Significantly improved vision lasts for more than a year in 3 out of 4 people whose cornea does not regenerate
A new study showed that transplanting stem cells to four patients with impaired vision with damaged corneas significantly improved their vision, and that the effect lasted for more than a year in three of the four patients. This is what the scientific journal Nature reported on the 8th (local time) based on a paper by researchers at Osaka University in Japan published in the medical journal Lancet.
The outermost layer of the cornea is maintained in constant renewal by a reservoir of stem cells in the limbal ring, a dark ring around the iris. However, in a condition called limbal stem cell deficiency (LSCD), this vital source of rejuvenation is depleted, scar tissue covers the cornea, and can eventually lead to blindness. It can also occur due to trauma to the eye, autoimmune disease, or genetic disease.
Treatment for LSCD is limited. Typically, corneal cells derived from stem cells from healthy eyes are transplanted, but the results are uncertain. If both eyes are in poor condition, it is possible to receive a cornea transplant from a deceased donor, but the recipient’s immune system may reject it.
The research team led by Professor Koji Nishida (Ophthalmology) at Osaka University used induced pluripotent stem cells (iPS), an alternative cell source, for corneal transplantation. They took blood cells from healthy donors, manipulated them into an embryo-like state, and transformed them into thin, pebble-like, transparent corneal epithelial membranes.
From June 2019 to November 2020, the research team conducted a small clinical trial on two women and two men aged 39 to 72 years with LSCD in both eyes. A layer of scar tissue covering the damaged cornea of one eye was scraped off, then a sheet of donor-derived epithelium was sewn together and a soft protective contact lens was placed on top.
Two years after transplantation, none of the recipients experienced serious side effects. The grafts did not form tumors, a known risk of iPS cell growth, and showed no clear signs of being attacked by the recipient’s immune system, even in two patients who were not receiving immunosuppressants. “It is reassuring that the graft was not rejected, but more clinical trial results are needed to confirm the safety of the intervention,” said Kapil Bharti, a researcher at the National Eye Institute of the National Institutes of Health (NIH), who reviewed the paper.
After transplantation, all four recipients experienced an immediate improvement in vision and a reduction in the corneal area affected by LSCD. This improvement was sustained in all recipients except one, who showed a slight reversal over the 1-year observation period.
Researcher Bharti pointed out that it is not clear what exactly causes the vision improvement. It is possible that the transplanted cells themselves proliferated in the recipient’s cornea. However, improved vision can also occur by removing scar tissue before transplantation or by moving the recipient’s own cells from other parts of the eye through transplantation to rejuvenate the cornea.
Professor Nishida said he plans to start a larger clinical trial to evaluate the treatment’s effectiveness in March. “Several iPS cell-based clinical trials are underway worldwide to treat eye diseases,” said Bharti. “These success stories suggest we are moving in the right direction.”
Source: kormedi.com