Title:
Bioactive SL-13R peptide expands human umbilical cord blood hematopoietic stem cells and maintains long-term reconstitution ability

 

Authors:

D. Sugiyama^1,2,3*, A. Yumine¹, K. Kulkeaw¹, M. Matsumoto⁴, T. Okazaki², Y. Nakanishi².

 

Affiliations:
¹Department of Research and Development of Next Generation Medicine, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
²Center for Clinical and Translational Research, Kyushu University, Fukuoka, Japan
³Center for Advanced Medical Innovation, Kyushu University, Fukuoka, Japan
⁴Division of Cell Biology, Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan

 

Keywords: Hematopoietic Stem Cells, In vitro expansion, Peptides.

 

Abstract:
Hematopoietic stem cell (HSC) transplantation is a curative treatment of hematological disorders that has been utilized for several decades. Although umbilical cord blood (UCB) is a promising source of HSCs, the presence of an insufficient number of HSCs in these preparations limits their use, prompting need for ex vivo HSC amplification. To establish a more efficient method to expand UCB HSCs, we developed the SL-13R peptide and cultured UCB CD34+ cells with peptide in serum-free medium containing a cytokine cocktail. Following 9 days of culture with peptide, the number of total cells, CD34+CD38– cells and hematopoietic colonies significantly increased relative to control cells grown without peptide. Transplantation of these cells into immunodeficient NOD/Shi-scid/IL-2Rγ knockout mice confirmed that they possess long-term reconstitution ability. To understand how the peptide promotes HSC expansion, we identified X and Y proteins as peptide interactors and undertook loss-of-function analysis to determine whether either was required for peptide function in our culture system. X knockdown UCB CD34+ cells cultured with peptide showed a decreased number of hematopoietic colonies relative to peptide-treated, non-knockdown controls. By contrast, Y knockdown had little effect in the presence of peptide. This work suggests that X functions in HSC expansion promoted by SL-13R. In summary, we have identified a novel peptide promoting expansion of UCB CD34+ cells with long-term reconstitution ability. Its use may facilitate clinical use of UCB HSCs.