@article{Véronique Lapostolle_Jean Chevaleyre_Pascale Duchez_Laura Rodriguez_Marija Vlaski-Lafarge_Ioanna Sandvig_Philippe Brunet de la Grange_Zoran Ivanovic_2018, place={Pavia, Italy}, title={Repopulating hematopoietic stem cells from steady-state blood before and after ex vivo culture are enriched in the CD34+CD133+CXCR4low fraction}, volume={103}, url={https://haematologica.org/article/view/8617}, DOI={10.3324/haematol.2017.183962}, abstractNote={The feasibility of <em>ex vivo</em> expansion allows us to consider the steady-state peripheral blood as an alternative source of hematopoietic stem progenitor cells for transplantation when growth factor-induced cell mobilization is contraindicated or inapplicable. <em>Ex vivo</em> expansion dramatically enhances the <em>in vivo</em> reconstituting cell population from steady-state blood. In order to investigate phenotype and the expression of homing molecules, the expression of CD34, CD133, CD90, CD45RA, CD26 and CD9 was determined on sorted CD34<sup>+</sup> cells according to CXCR4 (“neg”, “low” “bright”) and CD133 expression before and after <em>ex vivo</em> expansion. Hematopoietic stem cell activity was determined <em>in vivo</em> on the basis of hematopoietic repopulation of primary and secondary recipients - NSG immuno-deficient mice. <em>In vivo</em> reconstituting cells in the steady-state blood CD34<sup>+</sup> cell fraction before expansion belong to the CD133<sup>+</sup> population and are CXCR4<sup>low</sup> or, to a lesser extent, CXCR4<sup>neg</sup>, while after <em>ex vivo</em> expansion they are contained only in the CD133<sup>+</sup>CXCR4<sup>low</sup> cells. The failure of the CXCR4<sup>bright</sup> population to engraft is probably due to the exclusive expression of CD26 by these cells. The limiting-dilution analysis showed that both repopulating cell number and individual proliferative capacity were enhanced by <em>ex vivo</em> expansion. Thus, steady-state peripheral blood cells exhibit a different phenotype compared to mobilized and cord blood cells, as well as to those issued from the bone marrow. These data represent the first phenotypic characterization of steady-state blood cells exhibiting short- and long-term hematopoietic reconstituting potential, which can be expanded <em>ex vivo</em>, a <em>sine qua non</em&gt; for their subsequent use for transplantation.}, number={10}, journal={Haematologica}, author={Véronique Lapostolle and Jean Chevaleyre and Pascale Duchez and Laura Rodriguez and Marija Vlaski-Lafarge and Ioanna Sandvig and Philippe Brunet de la Grange and Zoran Ivanovic}, year={2018}, month={Sep.}, pages={1604-1615} }