参考文献

Human induced pluripotent stem cells (hiPSCs) can differentiate into notochordal cell (NC)-like cells when cultured in the presence of natural porcine nucleus pulposus (NP) tissue matrix. The method promises massive production of high-quality,functional cells to treat degenerative intervertebral discs (IVDs). Based on our previous work,we further examined the effect of cell-NP matrix contact and culture medium on the differentiation,and further assessed the functional differentiation ability of the generated NC-like. The study showed that direct contact between hiPSCs and NP matrix can promote the differentiation yield,whilst both the contact and non-contact cultures can generate functional NC-like cells. The generated NC-like cells are highly homogenous regarding the expression of notochordal marker genes. A culture medium containing a cocktail of growth factors (FGF,EGF,VEGF and IGF-1) also supported the notochordal differentiation in the presence of NP matrix. The NC-like cells showed excellent functional differentiation ability to generate NP-like tissue which was rich in aggrecan and collagen type II; and particularly,the proteoglycan to collagen content ratio was as high as 12.5-17.5 which represents a phenotype close to NP rather than hyaline cartilage. Collectively,the present study confirmed the effectiveness and flexibility of using natural NP tissue matrix to direct notochordal differentiation of hiPSCs,and the potential of using the generated NC-like cells for treating IVD degeneration. View Publication

BACKGROUND Glucocorticoids (GCs) are steroid hormones used to induce remission in moderate-to-severe inflammatory bowel disease (IBD). A substantial fraction of patients do not respond to GC treatment and require alternate therapies or surgery. At present,non-response can only be assessed empirically by observing continued disease activity. METHODS To identify potential biomarkers of GC response,we retrospectively identified and recruited 18 GC-responsive and 18 GC-nonresponsive IBD patients. This sample included 14 patients with ulcerative colitis (UC) and 22 patients with Crohn's disease (CD),all previously treated with steroids. In peripheral blood mononuclear cells from each patient,we performed in vitro assays to measure GC inhibition of three different immune stimulants (phytohemagglutinin [PHA],α-CD3/α-CD28,and lipopolysaccharide [LPS]). RESULTS In both diseases,we found that inhibition of PHA-mediated T cell proliferation was significantly associated with clinical GC response (P=0.04). Inhibition of proliferation due to direct T cell receptor stimulation using α-CD3/α-CD28 was also significantly associated with clinical GC response in UC patients (P=0.009),but not in CD patients (P=0.78). Interestingly,inhibition of LPS-mediated cytokine secretion showed the strongest association with clinical GC response across both diseases (P=0.005). CONCLUSIONS We show that inhibition of LPS stimulation is more strongly associated with clinical GC response in IBD patients than inhibition of PHA and α-CD3/α-CD28-mediated proliferation. These results support an important role of bacterial recognition and innate immunity in the etiology of IBD. This assay could be a powerful predictor of clinical response to GCs. View Publication

Reported herein are two imidazole-based small molecules,termed neurodazine (Nz) and neurodazole (Nzl),which induce neuronal differentiation of pluripotent P19 cells. Their ability to induce neurogenesis of P19 cells is comparable to that of retinoic acid. However,Nz and Nzl were found to be more selective neurogenesis inducers than retinoic acid owing to their unique ability to suppress astrocyte differentiation of P19 cells. Our results also show that Nz and Nzl promote production of physiologically active neurons because P19-cell-derived neurons induced by these substances have functional glutamate responsiveness. The present study suggests that Nz and Nzl could serve as important chemical tools to induce formation of specific populations of neuronal cell types from pluripotent cells. View Publication

The development of novel platforms for large scale production of human embryonic stem cells (hESC) derived cardiomyocytes (CM) becomes more crucial as the demand for CMs in preclinical trials,high throughput cardio toxicity assays and future regenerative therapeutics rises. To this end,we have designed a microcarrier (MC) suspension agitated platform that integrates pluripotent hESC expansion followed by CM differentiation in a continuous,homogenous process.Hydrodynamic shear stresses applied during the hESC expansion and CM differentiation steps drastically reduced the capability of the cells to differentiate into CMs. Applying vigorous stirring during pluripotent hESC expansion on Cytodex 1 MC in spinner cultures resulted in low CM yields in the following differentiation step (cardiac troponin-T (cTnT): 22.83. ??. 2.56%; myosin heavy chain (MHC): 19.30. ??. 5.31%). Whereas the lower shear experienced in side to side rocker (wave type) platform resulted in higher CM yields (cTNT: 47.50. ??. 7.35%; MHC: 42.85. ??. 2.64%). The efficiency of CM differentiation is also affected by the hydrodynamic shear stress applied during the first 3. days of the differentiation stage. Even low shear applied continuously by side to side rocker agitation resulted in very low CM differentiation efficiency (cTnT. textless. 5%; MHC. textless. 2%). Simply by applying intermittent agitation during these 3. days followed by continuous agitation for the subsequent 9. days,CM differentiation efficiency can be substantially increased (cTNT: 65.73. ??. 10.73%; MHC: 59.73. ??. 9.17%). These yields are 38.3% and 39.3% higher (for cTnT and MHC respectively) than static culture control.During the hESC expansion phase,cells grew on continuously agitated rocker platform as pluripotent cell/MC aggregates (166??88??105??m2) achieving a cell concentration of 3.74??0.55??106cells/mL (18.89??2.82 fold expansion) in 7days. These aggregates were further differentiated into CMs using a WNT modulation differentiation protocol for the subsequent 12days on a rocking platform with an intermittent agitation regime during the first 3days. Collectively,the integrated MC rocker platform produced 190.5??58.8??106 CMs per run (31.75??9.74 CM/hESC seeded). The robustness of the system was demonstrated by using 2 cells lines,hESC (HES-3) and human induced pluripotent stem cell (hiPSC) IMR-90. The CM/MC aggregates formed extensive sarcomeres that exhibited cross-striations confirming cardiac ontogeny. Functionality of the CMs was demonstrated by monitoring the effect of inotropic drug,Isoproterenol on beating frequency.In conclusion,we have developed a simple robust and scalable platform that integrates both hESC expansion and CM differentiation in one unit process which is capable of meeting the need for large amounts of CMs. ?? 2014. View Publication

The mammalian immune system constitutively senses vast quantities of commensal bacteria and their products through pattern recognition receptors,yet excessive immune reactivity is prevented under homeostasis. The intestinal microbiome can influence host susceptibility to extra-intestinal autoimmune disorders. Here we report that polysaccharide A (PSA),a symbiosis factor for the human intestinal commensal Bacteroides fragilis,protects against central nervous system demyelination and inflammation during experimental autoimmune encephalomyelitis (EAE),an animal model for multiple sclerosis,through Toll-like receptor 2 (TLR2). TLR2 mediates tissue-specific expansion of a critical regulatory CD39(+) CD4 T-cell subset by PSA. Ablation of CD39 signalling abrogates PSA control of EAE manifestations and inflammatory cytokine responses. Further,CD39 confers immune-regulatory phenotypes to total CD4 T cells and Foxp3(+) CD4 Tregs. Importantly,CD39-deficient CD4 T cells show an enhanced capability to drive EAE progression. Our results demonstrate the therapeutic potential and underlying mechanism by which an intestinal symbiont product modulates CNS-targeted demyelination. View Publication

Beige adipocytes in white adipose tissue (WAT) are similar to classical brown adipocytes in that they can burn lipids to produce heat. Thus,an increase in beige adipocyte content in WAT browning would raise energy expenditure and reduce adiposity. Here we report that adipose-specific inactivation of Notch1 or its signaling mediator Rbpj in mice results in browning of WAT and elevated expression of uncoupling protein 1 (Ucp1),a key regulator of thermogenesis. Consequently,as compared to wild-type mice,Notch mutants exhibit elevated energy expenditure,better glucose tolerance and improved insulin sensitivity and are more resistant to high fat diet-induced obesity. By contrast,adipose-specific activation of Notch1 leads to the opposite phenotypes. At the molecular level,constitutive activation of Notch signaling inhibits,whereas Notch inhibition induces,Ppargc1a and Prdm16 transcription in white adipocytes. Notably,pharmacological inhibition of Notch signaling in obese mice ameliorates obesity,reduces blood glucose and increases Ucp1 expression in white fat. Therefore,Notch signaling may be therapeutically targeted to treat obesity and type 2 diabetes. View Publication

Down's syndrome (DS),caused by trisomy of human chromosome 21,is the most common genetic cause of intellectual disability. Here we use induced pluripotent stem cells (iPSCs) derived from DS patients to identify a role for astrocytes in DS pathogenesis. DS astroglia exhibit higher levels of reactive oxygen species and lower levels of synaptogenic molecules. Astrocyte-conditioned medium collected from DS astroglia causes toxicity to neurons,and fails to promote neuronal ion channel maturation and synapse formation. Transplantation studies show that DS astroglia do not promote neurogenesis of endogenous neural stem cells in vivo. We also observed abnormal gene expression profiles from DS astroglia. Finally,we show that the FDA-approved antibiotic drug,minocycline,partially corrects the pathological phenotypes of DS astroglia by specifically modulating the expression of S100B,GFAP,inducible nitric oxide synthase,and thrombospondins 1 and 2 in DS astroglia. Our studies shed light on the pathogenesis and possible treatment of DS by targeting astrocytes with a clinically available drug. View Publication

Stirred-suspension bioreactors are a promising modality for large-scale culture of 3D aggregates of pluripotent stem cells and their progeny. Yet,cells within these clusters experience limitations in the transfer of factors and particularly O2 which is characterized by low solubility in aqueous media. Cultured stem cells under different O2 levels may exhibit significantly different proliferation,viability and differentiation potential. Here,a transient diffusion-reaction model was built encompassing the size distribution and ultrastructural characteristics of embryonic stem cell (ESC) aggregates. The model was coupled to experimental data from bioreactor and static cultures for extracting the effective diffusivity and kinetics of consumption of O2 within mouse (mESC) and human ESC (hESC) clusters. Under agitation,mESC aggregates exhibited a higher maximum consumption rate than hESC aggregates. Moreover,the reaction-diffusion model was integrated with a population balance equation (PBE) for the temporal distribution of ESC clusters changing due to aggregation and cell proliferation. Hypoxia was found to be negligible for ESCs with a smaller radius than 100 µm but became appreciable for aggregates larger than 300 µm. The integrated model not only captured the O2 profile both in the bioreactor bulk and inside ESC aggregates but also led to the calculation of the duration that fractions of cells experience a certain range of O2 concentrations. The approach described in this study can be employed for gaining a deeper understanding of the effects of O2 on the physiology of stem cells organized in 3D structures. Such frameworks can be extended to encompass the spatial and temporal availability of nutrients and differentiation factors and facilitate the design and control of relevant bioprocesses for the production of stem cell therapeutics. View Publication

DNA repair plays a crucial role in embryonic and somatic stem cell biology and cell reprogramming. The Fanconi anemia (FA) pathway,which promotes error-free repair of DNA double-strand breaks,is required for somatic cell reprogramming to induced pluripotent stem cells (iPSC). Thus,cells from Fanconi anemia patients,which lack this critical pathway,fail to be reprogrammed to iPSC under standard conditions unless the defective FA gene is complemented. In this study,we utilized the oncogenes of high-risk human papillomavirus 16 (HPV16) to overcome the resistance of FA patient cells to reprogramming. We found that E6,but not E7,recovers FA iPSC colony formation and,furthermore,that p53 inhibition is necessary and sufficient for this activity. The iPSC colonies resulting from each of these approaches stained positive for alkaline phosphatase,NANOG,and Tra-1-60,indicating that they were fully reprogrammed into pluripotent cells. However,FA iPSC were incapable of outgrowth into stable iPSC lines regardless of p53 suppression,whereas their FA-complemented counterparts grew efficiently. Thus,we conclude that the FA pathway is required for the growth of iPSC beyond reprogramming and that p53-independent mechanisms are involved. IMPORTANCE A novel approach is described whereby HPV oncogenes are used as tools to uncover DNA repair-related molecular mechanisms affecting somatic cell reprogramming. The findings indicate that p53-dependent mechanisms block FA cells from reprogramming but also uncover a previously unrecognized defect in FA iPSC proliferation independent of p53. View Publication

The recruitment of monocytes and their differentiation into macrophages at sites of inflammation are key events in determining the outcome of the inflammatory response and initiating the return to tissue homeostasis. To study monocyte trafficking and macrophage differentiation in vivo,we have generated a novel transgenic reporter mouse expressing a green fluorescent protein (GFP) under the control of the human CD68 promoter. CD68-GFP mice express high levels of GFP in both monocyte and embryo-derived tissue resident macrophages in adult animals. The human CD68 promoter drives GFP expression in all CD115(+) monocytes of adult blood,spleen,and bone marrow; we took advantage of this to directly compare the trafficking of bone marrow-derived CD68-GFP monocytes to that of CX3CR1(GFP) monocytes in vivo using a sterile zymosan peritonitis model. Unlike CX3CR1(GFP) monocytes,which downregulate GFP expression on differentiation into macrophages in this model,CD68-GFP monocytes retain high-level GFP expression for 72 hours after differentiation into macrophages,allowing continued cell tracking during resolution of inflammation. In summary,this novel CD68-GFP transgenic reporter mouse line represents a powerful resource for analyzing monocyte mobilization and monocyte trafficking as well as studying the fate of recruited monocytes in models of acute and chronic inflammation. View Publication