A bioengineered polymer that coaxes the body to grow its own blood vessels (a process called angiogenesis) could offer an attractive alternative to risky, expensive bypass surgery. Researchers report (Nature Biotechnology) promising results with an implantable biodegradable scaffold that delivers controlled-release doses of two human proteins (growth factors VEGF and PDGF) that are critical to angiogenesis.
Current tissue regeneration methods that depend on one-shot delivery of a single growth factor have not given good results for therapeutic angiogenesis—perhaps because the natural process depends on precisely timed signals from several growth factors over a period of time. Vascular endothelial growth factor (VEGF) kick-starts angiogenesis. But the leaky immature vessels it induces are prone to bursting or regression unless they are exposed to platelet-derived growth factor (PDGF), which recruits smooth-muscle cells to remodel the immature vessels into a dense network of functional, mature ones.
David Mooney and colleagues have mimicked the body's natural blood vessel building process by developing a biodegradable polymer matrix containing both factors, but encapsulating the PDGF in tiny polymer beads to delay its delivery. While the VEGF was released immediately, the PDGF was released only later as the beads gradually broke down, providing sustained release. Rats with the matrix implants grew larger, more mature vessels than rats receiving one-shot delivery of the two factors either alone or simultaneously. This system for controlled delivery of multiple factors could be of value for many tissue-regenerative uses.
David J. Mooney
Department of Biomedical Engineering
University of Michigan
Ann Arbor, MI 48109
(News & Views)
Peter Carmeliet University of Leuven
Flanders Interuniversity Institute for Biotechnology
(C) Nature Biotechnology press release.
Message posted by: Trevor M. D'Souza