Hematopoietic stem cell transplantation (HSCT) is an important mean for clinical treatment to many of hematological diseases, malignant diseases, hereditary diseases and autoimmune diseases. Whether the implanted hematopoietic stem cells (HSC) can home to bone marrow (BM) smoothly and reconstitute the hematopoiesis is the key to successful HSCT. With the cognition of HSC homing mechanism, the visual observation of HSC homing to BM is attracting more and more attention and helps to clarify the micro-dialogue between HSC and BM microenvironment. In recent years, with the development of imaging technology, confocal laser scanning microscope (CLSM) and two-photon microscope are able to make 3D reconstruction and real-time observation of the tissue or cells. Researches on HSC homing process visibly become reality. In this article the methods of visual research and their application in HSC homing observation are reviewed.
Cell Movement ; Hematopoiesis ; physiology ; Hematopoietic Stem Cells ; cytology ; physiology ; Humans ; Stem Cell Niche ; physiology

OBJECTIVETo explore the rapid neutrophil engraftment and long-term hematopoietic reconstitution.

METHODSMononuclear cells (MNCs) were isolated from 5-Fu treated male BDF1 mouse bone marrow and CD(34)(+)/c-kit(+) cells were selected from the MNCs by using MoFlo Cell Sorter. MNCs and CD(34)(+)/c-kit(+) cells were co-cultured with mouse bone marrow-derived mesenchymal stem cells (MSCs) in a two-step expansion. The expanded cells were then transplanted into sublethally irradiated female BDF1 mice.

RESULTSCo-culture with MSCs resulted in 10.8-, 4.8-, 65.9- and 38.8-fold increases yields of median total nucleated cells, CD(34)(+) cells, GM-CFC and HPP-CFC, respectively, as for the MNCs culture, and 76.1-, 2.9-, 71.7- and 51.8-fold increase respectively for the CD(34)(+)/c-kit(+) cell culture. The expanded cells could rapidly engraft in the sublethally, irradiated mice, reconstitute their hematopoiesis, and be detected in the recipients bone marrow 2 months after transplantation.

CONCLUSIONSHematopoietic stem/progenitor cells co-cultures with MSCs in two-step expansion could increase expansion yields of total nucleated cells, GM-CFC and HPP-CFC. The availability of increased numbers of expanded cells may result in more rapid engraftment of neutrophils following infusion to transplant recipients.

The homing and engraftment of hematopoietic stem cells (HSC) into bone marrow is the first critical step for successful clinical hematopoietic stem cell transplantation (HSCT). SDF-1 / CXCR4 is considered to be a very promising target to promote HSC homing. In recent years, with the in-depth research on the HSC homing, a variety of new strategies for promoting HSC homing and engraftment have been explored, such as nuclear hormone receptor, histone deacetylase inhibitor, prostaglandin and metabolic regulation, so as to increase the success rate of HSCT and improve the survival of patients. In this review, the recent research advances in the mechanism of HSC homing and strategies to promote HSC homing and engraftment were summarized and discussed.
Humans ; Hematopoietic Stem Cells/physiology* ; Bone Marrow ; Hematopoietic Stem Cell Transplantation ; Gene Expression Regulation ; Prostaglandins/metabolism*

As the progenitor of most cell components in the hematopoietic microenvironment, mesenchymal stem cells (MSC) exhibit self-renewal and multilineage differentiation capacity. Through direct interaction with hematopoietic cells, secreting extracellular matrix and factors, MSC maintain the integrity of hematopoietic microenvironment and regulate hematopoiesis accurately. This review summarized the function of MSC in hematopoietic regulation, such as secretion of cytokines supporting hematopoiesis, MSC expression and adhesion molecules interacting with hematopoietic cells, and supportive effects of transplantation combining MSC with HSC on hematopoietic reconstruction, and its clinical perspectives.
Cell Communication ; Cytokines ; biosynthesis ; Hematopoiesis ; physiology ; Hematopoietic Stem Cells ; physiology ; Mesenchymal Stromal Cells ; physiology

Hematopoietic development is characterized by the dynamic generation of hematopoietic stem/progenitor cells during embryogenesis, and afterward, the maintaining of hematopoietic homeostasis in adult. Mouse model has been appreciated valuable for dissecting the regulatory mechanisms of hematopoietic development. As an important cytokine playing pivotal and versatile roles in the regulation of hematopoiesis, transforming growth factor-beta (TGF-beta) attracts more and more attention. In particular, gene targeting by homologous recombination provides a key means for systematic evaluation of how TGF-beta signaling is involved in hematopoiesis under physiological conditions. To further illustrate the functions and possible mechanisms of TGF-beta in hematopoietic development, hematopoietic phenotypes of targeted mutations and/or dominant negative transgenes of molecules within the TGF-beta signaling pathway are categorized and discussed in this review.
Animals ; Hematopoiesis ; physiology ; Hematopoietic Stem Cells ; physiology ; Humans ; Signal Transduction ; physiology ; Transforming Growth Factor beta ; physiology

Bone marrow macrophage is an important component of bone marrow microenvironment, which is closely related to hematopoietic regulation and hematopoietic stem cell transplantation(HSCT). Recent studies have shown that bone marrow macrophage is an important part of hematopoietic stem cell niche, which can help regulate the mobilization and function of hematopoietic stem/progenitor cells. After HSCT, the microenvironment of bone marrow is damaged and a large number of macrophages infiltrate into the bone marrow. Regulating the macrophage-related signal pathways can promote the recovery of hematopoiesis and the reconstruction of hematopoietic function. Co-culture of macrophages and hematopoietic stem cells (HSC) in vitro significantly increased the number of HSCs and their ability of clone formation, which suggests that macrophages play an important role in the regulation of hematopoiesis in the hematopoietic microenvironment of bone marrow. This paper reviews the recent research progress on the role of macrophages in bone marrow hematopoietic microenvironment.
Humans ; Bone Marrow/metabolism* ; Hematopoietic Stem Cells/physiology* ; Hematopoiesis/physiology* ; Stem Cell Niche ; Macrophages/metabolism*

Recent progress in stem cell research is opening a new hope for cell therapy in regenerative medicine. Two breakthroughs were made in the stem cell era, one, new discoveries in multipotentiality of adult stem cells beyond the traditionally appreciated extent, and the other, establishment of pluripotent stem cell from human embryo. In addition to the newly identified multipotentiality of adult stem cells, their ability to be trans-differentiated toward other tissue types (stem cell plasticity) as well as to migrate toward the site of tissue damage make adult stem cells particularly attractive choice for stem cell based therapy. Stem cell therapy for organ regeneration, therefore, could be approached from three distinct dimensions: first, direct differentiation of multi-potent stem cells toward desired tissue types; secondly, regeneration of specific tissues through in vivo stem cell plasticity, and lastly, by tissue-specific stem cells from many types of organs. While each approach in stem cell therapy poses distinctive limitations for their success-ful clinical applications, understanding regulatory mechanisms of stem cell selfrenewal and their in vivo engraftment will mostly extend their medical efficacy of stem cell based therapy.
Animals ; *Hematopoietic Stem Cell Transplantation ; Humans ; Stem Cells/*physiology ; Umbilical Cord

Hematopoietic stem cells (HSCs) are tissue specific stem cells that replenish all mature blood lineages during the lifetime of an individual. Hematopoietic cell clusters in the aorta of vertebrate embryos play a pivotal role in the formation of the adult blood system. Recently, people have learned a lot about the embryonic HSCs on their development and homing. During their differentiation, HSCs are regulated by the transcription factors, such as Runx1 and Notch signaling pathway, etc. MicroRNAs also regulate the self-renewal and differentiation of hematopoietic stem/progenitor cells on the post-transcriptional levels. Since the onset of circulation, the formation of HSCs and their differentiation into blood cells, especially red blood cells, are regulated by the hemodynamic forces. It would be of great significance if we could treat hematologic diseases with induced HSCs in vitro on the basis of fully understanding of hemotopoietic stem cell development. This review is focused on the advances in the research of HSCs' development and regulation.
Blood Cells ; cytology ; Cell Differentiation ; Embryonic Stem Cells ; cytology ; Hematopoietic Stem Cells ; cytology ; Humans ; Signal Transduction ; Transcription Factors ; physiology

To elucidate the effect of established primary bone marrow stromal layers on the gene transduction of human hematopoietic stem/progenitor cells (HSC/HPC), mononuclear cells (MNC) from adult bone marrow were isolated by centrifugation on Ficoll-Hypaque gradients and plated in stromal culture medium. The cells were incubated until passage 4 to establish primary stromal layers. The HSC/HPC prestimulated by cytokines were transduced by retroviral supernatant containing mdr1 gene in presence of irradiated stroma-contact support. Transduced cells were plated in a colony-forming unit assay with and without vincristine (VCR) to assess the efficiency of transduction. Individual colonies were also analyzed by polymerase chain reaction (PCR) for the presence of provirus. The results showed that the mixed adherent cell layers were formed when adult bone marrow stromal cells were incubated for four to six weeks, mainly being composed of fibroblasts. In the presence of stroma-contact support, the average of gene transduction efficiency in marrow-derived progenitors increased 2.1 to 3.3 folds measured by colony-forming assay and/or PCR, significantly higher than those without support of stroma. It is concluded that the presence of bone marrow stroma support in combination with cytokine facilitates augmenting the extent of retroviral-mediated gene transduction.
Bone Marrow Cells ; physiology ; Genes, MDR ; Hematopoietic Stem Cells ; metabolism ; Humans ; Retroviridae ; genetics ; Stromal Cells ; physiology ; Transduction, Genetic

Animals ; Cell Differentiation ; Fetus ; cytology ; Hematopoietic Stem Cells ; cytology ; Hepatocytes ; cytology ; Humans ; Liver ; cytology ; Stem Cells ; cytology ; physiology