TGF-beta essential for retinal blood vessel health A new study finds that the growth factor known as TGF-beta is required by retinal blood vessels and that blocking it can cause retinal dysfunction.

Capillaries are the smallest blood vessels in the body and the site at which oxygen and nutrients are transferred from the blood to the tissues. A capillary is composed of an endothelial cell, which forms the lining of the small tube, and a pericyte, which wraps around the outside of the tube. Scientists have long believed that communication between these two cell types is necessary to maintain blood vessel structure and function. TGF-beta is believed to be involved in this communication process.

In this study, they injected mice with a virus that binds to and inhibits TGF-beta. When they examined the retinas of treated mice, the team found clear evidence that retinal blood vessels were losing their integrity -- blood was not moving efficiently through the smaller vessels into the retina tissue, and fluid was leaking out of the vessels. These defects led to the death of ganglion cells (nerve cells in the innermost part of the retina) and a loss of visual function.

The researchers conclude that TGF-beta in the adult mouse retina is required for the survival of both vascular and neural cells. Systemic inhibition of TGF-beta led to numerous abnormalities in the retinal microcirculation, with impaired perfusion and vascular leakage. The investigators believe that TGF-beta is part of a very complex set of controls that keeps retinal blood vessels healthy. This finding may have important implications in the prevention and treatment of diseases such as diabetic retinopathy and macular degeneration.

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