搜索结果: 'methocult media formulations for mouse hematopoietic cells serum containing'

Although the wild-type prion protein (PrP) is abundant and widely expressed in various types of tissues and cells,its physiological function(s) remain unknown,and PrP knockout mice do not exhibit overt and undisputed phenotypes. Here we showed that PrP is expressed on the surface of several bone marrow cell populations successively enriched in long-term (LT) hematopoietic stem cells (HSCs) using flow cytometry analysis. Affinity purification of the PrP-positive and -negative fractions from these populations,followed by competitive bone marrow reconstitution assays,shows that all LT HSCs express PrP. HSCs from PrP-null bone marrow exhibited impaired self-renewal in serial transplantation of lethally irradiated mouse recipients both in the presence and absence of competitors. When treated with a cell cycle-specific myelotoxic agent,the animals reconstituted with PrP-null HSCs exhibit increased sensitivity to hematopoietic cell depletion. Ectopic expression of PrP in PrP-null bone marrow cells by retroviral infection rescued the defective hematopoietic engraftment during serial transplantation. Therefore,PrP is a marker for HSCs and supports their self-renewal. View Publication

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hemolytic anemia caused by lack of CD55 and CD59 on blood cell membrane leading to increased sensitivity of blood cells to complement. Hematopoietic stem cell transplantation (HSCT) is the only curative therapy for PNH,however,lack of HLA-matched donors and post-transplant complications are major concerns. Induced pluripotent stem cells (iPSCs) derived from patients are an attractive source for generating autologous HSCs to avoid adverse effects resulting from allogeneic HSCT. The disease involves only HSCs and their progeny; therefore,other tissues are not affected by the mutation and may be used to produce disease-free autologous HSCs. This study aimed to derive PNH patient-specific iPSCs from human dermal fibroblasts (HDFs),characterize and differentiate to hematopoietic cells using a feeder-free protocol. Analysis of CD55 and CD59 expression was performed before and after reprogramming,and hematopoietic differentiation. Patients' dermal fibroblasts expressed CD55 and CD59 at normal levels and the normal expression remained after reprogramming. The iPSCs derived from PNH patients had typical pluripotent properties and differentiation capacities with normal karyotype. After hematopoietic differentiation,the differentiated cells expressed early hematopoietic markers (CD34 and CD43) with normal CD59 expression. The iPSCs derived from HDFs of PNH patients have normal levels of CD55 and CD59 expression and hold promise as a potential source of HSCs for autologous transplantation to cure PNH patients. View Publication

Recent studies support the notion that there is an intricate relationship between hematopoiesis and bone homeostasis in normal steady states. Using mice undergoing chronic inflammatory arthritis,we investigated the relationship between hematopoiesis and bone homeostasis in pathologic conditions. We demonstrate that mice undergoing chronic inflammatory arthritis displayed osteoporosis resulting from a severe defect in osteoblast function. Despite the defective osteoblast function,however,the hematopoietic stem cells from these mice exhibited normal properties in either long-term repopulation or cell cycling. Therefore,the bone-forming capacity of osteoblasts is distinct from their ability to maintain hematopoietic stem cells in chronic inflammatory conditions. View Publication

Hematopoiesis is dependent upon the bone marrow microenvironment,which is comprised of multiple mesenchymal cell types,including fibroblasts,endothelial cells,osteoblasts,and stroma progenitors. The canonical Wnt signaling pathway,which relies on the beta-catenin protein to mediate its signal,is necessary for the normal development of mesenchymal tissue. We hypothesized that canonical Wnt signaling regulates the cellular composition and function of the bone marrow microenvironment. We observed that a beta-catenin-deficient bone marrow microenvironment maintained hematopoietic stem cells but exhibited a decreased capacity to support primitive hematopoietic cells. These results correlated with decreased numbers of osteoblasts and with decreased production of basic fibroblast growth factor,stem cell factor,and vascular cell adhesion molecule-1. From these data,we propose a model in which beta-catenin in the microenvironment is required noncell autonomously for long-term maintenance of hematopoietic progenitors. View Publication

Infection with a recombinant murine-feline gammaretrovirus,MoFe2,or with the parent virus,Moloney murine leukemia virus,caused significant reduction in B-lymphoid differentiation of bone marrow at 2 to 8 weeks postinfection. The suppression was selective,in that myeloid potential was significantly increased by infection. Analysis of cell surface markers and immunoglobulin H gene rearrangements in an in vitro model demonstrated normal B-lymphoid differentiation after infection but significantly reduced viability of differentiating cells. This reduction in viability may confer a selective advantage on undifferentiated lymphoid progenitors in the bone marrow of gammaretrovirus-infected animals and thereby contribute to the establishment of a premalignant state. View Publication

Maintaining a steady pool of self-renewing hematopoietic stem cells (HSCs) is critical for sustained production of multiple blood lineages. Many transcription factors and molecules involved in chromatin and epigenetic modifications have been found to be critical for HSC self-renewal and differentiation; however,their interplay is less understood. The transcription factor GA binding protein (GABP),consisting of DNA-binding subunit GABPα and transactivating subunit GABPβ,is essential for lymphopoiesis as shown in our previous studies. Here we demonstrate cell-intrinsic,absolute dependence on GABPα for maintenance and differentiation of hematopoietic stem/progenitor cells. Through genome-wide mapping of GABPα binding and transcriptomic analysis of GABPα-deficient HSCs,we identified Zfx and Etv6 transcription factors and prosurvival Bcl-2 family members including Bcl-2,Bcl-X(L),and Mcl-1 as direct GABP target genes,underlying its pivotal role in HSC survival. GABP also directly regulates Foxo3 and Pten and hence sustains HSC quiescence. Furthermore,GABP activates transcription of DNA methyltransferases and histone acetylases including p300,contributing to regulation of HSC self-renewal and differentiation. These systematic analyses revealed a GABP-controlled gene regulatory module that programs multiple aspects of HSC biology. Our studies thus constitute a critical first step in decoding how transcription factors are orchestrated to regulate maintenance and multipotency of HSCs. View Publication

The mechanisms regulating key fate decisions such as self-renewal and differentiation in hematopoietic stem and progenitor cells (HSPC) remain poorly understood. We report here a screening strategy developed to assess modulators of human hematopoiesis using a lentiviral short hairpin RNA (shRNA) library transduced into cord blood-derived stem/progenitor cells. To screen for modifiers of self-renewal/differentiation,we used the limited persistence of HSPCs under ex vivo culture conditions as a baseline for functional selection of shRNAs conferring enhanced maintenance or expansion of the stem/progenitor potential. This approach enables complex,pooled screens in large numbers of cells. Functional selection identified novel specific gene targets (exostoses 1) or shRNA constructs capable of altering human hematopoietic progenitor differentiation or stem cell expansion,respectively,thereby demonstrating the potential of this forward screening approach in primary human stem cell populations. View Publication