Stem cells for Stargardt’s

Early trials show promise and improved visual acuity

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Rodrigo Brant MD, PhD
Injecting stem cell-derived retinal pigment epithelium (hESC-RPE) in Stargardt’s disease has been shown to be both safe and feasible in initial phase I/II trials of the technique, according to Rodrigo Brant MD, PhD. “The surgical procedure for subretinal implantation of hESC-RPE proved feasible and safe, without cell migration, signs of rejection or inflammation or development of ocular or systemic tumours. All patients improved their visual acuity over baseline and the gains have been maintained for up to four years in some patients. We have now treated 12 patients with this approach and the results are very promising,” he said at the World Ophthalmology Congress 2020 Virtual. Autosomal recessive Stargardt’s macular dystrophy is the most common form of inherited macular degeneration, affecting roughly in 1-in-10,000 people. There is currently no cure for the condition, in which patients develop irreversible vision loss due to atrophy of the macular RPE and loss of photoreceptors. Dr Brant’s initial study at the Federal University of Sao Paulo, Brazil, included six patients with Stargardt’s disease who received a hESC-RPE solution (2 million cells/0.1ml) implanted into the subretinal space. All patients received oral prednisolone and cyclosporine for the first three months postoperatively. Surgery to inject the cells was uneventful, said Dr Brant. “We performed a routine pars plana vitrectomy followed by the creation of a subretinal bleb with balanced salt solution. After creating the bleb, we then inject the suspended cell solution through another incision in the subretinal space. After that, we perform air-fluid exchange and the surgery is complete,” he said. In terms of results, the best-corrected visual acuity (BCVA), visual fields and electrophysiological tests showed improvement in all six patients. No adverse effects or complications related to the surgery occurred during the one-year follow up, said Dr Brant. Discussing the mechanism of action of the treatment, Dr Brant said that the gains seem to be coming from the zones adjacent to the area of central atrophy where some photoreceptor function is still present. “We never saw any improvement in any of the patients in the central area of atrophy where the RPE is entirely gone. However, in areas where the photoreceptors are suffering, the injection of cells perhaps improves that environment sufficiently for them to return to their previous function and they start to give some light perception. “There is therefore maybe a rationale to employ this type of treatment earlier in the disease course to avoid progressing to advanced degeneration,” he concluded. Rodrigo Brant: rodrigo.brant@ophthal.com.br