Chemotherapy, radiation treatments, organ transplants and illness can all depress numbers of platelets -- the cell fragments in the blood that help form clots -- in the human body. Patients often need platelet transfusions.
Unfortunately, platelets are scarce. Today, hospitals depend on blood donations to get them, and once they're in hand, they have a very short shelf life: only about a week.
But, researchers wrote Tuesday in the journal Cell Research, pluripotent stem cells -- that is, cells that have the potential to turn into any other type of cell in the body -- might one day provide a way to generate "an unlimited supply of platelets for transfusion" in the laboratory.
The team, including scientists affiliated with Advanced Cell Technology, a biotechnology company working with stem cells, Harvard Medical School, Cha University in Seoul and the University of Illinois, generated platelets on a large scale using human embryonic stem cells.
The researchers reported that the lab-grown platelets were "indistinguishable" from normal blood platelets -- similar in shape and size -- and that they behaved like the real thing, too, helping to form clots in lab dishes and in mice who had sustained injuries to blood vessels. The embryonic stem cell-derived platelets also helped retract clots, the team wrote, another key part of platelets' role in healing wounds.
The researchers said that the embryonic stem cells could "be propagated in vitro indefinitely," which might mean large numbers of donors would no longer be essential to replenish platelet supplies. They reported that this marked the first time that anyone had produced platelets from embryonic stem cells in large numbers. It was also the first time that anyone had shown such platelets could function after transplant in a living animal, they said.
According to the research, one day clinicians might use techniques like this one to make platelets from induced pluripotent stem (iPS) cells -- stem cells derived from adult cells in the body -- as well. These hold particular promise because they could be "donated" from the patient himself, creating a perfect match with little chance of being rejected by the body.
As with most stem cell advances, though, it will be some time before methods are perfected, said Gary Rabin, interim chief executive of ACT, in a news release. "More research is clearly needed before this technology can advance into the clinic," he said.
Related: Read more in the Los Angeles Times about blood made from stem cells.
Related: Read more in the Los Angeles Times about artificial blood and blood cells.