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

Substantial progress has been made in the development of radiation countermeasures,resulting in the recent approval of several mitigators; however,there has yet to be an approved prophylactic radioprotectant. Research on countermeasure performance in mixed neutron and gamma radiation fields has also been scarce. Fibroblast-stimulating lipopeptide (FSL-1) is a novel synthetic agonist for toll-like receptor 2/6. In previous studies,the administration of FSL-1 before and after gamma radiation significantly improved survival outcomes for mice through the activation of the NF-κB pathway. In the current study,we tested FSL-1’s radioprotective abilities in a mixed radiation field that models one produced by a nuclear detonation in 11–14-week-old C57BL/6 male and female mice. We demonstrate that a single dose of 1.5 mg/kg of FSL-1 administered 12 h prior to 65% neutron 35% gamma mixed-field (MF) irradiation enhances survival,accelerates recovery of hematopoietic cell and stem cell populations,reduces inflammation,and protects innate immune function in mice. FSL-1’s ability to recover blood and protect immune functions is important in countering the high rate of incidence of sepsis caused by MF radiation’s damaging effects. These results demonstrate that FSL-1 is a promising prophylactic countermeasure where exposure to MF radiation is anticipated. View Publication

The aorta-gonad-mesonephros region plays an important role in hematopoietic stem cell (HSC) development during mouse embryogenesis. The vascular endothelial cadherin�?� CD45�?� (VE-cad�?�CD45�?�) population contains the major type of immature pre-HSCs capable of developing into long-term repopulating definitive HSCs. In this study,we developed a new coaggregation culture system,which supports maturation of a novel population of CD45-negative (VE-cad�?�CD45�?�CD41�?�) pre-HSCs into definitive HSCs. The appearance of these pre-HSCs precedes development of the VE-cad�?�CD45�?� pre-HSCs (termed here type I and type II pre-HSCs,respectively),thus establishing a hierarchical directionality in the developing HSC lineage. By labeling the luminal surface of the dorsal aorta,we show that both type I and type II pre-HSCs are distributed broadly within the endothelial and subendothelial aortic layers,in contrast to mature definitive HSCs which localize to the aortic endothelial layer. In agreement with expression of CD41 in pre-HSCs,in vivo CD41-Cre-mediated genetic tagging occurs in embryonic pre-HSCs and persists in all lymphomyeloid lineages of the adult animal. View Publication

Hematopoiesis occurs in close association with a complex network of cells loosely termed the hematopoietic microenvironment. Analysis of the mechanisms of microenvironmental regulation of hematopoiesis has been hindered by the complexity of the microenvironment as well as the heterogeneity of hematopoietic stem cells and early progenitor cells. We have established immortalized primate bone marrow-derived stromal cell lines to facilitate analysis of the interactions of hematopoietic cells with the microenvironment in a large animal species. One such line,PU-34,was found to produce a variety of growth factors,including an activity that stimulates the proliferation of an interleukin 6-dependent murine plasmacytoma cell line. A cDNA encoding the plasmacytoma stimulatory activity was isolated through functional expression cloning in mammalian cells. The nucleotide sequence contained a single long reading frame of 597 nucleotides encoding a predicted 199-amino acid polypeptide. The amino acid sequence of this cytokine,designated interleukin 11 (IL-11),did not display significant similarity with any other sequence in the GenBank data base. Preliminary biological characterization indicates that in addition to stimulating plasmacytoma proliferation,IL-11 stimulates the T-cell-dependent development of immunoglobulin-producing B cells and synergizes with IL-3 in supporting murine megakaryocyte colony formation. These properties implicate IL-11 as an additional multifunctional regulator in the hematopoietic microenvironment. View Publication

Symptomatic dengue virus infection ranges in disease severity from an influenza-like illness to life-threatening shock. One model of the mechanism underlying severe disease proposes that weakly neutralizing,dengue serotype cross-reactive antibodies induced during a primary infection facilitate virus entry into Fc receptor-bearing cells during a subsequent secondary infection,increasing viral replication and the release of cytokines and vasoactive mediators,culminating in shock. This process has been termed antibody-dependent enhancement of infection and has significantly hindered vaccine development. Much of our understanding of this process has come from studies using mouse monoclonal antibodies (MAbs); however,antibody responses in mice typically exhibit less complexity than those in humans. A better understanding of the humoral immune response to natural dengue virus infection in humans is sorely needed. Using a high-efficiency human hybridoma technology,we isolated 37 hybridomas secreting human MAbs to dengue viruses from 12 subjects years or even decades following primary or secondary infection. The majority of the human antibodies recovered were broadly cross-reactive,directed against either envelope or premembrane proteins,and capable of enhancement of infection in vitro; few exhibited serotype-specific binding or potent neutralizing activity. Memory B cells encoding enhancing antibodies predominated in the circulation,even two or more decades following infection. Mapping the epitopes and activity of naturally occurring dengue antibodies should prove valuable in determining whether the enhancing and neutralizing activity of antibodies can be separated. Such principles could be used in the rational design of vaccines that enhance the induction of neutralizing antibodies,while lowering the risk of dengue shock syndrome. View Publication

A broad range of hematopoietic stem cells and progenitors reside within a fraction of umbilical cord blood (UCB) that exhibits low light scatter properties (SSC(lo)) and high expression of aldehyde dehydrogenase (ALDH(br)). Many SSC(lo) ALDH(br) cells coexpress CD34; however,other cells express either ALDH or CD34. To investigate the developmental potential of these cell subsets,purified ALDH(br) CD34+,ALDH(neg) CD34+,and ALDH(br) CD34(neg) UCB cells were characterized within a variety of in vivo and in vitro assays. Primitive progenitors capable of multilineage development were monitored in long- and short-term repopulation assays performed on nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice,and in primary and secondary long-term culture assays. These progenitors were highly enriched within the ALDH(br) CD34+ fraction. This cell fraction also enriched short-term myeloid progenitors that were detected in vitro. By comparison,ALDH(neg) CD34+ cells contained few primitive progenitors and had diminished short-term myeloid potential but exhibited enhanced short-term natural killer (NK) cell development in vitro. The ALDH(br) CD34(neg) cells were not efficiently supported by any of the assays used. These studies suggested that in particular the expression of ALDH delineated distinct CD34+ stem cell and progenitor compartments. The differential expression of ALDH may provide a means to explore normal and malignant processes associated with myeloid and lymphoid development. View Publication

Because of recent declining malaria transmission in Latin America,some authorities have recommended against chemoprophylaxis for most travelers to this region. However,the predominant parasite species in Latin America,Plasmodium vivax,can form hypnozoites sequestered in the liver,causing malaria relapses. Additionally,new evidence shows the potential severity of vivax infections,warranting continued consideration of prophylaxis for travel to Latin America. Individualized travel risk assessments are recommended and should consider travel locations,type,length,and season,as well as probability of itinerary changes. Travel recommendations might include no precautions,mosquito avoidance only,or mosquito avoidance and chemoprophylaxis. There are a range of good options for chemoprophylaxis in Latin America,including atovaquone-proguanil,doxycycline,mefloquine,and--in selected areas--chloroquine. Primaquine should be strongly considered for nonpregnant,G6PD-nondeficient patients traveling to vivax-endemic areas of Latin America,and it has the added benefit of being the only drug to protect against malaria relapses. View Publication

Hematopoietic stem cell (HSC) engraftment is a multistep process involving HSC homing to bone marrow,self-renewal,proliferation,and differentiation to mature blood cells. Here,we show that loss of p190-B RhoGTPase activating protein,a negative regulator of Rho GTPases,results in enhanced long-term engraftment during serial transplantation. This effect is associated with maintenance of functional HSC-enriched cells. Furthermore,loss of p190-B led to marked improvement of HSC in vivo repopulation capacity during ex vivo culture without altering proliferation and multilineage differentiation of HSC and progeny. Transcriptional analysis revealed that p190-B deficiency represses the up-regulation of p16(Ink4a) in HSCs in primary and secondary transplantation recipients,providing a possible mechanism of p190-B-mediated HSC functions. Our study defines p190-B as a critical transducer element of HSC self-renewal activity and long-term engraftment,thus suggesting that p190-B is a target for HSC-based therapies requiring maintenance of engraftment phenotype. View Publication

Transplantation-associated stress can compromise the hematopoietic potential of hematopoietic stem cells (HSCs). As a consequence,HSCs may undergo exhaustion" in serial transplant recipients� View Publication