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Summary Human pluripotent stem cells (hPSCs) are uniquely dependent on aerobic glycolysis to generate ATP. However,the importance of oxidative phosphorylation (OXPHOS) has not been elucidated. Detailed amino acid profiling has revealed that glutamine is indispensable for the survival of hPSCs. Under glucose- and glutamine-depleted conditions,hPSCs quickly died due to the loss of ATP. Metabolome analyses showed that hPSCs oxidized pyruvate poorly and that glutamine was the main energy source for OXPHOS. hPSCs were unable to utilize pyruvate-derived citrate due to negligible expression of aconitase 2 (ACO2) and isocitrate dehydrogenase 2/3 (IDH2/3) and high expression of ATP-citrate lyase. Cardiomyocytes with mature mitochondria were not able to survive without glucose and glutamine,although they were able to use lactate to synthesize pyruvate and glutamate. This distinguishing feature of hPSC metabolism allows preparation of clinical-grade cell sources free of undifferentiated hPSCs,which prevents tumor formation during stem cell therapy. View Publication

The establishment of protocols to differentiate human pluripotent stem cells (hPSCs) including embryonic (ESC) and induced pluripotent (iPSC) stem cells into functional hepatocyte-like cells (HLCs) creates new opportunities to study liver metabolism,genetic diseases and infection of hepatotropic viruses (hepatitis B and C viruses) in the context of specific genetic background. While supporting efficient differentiation to HLCs,the published protocols are limited in terms of differentiation into fully mature hepatocytes and in a smaller-well format. This limitation handicaps the application of these cells to high-throughput assays. Here we describe a protocol allowing efficient and consistent hepatic differentiation of hPSCs in 384-well plates into functional hepatocyte-like cells,which remain differentiated for more than 3 weeks. This protocol affords the unique opportunity to miniaturize the hPSC-based differentiation technology and facilitates screening for molecules in modulating liver differentiation,metabolism,genetic network,and response to infection or other external stimuli. View Publication

Synthetic biology has advanced the design of standardized transcription control devices that programme cellular behaviour. By coupling synthetic signalling cascade- and transcription factor-based gene switches with reverse and differential sensitivity to the licensed food additive vanillic acid,we designed a synthetic lineage-control network combining vanillic acid-triggered mutually exclusive expression switches for the transcription factors Ngn3 (neurogenin 3; OFF-ON-OFF) and Pdx1 (pancreatic and duodenal homeobox 1; ON-OFF-ON) with the concomitant induction of MafA (V-maf musculoaponeurotic fibrosarcoma oncogene homologue A; OFF-ON). This designer network consisting of different network topologies orchestrating the timely control of transgenic and genomic Ngn3,Pdx1 and MafA variants is able to programme human induced pluripotent stem cells (hIPSCs)-derived pancreatic progenitor cells into glucose-sensitive insulin-secreting beta-like cells,whose glucose-stimulated insulin-release dynamics are comparable to human pancreatic islets. Synthetic lineage-control networks may provide the missing link to genetically programme somatic cells into autologous cell phenotypes for regenerative medicine. View Publication

Generation of induced pluripotent stem cells (iPSCs) from human urine-derived cells (hUCs) provides a convenient and non-invasive way to obtain patient-specific iPSCs. However,many isolated hUCs exhibit very poor proliferation and are difficult to reprogram. In this study,we optimized reprogramming approaches for hUCs with very poor proliferation. We report here that a compound cocktail containing cyclic pifithrin-a (a P53 inhibitor),A-83-01,CHIR99021,thiazovivin,NaB,and PD0325901 significantly improves the reprogramming efficiency (170-fold more) for hUCs. In addition,we showed that replacement of Matrigel with autologous hUC feeders can overcome the reprogramming failure due to the massive cell death that occurs during delivery of reprogramming factors. In summary,we describe improved approaches to enable iPSC generation from hUCs that were otherwise difficult to reprogram,a valuable asset for banking patient-specific iPSCs. View Publication

BACKGROUND: Vascular trauma induced by surgical revascularization stimulates mobilization of hematopoietic and nonhematopoietic progenitor cells. However,it is not clear whether mobilized progenitors are functionally active and participate in peripheral homing. We have found no clinical studies available regarding the reaction of bone marrow to surgical revascularization. METHODS: This was an observational prospective study of 76 patients undergoing elective coronary artery bypass graft surgery. Bone marrow aspirates and blood samples were collected at baseline,at the end of surgery,and 24 hours postoperatively (blood samples only). The CD34+,CD34+CD133+,and CD34+CXCR4+ progenitor cell counts,CXCR4+ mononuclear cell counts,and CXCR4 expression on CD34+ cells were measured by flow cytometry. Progenitor cell functions were studied in vitro by clonogenic and migration assays. RESULTS: In response to coronary revascularization there was mobilization of CD34+ progenitors,having increased migratory and clonogenic function. The CD34+CXCR4+ subsets and CXCR4 expression on CD34+ cells in peripheral blood increased significantly 24 hours postoperatively. The CXCR4 expression on mobilized progenitors at the end of surgery was independently related to baseline CXCR4 expression on bone marrow resident CD34+ cells and duration of cardiopulmonary bypass in a multivariate model. At the end of surgery there was a significant fall in the expression of CXCR4 on CD34+ bone marrow cells,suggesting egress into peripheral circulation of the most active CXCR4-expressing progenitors. CONCLUSIONS: Coronary artery bypass graft surgery is associated with bone marrow release of functionally active progenitor cells. Further studies are needed to verify whether mobilized progenitors participate in regeneration of injured tissues. View Publication

Human (h) induced pluripotent stem cells (iPSCs) are a potentially abundant source of blood cells,but how best to select iPSC clones suitable for this purpose from among the many clones that can be simultaneously established from an identical source is not clear. Using an in vitro culture system yielding a hematopoietic niche that concentrates hematopoietic progenitors,we show that the pattern of c-MYC reactivation after reprogramming influences platelet generation from hiPSCs. During differentiation,reduction of c-MYC expression after initial reactivation of c-MYC expression in selected hiPSC clones was associated with more efficient in vitro generation of CD41a(+)CD42b(+) platelets. This effect was recapitulated in virus integration-free hiPSCs using a doxycycline-controlled c-MYC expression vector. In vivo imaging revealed that these CD42b(+) platelets were present in thrombi after laser-induced vessel wall injury. In contrast,sustained and excessive c-MYC expression in megakaryocytes was accompanied by increased p14 (ARF) and p16 (INK4A) expression,decreased GATA1 expression,and impaired production of functional platelets. These findings suggest that the pattern of c-MYC expression,particularly its later decline,is key to producing functional platelets from selected iPSC clones. View Publication

Retrovirus-mediated transduction of Hoxb4 enhances hematopoietic stem cell (HSC) activity and enforced expression of Hoxb4 induces in vitro development of HSCs from differentiating mouse embryonic stem cells,but the underlying molecular mechanism remains unclear. We previously showed that the HSC activity was abrogated by accumulated Geminin,an inhibitor for the DNA replication licensing factor Cdt1 in mice deficient in Rae28 (also known as Phc1),which encodes a member of Polycomb-group complex 1. In this study we found that Hoxb4 transduction reduced accumulated Geminin in Rae28-deficient mice,despite increasing the mRNA,and restored the impaired HSC activity. Supertransduction of Geminin suppressed the HSC activity induced by Hoxb4 transduction,whereas knockdown of Geminin promoted the clonogenic and replating activities,indicating the importance of Geminin regulation in the molecular mechanism underlying Hoxb4 transduction-mediated enhancement of the HSC activity. This facilitated our investigation of how transduced Hoxb4 reduced Geminin. We showed in vitro and in vivo that Hoxb4 and the Roc1 (also known as Rbx1)-Ddb1-Cul4a ubiquitin ligase core component formed a complex designated as RDCOXB4,which acted as an E3 ubiquitin ligase for Geminin and down-regulated Geminin through the ubiquitin-proteasome system. Down-regulated Geminin and the resultant E2F activation may provide cells with proliferation potential by increasing a DNA prereplicative complex loaded onto chromatin. Here we suggest that transduced Hoxb4 down-regulates Geminin protein probably by constituting the E3 ubiquitin ligase for Geminin to provide hematopoietic stem and progenitor cells with proliferation potential. View Publication

The reprogramming of human somatic cells to induced pluripotent stem (hiPS) cells enables the possibility of generating patient-specific autologous cells for regenerative medicine. A number of human somatic cell types have been reported to generate hiPS cells,including fibroblasts,keratinocytes and peripheral blood cells,with variable reprogramming efficiencies and kinetics. Here,we show that human astrocytes can also be reprogrammed into hiPS (ASThiPS) cells,with similar efficiencies to keratinocytes,which are currently reported to have one of the highest somatic reprogramming efficiencies. ASThiPS lines were indistinguishable from human embryonic stem (ES) cells based on the expression of pluripotent markers and the ability to differentiate into the three embryonic germ layers in vitro by embryoid body generation and in vivo by teratoma formation after injection into immunodeficient mice. Our data demonstrates that a human differentiated neural cell type can be reprogrammed to pluripotency and is consistent with the universality of the somatic reprogramming procedure. View Publication

We have used in vitro and mouse xenograft models to examine the interaction between breast cancer stem cells (CSC) and bone marrow-derived mesenchymal stem cells (MSC). We show that both of these cell populations are organized in a cellular hierarchy in which primitive aldehyde dehydrogenase expressing mesenchymal cells regulate breast CSCs through cytokine loops involving IL6 and CXCL7. In NOD/SCID mice,labeled MSCs introduced into the tibia traffic to sites of growing breast tumor xenografts where they accelerated tumor growth by increasing the breast CSC population. With immunochemistry,we identified MSC-CSC niches in these tumor xenografts as well as in frozen sections from primary human breast cancers. Bone marrow-derived MSCs may accelerate human breast tumor growth by generating cytokine networks that regulate the CSC population. View Publication

Human embryonic stem cells (hESCs) offer exciting potential in regenerative medicine for the treatment of a host of diseases including cancer,Alzheimer's and Parkinson's disease. They also provide insight into human development and disease and can be used as models for drug discovery and toxicity analyses. The key properties of hESCs that make them so promising for medical use are that they have the ability to self-renew indefinitely in culture and they are pluripotent,which means that they can differentiate into any of more than 200 human cell types. Since proteins are the effectors of cellular processes,it is important to investigate hESC expression at the protein level as well as at the transcript level. In addition,post-translational modifications,such as phosphorylation,may influence the activity of pivotal proteins in hESCs,and this information can only be determined by studying the proteome. In this review,we summarize the results obtained from several proteomics analyses of hESCs that have been reported in the last few years. View Publication

Nano- and microscale topographical cues play critical roles in the induction and maintenance of various cellular functions,including morphology,adhesion,gene regulation,and communication. Recent studies indicate that structure and function at the heart tissue level is exquisitely sensitive to mechanical cues at the nano-scale as well as at the microscale level. Although fabrication methods exist for generating topographical features for cell culture,current techniques,especially those with nanoscale resolution,are typically complex,prohibitively expensive,and not accessible to most biology laboratories. Here,we present a tunable culture platform comprised of biomimetic wrinkles that simulate the heart's complex anisotropic and multiscale architecture for facile and robust cardiac cell alignment. We demonstrate the cellular and subcellular alignment of both neonatal mouse cardiomyocytes as well as those derived from human embryonic stem cells. By mimicking the fibrillar network of the extracellular matrix,this system enables monitoring of protein localization in real time and therefore the high-resolution study of phenotypic and physiologic responses to in-vivo like topographical cues. View Publication

Adult T-cell leukemia-lymphoma (ATL) is an aggressive disease,incurable by standard chemotherapy. NK314,a new anticancer agent possessing inhibitory activity specific for topoisomerase IIα (Top2α),inhibited the growth of various ATL cell lines (50% inhibitory concentration: 23-70nM) with more potent activity than that of etoposide. In addition to the induction of DNA double-strand breaks by inhibition of Top2α,NK314 induced degradation of the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs),resulting in impaired DNA double-strand break repair. The contribution of DNA-PK to inhibition of cell growth was affirmed by the following results: NK314 inhibited cell growth of M059J (a DNA-PKcs-deficient cell line) and M059K (a cell line with DNA-PKcs present) with the same potency,whereas etoposide exhibited weak inhibition of cell growth with M059K cells. A DNA-PK specific inhibitor,NU7026,enhanced inhibitory activity of etoposide on M059K as well as on ATL cells. These results suggest that NK314 is a dual inhibitor of Top2α and DNA-PK. Because ATL cells express a high amount of DNA-PKcs,NK314 as a dual molecular targeting anticancer agent is a potential therapeutic tool for treatment of ATL. View Publication