In a groundbreaking procedure, transplanting human stem cell-derived retinal sheets into the eyes of non-human primates (Japanese Macaque) was found to successfully repair macular holes. Although there was mild rejection at the three-month mark after transplantation, it was effectively mitigated using local steroid injections at the three and six-month mark, according to the paper published in Stem Cell Reports.
Transplanting embryonic stem cell-derived retinal organoid sheets
“We confirmed for the first time in a non-human primate model that embryonic stem-derived retinal organoid sheet transplantation facilitates the closure of macular holes,” says senior study author Michiko Mandai of the Kobe City Eye Hospital in a media release. “Our results suggest that this method could become a practical, safe, and effective treatment option with minimal invasive risks, particularly for difficult macular hole cases.”
“The mild rejection may have limited the functional integration of the transplanted tissue,” Mandai says. “Additionally, this was a single-case result for one eye, and the model did not exactly replicate the pathology of human refractory macular holes. However, the findings suggest that the surgical technique is feasible for human macular holes.”
Macular holes occur when the central part of the retina develops a break or tear, most of the time this can be treated with surgery, but some patients experience recurring holes or those that are resistant to standard treatment. For this reason, researchers have been exploring other innovative approaches, including stem cell therapy.
Closing macular holes
This study used human embryonic stem cells to create lab-grown retinal tissue that was transplanted into a macular hole in the eye of a monkey. The transplanted tissue successfully filled the hole and showed signs of developing into functional retinal tissue.
Improving visual function
Progress was observed for seven months after the transplant to reveal that the stem cell-derived tissue filled the hole and began to develop into various types of retinal cells including light-sensitive photoreceptors that are crucial for vision. Through a series of tests, the monkey displayed signs of improved visual function, such as the ability to focus and fixate on targets significantly improving, and electrical recording showed increased retinal activity.
Promising results
This promising approach using lab-grown retinal tissue is particularly appealing because of the potential to overcome the limitations of current treatments that require using the patient’s own retinal tissue from other parts of the eye. This method could lead to treatment that could preserve more peripheral vision.
However promising and encouraging the findings from this study are, this is just a single study, additional research is required before eventually moving on to human trials. Additionally, we must keep in mind that animal research doesn’t always translate well to humans. Nevertheless, this study does offer promising results that warrant further research and open up new avenues for vision loss with possibilities for treating macular holes and potentially other retinal disorders via stem cell therapy.
Moving forward
Moving forward the researchers plan to examine whether some form of synaptic communication can be established between the host and graft over a longer period of observation, as well as investigate any protective effects for host retinal cells and how cell composition in the graft influences visual function.
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References/Sources/Materials provided by:
https://www.cell.com/stem-cell-reports/fulltext/S2213-6711(24)00264-9
