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

Abstract

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. In addition, among these CD34(+) cells, we confirm the presence of committed progenitors at frequencies similar to those found in cord blood CD34(+) cells. These cells, obtained from leukoreduction filters (LRFs) and rejected in the course of the preparation of red blood cell concentrates, are an abundant and reliable material for obtaining committed progenitors, short- and long-term HSCs of therapeutic interest, especially after the ex vivo expansion phase. Our results open a perspective to set up new therapeutic protocols using expanded LRFs-recovered CD34(+) cells as a source of HSCs for autologous or allogeneic transplantation.

Electrical Muscle Stimulation Induces an Increase of VEGFR2 on Circulating Hematopoietic Stem Cells in Patients With Diabetes

“…However, because of the small size further experiments are required, including independent replications, to truly validate the potential for EMS to activate HSCs. Nevertheless, our finding indicates that the EMS activates the migratory capabilities of the steady state HSCs of healthy participants, 62 independently of vessel injuries and is sufficient for extravasation. The treatment is acting rapidly, well tolerated, and inexpensive.…”

Human Intestinal Allografts Contain Functional Hematopoietic Stem and Progenitor Cells that Are Maintained by a Circulating Pool

“…Murine studies demonstrated HSC migration to ectopic niches via the circulation (Christensen et al, 2004;Wright et al, 2001). HSCs were detected in the blood of 12-to 18-week-old human fetuses (Gallacher et al, 2000), and long-term repopulating HSCs were demonstrated in adult human steady-state peripheral blood (Bourdieu et al, 2017;Brunet de la Grange et al, 2013). We now demonstrate the turnover of ''ectopic'' niche HSPCs from the circulating pool in humans.…”

Preterm Cord Blood Contains a Higher Proportion of Immature Hematopoietic Progenitors Compared to Term Samples

“…Side population (SP) cells were identified in both preterm and term CB as previously described [ 21 ]. Mononuclear cells were resuspended at 10 6 cells/mL in warmed staining buffer [DMEM supplemented with 2% fetal calf serum (FCS)] and incubated with 5 μM Dye Cycle Violet (DCV; Molecular Probes Invitrogen Inc.,) for 30 min at 37°C.…”