From the MIT Technology Review: researchers "developed a liquid that, when injected into patients, forms a matrix of loosely tangled nanofibers. Each of these fibers is covered in microscopic protuberances that mimic vascular endothelial growth factor, or VEGF - a protein that occurs naturally in the body and causes chemical reactions that result in the growth of new blood vessels. By mimicking VEGF, the nanofiber has the same biological effect. ... Tissue engineers have tried using VEGF itself to stimulate the growth of blood vessels, but clinical trials with the protein were unsuccessful ... This is because VEGF tends to diffuse out of the target tissue before it can do its job. Maintaining a therapeutic concentration in the target tissue would require a series of expensive, invasive injections. The new nanomaterial has a similar effect, but it lasts much longer, and is completely biodegradable once its job is finished. ... The researchers tested their material in mice. The blood supply to the animals' hind legs was restricted. Left untreated, these limbs would die. The nanofiber treatment rescued the limbs, and resulted in better motor function and blood circulation than the other treatments, including a treatment with VEGF. ... there could be more uses for nanofibers that mimic proteins from the body. For example, they could be used to stimulate the formation of connective tissues such as bone and cartilage, or to regenerate neurons in the brain."