The University of Ottawa Heart Institute reports (pdf) that its researchers have grown new blood vessels in lab animals using a collagen material that attracts new cells for tissue regeneration. The Ottawa team created an injectable material that forms a scaffold inside the body. It sends out signals to particular cells in the blood. Those cells, called progenitors, give rise to the type of cells that make up the lining of blood vessel walls. In experiments with laboratory rats, the team injected the scaffolding material into the muscle of a back leg, which had no blood flow after the main artery was cut. They found that the scaffold caused a great number of progenitor cells within the blood. After two weeks, more cells were seen in the muscle tissue. The teams used a blood flow monitor and found greater perfusion and blood circulation in the limb compared with the control. Further animal research is needed, the researchers say, including trying it out on larger animals like pigs to see if new arteries to supply the heart could be formed. The work was recently published online in the Journal of the Federation of American Societies for Experimental Biology.