Indian biologists have successfully adopted a technique to create retinal cells in the laboratory and are calling it a maiden step in their efforts to develop a cure for irreversible retinal disorders.
The scientists at an eye research centre in Hyderabad have borrowed a biological trick pioneered by a Japanese team seven years ago to generate retinal cells from stem cells produced from mouse embryos.
Indumathi Mariappan and her colleagues at the L V Prasad Eye Institute (LVPEI), Hyderabad, have also initiated efforts to use the technique to produce human retinal cells from skin cells of patients with retinal disorders.
Their work to develop retinal cells from mouse embryos will allow India to plunge, albeit a bit late, into an international race to develop human retinal cells that can be transplanted into patients with irreversible retinal disorders. Doctors are hoping such retinal cells when appropriately transplanted into the eyes will reverse the severe visual loss brought about by retinal degeneration caused by age or other factors.
"We're still in an early stage of research ' it could take three to five years for the technique to be refined for use in humans," Mariappan, a stem cell biologist at the LVPEI, told The Telegraph. Their work is described this month in the Journal of Bioscience, published by the Indian Academy of Sciences.
Mariappan's team used a two-step process first demonstrated by Shinya Yamanaka at Kyoto University in Japan in 2006. The scientists first took cells from mouse embryos and inserted four genes into them. The genes reprogrammed the embryonic cells, and turned them into "induced pluripotent stem cells" ' cells that have the potential to turn into virtually any cell type in the body.
In the second step, Mariappan said, the pluripotent stem cells are immersed into cocktails of nutrients, biochemicals and growth factors for several days to "gently nudge them to turn into retinal cells".
US-based researchers had announced last year that they had conducted the first human clinical study of retinal cells derived from human embryonic stem cells on two women with macular degeneration ' damage to a key retinal zone. The therapy appeared to be safe four months after the transplants, and both patients had some improvement in their vision, the scientists had said reporting their findings in the journal Lancet .
But the use of human embryonic stem cells remains controversial, given ethical concerns related to using embryos as raw material for treatment. The LVPEI initiative to produce retinal cells from the skin cells of adults is intended to provide an alternative to embryo-derived retinal cells."If we can get skin cells from patients themselves to turn into retinal cells, we won't need someone else's cells," said D. Balasubramanian, director of the LVPEI's research centre, who was not directly associated with Mariappan's study but guided her project, which was funded by India's department of biotechnology.
"But there are some challenges ahead," Balasubramanian told this newspaper. "We still need to determine where exactly and in what orientation should the retinal cells be transplanted into the retina. We need to understand this."
The LVPEI team plans to begin animal studies of retinal cells derived from adult human skin tissues later this year.
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