A molecule known as ABCB5, which acts as a marker for hard-to-find limbal stem cells of the eye, may offer a means for restoring vision by enhancing regrowth of human corneal tissue, say HMS researchers. Their research, which used a mouse model, is the result of a collaboration between the Massachusetts Eye and Ear/Schepens Eye Research Institute, Boston Children’s Hospital, Brigham and Women’s Hospital, and the VA Boston Healthcare System. The findings may help people who have been blinded by chemical injury, burns, and eye diseases.
The research, published in the July 7 issue of Nature, also describes the construction of tissue from an adult-derived human stem cell.
Limbal stem cells reside in the eye’s basal limbal epithelium, or limbus, and help maintain and regenerate corneal tissue. Their loss due to trauma or disease is one of the leading causes of blindness. In the past, tissue or cell transplants have been used to help the cornea regenerate, but the presence and number of actual limbal stem cells in the grafts has been uncertain and the outcomes of the grafts have been inconsistent.
“Limbal stem cells are rare, and successful transplants are dependent on these rare cells,” says Bruce Ksander, an HMS associate professor of ophthalmology at Mass Eye and Ear, who co-led the study. “This finding will now make it much easier to restore the corneal surface.”
Markus Frank, an HMS assistant professor of pediatrics at Boston Children’s, and Natasha Frank, an HMS assistant professor of medicine at Brigham and Women’s, who were co-senior investigators on the study, had previously discovered ABCB5 in tissue precursor cells in human skin and intestines. In the mouse model used for this study, they found that ABCB5 also occurs in limbal stem cells and is required for their maintenance and survival, and for corneal development and repair. Mice lacking a functional ABCB5 gene lost their populations of limbal stem cells, and their corneas healed poorly after injury.
Image: Kira Lathrop, Bruce Ksander, Markus Frank, and Natasha Frank/MEEI