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Center for Experimental Medicine and Systems Biology

Division of Cell Regulation
細胞制御研究分野
Professor

Satoshi Yamazaki, Ph.D.

教授

博士（生命科学） 山﨑聡

Our studies focus mainly on investigation of stem cell biology using thehematopoietic stem cell (HSC) as a research model. Recent identification of avariety of stem cell sources including embryonic and somatic (tissue-specific) stem
cells has brought about substantial progress in the field of stem cell research.

1.  
Understanding genetic heterogeneity in
gene-edited hematopoietic stem cell products
Hans Jiro Becker 1, Satoshi Yamazaki 2
1Laboratory for Stem Cell Therapy, Faculty of Medicine, Tsukuba University, Tsukuba, Japan; Divisionof Cell Regulation, Center of Experimental Medicine and Systems Biology, The Institute of Medical
Science, The University of Tokyo, Tokyo, Japan.
2Laboratory for Stem Cell Therapy, Faculty of Medicine, Tsukuba University, Tsukuba, Japan; Divisionof Cell Regulation, Center of Experimental Medicine and Systems Biology, The Institute of Medical
Science, The University of Tokyo, Tokyo, Japan.
CRISPR/Cas gene editing has transformed genetic
research and is poised to drive the next generation ofgene therapies targeting hematopoietic stem cells(HSCs). However, the installation of the “desired”
edit is most often only achieved in a minor subset ofalleles. The array of cellular pathways triggered bygene editing tools produces a broad spectrum of “undesired” editing outcomes, including short insertions
and deletions (indels) and chromosome rearrangements, leading to considerable genetic heterogeneity
in gene-edited HSC populations. This heterogeneity
may undermine the effect of the genetic intervention
since only a subset of cells will carry the intended
modification. Also, undesired mutations represent apotential safety concern as gene editing advances toward broader clinical use. Here, we will review thedifferent sources of “undesired” edits and will discuss strategies for their mitigation and control.
2.  Purging myeloma cell contaminants and simultaneous expansion of peripheral blood mobilised stem cells.
Kantaro Ishitsuka 1, Hidekazu Nishikii 2, Takaharu
Kimura 1, Ayano Sugiyama-Finnis 3, Satoshi Yamazaki 4
1
Laboratory for Stem Cell Therapy, Faculty of Medicine, Tsukuba University, Ibaraki, Japan.
2
Department of Hematology, Faculty of Medicine,University of Tsukuba, Tsukuba, Japan.
3Division of Cell Regulation, Center of Experimental Medicine and Systems Biology, The Institute ofMedical Science, The University of Tokyo, Tokyo,Japan.
4Laboratory for Stem Cell Therapy, Faculty of Medicine, Tsukuba University, Ibaraki, Japan; Divisionof Stem Cell Biology, Center for Stem Cell Therapy,
The Institute of Medical Science, The University ofTokyo, Tokyo, Japan; Division of Cell Regulation,
Center of Experimental Medicine and Systems Biology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.

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Human hematopoietic stem cells (HSCs) are widely used as a cellular source for hematopoietic stem
cell transplantation (HSCT) in the clinical treatmentof hematological malignancies. After transplantation
therapy, delays in hematopoietic recovery due to insufficient donor-derived HSCs can lead to increased
risks of life-threatening infections and bleeding. Our
previous studies developed an efficient ex vivo expansion culture medium (3a medium) for umbilicalcord blood-derived HSCs (CBSCs), offering a potential solution to this problem. Nevertheless, the broader applicability of our culture method to alternativecell sources, and, of greater significance, its efficacy ineliminating potentially disease-associated contaminated tumor cells, especially in autologous transplantation, raises critical clinical questions. In this study,
we modified the 3a medium by incorporating UM729

to replace UM171, added Flt3 ligand, and adjusted
the concentrations of butyzamide, 740Y-P, polyvinyl
caprolactam-polyvinyl acetate-polyethylene glycol
graft copolymer (PCL-PVAc-PEG, Soluplus®ฎ) to create the modified 3a medium. This sophistication allowed efficient expansion of not only CBSCs but also
peripheral blood mobilized HSCs (PBSCs). Additionally, we successfully removed contaminated myeloma cells by adding bortezomib and TNF-related apoptosis inducing ligand (TRAIL) at appropriate
concentrations, while maintaining HSCs through theaddition of lenalidomide. Our research findings present the potential for widespread clinical applicationof the modified 3a medium and suggest a safe ex vivo
culture technique for expanding human HSCs within
peripheral blood derived donor grafts used for autologous HSCT.

Publications
Becker HJ, Yamazaki S. Understanding genetic heterogeneity in gene-edited hematopoietic stem cellproducts. Exp Hematol. 2023 Nov 29:S0301472X(23)01770-8. doi: 10.1016/j.exphem.2023.11.007.
Online ahead of print.PMID: 38036097
Sugimoto E, Li J, Hayashi Y, Iida K, Asada S, Fukushima T, Tamura M, Shikata S, Zhang W, Yamamoto
K, Kawabata KC, Kawase T, Saito T, Yoshida T,Yamazaki S, Kaito Y, Imai Y, Denda T, Ota Y, Fukuyama T, Tanaka Y, Enomoto Y, Kitamura T, Goyama

S. Hyperactive Natural Killer cells in Rag2 knockout mice inhibit the development of acute myeloidleukemia. Commun Biol. 2023 Dec 21;6(1):1294. doi:
10.1038/s42003-023-05606-3.PMID: 38129572
Ishitsuka K, Nishikii H, Kimura T, Sugiyama-Finnis
A, Yamazaki S. Purging myeloma cell contaminants
and simultaneous expansion of peripheral blood
mobilised stem cells. Exp Hematol. 2023 Dec
25:104138. doi: 10.1016/j.exphem.2023.104138. Online ahead of print.PMID: 38151170