Chez les mammifères, on distingue principalement deux types de tissu adipeux (TA) : le TA blanc permet le stockage de l’énergie alors que le TA brun est spécialisé dans la thermogénèse induisant une dépense énergétique. Aujourd’hui, un troisième type d’adipocyte, nommé beige/ brite, est également reconnu. Ces cellules recrutées au sein du TA blanc, possèdent le même potentiel que les adipocytes bruns. L’identification des voies de signalisation permettant de réguler le développement des adipocytes blancs, beiges et bruns reste encore aujourd’hui à être déterminée. La génération des cellules souches pluripotentes induites (hiPS) a permis d’établir un nouveau modèle d’étude des étapes précoces de l’adipogénèse humaine. Nous avons démontré que la génération des progéniteurs adipeux (PA) blancs et bruns est régulée par la voie de l’acide rétinoïque pendant la différenciation in-vitro des cellules hiPS. La caractérisation moléculaire de ces deux types de PA a révélé l’implication du facteur Pax3 dans l’acquisition du phénotype brun. Au cours de cette étude, nous avons constaté que les PA dérivés de cellules hiPS (hiPSC-PA) présentaient un faible potentiel adipocytaire. Nous avons identifiés les facteurs permettant de différencier avec une forte efficacité les hiPSC-PA comprenant l’EGF, l’acide ascorbique, l’hydrocortisone et l’inhibiteur de la voie du TGFβ, le SB 431542. Lors d’expériences préliminaires, nous avons analysé l’effet de la surexpression du facteur HOXC8 sur la différenciation des PA. L’expression ectopique de ce facteur conduit à des réponses distinctes sur le phénotype et la différenciation des hiPSC-PA et ceux provenant de tissus adultes. / In mammals, two types of adipose tissue coexist: the white (WAT) wich is involved in energy storage and the brown (BAT) which is specialized in energy expenditure. Beige adipocytes have recently been described as brown –like adipocytes and represent a third type of adipocytes that are recruited in WAT. The molecular mechanisms involved in the generation of these different types of adipocytes remains unknow in humans, mainly because of the lack of appropriate in vitro cellular models. The human induced Pluripotent Stem (hips) cells are a good model to study the earliest steps of human adipogenesis. We have shown that the generation of white and brown adipocytes progenitors (AP) is regulated by acid retinoic signaling pathway during hips cells differentiation. Functional experiments indicated that the transcription factor Pax3 is a molecular mediator of the brown phenotype. During this study, we could see that AP derived from hips cells display a low adipogenic capacity as compared to progenitors derived from adult adipose tissue. We show in this work that treatment with TGFβ pathway inhibitor SB431542 together with ascorbic acid, hydrocortisone and EGF promoted differentiation of non- genetically modified hiPSCs-BAPs at a high rate. During preliminary results, we have analyzed the role of the transcription factor Hoxc8 on PA differentiation. The surexpression of this factor lead to distinct answers on the phenotype and differentiation between hiPSCs-AP and adult-derived AP.

Cardiovascular diseases are responsible for almost one third of all global deaths yearly, and therefore are largely studied. Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CM) have emerged as an exciting technology for cardiac disease modelling and personalised therapy. Nevertheless, issues concerning functional and molecular maturation are still faced. In addition to this, differentiation protocols generally yield a heterogeneous mixed population comprised of nodal, atrial and ventricular-like subtypes, being unsuitable for therapeutic purposes. Bradykinin (BK) is a vasoactive peptide which exerts important physiological roles in the cardiovascular system, having been previously described as important for cellular, keratinocyte and skeletal muscle differentiation. This project performed in cooperation with PluriCell Biotech, a startup specialized in the production and differentiation of hiPSC-CM, has sought (1) characterizing gene and protein expression of molecular markers of maturation and of subtype specification throughout of differentiation; (2) Assessing the electrical functionality of hiPSC-CM through the characterization of subtype-specific action potentials (APs) and (3) Investigating whether the progress of hiPSCCM maturation is regulated by BK through kinin-B2 receptors (B2R). Our results have validated the model that proposes a developmental-dependent switch between skeletal (ssTnI) and cardiac (cTnI) isoforms of troponin I as differentiation progresses, at least to some extent. Furthermore, prolonged time in culture has resulted in higher levels of expression of the ventricular marker MLC2v and in increased rates of ventricular-like action APs. Electrophysiological analysis of hiPSC-CM reveals a mixed population with AP morphologies correspondent to nodal, atrial and ventricular subtypes, all showing pronounced automaticity as well as other features of immature cardiomyocytes, such as low amplitude and depolarization velocity. Such findings are coherent with those from other groups who have attempted to differentiate mature native-like cardiac cells from pluripotent stem cells sources, without fully succeeding. After showing that differentiating hiPSC-CM express a functional and responsive B2R, the receptor was subjected to chronic activation with 10µM BK and 1µM BK or inhibition with 5µM Firazyr+BK. Even though B2R modulation has not interfered negatively with differentiation yields nor cell morphology, analysis of gene andprotein expression of ssTnI or cTnI and of the ventricular marker MLC2v, have revealed no significant results in comparison to untreated controls. This suggests that BK does not interfere on hiPSC-CM maturation nor subtype specification, although we cannot rule out that it could be leading to other unexplored effects. We recommend a closer look into which intracellular signalling pathways become active upon B2R stimulation in hiPSC-CM, in order to narrow down cellular processes for further investigation. / Doenças cardiovasculares são responsáveis por quase um terço de todas as mortes globais anualmente, e por isto o sistema cardiovascular é amplamente estudado. Cardiomiócitos derivados a partir de células-tronco pluripotentes induzidas humanas (hiPSCCM) emergiram como uma promissora tecnologia para modelagem de doenças cardíacas e terapia personalizada. No entanto, desafios acerca de sua maturação funcional e molecular ainda são enfrentados. Além disso, protocolos de diferenciação geralmente levam à obtenção de populações heterogêneas contendo células com fenótipos similares aos de cardiomiócitos nodais, atriais e ventriculares sendo, portanto, inapropriadas para fins terapêuticos. A bradicinina (BK) é um peptídio vasoativo que exerce importantes papeis fisiológicos no sistema cardiovascular, além de ter sido previamente descrita como importante para a diferenciação neuronal, de queratinócitos e de músculo esquelético. Este projeto foi realizado em colaboração com a empresa PluriCell Biotech, uma startup especializada na produção e diferenciação de hiPSC-CM, e buscou (1) caracterizar a expressão gênica e proteíca de marcadores moleculares de maturação e de especificação de subtipos cardíacos durante a diferenciação; (2) avaliar a funcionalidade elétrica de hiPSC-CM por meio da caracterização de seus potenciais de ação (PAs) e (3) Investigar se o progresso da diferenciação de hiPSCCM é regulado por bradicinina por meio do receptor B2 (B2R). Nossos resultados validaram o modelo que propõe um switch na expressão das isoformas funcionais de troponina I esquelética (ssTnI) e cardíaca (cTnI), durante o desenvolvimento e diferenciação celular, pelo menos parcialmente. Além disso, tempo prolongado em cultura resultou em maiores níveis de expressão do marcador ventricular MLC2v, assim como maiores frequências de PAs com morfologias similares a de cardiomiócitos ventriculares. Análise eletrofisiológica de hiPSCCM revelam a existência de uma população mista contendo PAs correspondentes aos subtipos nodais, atriais e ventriculares, assim como pronunciada automaticidade e outros atributos típicos de cardiomiócitos imaturos, como baixa amplitude e devagar velocidade de despolarização. Estes resultados são coerentes com os de outros grupos que ainda não foram totalmente bem-sucedidos em diferenciar células cardíacas maduras similares acardiomiócitos nativos a partir de células-troncos pluripotentes. Após mostrar que as hiPSCCM expressam receptores B2 funcionais e responsivos, submetemos o receptor a uma ativação crônica com BK 10µM e BK 1µM ou inibição crônica com Firazyr 5µM + BK. Apesar da modulação do B2R não ter interferido de forma negativa no rendimento da diferenciação ou na morfologia celular, análise de expressão gênica e proteica de ssTnI e cTnI e do marcador ventricular MLC2v não revelou resultados significativos em comparação aos controles não-tratados. Isto sugere que a BK não interfere na maturação e especificação de subtipos cardíacos em hiPSC-CM, apesar de não podermos ignorar o fato de que ela poderia estar desencadeando outros efeitos inexplorados. Nós recomendamos um estudo mais aprofundado acerca de quais vias de sinalização se tornam ativas após estimulação do receptor B2 em hiPSC-CM, com o objetivo de afunilar quais processos celulares poderiam ser investigados em uma próxima etapa deste estudo.

Cardiovascular diseases are responsible for almost one third of all global deaths yearly, and therefore are largely studied. Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CM) have emerged as an exciting technology for cardiac disease modelling and personalised therapy. Nevertheless, issues concerning functional and molecular maturation are still faced. In addition to this, differentiation protocols generally yield a heterogeneous mixed population comprised of nodal, atrial and ventricular-like subtypes, being unsuitable for therapeutic purposes. Bradykinin (BK) is a vasoactive peptide which exerts important physiological roles in the cardiovascular system, having been previously described as important for cellular, keratinocyte and skeletal muscle differentiation. This project performed in cooperation with PluriCell Biotech, a startup specialized in the production and differentiation of hiPSC-CM, has sought (1) characterizing gene and protein expression of molecular markers of maturation and of subtype specification throughout of differentiation; (2) Assessing the electrical functionality of hiPSC-CM through the characterization of subtype-specific action potentials (APs) and (3) Investigating whether the progress of hiPSCCM maturation is regulated by BK through kinin-B2 receptors (B2R). Our results have validated the model that proposes a developmental-dependent switch between skeletal (ssTnI) and cardiac (cTnI) isoforms of troponin I as differentiation progresses, at least to some extent. Furthermore, prolonged time in culture has resulted in higher levels of expression of the ventricular marker MLC2v and in increased rates of ventricular-like action APs. Electrophysiological analysis of hiPSC-CM reveals a mixed population with AP morphologies correspondent to nodal, atrial and ventricular subtypes, all showing pronounced automaticity as well as other features of immature cardiomyocytes, such as low amplitude and depolarization velocity. Such findings are coherent with those from other groups who have attempted to differentiate mature native-like cardiac cells from pluripotent stem cells sources, without fully succeeding. After showing that differentiating hiPSC-CM express a functional and responsive B2R, the receptor was subjected to chronic activation with 10µM BK and 1µM BK or inhibition with 5µM Firazyr+BK. Even though B2R modulation has not interfered negatively with differentiation yields nor cell morphology, analysis of gene andprotein expression of ssTnI or cTnI and of the ventricular marker MLC2v, have revealed no significant results in comparison to untreated controls. This suggests that BK does not interfere on hiPSC-CM maturation nor subtype specification, although we cannot rule out that it could be leading to other unexplored effects. We recommend a closer look into which intracellular signalling pathways become active upon B2R stimulation in hiPSC-CM, in order to narrow down cellular processes for further investigation. / Doenças cardiovasculares são responsáveis por quase um terço de todas as mortes globais anualmente, e por isto o sistema cardiovascular é amplamente estudado. Cardiomiócitos derivados a partir de células-tronco pluripotentes induzidas humanas (hiPSCCM) emergiram como uma promissora tecnologia para modelagem de doenças cardíacas e terapia personalizada. No entanto, desafios acerca de sua maturação funcional e molecular ainda são enfrentados. Além disso, protocolos de diferenciação geralmente levam à obtenção de populações heterogêneas contendo células com fenótipos similares aos de cardiomiócitos nodais, atriais e ventriculares sendo, portanto, inapropriadas para fins terapêuticos. A bradicinina (BK) é um peptídio vasoativo que exerce importantes papeis fisiológicos no sistema cardiovascular, além de ter sido previamente descrita como importante para a diferenciação neuronal, de queratinócitos e de músculo esquelético. Este projeto foi realizado em colaboração com a empresa PluriCell Biotech, uma startup especializada na produção e diferenciação de hiPSC-CM, e buscou (1) caracterizar a expressão gênica e proteíca de marcadores moleculares de maturação e de especificação de subtipos cardíacos durante a diferenciação; (2) avaliar a funcionalidade elétrica de hiPSC-CM por meio da caracterização de seus potenciais de ação (PAs) e (3) Investigar se o progresso da diferenciação de hiPSCCM é regulado por bradicinina por meio do receptor B2 (B2R). Nossos resultados validaram o modelo que propõe um switch na expressão das isoformas funcionais de troponina I esquelética (ssTnI) e cardíaca (cTnI), durante o desenvolvimento e diferenciação celular, pelo menos parcialmente. Além disso, tempo prolongado em cultura resultou em maiores níveis de expressão do marcador ventricular MLC2v, assim como maiores frequências de PAs com morfologias similares a de cardiomiócitos ventriculares. Análise eletrofisiológica de hiPSCCM revelam a existência de uma população mista contendo PAs correspondentes aos subtipos nodais, atriais e ventriculares, assim como pronunciada automaticidade e outros atributos típicos de cardiomiócitos imaturos, como baixa amplitude e devagar velocidade de despolarização. Estes resultados são coerentes com os de outros grupos que ainda não foram totalmente bem-sucedidos em diferenciar células cardíacas maduras similares acardiomiócitos nativos a partir de células-troncos pluripotentes. Após mostrar que as hiPSCCM expressam receptores B2 funcionais e responsivos, submetemos o receptor a uma ativação crônica com BK 10µM e BK 1µM ou inibição crônica com Firazyr 5µM + BK. Apesar da modulação do B2R não ter interferido de forma negativa no rendimento da diferenciação ou na morfologia celular, análise de expressão gênica e proteica de ssTnI e cTnI e do marcador ventricular MLC2v não revelou resultados significativos em comparação aos controles não-tratados. Isto sugere que a BK não interfere na maturação e especificação de subtipos cardíacos em hiPSC-CM, apesar de não podermos ignorar o fato de que ela poderia estar desencadeando outros efeitos inexplorados. Nós recomendamos um estudo mais aprofundado acerca de quais vias de sinalização se tornam ativas após estimulação do receptor B2 em hiPSC-CM, com o objetivo de afunilar quais processos celulares poderiam ser investigados em uma próxima etapa deste estudo.

abstract: Neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, or amyotrophic lateral sclerosis are defined by the loss of several types of neurons and glial cells within the central nervous system (CNS). Combatting these diseases requires a robust population of relevant cell types that can be employed in cell therapies, drug screening, or patient specific disease modeling. Human induced pluripotent stem cells (hiPSC)-derived neural progenitor cells (hNPCs) have the ability to self-renew indefinitely and differentiate into the various neuronal and glial cell types of the CNS. In order to realize the potential of hNPCs, it is necessary to develop a xeno-free scalable platform for effective expansion and differentiation. Previous work in the Brafman lab led to the engineering of a chemically defined substrate—vitronectin derived peptide (VDP), which allows for the long-term expansion and differentiation of hNPCs. In this work, we use this substrate as the basis for a microcarrier (MC)-based suspension culture system. Several independently derived hNPC lines were cultured on MCs for multiple passages as well as efficiently differentiated to neurons. Finally, this MC-based system was used in conjunction with a low shear rotating wall vessel (RWV) bioreactor for the integrated, large-scale expansion and neuronal differentiation of hNPCs. Finally, VDP was shown to support the differentiation of hNPCs into functional astrocytes. Overall, this fully defined and scalable biomanufacturing system will facilitate the generation of hNPCs and their derivatives in quantities necessary for basic and translational applications. / Dissertation/Thesis / Masters Thesis Biomedical Engineering 2018

BACKGROUND: The placenta is a multifunctional organ whose primary functions are to nourish and protect the fetus throughout gestation. The immune response of the placenta plays an important part in gestational outcome. Microbial infection during pregnancy can be detrimental to both maternal health and fetal development, increasing the risk for miscarriage, preterm birth, and congenital abnormalities. However, evaluating immunological response has been an on-going challenge for scientists and clinicians due to the complexity of the maternal-fetal interface. Research has been done to understand the mechanisms by which pathogens activate placental immune response, but our understanding is still lacking in many areas due to the dynamic changes that occur in immunology over the gestational timeline. The primary challenge faced by researchers is the availability of placental tissue, which is limited by donors and their finite viability in culture once harvested. Additionally, legal restrictions placed on fetal-tissue research have severely limited advancement in the field. Human induced pluripotent stem cells (hiPSCs) present a unique tool to study the differentiation of trophoblasts and maternal-placental immunology without the need of fetal tissue. OBJECTIVE: The goal of this project is to develop an in vitro model for studying placental immunology and pathogenesis using human induced pluripotent stem cell (hiPSC)-derived trophoblasts. Our aim is to report a robust protocol for producing hiPSC-derived trophoblasts and to characterize them against primary trophoblasts using both gene and protein expression detection techniques. Successful modeling of human trophoblasts would allow us the unique opportunity to investigate the cellular interface between the maternal and fetal systems without needing to isolate primary human trophoblasts. Once we produce and fully characterize several hiPSC cell clones from multiple normal individuals, we will demonstrate the use of these cells as a model for infections at the maternal-fetal interface by exposing them to viral pathogens known to target the placenta. METHODS: Earlier publications have reported the differentiation of embryonic stem cells into trophoblasts in culture by using bone morphogenetic protein-4 in conjunction with inhibitors of activin A and FGF2-signaling (BMP4/A83-01/PD173074; BAP-treatment). We applied this approach to hiPSC lines from two different lineage origins and characterized the outcome against known trophoblast markers. We also developed a novel approach to maintain proliferative trophoblast stem cells in culture long term. Two viral pathogens, a recombinant vesicular stomatitis virus strain engineered to express a green fluorescent protein (rVSV-GFP) and a strain of Zika virus (ZIKV-PRVABC59), were used to determine if it is possible to infect hiPSC-derived trophoblasts in culture. RESULTS: Using this approach, hiPSC readily differentiate into trophoblasts by day 8 of culture. These cells demonstrate formation of multinuclear syncytium, invasive capacities, and secretion of placental hormones. Further characterization using quantitative real-time PCR and immunofluorescent staining indicates that these cells express a number of trophoblast markers at levels comparable to those expressed by primary first-trimester trophoblasts. We were also able to maintain a putative CT population which retains the capacity to double and give rise to terminal cell types. HiPSC-derived trophoblasts infected with rVSV-GFP and ZIKV-PRVABC59 tested positive for viral infection by 72 hours post-infection (HPI), demonstrating the use of these cells as an in vitro model for studying placental pathogens at the maternal-fetal interface. / 2022-06-08T00:00:00Z

Indiana University-Purdue University Indianapolis (IUPUI) / Human pluripotent stem cells (hPSCs) have the ability to self renew indefinitely while maintaining their pluripotency, allowing for the study of virtually any human cell type in a dish. The focus of the current study was the differentiation of hPSCs to retinal ganglion cells (RGCs), the primary cell type affected in optic neuropathies. hPSCs were induced to become retinal cells using a stepwise differentiation protocol that allowed for formation of optic vesicle (OV)-like structures. Enrichment of OV like structures allowed for the definitive identification of RGCs. RGCs displayed the proper temporal, spatial, and phenotypic characteristics of RGCs developing in vivo. To test the ability of hPSC-RGCs to serve as a disease model, lines were generated from a patient with an E50K mutation in the Optineurin gene, causative for normal tension primary open angle glaucoma. E50K RGCs displayed significantly higher levels of apoptosis compared to a control lines. Apoptosis was reduced with exposure to neuroprotective factors. Lastly, hPSC-derived RGCs were studied for their ability to develop functional features possessed by mature in vivo RGCs. hPSC-derived RGCs displayed a few immature functional features and as such, strategies in which to expedite synaptogenesis using hPSC-derived astrocytes were explored. Astrocyte and RGG co-cultures displayed expedited synaptic and functional maturation, more closely resembling mature in vivo RGCs. Taken together, the results of this study have important implications for the study of RGC development and by extension, the advancement of translational therapies for optic neuropathies.

Les cellules souches induites à la pluripotence (iPSc) apparaissent comme une solution très intéressante pour créer et observer le comportement de cellules spécifiques et inaccessibles d'un patient. Notre équipe travaille sur les pathologies génétiques des nerfs périphériques et en particulier la maladie de Charcot-Marie-Tooth (CMT). Un de nos objectifs est le développement de modèles de motoneurones de patients utilisant la stratégie des iPSc afin de mieux comprendre la physiopathologie des neuropathies liées au gène GDAP1. Ce gène a été décrit en 1998 pour être responsable d'une forme axonale de CMT ; il code une protéine de la membrane externe mitochondriale dont la fonction précise reste encore méconnue. Des fibroblastes dermiques (FD) ont été obtenus après une biopsie de peau d'une personne saine (témoin) et d'un patient homozygote porteur de la mutation non-sens p.Gln163* dans le gène GDAP1. Par la suite, les FDs ont été reprogrammés en cellules iPSc en utilisant le cocktail de Yamanaka (plasmides non intégratifs composés d’Oct4, Sox2, Klf4 et l-Myc). Après amplification, tous les contrôles ont été effectués pour conclure que nos iPSc avaient les mêmes propriétés et les mêmes capacités que les cellules souches embryonnaires ainsi qu’un caryotype normal. Enfin, nous avons optimisé le protocole de différenciation avec succès de manière à obtenir à partir des iPSc des rosettes (structures pleines de progéniteurs neuronaux), puis des neurones et finalement des motoneurones pour le contrôle et le patient. Les premières différences entre le contrôle et le patient ont été observées lors de l’obtention de rosettes. Les cellules du patient présentaient de nombreuses gouttelettes lipidiques et la proportion de rosettes obtenue était plus faible. Une fois les motoneurones obtenus, des tests de microscopie confocale et électroniques ont montré des différences du réseau mitochondrial entre le témoin et le patient, ainsi qu’une morphologie des mitochondries se rapprochant de celle observée lors de biopsie de nerf de patient (rondes / accumulées). De manière à réduire la durée de différenciation, une méthode de tri cellulaire a été utilisée la SdFFF. Cette méthode nous a permis de trier différents progéniteurs (neuraux / endothéliaux). La génération de motoneurones à partir de fibroblastes dermiques de patient atteint de CMT axonale via les iPSc était une première étape cruciale pour mieux comprendre le rôle de GDAP1 dans cette pathologie. Ce modèle cellulaire de CMT4A est un premier pas pour réaliser des tests précliniques de médicaments afin d'identifier de futurs candidats pharmacologiques. / Induced pluripotent stem cells (iPSc) are a highly interesting tool to create and observe the behavior of specific and unattainable cells from a patient. Our team is interested in genetic peripheral nerves disorders and especially in Charcot-Marie-Tooth disease (CMT). One of our objectives is the development of motor neurons models from patients using the iPSc strategy in order to better understand the pathophysiology of GDAP1-related neuropathies. This gene was found in 1998 to be mutated in an axonal form of CMT and encodes a mitochondrial outer membrane protein, which function remains unclear. We first obtained dermal fibroblasts (DF) from skin biopsies of a healthy person and of a homozygous patient carrying GDAP1 non-sense mutation (p.Gln163*). Then, we reprogrammed DFs into iPSc using non-integrative plasmids (Oct4, Sox2, Klf4 and l-Myc). After amplification, all quality controls were performed to conclude that our iPSc had the same properties and capacities than embryonic stem cells and a normal karyotype. Finally, we optimized protocols to successfully differentiate these iPSc into rosettes (structures full of neural progenitors), then into neurons and finally into motor neurons for control and GDAP1 patients. The first differences between control and patient cells were observed during the rosette formation, where a lot of patient cells were full of lipid droplets, and the rosette proportion was lower than the control cells. Mitochondria morphology was totally different in motor neurons between control and patient, where mitochondria had the same morphology than the mitochondria observed in patient nerve biopsies (round and accumulated). In order to reduce the time of differentiation, a cell sorting method was used (SdFFF). It allowed us to sort different progenitors (neural / endothelial). Generation of motor neurons using axonal CMT-patient-derived iPSc was a first crucial step to better understand the role of GDAP1 in this pathology. This cellular model of CMT4A should ultimately allow us to perform preclinical drug screening in order to identify candidate pharmacological treatments for CMT patients.

BACKGROUND: Inflammation is a key regulator in skeletal homeostasis during normal growth and tissue repair. However, the role that inflammation plays in skeletal processes is not well understood. Previous studies showed that damage associated molecular pattern (DAMP) molecules released after injury may contribute to immune activation and subsequent fibrosis. OBJECTIVE: This project aims to elucidate the link between tissue damage caused by trauma and the subsequent inflammatory response in a genetic condition of bone morphogenetic protein (BMP) pathway over activation. METHODS: We investigated this potential link by examining immune cells from patients with fibrodysplasia ossificans progressiva (FOP), a genetic condition of endochondral heterotopic ossification caused by activating mutations in the Activin A type I receptor (ACVR1). Patients with FOP show sensitivity to trauma, elevated serum cytokines and abnormal cytokine/chemokine secretion from monocytes and macrophages when stimulated with lipopolysaccharide in vitro. This suggested that BMP pathway activation may alter immune responses in patients with FOP. We studied macrophages derived from peripheral blood monocytes or created from human induced pluripotent stem cells (iPSC) from FOP and control subjects. Macrophages were evaluated by gene expression and culture media by multiplex cytokine analysis after stimulation with key DAMPs that were previously identified to be released after tissue injury. These DAMPs act as endogenous activators of inflammation. RESULTS: Monocyte derived macrophages from control subjects showed increased expression of pro-inflammatory cytokines in response to stimulation with DAMPs, HMGB1 and S100A8/A9. FOP monocyte-derived macrophages treated with each DAMP showed elevated production of CCL22, IL-8, CCL3, and CCL8 when compared to control macrophages. However, both control and FOP macrophages showed increased production of pro-inflammatory cytokines in response to DAMPs compared to non-stimulated conditions. RNA expression profiles of FOP iPSC derived macrophages did not show significantly increased responsiveness to DAMPs compared to control. Surprisingly, control patient iPSC derived macrophages show elevated expression of TNF-a and IL-1B CONCLUSIONS: Macrophages derived from peripheral blood monocytes show that DAMPs may be responsible for macrophage activation and the development of inflammatory complications in patients with FOP. Control iPSC derived macrophages showed similarity to monocyte derived macrophages in their response to DAMPs, suggesting that our iPSC derived macrophages are an applicable model for investigating the human immune system. The dissimilarity in FOP macrophage responsiveness to endogenous activators of our two macrophage models, suggest that iPSC derived macrophages may be affected by the different differentiation and polarization methods, and needs to be characterized further. Similarly, RNA expression profiles may not reflect cytokine production patterns of stimulated iPSC macrophages and warrants further studies. / 2021-06-07T00:00:00Z

Familial hypertrophic cardiomyopathy (HCM) is a genetic disease largely caused by a mutation in myosin binding protein C (MYBPC3) and it affects about 1:500 population leading to arrhythmic sudden death, heart failure, and atrial fibrillation. MYBPC3 activates calcium-induced actin-myosin filament sliding within the cardiac sarcomere, creating the force necessary for heart contraction. The underlying molecular mechanisms causing HCM phenotype remain elusive, therefore, there is an urgent need for a reliable in vitro human HCM model to investigate the pathogenesis of HCM. This study utilized isogenic human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) with MYBPC3 gene mutation (wildtype, heterozygous, homozygous) and further micropatterned them into fiber-like structures on polyacrylamide hydrogels of physiological and fibrotic-like stiffnesses. Cells were cultured for an extended culture time up to 60 days and their morphology/attachment, contractility, and calcium transient were extensively and carefully evaluated. It was found that MYBPC3 knockout cells maintained the highest contraction amplitude, but had increased contraction, and relaxation durations, decreased calcium transient amplitude, as well as time to peak and decay times over the culture period in comparison to the isogenic wildtype. Overall, this study demonstrates that hiPSC-CMs can be successfully patterned and cultured for an extended time on hydrogels forming end-to-end connections, which can be served as a simple yet effective in vitro human model for studying mechanical dysfunction of HCM.

京都大学 / 新制・論文博士 / 博士(医学) / 乙第13539号 / 論医博第2279号 / 新制||医||1065(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 江藤 浩之, 教授 黒田 知宏, 教授 西浦 博 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM