05 June 2023

Scientists have discovered a method of growing haematopoietic stem cells (HSCs) that uses chemically-defined reagents, and avoids the use of cytokines, which they believe may transform stem cell transplantations and other HSC-based therapies.

Professor Satoshi Yamazaki of the University of Tsukuba, Japan, and colleagues looked for an alternative to using cytokines and serum albumin for sustaining HSCs outside of the body.

The team created a culture system allowing the growth of human HSCs, replacing cytokines and albumin with specific chemical compounds, and a polymer similar to nylon.

Publishing their research in Nature, the team explain that: “The limited extent to which human haematopoietic stem cells can be expanded ex vivo remains a substantial barrier to the wider and safer therapeutic use of haematopoietic stem cell transplantation.”

Their method was “sufficient to stimulate the expansion of umbilical cord blood haematopoietic stem cells”.

“Our chemically defined expansion culture system will help to advance clinical haematopoietic stem cell therapies,” they add.

Professor Yamazaki said: “Other teams have shown promising results using novel approaches for haematopoietic stem cell ex vivo expansion, including the addition of small molecules, certain hydrogels, various growth factors, or small molecule inhibitors to the cell culture media”.

HSCs generated using their new method were tested with RNA sequencing, confirming that the cells generated were indeed HSCs capable of long-term engraftment. They also showed their method was able to expand HSC clones from single cells, which could engraft in mice bone marrow.

These findings may play a role in future haematopoietic stem cell therapies, the team believes.


Sakurai M, Ishitsuka K, Ito R, Wilkinson AC, Kimura T, Mizutani E, Nishikii H, Sudo K, Becker HJ, Takemoto H, Sano T, Kataoka K, Takahashi S, Nakamura Y, Kent DG, Iwama A, Chiba S, Okamoto S, Nakauchi H, Yamazaki S. (2023) “Chemically defined cytokine-free expansion of human haematopoietic stem cells.” Nature, doi: 10.1038/s41586-023-05739-9

Link: https://www.nature.com/articles/s41586-023-05739-9

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