He also suggested that the cells could be used as a drug delivery system for the eyes, something Penn said would be an exciting development

vessels are going to form,” Friedlander said.

Newborn mice, for example, do not have blood vessels in their retina but have astrocytes forming a sort of template for future vessels, Friedlander explained.

In adult mice, he said, if the retina is injured, it encourages the development of astrocytes. By injecting the stem cells, the researchers can help stabilize a degenerating blood vessel system.

Friedlander said he was “flabbergasted” at the improvement when the stem cells were injected into the eyes of a type of mice that have eye degeneration and normally go blind within 30 days of birth.

Friedlander said he believes that because the stem cells target astrocytes, genetically modifying the stem cells before injection may make it possible to block the growth of unwanted blood vessels, which are also a factor in some eye disease.

He also suggested that the cells could be used as a drug delivery system for the eyes, something Penn said would be an exciting development.

Diabetic retinopathy is the leading cause of blindness in working age Americans, and almost all people who have had diabetes for more than 30 years will show signs of poor eyesight.

Age-related macular degeneration is a common cause of vision loss among people over age of 60. Both conditions are caused by damage to blood vessels of the retina.