Major Points and Findings:
- Objective: The review aimed to provide an update on the potential of cell therapies to restore or replace damaged and/or lost cells in retinal degenerative and optic nerve diseases. It described the available cell sources and the challenges involved when these techniques are applied in real clinical practice.
- Cell Sources: The cell sources for these therapies include:
- Human fetal retinal stem cells
- Allogenic cadaveric human cells
- Adult hippocampal neural stem cells
- Human CNS stem cells
- Ciliary pigmented epithelial cells
- Limbal stem cells
- Retinal progenitor cells (RPCs)
- Human pluripotent stem cells (PSCs) which include both human embryonic stem cells (ESCs) and human induced pluripotent stem cells (iPSCs)
- Mesenchymal stem cells (MSCs)
- Clinical Trials: RPCs, PSCs, and MSCs have entered early-stage clinical trials. They can differentiate into RPE, photoreceptors, or ganglion cells. These cells have demonstrated safety and have shown some indicators of efficacy.
- Challenges:
- Inhibition of proliferation and/or differentiation in vitro (except for RPE).
- Limited long-term survival and functioning of grafts in vivo.
- Issues related to cell delivery, which might require a scaffold to induce correct cell polarization, increasing the size of the retinotomy in surgery and the chance of severe complications.
- The need to induce a localized retinal detachment to perform the subretinal placement of the transplanted cell.
- Evaluation of the risk of tumor formation caused by undifferentiated stem cells and prolific progenitor cells.
- Conclusion: Despite the challenges, stem/progenitor cells represent the most promising strategy for treating retinal and optic nerve diseases in the near future. Therapeutics assisted by gene techniques, neuroprotective compounds, and artificial devices can be applied to meet clinical needs.