Recombinant TAT-BMI-1 fusion protein induces ex vivo expansion of human umbilical cord blood-derived hematopoietic stem cells
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Bruna Codispoti1, Nicola Rinaldo3, Emanuela Chiarella1, Michela Lupia2, Cristina Barbara Spoleti1, Maria Grazia Marafioti1, Annamaria Aloisio1, Stefania Scicchitano1, Marco Giordano2, Giovanna Nappo1,4, Valeria Lucchino1, Malcolm A.S. Moore5, Pengbo Zhou6, Maria Mesuraca1, Heather Mandy Bond1,* and Giovanni Morrone1,*
1Laboratory of Molecular Haematopoiesis and Stem Cell Biology, University Magna Græcia, Catanzaro, Italy
2Molecular Medicine Program, European Institute of Oncology, Milano, Italy
3Biogem S.C.a R.L., Ariano Irpino, Italy
4YCR Cancer Research Unit-Department of Biology, University of York, York, United Kingdom
5Department of Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
6Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, NY, USA
*These authors contributed equally to this work
Giovanni Morrone, email: [email protected]
Keywords: hematopoietic stem cells (HSCs), ex vivo expansion, BMI-1, TAT-fusion protein, protein transduction
Received: October 04, 2016 Accepted: January 17, 2017 Published: February 07, 2017
Transplantation of hematopoietic stem cells (HSCs) is a well-established therapeutic approach for numerous disorders. HSCs are typically derived from bone marrow or peripheral blood after cytokine-induced mobilization. Umbilical cord blood (CB) represents an appealing alternative HSC source, but the small amounts of the individual CB units have limited its applications. The availability of strategies for safe ex vivo expansion of CB-derived HSCs (CB-HSCs) may allow to extend the use of these cells in adult patients and to avoid the risk of insufficient engraftment or delayed hematopoietic recovery.
Here we describe a system for the ex vivo expansion of CB-HSCs based on their transient exposure to a recombinant TAT-BMI-1 chimeric protein. BMI-1 belongs to the Polycomb family of epigenetic modifiers and is recognized as a central regulator of HSC self-renewal. Recombinant TAT-BMI-1 produced in bacteria was able to enter the target cells via the HIV TAT-derived protein transduction peptide covalently attached to BMI-1, and conserved its biological activity. Treatment of CB-CD34+ cells for 3 days with repeated addition of 10 nM purified TAT-BMI-1 significantly enhanced total cell expansion as well as that of primitive hematopoietic progenitors in culture. Importantly, TAT-BMI-1-treated CB-CD34+ cells displayed a consistently higher rate of multi-lineage long-term repopulating activity in primary and secondary xenotransplants in immunocompromised mice. Thus, recombinant TAT-BMI-1 may represent a novel, effective reagent for ex vivo expansion of CB-HSC for therapeutic purposes.
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