TOKYO (Nikkei)--Protein Crystal Corp., a bioventure spun off from the Kyoto Institute of Technology, has developed a way to double the number of hematopoietic stem cells that can be obtained from umbilical cord blood.

Since hematopoietic stem cells can develop into all the different types of blood cells in the body, they are used to treat leukemia. Their main source is now bone marrow, but marrow transplants are a burden on the donor. Umbilical cord blood also contains hematopoietic stem cells, albeit in smaller amounts. Having these cells proliferate in culture would make umbilical cord blood a more promising source of cells for leukemia treatment.

Protein Crystal has developed a way to double the hematopoietic stem cells from umbilical cord blood by growing the cells in culture medium together with a growth factor protein that promotes cell proliferation. This growth factor protein is caged inside tiny, three-dimensional protein crystal structures that are made by a virus that infects silkworms.

The growth factor protein escapes from these cages into the culture medium a little at a time, acting to promote the proliferation of hematopoietic stem cells in a stable manner over a long period.

(The Nikkei Business Daily Wednesday edition)