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Acute myeloid leukemia (AML) is associated with unfavorable patient outcomes primarily related to disease relapse. Since specific types of leukemic hematopoietic stem and progenitor cells (HSPCs) are suggested to contribute to AML propagation,this study aimed to identify and explore relapse-initiating HSPC subpopulations present at diagnosis,using single-cell analysis (SCA). We developed unique high-resolution techniques capable of tracking single-HSPC-derived subclones during AML evolution. Each subclone was evaluated for chemo-resistance,in vivo leukemogenic potential,mutational profile,and the cell of origin. In BM samples of 15 AML patients,GMP-like and MLP-like HSPC subpopulations were identified as prevalent at relapse,exhibiting chemo-resistance to commonly used chemotherapy agents cytosine arabinoside (Ara-C) and daunorubicin. Reconstruction of phylogenetic lineage trees combined with genetic analysis of single HSPCs and single-HSPC-derived subclones demonstrated two distinct clusters,originating from MLP-like or GMP-like subpopulations,observed both at diagnosis and relapse. These subpopulations induced leukemia development ex vivo and in vivo. Genetic SCA showed that these relapse-related subpopulations harbored mutated EZH2 and TP53,detected already at diagnosis. This study,using combined molecular,functional,and genomic analyses at the level of single cells,identified patient-specific chemo-resistant HSPC subpopulations at the time of diagnosis,promoting AML relapse. View Publication

Human induced pluripotent stem (hiPS) cell lines with tissue-specific or ubiquitous reporter genes are extremely useful for optimizing in vitro differentiation conditions as well as for monitoring transplanted cells in vivo. The adeno-associated virus integration site 1 (AAVS1) locus has been used as a safe harbor" locus for inserting transgenes because of its open chromatin structure� View Publication

Tamoxifen is used widely in the treatment of endocrine-responsive breast cancers in humans. Studies were undertaken to examine the biological character (estrogenic-antiestrogenic properties) and estrogen receptor (ER) interaction of the cis- and trans-isomers of tamoxifen and hydroxytamoxifen in MCF-7 human breast cancer cells. For each compound,the following parameters were monitored: affinity for ER and effects on cellular ER levels; stimulation-inhibition of cell growth,plasminogen activator activity,and cellular progesterone receptor levels; and isomer interconversion and metabolism in vitro. The relative binding affinities of the compounds cis-tamoxifen,trans-tamoxifen,cis-hydroxytamoxifen,and trans-hydroxytamoxifen for cytosol ER were 0.3,2.5,1.8,and 310%,respectively,in which the affinity of estradiol is considered 100%. cis-Tamoxifen behaved as a weak estrogen agonist in all assays,while trans-tamoxifen was an effective estrogen antagonist. cis-Tamoxifen behaved like estradiol in stimulating MCF-7 cell growth and increasing plasminogen activator activity and cellular progesterone receptor content,although very much higher concentrations of cis-tamoxifen (10(-6) M) were needed to achieve the levels of stimulation observed with 10(-10) M estradiol. trans-Tamoxifen and trans-hydroxytamoxifen suppressed cell growth,inhibited plasminogen activator activity of control cells,and suppressed estradiol-stimulation of plasminogen activator activity,and they evoked minimal increases in cellular progesterone receptor levels. trans-Hydroxytamoxifen had a 100-fold increased affinity for ER and was approximately 100-times more potent than was trans-tamoxifen in suppressing cell growth and plasminogen activator activity. cis-Hydroxytamoxifen behaved as an estrogen antagonist,suppressing cell growth and plasminogen activator activity,and it elicited submaximal increases in progesterone receptor levels. This apparently paradoxical behavior of cis-hydroxytamoxifen was shown to be due to the fact that the cis- and trans-hydroxytamoxifens readily undergo isomeric interconversion upon exposure to our cell culture conditions,resulting in substantial accumulation of the higher-affinity trans-hydroxytamoxifen in the nuclear ER fraction of cells. In contrast to the facile interconversion of the hydroxytamoxifen isomers,there is no metabolism or interconversion of the parent compounds cis- and trans-tamoxifen in vitro. Hence,by the criteria we have used,the biological characters of trans-tamoxifen and trans-hydroxytamoxifen are similar,the major difference being the approximately 100-fold enhanced potency of the hydroxylated form. In contrast,cis-t View Publication

Data suggest that clinical applications of human induced pluripotent stem cells (hiPSCs) will be realized. Nonetheless,clinical applications will require hiPSCs that are free of exogenous DNA and that can be manufactured through Good Manufacturing Practice (GMP). Optimally,derivation of hiPSCs should be rapid and efficient in order to minimize manipulations,reduce potential for accumulation of mutations and minimize financial costs. Previous studies reported the use of modified synthetic mRNAs to reprogram fibroblasts to a pluripotent state. Here,we provide an optimized,fully chemically defined and feeder-free protocol for the derivation of hiPSCs using synthetic mRNAs. The protocol results in derivation of fully reprogrammed hiPSC lines from adult dermal fibroblasts in less than two weeks. The hiPSC lines were successfully tested for their identity,purity,stability and safety at a GMP facility and cryopreserved. To our knowledge,as a proof of principle,these are the first integration-free iPSCs lines that were reproducibly generated through synthetic mRNA reprogramming that could be putatively used for clinical purposes. View Publication

Physical stimuli can act in either a synergistic or antagonistic manner to regulate cell fate decisions,but it is less clear whether insoluble signals alone can direct human pluripotent stem (hPS) cell differentiation into specialized cell types. We previously reported that stiff materials promote nuclear localization of the Yes-associated protein (YAP) transcriptional coactivator and support long-term self-renewal of hPS cells. Here,we show that even in the presence of soluble pluripotency factors,compliant substrata inhibit the nuclear localization of YAP and promote highly efficient differentiation of hPS cells into postmitotic neurons. In the absence of neurogenic factors,the effective substrata produce neurons rapidly (2 wk) and more efficiently (textgreater75%) than conventional differentiation methods. The neurons derived from substrate induction express mature markers and possess action potentials. The hPS differentiation observed on compliant surfaces could be recapitulated on stiff surfaces by adding small-molecule inhibitors of F-actin polymerization or by depleting YAP. These studies reveal that the matrix alone can mediate differentiation of hPS cells into a mature cell type,independent of soluble inductive factors. That mechanical cues can override soluble signals suggests that their contributions to early tissue development and lineage commitment are profound. View Publication

INTRODUCTION: The induced pluripotent stem cell (iPSC) technology allows generation of patient-specific pluripotent stem cells,thereby providing a novel cell-therapy platform for severe degenerative diseases. One of the key issues for clinical-grade iPSC derivation is the accessibility of donor cells used for reprogramming. METHODS: We examined the feasibility of reprogramming mobilized GMP-grade hematopoietic progenitor cells (HPCs) and peripheral blood mononuclear cells (PBMCs) and tested the pluripotency of derived iPS clones. RESULTS: Ectopic expression of OCT4,SOX2,KLF4,and c-MYC in HPCs and PBMCs resulted in rapid iPSC derivation. Long-term time-lapse imaging revealed efficient iPSC growth under serum- and feeder-free conditions with frequent mitotic events. HPC- and PBMC-derived iPS cells expressed pluripotency-associated markers,including SSEA-4,TRA-1-60,and NANOG. The global gene-expression profiles demonstrated the induction of endogenous pluripotent genes,such as LIN28,TERT,DPPA4,and PODXL,in derived iPSCs. iPSC clones from blood and other cell sources showed similar ultrastructural morphologies and genome-wide gene-expression profiles. On spontaneous and guided differentiation,HPC- and PBMC-derived iPSCs were differentiated into cells of three germ layers,including insulin-producing cells through endodermal lineage,verifying the pluripotency of the blood-derived iPSC clones. CONCLUSIONS: Because the use of blood cells allows minimally invasive tissue procurement under GMP conditions and rapid cellular reprogramming,mobilized HPCs and unmobilized PBMCs would be ideal somatic cell sources for clinical-grade iPSC derivation,especially from diabetes patients complicated by slow-healing wounds. View Publication

Cancer stem cells (CSC) are purported to initiate and maintain tumor growth. Deregulation of normal stem cell signaling may lead to the generation of CSCs; however,the molecular determinants of this process remain poorly understood. Here we show that the transcriptional coactivator YAP1 is a major determinant of CSC properties in nontransformed cells and in esophageal cancer cells by direct upregulation of SOX9. YAP1 regulates the transcription of SOX9 through a conserved TEAD binding site in the SOX9 promoter. Expression of exogenous YAP1 in vitro or inhibition of its upstream negative regulators in vivo results in elevated SOX9 expression accompanied by the acquisition of CSC properties. Conversely,shRNA-mediated knockdown of YAP1 or SOX9 in transformed cells attenuates CSC phenotypes in vitro and tumorigenicity in vivo. The small-molecule inhibitor of YAP1,verteporfin,significantly blocks CSC properties in cells with high YAP1 and a high proportion of ALDH1(+). Our findings identify YAP1-driven SOX9 expression as a critical event in the acquisition of CSC properties,suggesting that YAP1 inhibition may offer an effective means of therapeutically targeting the CSC population. View Publication

Identification of prevalent specific markers is crucial to stem/progenitor cell purification. Determinants such as the surface antigens CD34 and CD38 are traditionally used to analyze and purify hematopoietic stem/progenitor cells (HSCs/HPCs). However,the variable expression of these membrane antigens poses some limitations to their use in HSC/HPC purification. Techniques based on drug/stain efflux through the ATP-binding cassette (ABC)G2 pump (side population [SP] phenotype) or on detection of aldehyde dehydrogenase (ALDH) activity have been independently developed and distinguish the SP and ALDH(Bright) (ALDH(Br)) cell subsets for their phenotype and proliferative capability. In this study,we developed a multiparametric flow cytometric method associating both SP and ALDH activities on human lineage negative (Lin(-)) bone marrow cells and sorted different cell fractions according to their SP/ALDH activity level. We find that Lin(-)CD34(+)CD38(Low/-) cells are found throughout the spectrum of ALDH expression and are enriched especially in ALDH(Br) cells when associated with SP functionality (SP/ALDH(Br) fraction). Furthermore,the SP marker identified G(0) cells in all ALDH fractions,allowing us to sort quiescent cells regardless of ALDH activity. Moreover,we show that,within the Lin(-)CD34(+)CD38(-)ALDH(Br) population,the SP marker identifies cells with higher primitive characteristics,in terms of stemness-related gene expression and in vitro and in vivo proliferative potential,than the Lin(-)CD34(+) CD38(-)ALDH(Br) main population cells. In conclusion,our study shows that the coexpression of SP and ALDH markers refines the Lin(-)CD34(+)CD38(-) hematopoietic compartment and identifies an SP/ALDH(Br) cell subset enriched in quiescent primitive HSCs/HPCs. View Publication

Mobilization of hematopoietic stem and progenitor cells (HSPCs) from bone marrow into peripheral blood by the cytokine granulocyte colony-stimulating factor (G-CSF) has become the preferred source of HSPCs for stem cell transplants. However,G-CSF fails to mobilize sufficient numbers of stem cells in up to 10% of donors,precluding autologous transplantation in those donors or substantially delaying transplant recovery time. Consequently,new regimens are needed to increase the number of stem cells in peripheral blood upon mobilization. Using a forward genetic approach in mice,we mapped the gene encoding the epidermal growth factor receptor (Egfr) to a genetic region modifying G-CSF-mediated HSPC mobilization. Amounts of EGFR in HSPCs inversely correlated with the cells' ability to be mobilized by G-CSF,implying a negative role for EGFR signaling in mobilization. In combination with G-CSF treatment,genetic reduction of EGFR activity in HSPCs (in waved-2 mutant mice) or treatment with the EGFR inhibitor erlotinib increased mobilization. Increased mobilization due to suppression of EGFR activity correlated with reduced activity of cell division control protein-42 (Cdc42),and genetic Cdc42 deficiency in vivo also enhanced G-CSF-induced mobilization. Our findings reveal a previously unknown signaling pathway regulating stem cell mobilization and provide a new pharmacological approach for improving HSPC mobilization and thereby transplantation outcomes. View Publication

Maintenance of blood DC homeostasis is essential to preventing autoimmunity while controlling chronic infection. However,the ability of bacteremic pathogens to directly regulate blood DC homeostasis has not been defined. One such bacteremic pathogen,Porphyromonas gingivalis,is shown by our group to survive within mDCs under aerobic conditions and therein,metastasize from its oral mucosal niche. This is accompanied by expansion of the blood mDC pool in vivo,independently of canonical DC poietins. We presently know little of how this bacteremic pathogen causes blood DC expansion and the pathophysiological significance. This work shows that optimum differentiation of MoDCs from primary human monocytes,with or without GM-CSF/IL-4,is dependent on infection with P. gingivalis strains expressing the DC-SIGN ligand mfa-1. DC differentiation is lost when DC-SIGN is blocked with its ligand HIV gp120 or knocked out by siRNA gene silencing. Thus,we have identified a novel,noncanonical pathway of DC differentiation. We term these PDDCs and show that PDDCs are bona fide DCs,based on phenotype and phagocytic activity when immature and the ability to up-regulate accessory molecules and stimulate allo-CD4(+) T cell proliferation when matured. The latter is dependent on the P. gingivalis strain used to initially educate" PDDCs. Moreover we show that P. gingivalis-infected conventional MoDCs become resistant to apoptosis and inflammatory pyroptosis as determined by levels of Annexin V and caspase-8 -3/7 and -1. Taken together we provide new insights into how a relatively asymptomatic bacteremia may influence immune homeostasis and promote chronic inflammation." View Publication

Our previous studies showed that anti-β2M monoclonal antibodies (mAbs) at high doses have direct apoptotic effects on myeloma cells,suggesting that anti-β2M mAbs might be developed as a novel therapeutic agent. In this study,we investigated the ability of the mAbs at much lower concentrations to indirectly kill myeloma cells by utilizing immune effector cells or molecules. Our results showed that anti-β2M mAbs effectively lysed MM cells via antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC),which were correlated with and dependent on the surface expression of β2M on MM cells. The presence of MM bone marrow stromal cells or addition of IL-6 did not attenuate anti-β2M mAb-induced ADCC and CDC activities against MM cells. Furthermore,anti-β2M mAbs only showed limited cytotoxicity toward normal B cells and nontumorous mesenchymal stem cells,indicating that the ADCC and CDC activities of the anti-β2M mAbs were more prone to the tumor cells. Lenalidomide potentiated in vitro ADCC activity against MM cells and in vivo tumor inhibition capacity induced by the anti-β2M mAbs by enhancing the activity of NK cells. These results support clinical development of anti-β2M mAbs,both as a monotherapy and in combination with lenalidomide,to improve MM patient outcome. View Publication

Traditionally,human embryonic stem cells (hESCs) are cultured on inactivated live feeder cells. For clinical application using hESCs,there is a requirement to minimize the risk of contamination with animal components. Extracellular matrix (ECM) derived from feeder cells is the most natural way to provide xeno-free substrates for hESC growth. In this study,we optimized the step-by-step procedure for ECM processing to develop a xeno-free ECM that supports the growth of undifferentiated hESCs. In addition,this newly developed xeno-free substrate can be stored at 4°C and is ready to use upon request,which serves as an easier way to amplify hESCs for clinical applications. View Publication