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Neurogenesis in the subventricular zone (SVZ) is regulated by diffusible factors and cell-cell contacts. In vivo,SVZ stem cells are associated with the abluminal surface of blood vessels and such interactions are thought to regulate their neurogenic capacity. SVZ neural stem cells (NSCs) have been described to contact endothelial-derived laminin via α6β1 integrin. To elucidate whether heterocellular contacts with brain endothelial cells (BEC) regulate SVZ cells neurogenic capacities,cocultures of SVZ neurospheres and primary BEC,both obtained from C57BL/6 mice,were performed. The involvement of laminin-integrin interactions in SVZ homeostasis was tested in three ways. Firstly,SVZ cells were analyzed following incubation of BEC with the protein synthesis inhibitor cycloheximide (CHX) prior to coculture,a treatment expected to decrease membrane proteins. Secondly,SVZ cells were cocultured with BEC in the presence of an anti-α6 integrin neutralizing antibody. Thirdly,BEC were cultured with β1-/- SVZ cells. We showed that contact with BEC supports,at least in part,proliferation and stemness of SVZ cells,as evaluated by the number of BrdU positive (+) and Sox2+ cells in contact with BEC. These effects are dependent on BEC-derived laminin binding to α6β1 integrin and are decreased in cocultures incubated with anti-α6 integrin neutralizing antibody and in cocultures with SVZ β1-/- cells. Moreover,BEC-derived laminin sustains stemness in SVZ cell cultures via activation of the Notch and mTOR signaling pathways. Our results show that BEC/SVZ interactions involving α6β1 integrin binding to laminin,contribute to SVZ cell proliferation and stemness. View Publication

Here,we show for the first time,that the familial breast/ovarian cancer susceptibility gene BRCA1 activates the Notch pathway in breast cells by transcriptional upregulation of Notch ligands and receptors in both normal and cancer cells. We demonstrate through chromatin immunoprecipitation assays that BRCA1 is localized to a conserved intronic enhancer region within the Notch ligand Jagged-1 (JAG1) gene,an event requiring $$Np63. We propose that this BRCA1/$$Np63-mediated induction of JAG1 may be important the regulation of breast stem/precursor cells,as knockdown of all three proteins resulted in increased tumoursphere growth and increased activity of stem cell markers such as Aldehyde Dehydrogenase 1 (ALDH1). Knockdown of Notch1 and JAG1 phenocopied BRCA1 knockdown resulting in the loss of Estrogen Receptor-$$ (ER-$$) expression and other luminal markers. A Notch mimetic peptide could activate an ER-$$ promoter reporter in a BRCA1-dependent manner,whereas Notch inhibition using a $$-secretase inhibitor reversed this process. We demonstrate that inhibition of Notch signalling resulted in decreased sensitivity to the anti-estrogen drug Tamoxifen but increased expression of markers associated with basal-like breast cancer. Together,these findings suggest that BRCA1 transcriptional upregulation of Notch signalling is a key event in the normal differentiation process in breast tissue. View Publication

Pantothenate kinase-associated neurodegeneration (PKAN) is an early onset and severely disabling neurodegenerative disease for which no therapy is available. PKAN is caused by mutations in PANK2,which encodes for the mitochondrial enzyme pantothenate kinase 2. Its function is to catalyze the first limiting step of Coenzyme A (CoA) biosynthesis. We generated induced pluripotent stem cells from PKAN patients and showed that their derived neurons exhibited premature death,increased ROS production,mitochondrial dysfunctions-including impairment of mitochondrial iron-dependent biosynthesis-and major membrane excitability defects. CoA supplementation prevented neuronal death and ROS formation by restoring mitochondrial and neuronal functionality. Our findings provide direct evidence that PANK2 malfunctioning is responsible for abnormal phenotypes in human neuronal cells and indicate CoA treatment as a possible therapeutic intervention. View Publication

Human embryonic stem cells (hESCs) and induced pluripotent cells have the potential to provide an unlimited source of tissues for regenerative medicine. For this purpose,development of defined/xeno-free culture systems under feeder-free conditions is essential for the expansion of hESCs. Most defined/xeno-free media for the culture of hESCs contain basic fibroblast growth factor (bFGF). Therefore,bFGF is thought to have an almost essential role for the expansion of hESCs in an undifferentiated state. Here,we report identification of small molecules,some of which were neurotransmitter antagonists (trimipramine and ethopropazine),which promote long-term hESC self-renewal without bFGF in the medium. The hESCs maintained high expression levels of pluripotency markers,had a normal karyotype after 20 passages,and could differentiate into all three germ layers. ?? 2013 Elsevier Inc. View Publication

Factor induced reprogramming of fibroblasts is an orchestrated but inefficient process. At the epigenetic level,it results in drastic chromatin changes to erase the existing somatic memory" and to establish the pluripotent state. Accordingly� View Publication

Blood of both humans and mice contains 2 main monocyte subsets. Here,we investigated the extent of their similarity using a microarray approach. Approximately 270 genes in humans and 550 genes in mice were differentially expressed between subsets by 2-fold or more. More than 130 of these gene expression differences were conserved between mouse and human monocyte subsets. We confirmed numerous of these differences at the cell surface protein level. Despite overall conservation,some molecules were conversely expressed between the 2 species' subsets,including CD36,CD9,and TREM-1. Other differences included a prominent peroxisome proliferator-activated receptor gamma (PPARgamma) signature in mouse monocytes,which is absent in humans,and strikingly opposed patterns of receptors involved in uptake of apoptotic cells and other phagocytic cargo between human and mouse monocyte subsets. Thus,whereas human and mouse monocyte subsets are far more broadly conserved than currently recognized,important differences between the species deserve consideration when models of human disease are studied in mice. View Publication

Inclusion body myositis (IBM) is an inflammatory myopathy that displays proximal and distal muscle weakness. At the histopathological level,the muscles of IBM patients show inflammatory infiltrates,rimmed vacuoles and mitochondrial changes. The etiology of IBM remains unknown,and there is a lack of validated disease models,biomarkers and effective treatments. To contribute to unveil disease underpins we developed a cell model based on myotubes derived from induced pluripotent stem cells (iPSC-myotubes) from IBM patients and compared the molecular phenotype vs. age and sex-paired controls (n?=?3 IBM and 4 CTL). We evaluated protein histological findings and the gene expression profile by mRNA-seq,alongside functional analysis of inflammation,degeneration and mitochondrial function. Briefly,IBM iPSC-myotubes replicated relevant muscle histopathology features of IBM,including aberrant expression of HLA,TDP-43 and COX markers. mRNA seq analysis identified 1007 differentially expressed genes (DEGs) (p-value adj? View Publication

The MAPT gene encodes Tau protein,a member of the large family of microtubule-associated proteins. Tau forms large insoluble aggregates that are toxic to neurons in several neurological disorders,and neurofibrillary Tau tangles represent a key pathological hallmark of Alzheimer’s disease (AD) and other tauopathies. Lowering Tau expression levels constitutes a potential treatment for AD but the mechanisms that regulate Tau expression at the transcriptional or translational level are not well understood. Natural antisense transcripts (NATs) are a particular class of long non-coding RNAs (lncRNAs) that can regulate expression of their overlapping protein-coding genes at the epigenetic,transcriptional,or translational level. We and others identified a long non-coding RNA associated with the MAPT gene,named MAPT antisense 1 (MAPT-AS1). We confirmed that MAPT-AS1 is expressed in neurons in human post mortem brain tissue. To study the role of MAPT-AS1 on MAPT expression regulation,we modulated the expression of this lncRNA in human neuroblastoma cell lines and in human induced pluripotent stem cell (iPSC) derived neurons. In contrast to previous reports,we observed no changes on MAPT mRNA or Tau protein levels upon modulation of MAPT-AS1 levels in these cellular models. Our data suggest that MAPT-AS1 does not regulate Tau expression levels in human neurons in vitro. Thus,MAPT-AS1 does not represent a valuable therapeutic target to lower Tau expression in patients affected by tauopathies including AD. View Publication

Organoids,derived from human induced pluripotent stem cells (hiPSCs),are intricate three-dimensional in vitro structures that mimic many key aspects of the complex morphology and functions of in vivo organs such as the retina and heart. Traditional histological methods,while crucial,often fall short in analyzing these dynamic structures due to their inherently static and destructive nature. In this study,we leveraged the capabilities of optical coherence tomography (OCT) for rapid,non-invasive imaging of both retinal,cerebral,and cardiac organoids. Complementing this,we developed a sophisticated deep learning approach to automatically segment the organoid tissues and their internal structures,such as hollows and chambers. Utilizing this advanced imaging and analysis platform,we quantitatively assessed critical parameters,including size,area,volume,and cardiac beating,offering a comprehensive live characterization and classification of the organoids. These findings provide profound insights into the differentiation and developmental processes of organoids,positioning quantitative OCT imaging as a potentially transformative tool for future organoid research. View Publication

Artificial skin models have emerged as valuable tools for evaluating cosmetic ingredients and developing treatments for skin regeneration. Among them,3D skin equivalent models (SKEs) using human primary skin cells are widely utilized and supported by standardized testing guidelines. However,primary cells face limitations such as restricted donor availability and challenges in conducting genotype-specific studies. To overcome these issues,recent approaches have focused on differentiating skin cells from human-induced pluripotent stem cells (hiPSCs). In this study,we developed a protocol to differentiate high-purity skin cells,such as fibroblasts (hFIBROs) and keratinocytes (hKERAs),from hiPSCs. To construct the hiPSC-derived SKE (hiPSC-SKE),a dermis was first formed by culturing a collagen and hFIBROs mixture within an insert. Subsequently,hKERAs were seeded onto the dermis,and keratinization was induced under air-liquid culture conditions to establish an epidermis. Histological analysis with hematoxylin and eosin staining confirmed that the hiPSC-SKE recapitulated the layered architecture of native human skin and expressed appropriate epidermal and dermal markers. Moreover,exposure to Triton X-100,a known skin irritant,led to marked epidermal damage and significantly reduced cell viability,validating the model’s functional responsiveness. These findings indicate that the hiPSC-SKE model represents a promising alternative for various skin-related applications,including the replacement of animal testing. View Publication

Outer radial glia (oRG) emerge as cortical progenitor cells that support the development of an enlarged outer subventricular zone (oSVZ) and the expansion of the neocortex. The in vitro generation of oRG is essential to investigate the underlying mechanisms of human neocortical development and expansion. By activating the STAT3 signaling pathway using leukemia inhibitory factor (LIF),which is not expressed in guided cortical organoids,we define a cortical organoid differentiation method from human pluripotent stem cells (hPSCs) that recapitulates the expansion of a progenitor pool into the oSVZ. The oSVZ comprises progenitor cells expressing specific oRG markers such as GFAP,LIFR,and HOPX,closely matching human fetal oRG. Finally,incorporating neural crest-derived LIF-producing cortical pericytes into cortical organoids recapitulates the effects of LIF treatment. These data indicate that increasing the cellular complexity of the organoid microenvironment promotes the emergence of oRG and supports a platform to study oRG in hPSC-derived brain organoids routinely. View Publication

CD38,an ecto-enzyme involved in NAD + catabolism,is highly expressed in exhausted CD8 + T cells and has emerged as an attractive target to improve response to immune checkpoint blockade (ICB) by blunting T cell exhaustion. However,the precise role(s) and regulation of CD38 in exhausted T cells and the efficacy of CD38-directed therapeutic strategies in human cancer remain incompletely defined. Here,we show that CD38 + CD8 + T cells are induced by chronic TCR activation and type I interferon stimulation and confirm their association with ICB resistance in human melanoma. Disrupting CD38 restores cellular NAD + pools and improves T cell bioenergetics and effector functions. Targeting CD38 restores ICB sensitivity in a cohort of patient-derived organotypic tumor spheroids from explanted melanoma specimens. These results support further preclinical and clinical evaluation of CD38-directed therapies in melanoma and underscore the importance of NAD + as a vital metabolite to enhance those therapies. View Publication