Blocking a second protein linked to blood vessel growth, along with one that is already well-known, could offer a new way to treat and prevent a blinding eye disease caused by diabetes, say researchers, one among them of Indian-origin.Diabetic eye disease occurs when the normal blood vessels in the eye are replaced over time with abnormal, leaky, fragile blood vessels that leak fluid or bleed into the eye, damaging the light-sensitive retina and causing blindness.Laser-sealing eye blood vessels can save central vision, but this often sacrifices peripheral and night vision, explained Akrit Sodhi, assistant professor of ophthalmology at the Johns Hopkins University School of Medicine.Several recently developed drugs -- bevacizumab, ranibizumab and aflibercept -- can help treat these blood vessels by blocking the action of VEGF which stimulates the growth of new, often abnormal, blood vessels.
But studies have shown that although these drugs slow progression to proliferative diabetic retinopathy, it does not reliably prevent it.Looking for an explanation, the researchers tested levels of VEGF in samples of fluid from the eye taken from healthy people, people with diabetes who did not have diabetic retinopathy and people with diabetic retinopathy of varying severity."The results suggested to us that although VEFG clearly plays an important role in blood vessel growth, it is not the only factor," Sodhi said.A series of experiments in lab-grown human cells and mice revealed a second culprit, a protein called angiopoietin-like 4.When the researchers blocked the action of both VEGF and angiopoietin-like 4 in fluid from the eyes of people with proliferative diabetic retinopathy, it markedly reduced blood vessel growth in lab-grown cells.The study appeared online in the journal Proceedings of the National Academy of Sciences.