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

BACKGROUND Transplantation of endothelial progenitor cells (EPCs) improves neovascularization after ischemia,but patients with coronary artery disease (CAD) or diabetes mellitus show a reduced number of EPCs and impaired functional activity. Therefore,we investigated the effects of risk factors,such as glucose and TNF-alpha,on the number of EPCs in vitro to elucidate the underlying mechanisms. METHODS AND RESULTS EPCs of patients or healthy subjects were isolated from peripheral blood. Incubation with glucose or TNF-alpha dose-dependently reduced the number of EPCs (79.9+/-1.3% and 74.3+/-8.1% of control; Ptextless0.05,respectively). This reduction was not caused by apoptosis. TNF-alpha and glucose induced a dose- and time-dependent activation of the p38 MAP kinase,the downstream kinase mitogen- and stress-activated kinase 1,and the transcription factor cAMP-responsive element-binding protein (CREB),in EPCs. Moreover,EPCs from CAD patients had significantly higher basal p38-phosphorylation levels (1.83+/-0.2-fold increase; Ptextless0.05) compared with healthy subjects. The inhibition of the p38-kinase by SB203580 or infection with a dominant negative p38 kinase adenovirus significantly increased basal number of EPCs (136.7+/-6.3% and 142.9+/-18% versus control,respectively). Likewise,ex vivo cultivation of EPCs from patients with CAD with SB203580 significantly increased the number of EPCs and partially reversed the impaired capacity for neovascularization of EPCs in vivo (relative blood flow: 0.40+/-0.03 versus 0.64+/-0.08,Ptextless0.05). The increased numbers of EPCs by SB203580 were associated with an augmentation of EPC proliferation and a reduction of cells expressing the monocytic marker proteins CD14 and CD64,suggesting that p38 regulates proliferation and differentiation events. CONCLUSIONS These results demonstrate that p38 MAP kinase plays a pivotal role in the signal transduction pathways regulating the number of EPCs ex vivo. SB203580 can prevent the negative effects of TNF-alpha and glucose on the number of EPCs and may be useful to improve the number of EPCs for potential cell therapy. View Publication

First developed for hematologic disorders,the concept of cancer stem cells (CSCs) was expanded to solid tumors,including colorectal cancer (CRC). The traditional model of colon carcinogenesis includes several steps that occur via mutational activation of oncogenes and inactivation of tumor suppressor genes. Intestinal epithelial cells exist for a shorter amount of time than that required to accumulate tumor-inducing genetic changes,so researchers have investigated the concept that CRC arises from the long-lived stem cells,rather than from the differentiated epithelial cells. Colon CSCs were originally identified through the expression of the CD133 glycoprotein using an antibody directed to its epitope AC133. It is not clear if CD133 is a marker of colon CSCs-other cell surface markers,such as epithelial-specific antigen,CD44,CD166,Musashi-1,CD29,CD24,leucine-rich repeat-containing G-protein-coupled receptor 5,and aldehyde dehydrogenase 1,have been proposed. In addition to initiating and sustaining tumor growth,CSCs are believed to mediate cancer relapse after chemotherapy. How can we identify and analyze colon CSCs and what agents are being designed to kill this chemotherapy-refractory population? View Publication

Development of resistance to therapy continues to be a serious clinical problem in breast cancer management. Cancer stem/progenitor cells have been shown to play roles in resistance to chemo�? and radiotherapy. Here,we examined their role in the development of resistance to the oestrogen receptor antagonist tamoxifen. Tamoxifen�?resistant cells were enriched for stem/progenitors and expressed high levels of the stem cell marker Sox2. Silencing of the SOX2 gene reduced the size of the stem/progenitor cell population and restored sensitivity to tamoxifen. Conversely,ectopic expression of Sox2 reduced tamoxifen sensitivity in vitro and in vivo. Gene expression profiling revealed activation of the Wnt signalling pathway in Sox2�?expressing cells,and inhibition of Wnt signalling sensitized resistant cells to tamoxifen. Examination of patient tumours indicated that Sox2 levels are higher in patients after endocrine therapy failure,and also in the primary tumours of these patients,compared to those of responders. Together,these results suggest that development of tamoxifen resistance is driven by Sox2�?dependent activation of Wnt signalling in cancer stem/progenitor cells. View Publication

Current laboratory methods used to passage adherent human pluripotent stem cells (hPSCs) are labor intensive,result in reduced cell viability and are incompatible with larger scale production necessary for many clinical applications. To meet the current demand for hPSCs,we have developed a new non-enzymatic passaging method using sodium citrate. Sodium citrate,formulated as a hypertonic solution,gently and efficiently detaches adherent cultures of hPSCs as small multicellular aggregates with minimal manual intervention. These multicellular aggregates are easily and reproducibly recovered in calcium-containing medium,retain a high post-detachment cell viability of 97%±1% and readily attach to fresh substrates. Together,this significantly reduces the time required to expand hPSCs as high quality adherent cultures. Cells subcultured for 25 passages using this novel sodium citrate passaging solution exhibit characteristic hPSC morphology,high levels (textgreater80%) of pluripotency markers OCT4,SSEA-4,TRA-1-60 andTRA-1-81,a normal G-banded karyotype and the ability to differentiate into cells representing all three germ layers,both in vivo and in vitro. View Publication

The decreased proportion of antigen-inexperienced,na{\{i}}ve T cells is a hallmark of aging in both humans and mice and contributes to reduced immune responses particularly against novel and re-emerging pathogens. Na{\"{i}}ve T cells depend on survival signals received during their circulation among the lymph nodes by direct contacts with stroma in particular fibroblastic reticular cells. Macroscopic changes to the architecture of the lymph nodes have been described but it is unclear how lymph node stroma are altered with age and whether these changes contribute to reduced na{\"{i}}ve T cell maintenance. Here using 2-photon microscopy we determined that the aged lymph node displayed increased fibrosis and correspondingly that na{\"{i}}ve T-cell motility was impaired in the aged lymph node especially in proximity to fibrotic deposition. Functionally adoptively transferred young na{\"{i}}ve T-cells exhibited reduced homeostatic turnover in aged hosts supporting the role of T cell-extrinsic mechanisms that regulate their survival. Further we determined that early development of resident fibroblastic reticular cells was impaired which may correlate to the declining levels of na{\"{i}}ve T-cell homeostatic factors observed in aged lymph nodes. Thus our study addresses the controversy as to whether aging impacts the composition lymph node stroma and supports a model in which impaired differentiation of lymph node fibroblasts and increased fibrosis inhibits the interactions necessary for na{\"{i}}ve T cell homeostasis." View Publication

The human peripheral B-cell compartment displays a large population of immunoglobulin M-positive,immunoglobulin D-positive CD27(+) (IgM(+)IgD(+)CD27(+)) memory" B cells carrying a mutated immunoglobulin receptor. By means of phenotypic analysis� View Publication

We have previously shown that coculture of human embryonic stem cells (hESCs) for 14 days with immortalized fetal hepatocytes yields CD34(+) cells that can be expanded in serum-free liquid culture into large numbers of megaloblastic nucleated erythroblasts resembling yolk sac-derived cells. We show here that these primitive erythroblasts undergo a switch in hemoglobin (Hb) composition during late terminal erythroid maturation with the basophilic erythroblasts expressing predominantly Hb Gower I (zeta(2)epsilon(2)) and the orthochromatic erythroblasts hemoglobin Gower II (alpha(2)epsilon(2)). This suggests that the switch from Hb Gower I to Hb Gower II,the first hemoglobin switch in humans is a maturation switch not a lineage switch. We also show that extending the coculture of the hESCs with immortalized fetal hepatocytes to 35 days yields CD34(+) cells that differentiate into more developmentally mature,fetal liver-like erythroblasts,that are smaller,express mostly fetal hemoglobin,and can enucleate. We conclude that hESC-derived erythropoiesis closely mimics early human development because the first 2 human hemoglobin switches are recapitulated,and because yolk sac-like and fetal liver-like cells are sequentially produced. Development of a method that yields erythroid cells with an adult phenotype remains necessary,because the most mature cells that can be produced with current systems express less than 2% adult beta-globin mRNA. View Publication

The purpose of this study was to examine the in vitro and in vivo osteogenic potential of human induced pluripotent stem cells (hiPSCs) against that of human bone marrow mesenchymal stem cells (hBMMSCs). Embryoid bodies (EBs),which were formed from undifferentiated hiPSCs,were dissociated into single cells and underwent osteogenic differentiation using the same medium as hBMMSCs for 14 days. Osteoinduced hiPSCs were implanted on the critical-size calvarial defects and long bone segmental defects in rats. The healing of defects was evaluated after 8 weeks and 12 weeks of implantation,respectively. Osteoinduced hiPSCs showed relatively lower and delayed in vitro expressions of the osteogenic marker COL1A1 and bone sialoprotein,as well as a weaker osteogenic differentiation through alkaline phosphatase staining and mineralization through Alizarin red staining compared with hBMMSCs. Calvarial defects treated with osteoinduced hiPSCs had comparable quality of new bone formation,including full restoration of bone width and robust formation of trabeculae,to those treated with hBMMSCs. Both osteoinduced hiPSCs and hBMMSCs persisted in regenerated bone after 8 weeks of implantation. In critical-size long bone segmental defects,osteoinduced hiPSC treatment also led to healing of segmental defects comparable to osteoinduced hBMMSC treatment after 12 weeks. In conclusion,despite delayed in vitro osteogenesis,hiPSCs have an in vivo osteogenic potential as good as hBMMSCs. View Publication

Human embryonic stem cells (hESCs) are considered a potential alternative to cadaveric islets as a source of transplantable cells for treating patients with diabetes. We previously described a differentiation protocol to generate pancreatic progenitor cells from hESCs,composed of mainly pancreatic endoderm (PDX1/NKX6.1-positive),endocrine precursors (NKX2.2/synaptophysin-positive,hormone/NKX6.1-negative),and polyhormonal cells (insulin/glucagon-positive,NKX6.1-negative). However,the relative contributions of NKX6.1-negative versus NKX6.1-positive cell fractions to the maturation of functional β-cells remained unclear. To address this question,we generated two distinct pancreatic progenitor cell populations using modified differentiation protocols. Prior to transplant,both populations contained a high proportion of PDX1-expressing cells (˜85%-90%) but were distinguished by their relatively high (˜80%) or low (˜25%) expression of NKX6.1. NKX6.1-high and NKX6.1-low progenitor populations were transplanted subcutaneously within macroencapsulation devices into diabetic mice. Mice transplanted with NKX6.1-low cells remained hyperglycemic throughout the 5-month post-transplant period whereas diabetes was reversed in NKX6.1-high recipients within 3 months. Fasting human C-peptide levels were similar between groups throughout the study,but only NKX6.1-high grafts displayed robust meal-,glucose- and arginine-responsive insulin secretion as early as 3 months post-transplant. NKX6.1-low recipients displayed elevated fasting glucagon levels. Theracyte devices from both groups contained almost exclusively pancreatic endocrine tissue,but NKX6.1-high grafts contained a greater proportion of insulin-positive and somatostatin-positive cells,whereas NKX6.1-low grafts contained mainly glucagon-expressing cells. Insulin-positive cells in NKX6.1-high,but not NKX6.1-low grafts expressed nuclear MAFA. Collectively,this study demonstrates that a pancreatic endoderm-enriched population can mature into highly functional β-cells with only a minor contribution from the endocrine subpopulation. View Publication

Natural killer (NK) cells are cytotoxic immune cells that can eliminate target cells without prior stimulation. Human induced pluripotent stem cells (iPSCs) provide a robust source of NK cells for safe and effective cell-based immunotherapy against aggressive cancers. In this in vitro study,a feeder-free iPSC differentiation was performed to obtain iPSC-NK cells,and distinct maturational stages of iPSC-NK were characterized. Mature cells of CD56bright CD16bright phenotype showed upregulation of CD56,CD16,and NK cell activation markers NKG2D and NKp46 upon IL-15 exposure,while exposure to aggressive atypical teratoid/rhabdoid tumor (ATRT) cell lines enhanced NKG2D and NKp46 expression. Malignant cell exposure also increased CD107a degranulation markers and stimulated IFN-? secretion in activated NK cells. CD56bright CD16bright iPSC-NK cells showed a ratio-dependent killing of ATRT cells,and the percentage lysis of CHLA-05-ATRT was higher than that of CHLA-02-ATRT. The iPSC-NK cells were also cytotoxic against other brain,kidney,and lung cancer cell lines. Further NK maturation yielded CD56?ve CD16bright cells,which lacked activation markers even after exposure to interleukins or ATRT cells - indicating diminished cytotoxicity. Generation and characterization of different NK phenotypes from iPSCs,coupled with their promising anti-tumor activity against ATRT in vitro,offer valuable insights into potential immunotherapeutic strategies for brain tumors. Graphical abstractImage 1 Highlights•Natural killer (NK) cells were derived from human induced pluripotent stem cells (iPSCs) in the absence of feeder cells.•Various maturational subtypes of iPSC-NK cells were characterized,and the phenotypic and functional properties were studied.•iPSC-NK cells of CD56bright CD16bright phenotype expressed activation markers in response to interleukin stimuli.•iPSC-NK cells were cytotoxic toward human atypical teratoid and rhabdoid tumor (ATRT) cells and other human cancer cells.•The cytotoxicity of iPSC-NK cells against various cancer cells in vitro might be translated into an in vivo immunotherapy. View Publication

Schwann cells (SCs) play a crucial role in peripheral nerve repair by supporting axonal regeneration and remyelination. While extensive research has been conducted using rodent SCs,increasing attention is being directed toward human SCs due to species-specific differences in phenotypical and functional properties,and accessibility of human SCs derived from diverse sources. A major challenge in translating SC-based therapies for nerve repair lies in the inability to replicate human SC myelination in vitro,posing a significant obstacle to drug discovery and preclinical research. In this study,we compared the myelination capacity of human,rodent,and porcine SCs in various co-culture conditions,including species-matched and cross-species neuronal environments in a serum-free medium. Our results confirmed that rodent and porcine SCs readily myelinate neurites under standard culture conditions after treatment with ascorbic acid for two weeks,whereas human SCs,at least within the four-week observation period,failed to show myelin staining in all co-cultures. Furthermore,we investigated whether cell culture manipulation impairs human SC myelination by transplanting freshly harvested and predegenerated human nerve segments into NOD-SCID mice for four weeks. Despite supporting host axonal regeneration into the grafts,human SCs exhibited very limited myelination,suggesting an intrinsic species-specific restriction rather than a cell culture-induced defect. These observations suggest fundamental differences between human and rodent SCs and highlight the need for human-specific models and protocols to advance our understanding of SC myelination. View Publication

Human complement receptor type 2 (CR2/CD21) is a B lymphocyte membrane glycoprotein that plays a central role in the immune responses to foreign Ags as well as the development of autoimmunity to nuclear Ags in systemic lupus erythematosus. In addition to these three well-characterized ligands,C3d/iC3b,EBV-gp350,and CD23,a previous study has identified CR2 as a potential receptor for IFN-alpha. IFN-alpha,a multifunctional cytokine important in the innate immune system,has recently been proposed to play a major pathogenic role in the development of systemic lupus erythematosus in humans and mice. In this study,we have shown using surface plasmon resonance and ELISA approaches that CR2 will bind IFN-alpha in the same affinity range as the other three well-characterized ligands studied in parallel. In addition,we show that IFN-alpha interacts with short consensus repeat domains 1 and 2 in a region that serves as the ligand binding site for C3d/iC3b,EBV-gp350,and CD23. Finally,we show that treatment of purified human peripheral blood B cells with the inhibitory anti-CR2 mAb 171 diminishes the induction of IFN-alpha-responsive genes. Thus,IFN-alpha represents a fourth class of extracellular ligands for CR2 and interacts with the same domain as the other three ligands. Defining the role of CR2 as compared with the well-characterized type 1 IFN-alpha receptor 1 and 2 in mediating innate immune and autoimmune roles of this cytokine should provide additional insights into the biologic roles of this interaction. View Publication