Abstract　　Hematopoietic stem cells are able to self-renewal and differentiate to all blood lineages. With the development of new technologies, recent studies have proposed the revised versions of hematopoiesis. In the classical model of hematopoietic differentiation, HSCs were located at the apex of hematopoietic hierarchy. During differentiation process, HSCs progressively lose self-renewal potential to be commited to progenitors with restricted differentiation potential. For instance, HSCs first give rise to multipotent progenitor cells, then produce bipotent and unipotent progenitors, and finally differentiate to mature blood cells. For the differentiation of megakaryocytes, common myeloid progenitors derived from HSCs give rise to megakaryocyte-erythrocyte progenitors and then develop to megakaryocytes. However, recent results show that megakaryocytes can be directly generated from HSCs without multipotent or bipotent phases. Alternatively, platelet-biased HSCs produce megakaryocyte progenitors. In this article, recent advances in the hematopoiesis and megakaryocyte differentiation pathway are reviewed.
Cell Differentiation ; Cell Lineage ; Hematopoiesis ; Hematopoietic Stem Cells ; Megakaryocytes ; Multipotent Stem Cells

Current dogma suggests that hematopoietic stem cells (HSC) reside in the top of the hematopoietic hierarchy, which can provide all kinds of mature blood cells constantly through self-renewal and multilineage differentiation potential. HSC has been regarded as the main cell population that maintains the stable hematopoiesis and several differentiation and development patterns of HSC have been summarized based on transplantation results. However, in deed the transplantation experiment is based on an extremely situation of stress which could not really reflect the function of HSC in normal homeostatic condition. Recent studies show that hematopoietic progenitor cells (HPC) play the most important role in hematopoiesis based on different experimental strategies. This article focuses on the controversial subject of the function of HSC and HPC under homostasis.
Cell Differentiation ; Hematopoiesis ; Hematopoietic Stem Cells

Hematopoietic stem cells (HSC) maintain homeostatic hematopoiesis via their multi-lineage differentiation and self-renewal potentials. HSC can be enriched and purified by flow cytometry relying on their cell surface markers and functional characteristics, however, these methods can not meet the need for deep analysis of HSC biological property and function because of the poor purity. Recent studies have successfully purified and tracked HSC using specifically expressed genes, which can enhance the purification efficiency of HSC, thus provide a better tool for the in-vivo study of HSC. This review summarizes the new techniques and discusses their advantages and disadvantages.
Cell Differentiation ; Flow Cytometry ; Gene Expression ; Hematopoiesis ; Hematopoietic Stem Cells

Abstract　　Currently, hematopoietic stem cell (HSC) transplantation is widely used in the therapy of hematological malignancies, non-malignant refractory anemia, genetic diseases and certain tumors with satisfactory therapeutic efficacy. HSC sources used for transplantation include bone marrow, mobilized peripheral blood and neonate umbilical cord blood. However, for many patients, sufficient number of human leukocyte antigen (HLA) -matched HSC cannot be found for transplantation, because the number of HSC in these tissues is small and HLA-identical donors are rare. Thus, in vitro generation of HSC has recently been focused. At present, the origin of HSC is hPSC, including hESC and hiPSC, which is worth to be the new origin of HSC transplantation. However, to generate functional hematopoietic stem cells which have efficient multi-lineage differentiation and in vivo engraftment potentials still is a big challenge to be confronted. In this review, the recent technical progress in HSC generation is summarizd, and the problems to be solved and new challenges to be confronted were discussed.

Mitochondria are double-membrane organelles existing only in eukaryotic cells. Mitochondria perform various important functions，such as producing energy，regulating signal transduction，and contributing to stress response. Recent studies have highlighted an important role of mitochondria in the determination of hematopoietic stem cells （HSC） fate. Limited biogenesis or timely clearance of mitochondria is an important way against oxidative stress，which favors the quiescence of HSC. Accumulation of mitochondria may lead to proliferation of HSC，even the aging of HSC. Mitochondrial signaling regulates Ca concentration，which is essential for HSC differentiation. This review summarizes the current findings of the mitochondrial roles in HSC quiescence，self-renewal，lineage differentiation and aging.
Cell Differentiation ; Hematopoiesis ; Hematopoietic Stem Cells ; Mitochondria ; Oxidative Stress

Hematopoietic stem cells (HSCs) reside at the top of the hierarchy and have the ability to differentiate to variety of hematopoietic progenitor cells (HPCs) or mature hematopoietic cells in each system. At present, the procress of HSC and HPC differentiating to the complete hematopoietic system under physiological and stressed conditions is poorly understood. In vivo lineage tracing is a powerful technique that can mark the individual cells and identify the differentiation pathways of their daughter cells, it takes as a strong technical system to research HSC. Traditional lineage tracing studies mainly rely on imaging techniques with fluorescent dyes and nucleic acid analogs. Recently, newly cell tracing technologies have been invented, and the combination of clonal tracing and DNAsequencing technologies have provided a new perspective on cell state, cell fate, and lineage commitment at the single cell level. In this review, these new tracing methods were introduce and discuss, and their advantages over traditional methods in the study of hematopoiesis were summarized briefly.
Cell Differentiation ; Hematopoiesis ; Hematopoietic Stem Cells

OBJECTIVETo investigate the relationship between early peak body temperature and neutropenia duration and its potential mechanism.

METHODSA total of 111 patients with CR1 phase acute leukemia (AL) with neutropenia infection were enrolled in this study. The relationship between early peak body temperature and neutropenia duration was analyzed retrospectively, and the IL-6 serum level in patients with different peak of body temperature was detected, and the single cell culture system in vitro was established, the incorparation rate of EdU in vivo was detected, and the effect of IL-6 on mouse hematopoietic stem cells /progenitor cells was analyzed.

RESULTSOut of 111 patients with nentropenia, the body temperature <38 °C and the neutropenia duration 9.5±3.69 d were observed in 44 patients, while the body temperature >38 °C and neutropenia duration 7.33±4.20 d were observed in 69 patients, the differences between 2 groups was statistically signficant (P<0.05). The EdU test showed that the number of EdU hematopoietic stem cells and progenitor cells increased. The IL-6 level was different in patients with different peaks of initial bady temperature (P<0.05). The results of amimal experiment showed that the IL-6 could promote the proliferation of hematopoietic stem cells/ progenitor cells in vitro and in vivo.

CONCLUSIONFor patients with neutropenic infection when initial body temperature peak is <38 °C, the probability of neutropenia duration prolonging after chamotherapy increases, which may relate with promotive effect of pro-inflammatory cytokins on prliferation of hematopoietic stem cells/progenitor cells.

Acute Disease ; Animals ; Hematopoietic Stem Cells ; Humans ; Leukemia ; Mice ; Neutropenia ; Retrospective Studies ; Temperature