Test tube eyes pave way for artificial human eyes
22 April 2002
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A frog with the transplanted artificial eye on the left. |
The successful culture of new tadpole eyes in the laboratory by a Japanese embryologist may have brought us one step closer to growing human organs in culture.
Professor Makoto Asashima of Tokyo University in Japan has used stem cell-like cells from a frog embryo to grow complete eyes which were then successfully transplanted into tadpoles. His culture of the artificial eyes is a world first.
This success is the culmination of 20 years of work for Professor Asashima, who believes that his groundbreaking research could pave the way for the same procedure to be used to restore vision in humans.
The eyes took 3 days to culture in the laboratory before they were implanted into tadpoles which had had an eye removed. One week after transplantation, nerves from the transplanted eye had grown out and into the tadpole’s brain, thus setting up the nerve pathways for the sensory signals between the eye and the brain.
Three weeks after transplantation, the new eyes were observed to react to light and other stimuli. The reaction of the eyes is measured objectively by using electrodes on the brain to measure the response of the eyes to visual stimuli.
So far, Professor Asashima and his team have transplanted new eyes into about 60 tadpoles, of which nearly three-quarters could then see. And 7 of the transplanted eyes have survived the metamorphosis from tadpole to frog.
The stem cell-like cells that are used to generate the eyes in culture are stimulated by a protein called activin. During the course of his research on organ regeneration, Professor Asashima discovered that activin promoted cell differentiation. He found that varying the level of activin initiated different genetic instructions in cells.
So far, the Professor has successfully grown 14 different frog organs and tissues, including kidneys and a heart. He will now try to repeat his artificial eye transplantation in mice, which provide a model closer to the human situation than the tadpoles.
Professor Asashima supports the use of human embryos for stem cell research, with the proviso that there are appropriate controls.
‘It’s very important because it’s necessary to assist further research for organ and tissue defects or functional diseases,’ he said.
The potential of Professor Asashima’s work is tremendous, according to Dr Frank Martin, Head of Ophthalmology at New Children’s Hospital, Westmead, Sydney, and Chair of the XXIXth International Congress of Ophthalmology which is being held in Sydney this week. It may eventually become possible to give sight back to people who have lost their sight to trauma or tumours, or to people born without eyes, a condition known as congenital anophthalmos, which affects 2-3 babies each year in Australia.
Professor Asashima is presenting his work at the XXIXth International Congress of Ophthalmology in Sydney this week.
Last Reviewed: 22 April 2002
- 1. XXIXth International Congress of Ophthalmology, Sydney, Australia. April 2002.
