Rebuilding a Human Cornea

by bluevase

Imagine for a moment that doctors had the capability to recreate human corneas within the confines of a laboratory. It may seem impossible, but a team of researchers has managed to accomplish this very feat. Their groundbreaking experiment may prove very helpful to those suffering from diminished eyesight.

Corneal Tissue and Vision Loss

Some very recognizable names were attached to this research; appearing online in the journal Nature, the study featured contributors from Boston Children’s Hospital, Brigham and Women’s Hospital, the Massachusetts Eye and Ear/Schepens Eye Research Institute and the VA Boston Healthcare System. In order to develop new corneas, the researchers relied on tissue samples from deceased human donors.

The key to these efforts was identifying limbal stem cells, which the human eye uses to perform regular maintenance on its cornea. Without them, the cornea would be unable to heal damage caused by exposure to external elements and constant blinking. When a large number of limbal stem cells are lost due to disease or injury, the eye can no longer effectively repair and replenish its corneal tissues. Consequentially, the eye’s vision steadily deteriorates. A significant number of people experience this problem, to the point that one of most common reasons for blindness is the loss of tissue in the cornea.

Hunting for Stem Cells

The idea of using stem cells to reconstruct the cornea is not new, as doctors have previously attempted to achieve this goal using cell and tissue transplants. Unfortunately, these procedures were met with mixed results, since researchers could not conclusively determine if their grafts actually contained limbal stem cells. Such cells are notably difficult to pinpoint in tissue samples.

The authors of the study devised a new method for getting around this roadblock. With the aid of antibodies, the research team successfully highlighted a molecular marker carried by limbal stem cells, called ABCB5. The ABCB5 molecule, which was first discovered more than a decade ago, doesn’t just identify limbal stem cells ‒ it also prevents them from dying off.

After these elusive stem cells had been located, they were subsequently removed from the human tissue samples and injected into the corneas of a group of mice. The mice responded positively to this infusion of stem cells, with each developing corneas that allowed them to see clearly. To further solidify the importance of the ABCB5 molecule, a control group of mice was also included in the study. These rodents were either given stem cells without ABCB5 markers, or received no stem cells whatsoever. As a result, the authors found that the control group of mice exhibited no signs of corneal recovery.

People with vision impaired by disease or accident may eventually reap the benefits of this research. One of the report’s co-lead authors, Bruce Ksander of the Massachusetts Eye and Ear Institute, noted that “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.”

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