After allowing the stem cells to begin the earliest stages of embryonic development, the researchers prompted some of them to grow into red blood cells by exposing them to a variety of proteins. Up to 65 per cent of the resulting cells matured to the point where they shed their nucleus, which allows them to take on the distinctive doughnut shape of circulating red blood cells, said Dr Robert Lanza, chief scientific officer at Advanced Cell Technology Inc. and the study’s senior author.

The team, which also included researchers from the University of Illinois at Chicago and the Mayo Clinic in Rochester, produced blood of types A-positive, A-negative, B-positive, B-negative and O-positive.

The method was 100 times more efficient than previous efforts, said Eric Bouhassira, a professor of stem cell biology and regenerative medicine at Albert Einstein College of Medicine in New York. But most of the cells had embryonic or fetal versions of globin, the compound in red blood cells that carries oxygen. Only a relative handful appeared to contain the adult globin that would be needed by patients, he said.

“Whether they would be good enough for transfusion is very unclear,” said Bouhassira, who was not involved in the research.

Lanza said the research team is conducting additional experiments to see whether the stem cells will produce more adult globin if given more time to mature in the lab.

Even with substantial improvements, the method faces another big hurdle. Roger Dodd, vice president of research and development at the American Red Cross’ Holland Laboratory in Rockville, said producing blood in the lab could cost thousands of dollars per unit — far too expensive to replace the 14 million pints of red blood cells that are transfused every year. “It’s a rather ambitious goal,” Dodd said.

... contd.