Researchers from Harvard Medical School had discovered a kind of immune cells called macrophages are behind the growth of new lymph vessels in the eyes. These new lymph vessels help in healing of the eyes in case of there being any wounds.
The discovery of this new role for the macrophage, published in the September 2005 Journal of Clinical Investigation, may ultimately inspire innovative treatments for blinding eye disease, as well as for other diseases, such as cancer, that rely on the lymph vessels to spread abnormal cells throughout the body.
Researchers began to suspect a new connection between macrophages and lymph vessels while studying corneal transplants in mice. They had become aware of lymph vessels that seemed to be forming "in place," away from those produced at the edge of the cornea. They also noticed that these lymph vessels disappeared after the wounds were healed. Because the cell structure of the new vessels resembled that of macrophages, they began to believe there might be a relationship.
the study tested this idea, placing sutures in the corneas of two groups of mice to create injuries that would induce a healing response. Then one group of mice were given a drug to cause macrophages to commit suicide. When the eyes of both groups were examined, it was found that those given the drug did not grow as many lymph vessels as the control group without the drug.
Researchers believe that harnessing this newly found ability of the macrophages could lead to the creation of new drugs or therapies for eye disease. For instance, inducing new "temporary" lymph vessels in retinas could aid in treating diabetic retinopathy by removing fluids leaking from abnormal blood vessels. It is this leaking fluid, characteristic of diabetic retinopathy that can permanently damage the retina and vision.
The team is now researching the same process in skin wounds and cancer.