Hematopoietic stem cell (HSC) numbers are tightly regulated and maintained in postnatal hematopoiesis. Extensive studies have supported a role of the cytokine tyrosine kinase receptor Kit in sustaining cycling HSCs when competing with wild-type HSCs posttransplantation, but not in maintenance of quiescent HSCs in steady state adult bone marrow. In this study, we investigated HSC regulation in W...

The endocannabinoid system (CS) has been implicated in the development of hepatic fibrosis such as schistosomiasis-associated liver fibrosis (SSLF). However, the mechanisms mediating the action of the CS in hepatic fibrosis are unclear. The present study hypothesized that Schistosoma J. infection upregulates cannabinoid receptor 1 (CB1) due to activation of NADPH oxidase leading to a fibrotic p...

Hepatic stellate cells (HSCs) have immunosuppressive abilities and may be responsible for the occurrence and development of hepatocellular carcinoma (HCC). However, the mechanisms through which HSCs affect T-cell-mediated immune responses remain unclear. The aim of this study was to elucidate these mechanisms. We examined the effect of HSCs on T-cell proliferation and apoptosis, regulatory T ce...

S tem cells are governed by epigenetic mechanisms that can either help maintain the necessary gene expression programs to preserve the stem cell state or ensure the establishment of new cell-specific expression programs during differentiation. One important level of epigenetic control originates from histone modifications such as methylation or acetylation. These modifications can be associated...

objective: the peroxisome proliferator-activated receptors (ppars) are a group of nuclear receptor proteins whose functions as transcription factors regulate gene expressions. ppars play essential roles in the regulation of cellular differentiation, development, and metabolism (carbohydrate, lipid, protein), and tumorigenesis of higher organisms. this study attempts to determine the effect of b...

Hematopoietic stem cells (HSCs) exist in the bone marrow and circulate in the blood. In this issue, Massberg et al. (2007) report that HSCs also travel through the lymphatic system. Furthermore, migration of HSCs--which express Toll-like receptors--allows the recognition of pathogenic molecules in peripheral tissues thereby promoting the local generation of innate immune cells at the site of in...

The good outcome of hematopoietic stem cell (HSC) transplantation is hampered by low doses of CD34+ cell infusion. Transplanted HSCs undergo a replicative stress that causes accelerated senescence due to rapid telomere shortening. The expansion of human cord blood HSCs is instrumental in obtaining a large number of "good quality" cells, in terms of telomere length and telomerase activity compar...

AIMS Bone marrow-derived mesenchymal stem cells (BMSCs) can reduce liver fibrosis. Apart from the paracrine mechanism by which the antifibrotic effects of BMSCs inhibit activated hepatic stellate cells (HSCs), the effects of direct interplay and juxtacrine signaling between the two cell types are poorly understood. The purpose of this study was to explore the underlying mechanisms by which BMSC...

MicroRNAs are endogenous small non-coding RNAs that regulate gene expression and cancer development. A rare population of hepatocellular cancer stem cells (HSCs) holds the extensive proliferative and self-renewal potential necessary to form a liver tumour. We postulated that specific transcriptional factors might regulate the expression of microRNAs and subsequently modulate the expression of g...

During hepatic fibrogenesis, quiescent hepatic stellate cells (HSCs) undergo phenotypic transformation into activated matrix-producing cells. This process is recapitulated in primary HSCs cultured on plastic. Based on studies in rats, peroxisome proliferator-activated receptor gamma (PPARgamma) has been suggested to play a key role in the control of HSC activation. Indeed, in rats, PPARgamma ex...