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We demonstrate a highly efficient method for gene delivery into clinically relevant human cell types,such as induced pluripotent stem cells (iPSCs) and fibroblasts,reducing the protocol time by one full day. To preserve cell physiology during gene transfer,we designed a microfluidic strategy,which facilitates significant gene delivery in a short transfection time (textless1 min) for several human cell types. This fast,optimized and generally applicable cell transfection method can be used for rapid screening of different delivery systems and has significant potential for high-throughput cell therapy applications. View Publication

Myoclonus epilepsy associated with ragged-red fibers (MERRF) is a mitochondrial disorder characterized by myoclonus epilepsy,generalized seizures,ataxia and myopathy. MERRF syndrome is primarily due to an A to G mutation at mtDNA 8344 that disrupts the mitochondrial gene for tRNA(Lys). However,the detailed mechanism by which this tRNA(Lys) mutation causes mitochondrial dysfunction in cardiomyocytes or neurons remains unclear. In this study,we generated human induced pluripotent stem cells (hiPSCs) that carry the A8344G genetic mutation from patients with MERRF syndrome. Compared with mutation-free isogenic hiPSCs,MERRF-specific hiPSCs (MERRF-hiPSCs) exhibited reduced oxygen consumption,elevated reactive oxygen species (ROS) production,reduced growth,and fragmented mitochondrial morphology. We sought to investigate the induction ability and mitochondrial function of cardiomyocyte-like cells differentiated from MERRF-hiPSCs. Our data demonstrate that that cardiomyocyte-like cells (MERRF-CMs) or neural progenitor cells (MERRF-NPCs) differentiated from MERRF-iPSCs also exhibited increased ROS levels and altered antioxidant gene expression. Furthermore,MERRF-CMs or -NPCs contained fragmented mitochondria,as evidenced by MitoTracker Red staining and transmission electron microscopy. Taken together,these findings showed that MERRF-hiPSCs and MERRF-CM or -NPC harboring the A8344G genetic mutation displayed contained mitochondria with an abnormal ultrastructure,produced increased ROS levels,and expressed upregulated antioxidant genes. View Publication

Under defined differentiation conditions,human embryonic stem cells (hESCs) can be directed toward a mesendoderm (ME) or neuroectoderm (NE) fate,the first decision during hESC differentiation. Coupled with lineage-specific G1 lengthening,a divergent ciliation pattern emerged within the first 24 hr of induced lineage specification,and these changes heralded a neuroectoderm decision before any neural precursor markers were expressed. By day 2,increased ciliation in NE precursors induced autophagy that resulted in the inactivation of Nrf2 and thereby relieved transcriptional activation of OCT4 and NANOG. Nrf2 binds directly to upstream regions of these pluripotency genes to promote their expression and repress NE derivation. Nrf2 suppression was sufficient to rescue poorly neurogenic iPSC lines. Only after these events had been initiated did neural precursor markers get expressed at day 4. Thus,we have identified a primary cilium-autophagy-Nrf2 (PAN) control axis coupled to cell-cycle progression that directs hESCs toward NE. View Publication

The neutralization of integrin α4 (Itga4) is currently used as treatment in multiple sclerosis. Although most studies have focused on its function on lymphocyte migration to the CNS,we have uncovered the importance of Itga4 for the generation of regulatory B cells in peripheral immune organs and their control of pathogenic T cell response and CNS pathology. Our study underscores the importance of looking at the dual role of B cells in CNS autoimmunity and provides important perspectives regarding the efficacy and side effects associated with Itga4 neutralization and other B cell-targeting therapies. View Publication

Innate Defense Regulators (IDRs) are short synthetic peptides that target the host innate immune system via an intracellular adaptor protein which functions at key signaling nodes. In this work,further details of the mechanism of action of IDRs have been discovered. The studies reported here show that the lead clinical IDR,SGX94,has broad-spectrum activity against Gram-negative and Gram-positive bacterial infections caused by intracellular or extracellular bacteria and also complements the actions of standard of care antibiotics. Based on in vivo and primary cell culture studies,this activity is shown to result from the primary action of SGX94 on tissue-resident cells and subsequent secondary signaling to activate myeloid-derived cells,resulting in enhanced bacterial clearance and increased survival. Data from non-clinical and clinical studies also show that SGX94 treatment modulates pro-inflammatory and anti-inflammatory cytokine levels,thereby mitigating the deleterious inflammatory consequences of innate immune activation. Since they act through host pathways to provide both broad-spectrum anti-infective capability as well as control of inflammation,IDRs are unlikely to be impacted by resistance mechanisms and offer potential clinical advantages in the fight against emerging and antibiotic resistant bacterial infections. View Publication

Immune recognition by T cells relies on the presentation of pathogen-derived peptides by infected cells,but the persistence of chronic infections calls for new approaches to modulate immune recognition. Ag cross-presentation,the process by which pathogen Ags are internalized,degraded,and presented by MHC class I,is crucial to prime CD8 T cell responses. The original degradation of Ags is performed by pH-dependent endolysosomal cathepsins. In this article,we show that HIV protease inhibitors (PIs) prescribed to HIV-infected persons variably modulate cathepsin activities in human APCs,dendritic cells and macrophages,and CD4 T cells,three cell subsets infected by HIV. Two HIV PIs acted in two complementary ways on cathepsin hydrolytic activities: directly on cathepsins and indirectly on their regulators by inhibiting Akt kinase activities,reducing NADPH oxidase 2 activation,and lowering phagolysosomal reactive oxygen species production and pH,which led to enhanced cathepsin activities. HIV PIs modified endolysosomal degradation and epitope production of proteins from HIV and other pathogens in a sequence-dependent manner. They altered cross-presentation of Ags by dendritic cells to epitope-specific T cells and T cell-mediated killing. HIV PI-induced modulation of Ag processing partly changed the MHC self-peptidome displayed by primary human cells. This first identification,to our knowledge,of prescription drugs modifying the regulation of cathepsin activities and the MHC-peptidome may provide an alternate therapeutic approach to modulate immune recognition in immune disease beyond HIV. View Publication

mTOR inhibition is beneficial in neurodegenerative disease models and its effects are often attributable to the modulation of autophagy and anti-apoptosis. Here,we report a neglected but important bioenergetic effect of mTOR inhibition in neurons. mTOR inhibition by rapamycin significantly preserves neuronal ATP levels,particularly when oxidative phosphorylation is impaired,such as in neurons treated with mitochondrial inhibitors,or in neurons derived from maternally inherited Leigh syndrome (MILS) patient iPS cells with ATP synthase deficiency. Rapamycin treatment significantly improves the resistance of MILS neurons to glutamate toxicity. Surprisingly,in mitochondrially defective neurons,but not neuroprogenitor cells,ribosomal S6 and S6 kinase phosphorylation increased over time,despite activation of AMPK,which is often linked to mTOR inhibition. A rapamycin-induced decrease in protein synthesis,a major energy-consuming process,may account for its ATP-saving effect. We propose that a mild reduction in protein synthesis may have the potential to treat mitochondria-related neurodegeneration. View Publication

textlessptextgreater Hundreds of textlessitalictextgreaterL1CAMtextless/italictextgreater gene mutations have been shown to be associated with congenital hydrocephalus,severe intellectual disability,aphasia,and motor symptoms. How such mutations impair neuronal function,however,remains unclear. Here,we generated human embryonic stem (ES) cells carrying a conditional textlessitalictextgreaterL1CAMtextless/italictextgreater loss-of-function mutation and produced precisely matching control and textlessitalictextgreaterL1CAMtextless/italictextgreater -deficient neurons from these ES cells. In analyzing two independent conditionally mutant ES cell clones,we found that deletion of textlessitalictextgreaterL1CAMtextless/italictextgreater dramatically impaired axonal elongation and,to a lesser extent,dendritic arborization. Unexpectedly,we also detected an ∼20–50% and ∼20–30% decrease,respectively,in the levels of ankyrinG and ankyrinB protein,and observed that the size and intensity of ankyrinG staining in the axon initial segment was significantly reduced. Overexpression of wild-type L1CAM,but not of the L1CAM point mutants R1166X and S1224L,rescued the decrease in ankyrin levels. Importantly,we found that the textlessitalictextgreaterL1CAMtextless/italictextgreater mutation selectively decreased activity-dependent Na textlesssuptextgreater+textless/suptextgreater -currents,altered neuronal excitability,and caused impairments in action potential (AP) generation. Thus,our results suggest that the clinical presentations of textlessitalictextgreaterL1CAMtextless/italictextgreater mutations in human patients could be accounted for,at least in part,by cell-autonomous changes in the functional development of neurons,such that neurons are unable to develop normal axons and dendrites and to generate normal APs. textless/ptextgreater View Publication

Smith-Lemli-Opitz syndrome (SLOS) is a malformation disorder caused by mutations in DHCR7,which impair the reduction of 7-dehydrocholesterol (7DHC) to cholesterol. SLOS results in cognitive impairment,behavioral abnormalities and nervous system defects,though neither affected cell types nor impaired signaling pathways are fully understood. Whether 7DHC accumulation or cholesterol loss is primarily responsible for disease pathogenesis is also unclear. Using induced pluripotent stem cells (iPSCs) from subjects with SLOS,we identified cellular defects that lead to precocious neuronal specification within SLOS derived neural progenitors. We also demonstrated that 7DHC accumulation,not cholesterol deficiency,is critical for SLOS-associated defects. We further identified downregulation of Wnt/$$-catenin signaling as a key initiator of aberrant SLOS iPSC differentiation through the direct inhibitory effects of 7DHC on the formation of an active Wnt receptor complex. Activation of canonical Wnt signaling prevented the neural phenotypes observed in SLOS iPSCs,suggesting that Wnt signaling may be a promising therapeutic target for SLOS. View Publication

Human embryonic stem cell (hESC) line was derived from abnormal blastocyst donated by Marfan syndrome patient after preimpantation genetic diagnosis (PGD) treatment. DNA sequencing analysis confirmed that the hESC line carried the heterozygous deletion mutation,c.3536delA,of FBN1 gene. Characteristic tests proved that the hESC line presented typicalmarkers of pluripotency and had the capability to formthe three germlayers both in vitro and in vivo. View Publication

Human induced pluripotent stem cells (iPSCs) and derived progeny provide invaluable regenerative platforms,yet their clinical translation has been compromised by their biosafety concern. Here,we assessed the safety of transplanting patient-derived iPSC-generated pancreatic endoderm/ progenitor cells. Transplantation of progenitors from iPSCs reprogrammed by lentiviral vectors (LV-iPSCs) led to the formation of invasive teratocarcinoma-like tumors in more than 90% of immu-nodeficient mice. Moreover,removal of primary tumors from LV-iPSC progeny-transplanted hosts generated secondary and metastatic tumors. Combined transgene-free (TGF) reprogramming and elimination of residual pluripotent cells by enzymatic dissociation ensured tumor-free transplanta-tion,ultimately enabling regeneration of type 1 diabetes-specific human islet structures in vivo. The incidence of tumor formation in TGF-iPSCs was titratable,depending on the oncogenic load,with reintegration of the cMYC expressing vector abolishing tumor-free transplantation. Thus,transgene-free cMYC-independent reprogramming and elimination of residual pluripotent cells are mandatory steps in achieving transplantation of iPSC progeny for customized and safe islet regeneration in vivo. STEM CELLS TRANSLATIONAL MEDICINE 2016;5:694–702 SIGNIFICANCE Pluripotent stem cell therapy for diabetes relies on the safety as well as the quality of derived insulin-producing cells. Data from this study highlight prominent tumorigenic risks of induced pluripotent stem cell (iPSC) products,especially when reprogrammed with integrating vectors. Two major under-lying mechanisms in iPSC tumorigenicity are residual pluripotent cells and cMYC overload by vector integration. This study also demonstrated that combined transgene-free reprogramming and enzy-matic dissociation allows teratoma-free transplantation of iPSC progeny in the mouse model in test-ing the tumorigenicity of iPSC products. Further safety assessment and improvement in iPSC specification into a mature b cell phenotype would lead to safe islet replacement therapy for diabetes. View Publication

BACKGROUND The clinical use of doxorubicin is limited by cardiotoxicity. Histopathological changes include interstitial myocardial fibrosis and the appearance of vacuolated cardiomyocytes. Whereas dysregulation of autophagy in the myocardium has been implicated in a variety of cardiovascular diseases,the role of autophagy in doxorubicin cardiomyopathy remains poorly defined. METHODS AND RESULTS Most models of doxorubicin cardiotoxicity involve intraperitoneal injection of high-dose drug,which elicits lethargy,anorexia,weight loss,and peritoneal fibrosis,all of which confound the interpretation of autophagy. Given this,we first established a model that provokes modest and progressive cardiotoxicity without constitutional symptoms,reminiscent of the effects seen in patients. We report that doxorubicin blocks cardiomyocyte autophagic flux in vivo and in cardiomyocytes in culture. This block was accompanied by robust accumulation of undegraded autolysosomes. We go on to localize the site of block as a defect in lysosome acidification. To test the functional relevance of doxorubicin-triggered autolysosome accumulation,we studied animals with diminished autophagic activity resulting from haploinsufficiency for Beclin 1. Beclin 1(+/-) mice exposed to doxorubicin were protected in terms of structural and functional changes within the myocardium. Conversely,animals overexpressing Beclin 1 manifested an amplified cardiotoxic response. CONCLUSIONS Doxorubicin blocks autophagic flux in cardiomyocytes by impairing lysosome acidification and lysosomal function. Reducing autophagy initiation protects against doxorubicin cardiotoxicity. View Publication