Researchers in the United States have discovered that specialised stem cells – that can be readily isolated from the patient’s own bone marrow – can be safely administered into retinitis pigmentosa (RP) patients’ eyes.
“It was a small study, and we wanted to show we could effectively isolate the CD34+ cells from bone marrow, inject them safely, and perhaps see some visual benefits,” said Professor Susanna Park, from the UC Davis Health’s Department of Ophthalmology and Vision Science.1 “We found the treatment is safe, and four of the seven patients showed measurable improvements in vision.”
RP is caused by as many as 100 different genetic mutations. As retinal cells die off, people lose peripheral vision and the ability to see in low light, ultimately progressing to complete blindness.
Because RP genetics are so complex, correcting the root cause is challenging. One existing gene therapy for RP is only effective in the 1% of RP patients who have that specific mutation. Other gene therapies are in development, however, each one could help only a small group of patients with RP.
We showed some preservation of retinal function using these stem cells in one of our animal models of RP
Rather than trying to correct the underlying genetic anomaly, the UC Davis team began investigating whether stem cells could regenerate retinal tissue and vision.
CD34+ stem cells are particularly promising because they home in on damaged tissues to repair them.
“We believe the CD34+ cells find the degenerating retina, grab onto it and could generate molecular changes to reduce the degeneration,” Prof Park said.
“We showed some preservation of retinal function using these stem cells in one of our animal models of RP.”
Researchers recruited seven people with RP, who had lost most of their peripheral vision. Study participants received a single stem cell injection in one of their affected eyes.
The study – published in Ophthalmology Science2 – showed that, overall, the therapy was well tolerated.
“The most important result is that we were able to isolate the CD34+ cells of high quality for eye injection,” Prof Park explained. “Around 90% of the isolated cells were viable, and there were no infections or other serious adverse effects after cell injection in the eye.”
While this Phase 1 study focussed mainly on safety, most participants felt their vision had improved, and objective eye tests confirmed this.
The UC Davis team plans to pursue a larger safety and efficacy trial in the future.
References
- UC Davis Health News, Early-stage trial finds stem cell therapy for retinitis pigmentosa is safe, available at: health.ucdavis.edu/news/headlines/early-stage-trial-finds-stem-cell-therapy-for-retinitis-pigmentosa-is-safe/2024/11 [accessed Nov 2024].
- Park SS, Bauer G, Nolta JA, et al. Phase I study of intravitreal injection of autologous CD34+ stem cells from bone marrow in eyes with vision loss from retinitis pigmentosa. Ophthalmol Sci. 2024 Jul 31;5(1):100589. doi: 10.1016/j.xops.2024.100589.
