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  • Subretinal stem cell implant does not improve visual acuity

    Retina/Vitreous

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    Stem cells have been heralded by the popular press as a breakthrough therapy for a number of diseases, including some eye conditions, but these claims are not always backed up by the scientific literature. This study assessed the safety and feasibility of delivering retinal pigment epithelial (RPE) cells derived from a human embryo into the subretinal space of patients with macular degeneration.

    Study design

    This phase 1/2 open-label dose-escalation trial included 12 patients with advanced Stargardt’s disease. These patients received subretinal transplantation of 200,000 embryo-derived RPE cells along with concomitant systemic immunosuppression for 13 weeks. The study assessed the safety and tolerability of human embryonic stem cell (hESC)-derived RPE cell administration. The researchers also tracked survival of the transplanted cells and measured retinal structure and function using microperimetry and spectral-domain OCT.

    Outcomes

    Subretinal hyperpigmentation was identified in all participants, and persisted even after cessation of systemic immunosuppression. The authors found no significant proliferation of cells or inflammation. There was no benefit when measured by microperimetry and little to no change in visual acuity. There was also no significant improvement in the vision-related quality of life (NEI-VFQ).

    Limitations

    This short-term trial found no change in visual acuity. It’s possible that visual acuity improvement is not a realistic goal in patients who already have significant vision loss, or vision restoration may not appear after only 13 weeks.

    Clinical significance

    The potential to transplant a specific cell layer for retinal diseases is appealing. It’s reassuring that there were no significant safety signals from this technology. There has been concern of teratoma formation after transplantation of some embryonic cells, but this was not seen in this study population.

    Further work is needed to determine if these treatments improve visual acuity over an extended period of time, or if intervening at different points in the disease process produces different, and possibly better, outcomes.