Blood types

A major challenge in tissue engineering has been the need to provide a blood supply to the implanted tissues and organs. Now, Juan Melero-Martin, PhD, research fellow in the Department of Surgery and the Vascular Biology Program, Joyce Bischoff, PhD, principal investigator in the Vascular Biology Program, and colleagues have successfully grown functioning human blood vessels in mice by implanting progenitor cells from human blood and bone marrow.

Within seven days, the cells had formed extensive networks of two-layered blood vessels, without the need for genetic manipulation to improve their growth (important since many growth-promoting genes are also activated in cancer). The vessels continued to transport blood throughout the month-long study.

Getting new vessels to form—by injecting progenitor cells in the right locations—may also help patients with heart attacks, atherosclerosis and other conditions where tissues are starved for blood. "What we're most interested in right now is speeding up the vascularization," Bischoff says. "We'd like to see good vasculature within 24 or 48 hours. If you have ischemic tissue, it's dying tissue, so the faster you can establish blood flow the better." The study appeared in the July issue of Circulation Research.