Growth factor delivery method makes long-lasting blood vessels

Growth factors are very potent molecules that control many different functions in our bodies. They're so potent that if any are caught just roaming free, the body destroys them immediately. This is a problem for scientists who would like to use concentrated growth factor to do things like regrow blood vessels after a heart attack. Now there is a way, according to Yadong Wang of the University of Pittsburgh, who writes in the Proceedings of the National Academy of Sciences that he has developed a minimally invasive method of delivering growth factor to regrow blood vessels.

Most growth factors, when injected under the skin, last for a half-hour or less in the body. So Wang and colleagues settled on heparin to deliver it. Heparin increases the activity of growth factor, and stabilizes it, when it bonds onto the cell's surface. That was only part of the solution, since the heparin/growth factor combo is extremely water soluble so still does not last long in the body. Wang's secret sauce involves using a polycation--a molecule with multiple positive charges to counteract heparin's negative charges. The result is a coacervate--an aggregate of tiny oil droplets--that can then last longer inside the body.

The researchers injected the concoction into mice and new blood vessels grew. "We had structures that resembled arterioles--small arteries that lead to a network of capillaries," Wang said in a release. And the new blood vessels were still there a month later.

Wang then went on to use the delivery platform to study controlled release of other growth factors that bind heparin, including nerve, vascular, endothelial and epidermal. "In all cases, the controlled delivery using coacervate was much more effective," Wang said.

- read the University of Pittsburgh release
- and the abstract in PNAS

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