Stem cells constitute cell populations with unlimited self-renewal and differentiation abilities, which can potentially generate any cell type. These properties have made them a promising treatment for degenerative eye disorders that lead to blindness. Currently, stem cell delivery is not an approved standard of care treatment for retinal diseases. Early human clinical trials have begun, mainly for stem cell derived retinal pigment epithelium (RPE), to assess preliminary efficacy and safety considerations (including the possibility of neoplastic cell growth and unrestricted proliferative changes). It is hoped that these and future neuro-retinal replacement strategies will progress to treatments in the coming years.
The steps required to achieve a stem cell-based treatment are:
Candidates include those characterized by progressive degeneration of the photoreceptor-RPE cell complex or retinal ganglion cells, for example:
1.Acquired retinal diseases
The use of autologous cells, in theory, should not pose a risk of a severe immunological response compared to an allogenic source. However, stem cells may trigger T-cell mediated immunogenicity that could subsequently destroy adjacent tissues and the graft itself. For this reason, appropriate local and/or systemic immunosuppression should be administered concomitantly irrespective of the source type.
Currently, sources available in retinal treatments include:
All of these should be ultimately induced to differentiate in the selected target cell to be delivered to the eye (neural retinal cells, photoreceptors or RPE cells).
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Westmead Eye Manual
This invaluable open-source textbook for eye care professionals summarises the steps ophthalmologists need to perform when examining a patient.