Early megakaryocyte lineage-committed progenitors in adult mouse bone marrow.

Hematopoietic stem cells (HSCs) have been considered to progressively lose their self-renewal and differentiation potentials prior to the commitment to each blood lineage. However, recent studies have suggested that megakaryocyte progenitors (MkPs) are generated at the level of HSCs. In this study, we newly identified early megakaryocyte lineage-committed progenitors (MgPs) mainly in CD201-CD48- cells and CD48+ cells separated from the CD150+CD34-Kit+Sca-1+Lin- HSC population of the bone marrow in adult mice. Single-cell colony assay and single-cell transplantation showed that MgPs, unlike platelet-biased HSCs, had little repopulating potential in vivo, but formed larger megakaryocyte colonies in vitro (on average 8 megakaryocytes per colony) than did previously reported MkPs. Single-cell RNA sequencing supported that HSCs give rise to MkPs through MgPs along a Mk differentiation pathway. Single-cell reverse transcription polymerase chain reaction (RT-PCR) analysis showed that MgPs expressed Mk-related genes, but were transcriptionally heterogenous. Clonal culture of HSCs suggested that MgPs are not direct progeny of HSCs. We propose a differentiation model in which HSCs give rise to MgPs which then give rise to MkPs, supporting a classic model in which Mk-lineage commitment takes place at a late stage of differentiation.

Advances of studies on Purification and Tracking of Hematopoietic Stem Cells Using Their Specific Gene Expression--Review / 中国实验血液学杂志

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.

Hematopoietic Stem Cells or Hematopoietic Progenitor Cells Maintain the Steady-State Hematopoiesis? -Editorial / 中国实验血液学杂志

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.

Relationship between Early Peak Temperature and Neutropenia Duration in Acute Leukemia Patients after Chemotherapy and Its Mechanism / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between early peak body temperature and neutropenia duration and its potential mechanism.</p><p><b>METHODS</b>A 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.</p><p><b>RESULTS</b>Out 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.</p><p><b>CONCLUSION</b>For 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.</p>