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U.S. Scientists Regrow Corneas From Stem Cells

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In a groundbreaking laboratory trial, researchers at the Massachusetts Eye and Ear Research Institute in the U.S. have successfully regrown corneal tissues using adult stem cells. The team behind the study believe that this breakthrough could potentially help people battling eye diseases, and those who have suffered burns or chemical attacks/accidents.

The major breakthrough involved growing adult stem cells for the very first time, and the scientists heading up the study are hoping that their research could be used to help develop a cure for blindness.

The team at the Massachusetts Eye and Ear Research Institute identified a molecule known as ABCB5, which is a kind of indicator for the typically difficult to locate limbal stem cells. Limbal stem cells are found in the eye’s basal limbal epithelium, or limbus. It is these limbal stem cells that are essential to maintaining and regenerating the tissue in the cornea. Losing the limbal cells, due to an injury or disease, is the biggest causes of sight impairment and blindness.

Historically, any treatment concerning cornea regeneration has been down the tissue or transplant route, but it has been proven difficult to establish whether any limbal stem cells were present in the grafts. As such, results were inconclusive.

The team at Massachusetts used antibodies to detect any ABCB5 molecules in tissue from dead human donors. They then used them to regrow anatomically correct, fully functional human corneas in mice. The study has been published in the medical journal Nature, with the study’s co-lead author Doctor Bruce Ksander, stating: “Limbal stem cells are very rare, and successful transplants are dependent on these rare cells. This finding will now make it much easier to restore the corneal surface. It’s a very good example of basic research moving quickly to a translational application.”

Lead researchers, Dr. Markus Frank of Boston Children’s Hospital, told Fox News: “[The corneal tissue] – this is a tissue that has inherent turnover capacity; the cells are being shed and being replaced continuously. This capacity to restore is produced by the limbal stem cell population, and while it’s known that such cells exist, the identity and their exact molecular markers…have not been known.”

The Boston lab crucially found the elusive ABCB5 molecule some 10 years ago, discovering it in skin and intestine precursor cells. It was only more recently that the team realised that it was an important factor in the eye’s limbal stem cells. The team carried out tests to prove their suspicions, which involved two sets of mice; one set which lacked a fully functioning ABCB5 gene and ones with a fully functioning ABCB5 gene.

The mice with no ABCB5 lost their limbal stem cells and could not repair injuries to their corneas. Dr Frank said: “When we found this…we thought if we could enrich or isolate these ABCB5-positive cells and transplant them, they should be able to cure corneal disease. We showed that this capacity to regrow tissue was only located within the ABCB5-posivite graft,” He added: “When we grafted in the same setup the ABCB5-negative cells, these cells were unable to do that.”

The team feel that they are now ready to move onto human patients, as Dr Frank says: “For the first step, we’re really working towards an autologous graft in patients who are blind in one eye. And then the second step, we’d really work towards using donor derived cells to transplant in a similar manner that may require immune suppression – but it may not.”

And experts around the world are impressed, Harminder Dua, a professor of ophthalmology at the University of Nottingham, who was not involved in this study, said: “This paper represents a very comprehensive and well conducted piece of work that takes use closer to the precise identification of stem cells. Applying this knowledge to a clinical setting could help improve the outcomes for patients who need corneal reconstruction.”

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