Red Cell Growth Factor Linked to Eye Disease in People With Diabetes

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Erythropoietin as a retinal angiogenic factor in proliferative diabetic retinopathy, by D. Watanabe and colleagues. N Engl J Med 353:782–792, 2005.

What is the problem and what is known about it so far?

Some people with diabetes develop a serious eye disease called proliferative diabetic retinopathy, which often results in blindness. The abnormal growth of new blood vessels in the inner lining of the eye, or retina, is usually involved in the development of this disease.

Some researchers believe that several hormone-like growth factors are involved in growing these abnormal blood vessels. One is called vascular endothelial growth factor (VEGF). Another substance, a red cell growth factor known as erythropoietin, is known to have a role in the growth of new blood vessels. But it isn’t known whether erythropoietin is involved in proliferative diabetic retinopathy.

Why did the researchers do this particular study?

They wanted to see whether erythropoietin is linked to proliferative diabetic retinopathy.

Who was studied?

The study included 144 people with proliferative diabetic retinopathy or other eye diseases not linked to diabetes.

How was the study done?

Researchers measured levels of VEGF and erythropoietin in the fluid within each participant's eyeball.

What did the researchers find?

Erythropoietin levels were much higher in the eyes of people with proliferative diabetic retinopathy than those without diabetes. Tests suggest that the growth factor is produced within the eye and not elsewhere in the body. Both erythropoietin and VEGF were linked to proliferative diabetic retinopathy, but the effect of erythropoietin was stronger.

What were the limitations of the study?

Other conditions, such as inflammation, could account for the levels of growth factors seen in the study, which could confuse the findings. There could be other growth factors involved in the development of new blood vessels that are not yet known.

What are the implications of the study?

Blocking the activity of erythropoietin in the eye could become a new type of treatment for proliferative diabetic retinopathy. More research is needed to see whether this will work safely and effectively.