Differentiation Of iPSCs Research Articles

APPLICATION OF GENETICALLY MODIFIED INDUCED PLURIPOTENT STEM CELL LINES IN ARTICULAR CARTILAGE TISSUE ENGINEERING

The restoration of hyaline cartilage poses a complex clinical and scientific challenge due to its low regenerative potential. Joint cartilage injuries contribute to the development of osteoarthritis and, as a consequence, loss of joint function, and subsequent disability. Surgical approaches such as mosaic chondroplasty and microfracture are applicable only to relatively small defects and are unsuitable for patients with degenerative cartilage conditions. Developing of cell therapies using chondrocytes differentiated from induced pluripotent stem cells (iPSCs) is a promising direction for joint cartilage tissue reconstruction. iPSCs have high proliferative activity, allowing the generation of autologous cells in the amount required to restore an individual’s articular defect. The CRISPR-Cas genome editing technology, based on the bacterial adaptive immune system, enables genetic modification of iPSCs to produce progenitor cells with specific characteristics and properties. This review contains scientific studies of highly specialized focus on combining iPSC and CRISPR-Cas technologies for research in cartilage regenerative medicine. We have compiled articles over the past twelve years, since CRISPR-Cas became available to the world community. Currently, for the field of regenerative medicine of articular cartilage CRISPR-Cas is used to increase the effectiveness of chondrogenic differentiation of iPSCs and to obtain a chondroprogenitor population with a high homogeneity. Additionally, deletion of a sequence of pro-inflammatory cytokine receptors is conducted to produce inflammation-resistant tissue. Finally, knockout of major histocompatibility complex components allows the creation of hypoimmunogenic chondrocytes. These approaches contribute to the development of personalized medicine and may, in the long term, lead to improved quality of life for the global population.

The role and mechanism of NRG1/ErbB4 in inducing the differentiation of induced pluripotent stem cells into cardiomyocytes

BackgroundWe aimed to investigate the effect and potential mechanism of enhancing Neuregulin1 (NRG1)/v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 4 (ErbB4) expression on the differentiation of induced pluripotent stem cells (iPSCs) into cardiomyocytes.MethodsWe utilized CRISPR-CAS9 technology to knock in ErbB4 and obtained a single-cell clone IPSN-AAVS1-CMV-ErbB4 (iPSCs-ErbB4). Subsequently, we induced the differentiation of iPSCs into cardiomyocytes and quantified the number of beating embryoid bodies. Furthermore, quantitative real-time PCR assessed the expression of cardiomyocyte markers, including ANP (atrial natriuretic peptide), Nkx2.5 (NK2 transcription factor related locus 5), and GATA4 (GATA binding protein 4). On the 14th day of differentiation, we observed the α-MHC (α-myosin heavy chain)-positive area using immunofluorescent staining and conducted western blotting to detect the expression of cTnT (cardiac troponin) protein and PI3K/Akt signaling pathway-related proteins. Additionally, we intervened the iPSCs-ErbB4 + NRG1 group with the PI3K/Akt inhibitor LY294002 and observed alterations in the expression of cardiomyocyte differentiation-related genes.ResultsThe number of beating embryoid bodies increased after promoting the expression of NRG1/ErbB4 compared to the iPSCs control group. Cardiomyocyte markers ANP, Nkx2.5, and GATA4 significantly increased on day 14 of differentiation, and the positive area of α-MHC was three times that of the iPSCs control group. Moreover, there was a marked increase in cTnT protein expression. However, there was no significant difference in cardiomyocyte differentiation between the iPSCs-ErbB4 group and the iPSCs control group. Akt phosphorylation was significantly increased in the iPSCs-ErbB4 + NRG1 group. LY294002 significantly reversed the enhancing effect of NRG1/ErbB4 overexpression on Akt phosphorylation as well as the increase in α-MHC and cTnT expression.ConclusionsIn conclusion, promoting the expression of NRG1/ErbB4 induced the differentiation of iPSC into cardiomyocytes, possibly through modulation of the PI3K/Akt signaling pathway.

Modification of Lhx2 activity for ex vivo amplification of human iPSC-derived hematopoietic stem/progenitor cells.

Hematopoietic stem cells (HSCs) obtained from patient-derived human induced pluripotent stem cells (iPSCs) are a promising tool for curing various hematological disorders. We previously demonstrated that enforced expression of the LIM-homeobox transcription factor Lhx2, which is essential for mouse embryonic hematopoiesis, leads to generation of engraftable and expandable hematopoietic stem cells (HSCs) from mouse iPSCs. However, it remained unknown whether Lhx2 can induce HSCs from human iPSCs. Here, we investigated the effect of Lhx2 overexpression on hematopoietic differentiation of human iPSCs. Unexpectedly, Lhx2 severely inhibited proliferation of human iPSC-derived hematopoietic cells. Thus, Lhx2 exhibited differential effects on mouse and human hematopoietic cells. Further studies implied that the inhibitory effect of Lhx2 on human iPSC-derived hematopoietic cells was due to insufficient transcriptional activation ability. Therefore, we modified Lhx2 to strengthen its activity as a transcriptional activator. This modified Lhx2 could induce ex vivo amplification of human iPSC-derived hematopoietic stem/progenitor cells (HSPCs). We believe that these findings will facilitate the development of a method to efficiently produce HSCs from human iPSCs.

9194 Generation of a Human-Induced Pluripotent Stem Cell Line From a Patient With Hypopituitarism and a Novel Nonsense Variant in FOXA2

Abstract Disclosure: M.A. Camilletti: None. G.T. Chirino Felker: None. G. Amin: None. S. Castañeda: None. F. Zabalegui: None. C. Romano Florit: None. A. Waisman: None. M. Ciaccio: None. M.I. Di Palma: None. E. Vaiani: None. A. Belgorosky: None. S.G. Miriuka: None. L.N. Moro: None. M.I. Perez-Millan: None. Congenital Hypopituitarism (CH) is a genetically complex disease characterized by one or more pituitary hormone deficiencies. Forkhead Box A2 (FOXA2, 600288) is a pioneer transcription factor associated with development of multiple tissues in humans and mice. Heterozygous loss of function mutations in FOXA2 were recently shown to cause CH with hyperinsulinemic hypoglycemia, but little is known about the molecular mechanism of FOXA2 action during pituitary development. We identified a novel, heterozygous nonsense variant in FOXA2 (c.686C<A; p.S229X) in a patient diagnosed with GH deficiency at 1.7 years of age, with anterior lobe hypoplasia and absent pituitary stalk, asymptomatic hypoglycemia, and craniofacial malformations. To discover the mechanism of FOXA2 regulation of pituitary development we generated an induced pluripotent stem cell line (FOXA2mut-iPSC) from the patient’s polymorphonuclear blood cells (PBMCs) using an EF1a-hSTEMCCA-loxP vector containing the pluripotency genes OCT-4, SOX-2, c-MYC and KLF4. FOXA2mut-iPSC clone R1 had a normal karyotype and embryonic stem cell-like morphology. These cells express endogenous pluripotency-associated markers NANOG, SOX2, and OCT4, have alkaline phosphatase activity, and can differentiate into all three developmental layers, indicating that these cells are pluripotent. Short tandem repeat (STR) analysis confirmed that FOXA2mut-iPSC R1 clone profiles matched those of the donor PBMCs. Next, we compared pituitary differentiation of FOXA2mut-iPSC vs. control-iPSCs in vitro. Cells were cultured in a differentiation medium containing BMP4, the smoothened agonist SAG, and fibroblast growth factor (FGF), as described in Zimmer et al., 2016 (1). Gene expression analysis (by qRT-PCR) of samples collected on days 0, 4, 7, and 15 of the differentiation protocol showed an increased expression of genes associated with anterior pituitary development including OTX2, PITX1/2, and SIX1 in both cell lines (n=2). These preliminary data suggest that pituitary cell fate can be induced in the heterozygous FOXA2mut-iPSC clone. Ongoing studies will assess pituitary hormone-producing cell differentiation after longer periods of FOXA2mut-iPSC cell culture. In sum, patient iPSC differentiation is a promising tool for assessment of normal and variant FOXA2 function in human pituitary development, and for enlightening the mechanisms of FOXA2 action in human pituitary development. (1) Zimmer et al., Stem Cell Reports. 2016 Jun 14;6(6):858-872. Presentation: 6/1/2024

7151 Generation of a Human-Induced Pluripotent Stem Cell Line From a Patient With Hypopituitarism and a Novel Nonsense Variant in FOXA2

Abstract Disclosure: M.A. Camilletti: None. G.T. Chirino Felker: None. G. Amin: None. S. Castañeda: None. F. Zabalegui: None. C. Romano Florit: None. A. Waisman: None. M. Ciaccio: None. M.I. Di Palma: None. E. Vaiani: None. A. Belgorosky: None. S.G. Miriuka: None. L.N. Moro: None. M.I. Perez-Millan: None. Congenital Hypopituitarism (CH) is a genetically complex disease characterized by one or more pituitary hormone deficiencies. Forkhead Box A2 (FOXA2, 600288) is a pioneer transcription factor associated with development of multiple tissues in humans and mice. Heterozygous loss of function mutations in FOXA2 were recently shown to cause CH with hyperinsulinemic hypoglycemia, but little is known about the molecular mechanism of FOXA2 action during pituitary development. We identified a novel, heterozygous nonsense variant in FOXA2 (c.686C<A; p.S229X) in a patient diagnosed with GH deficiency at 1.7 years of age, with anterior lobe hypoplasia and absent pituitary stalk, asymptomatic hypoglycemia, and craniofacial malformations. To discover the mechanism of FOXA2 regulation of pituitary development we generated an induced pluripotent stem cell line (FOXA2mut-iPSC) from the patient’s polymorphonuclear blood cells (PBMCs) using an EF1a-hSTEMCCA-loxP vector containing the pluripotency genes OCT-4, SOX-2, c-MYC and KLF4. FOXA2mut-iPSC clone R1 had a normal karyotype and embryonic stem cell-like morphology. These cells express endogenous pluripotency-associated markers NANOG, SOX2, and OCT4, have alkaline phosphatase activity, and can differentiate into all three developmental layers, indicating that these cells are pluripotent. Short tandem repeat (STR) analysis confirmed that FOXA2mut-iPSC R1 clone profiles matched those of the donor PBMCs. Next, we compared pituitary differentiation of FOXA2mut-iPSC vs. control-iPSCs in vitro. Cells were cultured in a differentiation medium containing BMP4, the smoothened agonist SAG, and fibroblast growth factor (FGF), as described in Zimmer et al., 2016 (1). Gene expression analysis (by qRT-PCR) of samples collected on days 0, 4, 7, and 15 of the differentiation protocol showed an increased expression of genes associated with anterior pituitary development including OTX2, PITX1/2, and SIX1 in both cell lines (n=2). These preliminary data suggest that pituitary cell fate can be induced in the heterozygous FOXA2mut-iPSC clone. Ongoing studies will assess pituitary hormone-producing cell differentiation after longer periods of FOXA2mut-iPSC cell culture. In sum, patient iPSC differentiation is a promising tool for assessment of normal and variant FOXA2 function in human pituitary development, and for enlightening the mechanisms of FOXA2 action in human pituitary development. (1) Zimmer et al., Stem Cell Reports. 2016 Jun 14;6(6):858-872. Presentation: 6/1/2024

Detection of Residual iPSCs Following Differentiation of iPSC-Derived Retinal Pigment Epithelial Cells.

Purpose: The goal of this study was to develop a lot release assay for iPSC residuals following directed differentiation of iPSCs to retinal pigment epithelial (RPE) cells. Methods: RNA Sequencing (RNA Seq) of iPSCs and RPE derived from them was used to identify pluripotency markers downregulated in RPE cells. Quantitative real time PCR (qPCR) was then applied to assess iPSC residuals in iPSC-derived RPE. The limit of detection (LOD) of the assay was determined by performing spike-in assays with known quantities of iPSCs serially diluted into an RPE suspension. Results: ZSCAN10 and LIN28A were among 8 pluripotency markers identified by RNA Seq as downregulated in RPE. Based on copy number and expression of pseudogenes and lncRNAs ZSCAN10 and LIN28A were chosen for use in qPCR assays for residual iPSCs. Reverse transcription PCR indicated generally uniform expression of ZSCAN10 and LIN28A in 21 clones derived from 8 iPSC donors with no expression of either in RPE cells derived from 5 donor lines. Based on qPCR, ZSCAN10, and LIN28A expression in iPSCs was generally uniform. The LOD for ZSCAN10 and LIN28A in qPCR assays was determined using spike in assays of RPE derived from 2 iPSC lines. Analysis of ΔΔCt found the limit of detection to be <0.01% of cells, equivalent to <1 iPSC/10,000 RPE cells in both iPSC lines. Conclusions: qPCR for ZSCAN10 and LIN28A detects <1 in 10,000 residual iPSCs in a population of iPSC-derived RPE providing an adequate LOD of iPSC residuals for lot release testing.

How is Excitotoxicity Being Modelled in iPSC-Derived Neurons?

Excitotoxicity linked either to environmental causes (pesticide and cyanotoxin exposure), excitatory neurotransmitter imbalance, or to intrinsic neuronal hyperexcitability, is a pathological mechanism central to neurodegeneration in amyotrophic lateral sclerosis (ALS). Investigation of excitotoxic mechanisms using in vitro and in vivo animal models has been central to understanding ALS mechanisms of disease. In particular, advances in induced pluripotent stem cell (iPSC) technologies now provide human cell-based models that are readily amenable to environmental and network-based excitotoxic manipulations. The cell-type specific differentiation of iPSC, combined with approaches to modelling excitotoxicity that include editing of disease-associated gene variants, chemogenetics, and environmental risk-associated exposures make iPSC primed to examine gene-environment interactions and disease-associated excitotoxic mechanisms. Critical to this is knowledge of which neurotransmitter receptor subunits are expressed by iPSC-derived neuronal cultures being studied, how their activity responds to antagonists and agonists of these receptors, and how to interpret data derived from multi-parameter electrophysiological recordings. This review explores how iPSC-based studies have contributed to our understanding of ALS-linked excitotoxicity and highlights novel approaches to inducing excitotoxicity in iPSC-derived neurons to further our understanding of its pathological pathways.

Identifying SETBP1 haploinsufficiency molecular pathways to improve patient diagnosis using induced pluripotent stem cells and neural disease modelling

BackgroundSETBP1 Haploinsufficiency Disorder (SETBP1-HD) is characterised by mild to moderate intellectual disability, speech and language impairment, mild motor developmental delay, behavioural issues, hypotonia, mild facial dysmorphisms, and vision impairment. Despite a clear link between SETBP1 mutations and neurodevelopmental disorders the precise role of SETBP1 in neural development remains elusive. We investigate the functional effects of three SETBP1 genetic variants including two pathogenic mutations p.Glu545Ter and SETBP1 p.Tyr1066Ter, resulting in removal of SKI and/or SET domains, and a point mutation p.Thr1387Met in the SET domain.MethodsGenetic variants were introduced into induced pluripotent stem cells (iPSCs) and subsequently differentiated into neurons to model the disease. We measured changes in cellular differentiation, SETBP1 protein localisation, and gene expression changes.ResultsThe data indicated a change in the WNT pathway, RNA polymerase II pathway and identified GATA2 as a central transcription factor in disease perturbation. In addition, the genetic variants altered the expression of gene sets related to neural forebrain development matching characteristics typical of the SETBP1-HD phenotype.LimitationsThe study investigates changes in cellular function in differentiation of iPSC to neural progenitor cells as a human model of SETBP1 HD disorder. Future studies may provide additional information relevant to disease on further neural cell specification, to derive mature neurons, neural forebrain cells, or brain organoids.ConclusionsWe developed a human SETBP1-HD model and identified perturbations to the WNT and POL2RA pathway, genes regulated by GATA2. Strikingly neural cells for both the SETBP1 truncation mutations and the single nucleotide variant displayed a SETBP1-HD-like phenotype.

Developmental regulation of endothelial-to-hematopoietic transition from induced pluripotent stem cells.

Hematopoietic stem cells (HSCs) arise in embryogenesis from a specialized hemogenic endothelium (HE). In this process, HE cells undergo a unique fate change termed endothelial-to-hematopoietic transition, or EHT. While induced pluripotent stem cells (iPSCs) give rise to HE with robust hemogenic potential, the generation of bona fide HSCs from iPSCs remains a challenge. Here, we map single cell dynamics of EHT during embryoid body differentiation from iPSCs and integrate it with human embryo datasets to identify key transcriptional differences between in vitro and in vivo cell states. We further map ligand-receptor interactions associated with differential expression of developmental programs in the iPSC system. We found that the expression of endothelial genes was incompletely repressed during iPSC EHT. Elevated FGF signaling by FGF23, an endothelial pathway ligand, was associated with differential gene expression between in vitro and in vivo EHT. Chemical inhibition of FGF signaling during EHT increased HSPC generation in the zebrafish, while an FGF agonist had the opposite effect. Consistently, chemical inhibition of FGF signaling increased hematopoietic output from iPSCs. In summary, we map the dynamics of EHT from iPSCs at single cell resolution and identify ligand-receptor interactions that can be modulated to improve iPSC differentiation protocols. We show, as proof of principle, that chemical inhibition of FGF signaling during EHT improves hematopoietic output in zebrafish and the iPSC system.

Early markers of induced pluripotent stem cell hematopoietic development

The generation of immune cell populations from induced pluripotent stem cells (iPSCs) is a valuable model to study mechanisms that control hematopoietic development; it also is a promising approach to develop immunotherapeutic strategies to treat various diseases, including hereditary, oncological and infectious ones. To date, it has been demonstrated that iPSCs can differentiate into different immune cells, including macrophages, neutrophils, natural killer cells and T cells. However, the protocols suggested so far are experimental, and they require optimization, standardization and scaling. Solution to these tasks requires methods allowing to predict the efficacy of ongoing differentiation at early differentiation stages. Here, we evaluated whether iPSC hematopoietic/myeloid differentiation can be monitored by means of flow cytometry. Human iPSCs were differentiated into hematopoietic/myeloid cells using two protocols previously suggested for the generation of macrophages from iPSCs. The protocols differed by methods used to induce early and late stages of cell differentiation. At early differentiation stages, the protocols differed by approaches used to induce the generation of mesoderm and hemogenic endothelium, i.e., 2D differentiation in the presence of exogenous factors known to promote mesoderm and hemogenic endothelium development (“factor-dependent” protocol) or 3D differentiation in the absence of exogenous cytokines and growth factors (“spontaneous” protocol). At late differentiation stages, the protocols differed by factors added to the cultures to promote hematopoietic/myeloid specification (i.e., SCF, FGF2, IL-6, IL-3 and M-CSF or only IL-3 and M-CSF). At different stages of differentiation, the expressions of antigens known to be expressed by mesoderm, hemogenic endothelium and hematopoietic cells (i.e., CD309, CD34, CD31, CD43 and CD45) were evaluated. At early differentiation stages, the main phenotypic changes observed in cell cultures were an upregulation of the expression of CD309 (a receptor for vascular endothelial growth factor), the appearance of the expression of sialophorin CD43 and the expression of CD34 antigen. In cells cultured in 2D factor-dependent conditions, these changes appeared earlier and were more pronounced as compared with cells cultured in 3D “spontaneous” conditions. The results suggest that CD309 and/or CD43 are valuable markers for an early prediction of the effectiveness of iPSC differentiation into hematopoietic/ myeloid progeny.

Clinical trials in-a-dish for cardiovascular medicine.

Cardiovascular diseases persist as a global health challenge that requires methodological innovation for effective drug development. Conventional pipelines relying on animal models suffer from high failure rates due to significant interspecies variation between humans and animal models. In response, the recently enacted Food and Drug Administration Modernization Act 2.0 encourages alternative approaches including induced pluripotent stem cells (iPSCs). Human iPSCs provide a patient-specific, precise, and screenable platform for drug testing, paving the way for cardiovascular precision medicine. This review discusses milestones in iPSC differentiation and their applications from disease modelling to drug discovery in cardiovascular medicine. It then explores challenges and emerging opportunities for the implementation of 'clinical trials in-a-dish'. Concluding, this review proposes a framework for future clinical trial design with strategic incorporations of iPSC technology, microphysiological systems, clinical pan-omics, and artificial intelligence to improve success rates and advance cardiovascular healthcare.

Revolutionizing Cancer Treatments through Stem Cell-Derived CAR T Cells for Immunotherapy: Opening New Horizons for the Future of Oncology.

Recent advances in cellular therapies have paved the way for innovative treatments of various cancers and autoimmune disorders. Induced pluripotent stem cells (iPSCs) represent a remarkable breakthrough, offering the potential to generate patient-specific cell types for personalized as well as allogeneic therapies. This review explores the application of iPSC-derived chimeric antigen receptor (CAR) T cells, a cutting-edge approach in allogeneic cancer immunotherapies. CAR T cells are genetically engineered immune cells designed to target specific tumor antigens, and their integration with iPSC technology holds immense promise for enhancing the efficacy, safety, and scalability of cellular therapies. This review begins by elucidating the principles behind iPSC generation and differentiation into T cells, highlighting the advantage of iPSCs in providing a uniform, inexhaustible source of CAR T cells. Additionally, we discuss the genetic modification of iPSC-derived T cells to express various CARs, emphasizing the precision and flexibility this affords in designing customized therapies for a diverse range of malignancies. Notably, iPSC-derived CAR T cells demonstrate a superior proliferative capacity, persistence, and anti-tumor activity compared to their conventionally derived counterparts, offering a potential solution to challenges associated with conventional CAR T cell therapies. In conclusion, iPSC-derived CAR T cells represent a groundbreaking advancement in cellular therapies, demonstrating unparalleled potential in revolutionizing the landscape of immunotherapies. As this technology continues to evolve, it holds the promise of providing safer, more effective, and widely accessible treatment options for patients battling cancer and other immune-related disorders. This review aims to shed light on the transformative potential of iPSC-derived CAR T cells and inspire further research and development in this dynamic field.

From iPSCs to Pancreatic β Cells: Unveiling Molecular Pathways and Enhancements with Vitamin C and Retinoic Acid in Diabetes Research.

Diabetes mellitus, a chronic and non-transmissible disease, triggers a wide range of micro- and macrovascular complications. The differentiation of pancreatic β-like cells (PβLCs) from induced pluripotent stem cells (iPSCs) offers a promising avenue for regenerative medicine aimed at treating diabetes. Current differentiation protocols strive to emulate pancreatic embryonic development by utilizing cytokines and small molecules at specific doses to activate and inhibit distinct molecular signaling pathways, directing the differentiation of iPSCs into pancreatic β cells. Despite significant progress and improved protocols, the full spectrum of molecular signaling pathways governing pancreatic development and the physiological characteristics of the differentiated cells are not yet fully understood. Here, we report a specific combination of cofactors and small molecules that successfully differentiate iPSCs into PβLCs. Our protocol has shown to be effective, with the resulting cells exhibiting key functional properties of pancreatic β cells, including the expression of crucial molecular markers (pdx1, nkx6.1, ngn3) and the capability to secrete insulin in response to glucose. Furthermore, the addition of vitamin C and retinoic acid in the final stages of differentiation led to the overexpression of specific β cell genes.

Bioinspired Hyaluronic Acid‐Based Hydrogel Fuels Bi‐Directional Lung Organoid Maturation via PIEZO1 and ITGB1 Mediated Mechanosensation

AbstractLung diseases are one of the leading causes of global mortality. Advances in induced pluripotent stem cell (iPSC) differentiation have enabled the creation of bronchiolar and alveolar lung organoids, advancing research on lung conditions. Traditional Matrigel encapsulation, reliant on the spontaneous assembly and propagation of cells with limited external intervention, often results in variability and low reproducibility. The absence of hyaluronic acid (HA) in Matrigel, a key lung extracellular matrix component, limits bronchiolar and alveolar cell differentiation, reducing the efficacy and reproducibility of iPSC‐derived organoid generation. To address this, a novel hybrid hydrogel combining HA and 23% Matrigel, inspired by the natural lung environment, is developed. This hydrogel offers improved biochemical support and viscoelastic properties, significantly accelerating organoid development. Within eight days, the hydrogel produces uniformly sized organoids containing both bronchiolar and alveolar epithelial cells. Increased levels of active mechanosensors and transducers, including PIEZO1, Integrin, and Myosin, suggest that the hydrogel's altered viscoelasticity triggers a mechanotransduction cascade. This bioinspired hydrogel provides a robust, fast model for biomedical research, facilitating rapid drug screening, respiratory disease treatment studies, and surfactant trafficking investigations. Furthermore, it enables the exploration of underlying biomechanical mechanisms to enhance the controllability of organoid generation and maturation.

LMNA-Related Dilated Cardiomyopathy: Single-Cell Transcriptomics during Patient-Derived iPSC Differentiation Support Cell Type and Lineage-Specific Dysregulation of Gene Expression and Development for Cardiomyocytes and Epicardium-Derived Cells with Lamin A/C Haploinsufficiency.

LMNA-related dilated cardiomyopathy (DCM) is an autosomal-dominant genetic condition with cardiomyocyte and conduction system dysfunction often resulting in heart failure or sudden death. The condition is caused by mutation in the Lamin A/C (LMNA) gene encoding Type-A nuclear lamin proteins involved in nuclear integrity, epigenetic regulation of gene expression, and differentiation. The molecular mechanisms of the disease are not completely understood, and there are no definitive treatments to reverse progression or prevent mortality. We investigated possible mechanisms of LMNA-related DCM using induced pluripotent stem cells derived from a family with a heterozygous LMNA c.357-2A>G splice-site mutation. We differentiated one LMNA-mutant iPSC line derived from an affected female (Patient) and two non-mutant iPSC lines derived from her unaffected sister (Control) and conducted single-cell RNA sequencing for 12 samples (four from Patients and eight from Controls) across seven time points: Day 0, 2, 4, 9, 16, 19, and 30. Our bioinformatics workflow identified 125,554 cells in raw data and 110,521 (88%) high-quality cells in sequentially processed data. Unsupervised clustering, cell annotation, and trajectory inference found complex heterogeneity: ten main cell types; many possible subtypes; and lineage bifurcation for cardiac progenitors to cardiomyocytes (CMs) and epicardium-derived cells (EPDCs). Data integration and comparative analyses of Patient and Control cells found cell type and lineage-specific differentially expressed genes (DEGs) with enrichment, supporting pathway dysregulation. Top DEGs and enriched pathways included 10 ZNF genes and RNA polymerase II transcription in pluripotent cells (PP); BMP4 and TGF Beta/BMP signaling, sarcomere gene subsets and cardiogenesis, CDH2 and EMT in CMs; LMNA and epigenetic regulation, as well as DDIT4 and mTORC1 signaling in EPDCs. Top DEGs also included XIST and other X-linked genes, six imprinted genes (SNRPN, PWAR6, NDN, PEG10, MEG3, MEG8), and enriched gene sets related to metabolism, proliferation, and homeostasis. We confirmed Lamin A/C haploinsufficiency by allelic expression and Western blot. Our complex Patient-derived iPSC model for Lamin A/C haploinsufficiency in PP, CM, and EPDC provided support for dysregulation of genes and pathways, many previously associated with Lamin A/C defects, such as epigenetic gene expression, signaling, and differentiation. Our findings support disruption of epigenomic developmental programs, as proposed in other LMNA disease models. We recognized other factors influencing epigenetics and differentiation; thus, our approach needs improvement to further investigate this mechanism in an iPSC-derived model.

Epigenetic insights into GABAergic development in Dravet Syndrome iPSC and therapeutic implications

Dravet syndrome (DS) is a devastating early-onset refractory epilepsy syndrome caused by variants in the SCN1A gene. A disturbed GABAergic interneuron function is implicated in the progression to DS but the underlying developmental and pathophysiological mechanisms remain elusive, in particularly at the chromatin level. Induced pluripotent stem cells (iPSCs) derived from DS cases and healthy donors were used to model disease-associated epigenetic abnormalities of GABAergic development. Chromatin accessibility was assessed at multiple time points (Day 0, Day 19, Day 35, and Day 65) of GABAergic differentiation. Additionally, the effects of the commonly used anti-seizure drug valproic acid (VPA) on chromatin accessibility were elucidated in GABAergic cells. The distinct dynamics in the chromatin profile of DS iPSC predicted accelerated early GABAergic development, evident at D19, and diverged further from the pattern in control iPSC with continued differentiation, indicating a disrupted GABAergic maturation. Exposure to VPA at D65 reshaped the chromatin landscape at a variable extent in different iPSC-lines and rescued the observed dysfunctional development of some DS iPSC-GABA. The comprehensive investigation on the chromatin landscape of GABAergic differentiation in DS-patient iPSC offers valuable insights into the epigenetic dysregulations associated with interneuronal dysfunction in DS. Moreover, the detailed analysis of the chromatin changes induced by VPA in iPSC-GABA holds the potential to improve the development of personalized and targeted anti-epileptic therapies.

Epigenetic insights into GABAergic development in Dravet Syndrome iPSC and therapeutic implications.

Dravet syndrome (DS) is a devastating early-onset refractory epilepsy syndrome caused by variants in the SCN1A gene. A disturbed GABAergic interneuron function is implicated in the progression to DS but the underlying developmental and pathophysiological mechanisms remain elusive, in particularly at the chromatin level. Induced pluripotent stem cells (iPSCs) derived from DS cases and healthy donors were used to model disease-associated epigenetic abnormalities of GABAergic development. Chromatin accessibility was assessed at multiple time points (Day 0, Day 19, Day 35, and Day 65) of GABAergic differentiation. Additionally, the effects of the commonly used anti-seizure drug valproic acid (VPA) on chromatin accessibility were elucidated in GABAergic cells. The distinct dynamics in the chromatin profile of DS iPSC predicted accelerated early GABAergic development, evident at D19, and diverged further from the pattern in control iPSC with continued differentiation, indicating a disrupted GABAergic maturation. Exposure to VPA at D65 reshaped the chromatin landscape at a variable extent in different iPSC-lines and rescued the observed dysfunctional development of some DS iPSC-GABA. The comprehensive investigation on the chromatin landscape of GABAergic differentiation in DS-patient iPSC offers valuable insights into the epigenetic dysregulations associated with interneuronal dysfunction in DS. Moreover, the detailed analysis of the chromatin changes induced by VPA in iPSC-GABA holds the potential to improve the development of personalized and targeted anti-epileptic therapies.

Abstract We091: Maternal hyperglycemia disrupts human cardiac cell lineage differentiation

Maternal diabetes is associated with a 4-fold increased risk of offspring developing congenital heart defects (CHDs). It remains unknown how maternal diabetes interferes with cardiac cell lineage determination and leads to malformations in the heart. In this study, we aim to elucidate the cellular mechanisms by which maternal hyperglycemia causes high risk of CHDs in newborns. Here we leverage an in vitro hyperglycemic model using human induced pluripotent stem cells (iPSCs), which could recapture cardiac differentiation and cell lineage commitment during embryonic heart development. We collected differentiating cells at D5 (cardiac mesoderm), D10 (cardiac progenitors), and D14 (early cardiomyocytes) during cardiac differentiation under normal and hyperglycemic conditions, and performed single-cell transcriptomic analysis. We found that hyperglycemia significantly impedes cardiac differentiation of human iPSCs as robust cardiac differentiation is rarely observed in multiple iPSC lines (n=10) under hyperglycemia. At the cellular level, hyperglycemia interferes with cardiac differentiation of human iPSCs in response to WNT signaling activation, which is manifested by reduced number of cardiac mesoderm (MESP1+ PDGFRA+) cells at D5 of differentiation. In contrast, neural differentiation is enhanced under hyperglycemia, with a high proportion of neural cell lineage (SOX2+ PAX6+). At D10, differentiated neural cell lineage dominates the cell population under hyperglycemia at the expense of cardiac progenitors and early cardiomyocytes. At D14, the prevalence of neural lineage persist whereas early cardiomyocytes only accounts for a small portion of cell population under hyperglycemia. Moreover, we treated D30 iPSC-derived cardiomyocytes (iPSC-CMs) with high glucose concentration (25 mM) for 7 days and found that iPSC-CMs show reduced mitochondria respiration and ATP production, but elevated apoptosis and reactive oxygen species (ROS) generation. Together, our data suggest that maternal hyperglycemia could interrupt human embryonic heart morphogenesis through overriding WNT-medicated cardiac differentiation and promoting neural cell lineage determination by default.

The Efficiency of In Vitro Differentiation of Primate iPSCs into Cardiomyocytes Depending on Their Cell Seeding Density and Cell Line Specificity.

A thorough characterization of induced pluripotent stem cells (iPSCs) used with in vitro models or therapeutics is essential. Even iPSCs derived from a single donor can exhibit variability within and between cell lines, which can lead to heterogeneity in results and hinder the promising future of cell replacement therapies. In this study, the cell seeding density of human and rhesus monkey iPSCs was tested to maximize the cell line-specific yield of the generated cardiomyocytes. We found that, despite using the same iPSC generation and differentiation protocols, the cell seeding density for the cell line-specific best differentiation efficiency could differ by a factor of four for the four cell lines used here. In addition, the cell lines showed differences in the range of cell seeding densities that they could tolerate without the severe loss of differentiation efficiency. Overall, our data show that the cell seeding density is a critical parameter for the differentiation inefficiency of primate iPSCs to cardiomyocytes and that iPSCs generated with the same episomal approach still exhibit considerable heterogeneity. Therefore, individual characterization of iPSC lines is required, and functional comparability with in vivo processes must be ensured to warrant the translatability of in vitro research with iPSCs.

Abstract We036: Recapitulating Cardiac Microenvironment: Elucidating the Role of ECM Components and Architecture on Cardiac Differentiation

The discovery of iPSCs was revolutionary for regenerative medicine, especially as a source to replace a cell population with limited regeneration capability, like cardiomyocytes (CMs). However, the exact mechanism(s) governing how the microenvironment influences cardiac differentiation at a cellular scale is still widely unclear. To bridge this gap, we created an in vitro fibrous model from a decellularized porcine cardiac extracellular matrix. The aim is to assess the impact of the microenvironment, specifically the effects of protein composition and micro-architecture, on the cardiac differentiation of iPSCs. To study the role of protein composition, atrial and ventricular regions of the porcine heart are manually identified and separated as their protein composition is observed to be different. To test this, the material was subjected to proteomics analysis with LS-Mass Spectrometry where about 1000 proteins were identified in the ventricular region and only 300 proteins in atria. The decellularized tissue was tested for complete removal of nuclei by staining and further validated with DNA quantification. The dECM was blended with synthetic polymer (polycaprolactone) for electrospinning. The average collected fiber diameter was 14.8 ± 3.9 μm. The fibrous scaffolds were seeded with iPSCs and differentiated towards cardiac lineage. dECM samples show comparable signs of biocompatibility as laminin-521 coated TCPS, forming clusters throughout the differentiation process indicating that the scaffolds encourage cardiac differentiation. Further analysis is being conducted to compare the cellular expressions of differentiation markers including mesoderm formation, cardiac specification, and cardiomyocyte structural and functional markers. The effects of the ECM composition will be checked with myosin light and heavy chain expressions, as their expressions vary in the atrial and ventricular regions of the heart.