Repopulating hematopoietic stem cells from steady-state blood before and after culture are enriched in the CD34CD133CXCR4 fraction.

The feasibility of 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. expansion dramatically enhances the 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 cells according to CXCR4 ("neg", "low" "bright") and CD133 expression before and after expansion.

Steady state peripheral blood provides cells with functional and metabolic characteristics of real hematopoietic stem cells.

Hematopoietic stem cells (HSCs), which are located in the bone marrow, also circulate in cord and peripheral blood. Despite high availability, HSCs from steady state peripheral blood (SSPB) are little known and not used for research or cell therapy. We thus aimed to characterize and select HSCs from SSPB by a direct approach with a view to delineating their main functional and metabolic properties and the mechanisms responsible for their maintenance.

Interleukin-6 enhances the activity of in vivo long-term reconstituting hematopoietic stem cells in "hypoxic-like" expansion cultures ex vivo.

Background: Since interleukin (IL)-6 synergizes with the physiologically relevant O2 concentration in the maintenance of primitive hematopoietic stem cell (HSC) subpopulations, we hypothesized that its addition to our hypoxic response mimicking cultures (HRMCs), composed of an antioxidant-supplied serum-free xeno-free medium supplemented with the cytokines stabilizing hypoxia-inducible factor-1α and balancing HSC self-renewal and commitment, will result in a similar effect even if they are exposed to 20% O2 .

Study Design And Methods: HRMCs were exposed to 20 and 5% O2 with and without IL-6. Functional committed progenitors (colony-forming cells [CFCs]: CFU-GM, BFU-E, CFU-Mix, and CFU-Mk) were evaluated as well as the short- and long-term repopulating HSCs using in vivo NSG mice model (primary and secondary recipients, respectively).

A novel procedure to improve functional preservation of hematopoietic stem and progenitor cells in cord blood stored at +4°c before cryopreservation.

During storage and transportation of collected cord blood units (CBUs) to the bank prior to their processing and cryopreservation, it is imperative to preserve the functional capacities of a relatively small amount of cells of interest (stem and progenitor cells) which are critical for graft potency. To improve CBU storage efficiency, we conceived an approach based on the following two principles: (1) to provide a better nutritive and biochemical environment to stem and progenitor cells in CB and (2) to prevent the hyperoxygenation of these cells transferred from a low- (1.1%-4% O2 in the CB) to a high-oxygen (20%-21% O2 in atmosphere) concentration.

Long-term repopulating hematopoietic stem cells and "side population" in human steady state peripheral blood.

This report brings the first experimental evidence for the presence of long-term (LT) repopulating hematopoietic stem cells (HSCs) and Side Population (SP) cells within human steady state peripheral blood CD34(+) cells. Ex vivo culture, which reveals the LT-HSC, also increases short-term (ST) HSC engraftment capacity and SP cell number (as well as the SP subpopulations defined on the basis of CD38, CD90 and CD133 expression) which are very low in freshly isolated cells. Thus, ex vivo incubation either allows the expansion of the small fraction of HSCs or reveals "Scid Repopulating Cells - SRC" that are present in the initial CD34(+) cell population but unable to engraft.