Controlled delivery of peptide nanofibers for myocardial protection

Reminiscent of the 1966 sci-fi thriller Fantastic Voyage, where a surgical team is miniaturized and injected into a dying man, researchers from Harvard Medical School have used injectable self-assembling peptide nanofibers loaded with the pro-survival factor PDGF-BB to protect rat cardiomyocytes from injury and subsequent heart failure.

Their study appears online on December 15 in advance of print publication in the January 2006 issue of the Journal of Clinical Investigation.

Narrowed or blocked blood vessels are unable to deliver sufficient levels of oxygen to cardiomyocytes, which results in cardiomyocyte death, loss of the middle layer of the heart wall (the myocardium), and ultimately, heart failure. Therefore, therapies that protect cardiomyocytes from death may help prevent heart failure. In normal heart tissue, cardiomyocytes are surrounded by an intricate network of capillaries, and interaction of cardiomyocytes with endothelial cells that line the vessel wall and secrete PDGF-BB is integral to cardiomyocyte development and function. In the current study, Richard Lee and colleagues show that PDGF-BB has a direct pro-survival effect on cardiomyocytes. The authors went on to design a strategy in which short, self-assembling peptide nanofibers bind this pro-survival growth factor and, following injection into rat myocardium, facilitated prolonged and controlled delivery of PDGF-BB to the infarcted heart for up to 14 days. This strategy protected cardiomyocytes from injury, reduced infarct size, and preserved cardiac function. This effect could not be achieved by injecting nanofibers or PDGF-BB alone.

These nanofibers represent unique biomaterials able to deliver therapeutic agents directly to the injured tissue and as such hold great potential in the field of tissue regeneration, particularly following cardiac injury.