New and previously unpublished clinical data were presented today at ISSCR 2026 showing that transplanted human neural progenitor cells survive for at least 1 year and maintain a favorable safety profile after subretinal transplantation in patients with retinitis pigmentosa (RP).
Retinitis pigmentosa is a group of inherited retinal diseases that cause progressive vision loss, and there is currently no treatment for most patients. Developing mutation-specific gene therapies remains challenging because thousands of different genetic mutations can cause the disease. Cell-based therapies offer the potential for gene-independent approaches that may benefit a broader patient population.
A Phase 1/2a clinical study funded by the California Institute for Regenerative Medicine (CIRM) evaluated the safety and feasibility of a single subretinal injection of CNS10-NPC, a human neural progenitor cell product derived from fetal brain cortex, in 13 patients with retinitis pigmentosa. Participants received either 300,000 or 1,000,000 cells and were followed for 12 months before being enrolled in a long-term follow-up protocol.
Visual acuity remained stable throughout the study, and optical coherence tomography (OCT) imaging demonstrated that the transplanted cells continued to reside in the subretinal space for at least 1 year. Cell-related adverse events included 3 epiretinal membranes and 1 persistent subretinal bleb. Overall, the researchers concluded that the treatment was well tolerated and resulted in long-term cell engraftment.
This study is the first to demonstrate long-term survival of fetal-derived neural progenitor cells in patients with retinitis pigmentosa, while maintaining a favorable safety profile. Long-term engraftment is an important milestone for the development of stem cell-based therapies for retinal diseases and provides an important foundation for future research. ”
Dr. Clive Svendsen, Cedars-Sinai Regenerative Medicine Institute Board of Directors, Project Sponsor
Unlike gene therapy, which targets individual mutations, neural progenitor cell transplantation is designed as a mutation-independent strategy. Preclinical studies showed that CNS10-NPC preserves photoreceptors and vision in animal models through reduced inflammation and release of potent growth factors, supporting its evaluation in patients.
Although retinitis pigmentosa progresses slowly and no changes in vision were expected during the first year of the study, researchers are continuing to follow participants to determine whether long-term survival of the transplanted cells will help maintain vision in treated eyes over time.
“Our goal is to help patients preserve their vision for as long as possible,” said Dr. Liao, the project’s clinical lead. “The next key question is whether these surviving cells can slow the continued deterioration that occurs in retinitis pigmentosa.”
During his presentation, Svendsen also presented data on neural progenitor cell products derived from induced pluripotent stem cells (iPSCs). iPSC-based approaches have the potential to offer more scalable therapies that can treat substantially more patients in the future while avoiding ethical concerns associated with fetal tissue sources.
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International Stem Cell Research Association
