Hematopoietic stem cells (HSCs) develop during embryogenesis in a complex process that involves multiple anatomical sites. Once HSC precursors have been specified from mesoderm, they have to mature into functional HSCs and undergo self-renewing divisions to generate a pool of HSCs. During this process, developing HSCs migrate through various embryonic niches, which provide signals for their est...

Fetal hematopoietic stem cells (HSCs) regenerate daughter HSCs in irradiated recipients more rapidly than do adult HSCs. However, both types of HSCs divide in vitro with the same cell-cycle transit times, suggesting different intrinsically determined self-renewal activities. To investigate the mechanism(s) underlying these differences, we compared fetal and adult HSC responses to Steel factor (...

background and aims: the e2f family of transcription factors is encoded by at least eight genes, e2f1-8. these proteins are important targets of the retinoblastoma protein (rb) contributed in regulation of transcription, cell cycle and apoptosis. the aim of this study was to investigate the expression levels of e2f protein family including e2f1, e2f2, e2f7, e2f8 and rb1 in the lineage negative ...

MicroRNAs (miRs) are small noncoding RNAs that regulate gene expression posttranscriptionally by binding to the 3′ untranslated regions of their target mRNAs. The evolutionarily conserved microRNA-125a (miR-125a) is highly expressed in both murine and human hematopoietic stem cells (HSCs), previous studies have found miR-125 strongly enhances self-renewal HSCs progenitors. In this study we expl...

Umbilical cord blood (UCB) has been used for transplantation in the treatment of hematologic disorders as a source of hematopoietic stem cells (HSCs). Because of insufficient number of cord blood CD34+ cells, the expansion of these cells seems to be important for clinical application. Mesenchymal stromal cells (MSCs), playing an important role in HSCs maintenance, were used as feeder layer. Apo...

Allogeneic umbilical cord blood haematopoietic stem cells (UCB-HSCs) can be transplanted into a host with the intact innate immunity with limited immuno-reaction, although the mechanisms remain unclear. The present studies aimed at investigating potential mechanisms of allogeneic UCB-HSCs escape from the cytolysis of natural killer (NK) cells. We compared UCB-HSCs ability to protect from NK-med...

Fetal stem cells differ phenotypically and functionally from adult stem cells in diverse tissues. However, little is known about how these differences are regulated. To address this we compared the gene expression profiles of fetal versus adult hematopoietic stem cells (HSCs) and discovered that the Sox17 transcriptional regulator is specifically expressed in fetal and neonatal but not adult HS...

The quiescent state is thought to be an indispensable property for the maintenance of hematopoietic stem cells (HSCs). Interaction of HSCs with their particular microenvironments, known as the stem cell niches, is critical for adult hematopoiesis in the bone marrow (BM). Here, we demonstrate that HSCs expressing the receptor tyrosine kinase Tie2 are quiescent and antiapoptotic, and comprise a s...

Telomere shortening ultimately limits the replicative life span of cultured human somatic cells. Telomeres also shorten during replicative aging in vivo in hematopoietic cells, including early hematopoietic progenitors and hematopoietic stem cells (HSCs), from humans and mice, despite readily detectable levels of telomerase in these cells. To assess the relevance of telomerase to the long-term ...