Stem cells used to produce blood platelets

Reuters News
Posted: Dec 10, 2011 11:13 AM
Stem cells used to produce blood platelets

By Deena Beasley

SAN DIEGO (Reuters) - Scientists have for the first time created blood platelet cells by reprogramming stem cells derived from adult cells, offering the potential for a renewable supply of he fragile blood component.

Researchers at the Center for iPS Cell Research and Application at Kyoto University in Japan presented data here at a meeting of the American Society of Hematology showing that they were able to create the cells in the laboratory and confirm that they had the same life span as normal human platelets when infused in mice.

"The next step will be to conduct a trial to determine whether our platelets can function in the human body and potentially provide a stable supply of platelets at a predefined quality and quantity that can then be used for transfusion therapy," D. Koji Eto, professor at the Kyoto center and senior author of the study, said in a statement.

Induced pluripotent stem cells, or iPS cells, are produced by manipulating ordinary human skin or blood cells back to a state in which they are able to differentiate into a number of different cell types.

When they were first discovered in 2006, iPS cells looked like a perfect solution to the ethical debate over the use of embryonic stem cells, but the process of producing non-mutated cells has proved challenging.

The limitation in using stem cells to produce platelets has been the ability to find a method that creates a large number of high-quality, functional platelets.

The Japanese researchers set out to create an immortalized cell line with a large number of high-quality megakaryocytes -- precursor cells that develop into platelets -- from stem cells that can be grown indefinitely and differentiate into a variety of cell types in the body.

They were able to produce a cell line that turned off certain genes to generate functional platelets. They then tested the functionality of the cultured platelets by infusing them into immunodeficient mouse models and confirmed that they had the same life span as human platelets infused in mice.

In normal clotting, platelets (cells that cause the blood to clot) stick together and form a plug at the site of an injured blood vessel, allowing the injured site to heal.

"In contrast to red blood cells and plasma ... there is always a shortage of platelets," said Dr. Charles Abrams, ASH secretary and associate chief of hematology/oncology at the University of Pennsylvania in Philadelphia. "Other components can be banked or frozen for long periods of time ... Platelets go bad after a couple of days."

In addition, he explained, some people are very sensitive to the type of platelets they receive, so having a one-size-fits all platelet source would be a major accomplishment.

(Reporting by Deena Beasley)