Science - Blood platelets to be made in lab

WASHINGTON: Blood banks may soon be able to grow human blood platelets for transfusion in their labs, say researchers at The Ohio State University
Medical Center.

Publishing their study report in the journal Experimental Hematology, the researchers said that one day it might be possible to grow platelets continuously and in quantities that could ease the chronically tight supply of these critical blood components.

Their suggestion attains significance because presently platelet concentrates coming from volunteer donors involve huge costs, require 10 or more tests for pathogens, and have a shelf life of only five days.

Principal investigator Larry C. Lasky, associate professor of pathology at Ohio State and a specialist in transfusion medicine and blood banking, says that attempts by others to grow platelets have produced only small numbers for a short time.

"We were pleasantly surprised to achieve continuous production for a month. It is easy to imagine a series of these chambers producing platelets. It would be ideal for clinical use and possibly solve the short shelf-life problem. Using good manufacturing practices would prevent bacterial contamination," Lasky says.

Currently, platelets are collected either from donated blood or by apheresis--an expensive and time-consuming process that involves taking blood from one arm, passing it through a machine that isolates the platelets, and then returning it to the other arm. The method yields four to six platelet units per donor.

For their study, Lasky and his colleagues isolated haematopoietic stem cells, which produce blood cells, from blood taken from umbilical cords following normal, full-term deliveries.

The researcher grew the stem cells to greater numbers, and then added them to the bioreactors - chambers with several layers for gas and growth-media control.

They revealed that control cells were grown in culture flasks. Other attempts to grow platelets have usually used culture flasks or similar two-dimensional systems.

After a few days of growth, the researchers added a solution of growth factors to both groups to stimulate the cells to form large, bone-marrow cells called megakaryocytes, which shed bits of themselves as platelets.

The three-dimensional bioreactor produced up to 1.2 million platelets per day, with production continuing for more than 32 days, while the two-dimensional system generated a maximum of about 350,000 platelets per day over a ten-day period.

Lasky said that his team was trying to modify the process to increase the yield of platelets.