The efficacy and the safety of the administration of multipotent mesenchymal stromal cells (MMSCs) for acute graft-versus-host disease (aGVHD) prophylaxis following allogeneic hematopoietic cell transplantation (HSCT) were studied. This prospective clinical trial was based on the random patient allocation to the following two groups receiving (1) standard GVHD prophylaxis and (2) standard GVHD prophylaxis combined with MMSCs infusion. Bone marrow MMSCs from hematopoietic stem cell donors were cultured and administered to the recipients at doses of 0.91.3×106/kg when the blood counts indicated recovery. aGVHD of stage IIIV developed in 38.9% and 5.3% of patients in group 1 and group 2, respectively, (𝑃=0.002). There were no differences in the graft rejection rates, chronic GVHD development, or infectious complications. Overall mortality was 16.7% for patients in group 1 and 5.3% for patients in group 2. The efficacy and the safety of MMSC administration for aGVHD prophylaxis were demonstrated in this study.

In the bone marrow of vertebrates, two types of stem cells coexist—hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs). Hematopoiesis only occurs when these two stem cell types and their descendants interact. The descendants of HSCs supply the body with all the mature blood cells, while MSCs give rise to stromal cells that form a niche for HSCs and regulate the process of hematopoiesis. The studies of hematopoiesis were initially based on morphological observations, later extended by the use of physiological methods, and were subsequently augmented by massive application of sophisticated molecular techniques. The combination of these methods produced a wealth of new data on the organization and functional features of hematopoiesis in the ontogenesis of mammals and humans. This review summarizes the current views on hematopoiesis in mice and humans, discusses the development of blood elements and hematopoiesis in the embryo, and describes how the hematopoietic system works in the adult organism and how it changes during aging.

Allogeneic bone marrow transplantation (allo-BMT) is currently the only way to cure many hematoproliferative disorders. However, allo-BMT use is limited by severe complications, the foremost being...

Bone marrow (BM) derived adult multipotent mesenchymal stromal cells (MMSCs) and fibroblast colony-forming units (CFU-Fs) of 20 patients with acute myeloid leukemia (AML) and 15 patients with acute lymphoblastic leukemia (ALL) before and during 1 year after receiving allogeneic hematopoietic stem cell transplantation (allo-HSCT) were studied. The growth characteristics of MMSCs of all patients before allo-HSCT were not altered; however, relative expression level (REL) of some genes in MMSCs, but not in CFU-Fs, from AML and ALL patients significantly changed. After allo-HSCT, CFU-F concentration and MMSC production were significantly decreased for 1 year; REL of several genes in MMSCs and CFU-F-derived colonies were also significantly downregulated. Thus, chemotherapy that was used for induction of remission did not impair the function of stromal precursors, but gene expression levels were altered. Allo-HSCT conditioning regimens significantly damaged MMSCs and CFU-Fs, and the effect lasted for at least 1 year.

Multipotent mesenchymal stromal cells (MSCs) participate in the formation of bone marrow niches for hematopoietic stem cells. Donor MSCs can serve as a source of recovery for niches in patients with graft failure (GF) after allogeneic bone marrow (BM) transplantation. Since only few MSCs reach the BM after intravenous injection, MSCs were implanted into the iliac spine. For 8 patients with GF after allo-BMT, another hematopoietic stem cell transplantation with simultaneous implantation of MSCs from their respective donors into cancellous bone was performed. BM was aspirated from the iliac crest of these patients at 1-2, 4-5, and 9 months after the intraosseous injection of donor MSCs. Patients’ MSCs were cultivated, and chimerism was determined. In 6 out of 8 patients, donor hematopoiesis was restored. Donor cells (9.4 ± 3.3%) were detected among MSCs. Thus, implanted MSCs remain localized at the site of administration and do not lose the ability to proliferate. These results suggest that MSCs could participate in the restoration of niches for donor hematopoietic cells or have an immunomodulatory effect, preventing repeated rejection of the graft. Perhaps, intraosseous implantation of MSCs contributes to the success of the second transplantation of hematopoietic stem cells and patient survival.