February 24, 2023
University of Tsukuba
The Institute of Medical Science, The University of Tokyo
Keio University School of Medicine
Hematopoietic stem cells (HSCs) have the ability to differentiate into various blood cells, such as red blood cells, white blood cells, and platelets. They play a crucial role in the post-transplant reconstitution of hematopoiesis and immunity in hematopoietic stem cell transplantation for intractable hematological diseases. However, HSCs are very rare. Particularly in cord blood transplantation, this scarcity can increase transplant risks and limit donor selection, creating a need for the establishment of ex vivo expansion technology.
Until now, a culture medium combining serum albumin and cytokines has been considered essential for the ex vivo maintenance of HSCs. In reality, however, while this method can maintain HSCs for a short period, its expansion effect has been limited.
In 2019, a joint Japan-US-UK-Germany research group reported that adding cytokines to a polyvinyl alcohol (PVA)-based medium could stably expand mouse HSCs long-term without using serum albumin. Based on this finding, we have now developed a novel culture technology that enables long-term ex vivo expansion of human HSCs using a medium in which albumin and cytokines are replaced with a macromolecular polymer and specific compounds, respectively. This allows for the expansion of human HSCs from cord blood over a one-month period. Furthermore, single-cell RNA sequencing analysis suggested that HSCs are selectively expanded compared to existing culture techniques.
In the future, we will provide this culture technology as a basic research tool for human HSCs and aim for its clinical application to realize safer hematopoietic stem cell transplantation and address the donor shortage.
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