embryonic eyes, this way, the stem cells will not develop into tumour cells. We choose the best retinal progenitor cells from the embryonic eyes and inject them into the animal’s retina. We observe that it can differentiate into pigment epithelial cells and other neurons, which are good seed cells and can also charge other optic cells. The animal models’ vision is restored for more than half a year without any side effects. This kind of stem cell is quite easy for mass production and the cost is also lower than other stem cell products. It’s a promising stem cell treatment for the not distant future. We are now doing the second phase clinical trial and hope to promote it for the RP patients soon.