Stem Cell Research

The Sinha laboratory has developed protocols for differentiating human pluripotent stem cells (hPSCs) into vascular smooth muscle cells along developmental lineage-specific pathways. In development, paraxial mesoderm (PM), lateral plate mesoderm (LM) and neural crest (NC) linages each give rise to smooth muscle cells significant in a location-specific manner. Induced PSCs derived from patients enduring disease provide a platform from which disease-relevant cell models can be established in the laboratory. Here we describe a robust protocol for differentiating hPSCs into vascular smooth muscle cells via a neural crest lineage and the control steps required to ensure consistently high-quality differentiated cells.

In vitro stem cell culture is demanding in terms of manpower and media supplements. In recent years, new protocols have been developed to expand pluripotent embryonic stem cells in suspension culture, which greatly simplifies cell handling and scalability. However, it is still unclear how suspension culture protocols with different supplements affect pluripotency, cell homogeneity and cell differentiation compared to established adherent culture methods. Here we tested four different culture conditions for mouse embryonic stem cells (mESC) and quantified chimerism and germ line transmission as well as in vitro differentiation into three-dimensional neuro-epithelia. We found that suspension culture supplemented with CHIR99021/LIF offers the best compromise between culturing effort, robust pluripotency and cell homogeneity. Our work provides a guideline for simplifying mESC culture and should encourage more cell biology labs to use stem cell-based organoids as model systems.

We describe here a new NHGRI Sample Repository for Human Genetic Research collection of induced pluripotent stem cell (iPSC) lines reprogrammed from whole blood derived peripheral blood mononuclear cells (PBMCs). PBMCs were reprogrammed using Sendai viral vectors carrying transcription factors OCT4, SOX2, KLF4, and c-MYC. All iPSC lines exhibit a normal karyotype, express common stemness and pluripotency markers, and demonstrate the ability to differentiate into cell types representing all three germ layers. This iPSC collection (n=7) will have accompanying public, near telomere to telomere genomic data through the Human Pangenome Reference Consortium, and provides an invaluable new in vitro resource for studying common genetic and genomic variation and its functional implications.

Induced pluripotent stem cells (iPSCs) derived from human somatic cells have created new opportunities to generate disease-relevant cells. Thus, as the use of patient-derived stem cells has become more widespread, having a workflow to monitor each line is critical. This ensures iPSCs pass a suite of quality control measures, promoting reproducibility across experiments and between labs. With this in mind, we established a multistep workflow to assess our newly generated iPSCs for variations and reproducibility relative to each other and iPSCs obtained from external sources. Our benchmarks for evaluating iPSCs include examining iPSC morphology and proliferation in two different media conditions and evaluating their ability to differentiate into each of the three germ layers, with a particular focus on neurons. Genomic integrity in the human iPSCs was analyzed by G-band karyotyping and a qPCR-based test for the detection of hotspot mutations test. Cell-line identity was authenticated by Short Tandem Repeat (STR) analysis. Using standardized dual SMAD inhibition methods, all iPSC lines gave rise to neural progenitors that could subsequently be differentiated into cortical neurons. Neural differentiation was analyzed qualitatively by immunocytochemistry and quantitatively by qPCR for progenitor, neuronal, cortical, and glial markers. Taken together, we present a multistep quality control workflow to evaluate variability and reproducibility across and between iPSCs.

At the Wisconsin National Primate Research Center, we have identified a family of rhesus carrying the microtubule-associated protein tau (MAPT) R406W mutation linked to frontotemporal dementia (FTD). Rhesus induced pluripotent stem cells (RhiPSCs) derived from these monkeys present a unique opportunity for in vitro modeling and comparison with cells derived from MAPT R406W human carriers. Here, we report the development of a reproducible method to generate RhiPSCs compliant with the standards of the International Society for Stem Cell Research (ISSCR) to support in vitro modeling of FTD-MAPT R406W. Our stepwise approach identified efficient methods for fibroblast derivation, fibroblast reprogramming to RhiPSC, and RhiPSC maintenance over continued culture. To derive fibroblasts from MAPT wild type (WT) and R406W monkeys, a combination of manual processing and overnight enzymatic digestion was required to maximize the number of low passage fibroblasts available for reprogramming. Fibroblast reprogramming to RhiPSC using Sendai viral vectors versus oriP/EBNA1 episomal plasmids revealed the latter as most efficient. Electroporation conditions for oriP/EBNA1 reprogramming were optimized to maximize plasmid uptake and cell survival. Ultimately, eight RhiPSC lines were derived from 4 donor rhesus monkeys (n=2 WT, n=2 R406W; two clonal lines per donor) and fully characterized according to ISSCR standards. RhiPSC stemness and genetic stability was best maintained on mouse embryonic fibroblast feeders in Universal Primate Pluripotency Stem Cell medium, as opposed to Essential 12 medium supplemented with IWR1, which produced cytogenetic abnormalities. Rhesus neural progenitor cells were generated using a monolayer protocol and expressed PAX6 and NESTIN after 21 days of differentiation. Our reliable method will be useful to labs seeking to derive RhiPSCs for preclinical studies. Overall, the RhiPSCs generated from MAPT R406W carriers will be a critical resource for evaluating the molecular underpinnings of tau-related neurodegeneration across primate species.

The CHOPWT17_TPM1KOc28 iPSC line was generated to interrogate the functions of Tropomyosin 1 (TPM1) in primary human cell development. This line was reprogrammed from a previously published wild type control iPSC line.

SUMMARYCurrent protocols for the differentiation of cardiomyocytes from human induced pluripotent stem cells (iPSCs) generally require prolonged time in culture and result in heterogeneous cellular populations. We present a method for the generation of beating cardiomyocytes expressing specific ventricular markers after just 14 days. Addition of the pan-retinoic acid receptor inverse agonist BMS 493 to human iPSCs for the first 8 days of differentiation resulted in increased protein expression of the ventricular isoform of myosin regulatory light chain (MLC2V) from 18.7% {+/-} 1.72% to 55.8% {+/-} 11.4% (p <0.0001) in cells co-expressing the cardiac muscle protein troponin T (TNNT2). Increased MLC2V expression was also accompanied by a slower beating rate (49.4 {+/-} 1.53 vs. 93.0 {+/-} 2.81 beats per minute, p <0.0001) and increased contraction amplitude (201% {+/-} 8.33% vs. 100% {+/-} 10.85%, p <0.0001) compared to untreated cells. Improved directed differentiation will improve in vitro cardiac modeling.

Producing an adequate number of muscle stem cells (MuSCs) with robust regenerative potential is essential for the successful cell therapy of muscle-wasting disorders. We have recently developed a method to produce skeletal myogenic cells with exceptional engraftability and expandability through an in vivo pluripotent stem cell (PSC) differentiation approach. We have subsequently mapped engraftment and gene expression and found that leukemia inhibitory factor receptor (Lifr) expression is positively correlated with engraftability. We therefore investigated the effect of LIF, the endogenous ligand of LIFR, on cultured MuSCs and examined their engraftment potential. We found that LIF-treated MuSCs exhibited elevated expression of PAX7, formed larger colonies from single cells, and favored the retention of PAX7+ "reserve cells" upon myogenic differentiation. This suggested that LIF promoted the maintenance of cultured MuSCs at a stem cell stage. Moreover, LIF enhanced the engraftment capability of MuSCs that had been expanded in vitro for 12 days by 5-fold and increased the number of MuSCs that repopulated the stem cell pool post-transplantation. These results thereby demonstrated the effectiveness of our in vivo PSC differentiation platform to identify positive regulators of the engraftability of cultured MuSCs.

-Synuclein (Syn) is a small, disordered protein that becomes aggregated in Lewy body diseases, such as Parkinsons disease (PD) and dementia with Lewy bodies (DLB). Human induced pluripotent stem cells (hiPSCs) potentially provide a tractable disease model to monitor early molecular changes associated with PD/DLB. We and others have previously derived hiPSC lines from patients with duplication and triplication of the SNCA gene, encoding for Syn. It is now recognised that to perform meaningful disease modelling with these hiPSC lines, it is critical to generate isogenic control cell lines that lack the disease causing mutations. In order to complement the existing and emerging hiPSC models for PD/DLB, we have generated an allelic series of Syn over-expressing hESC lines on the same isogenic background. An unresolved question is whether pluripotent stem cell lines, with elevated levels of Syn, can undergo efficient differentiation into dopaminergic and cortical neurons to model PD and DLB, respectively. We took advantage of our isogenic collection of hESC lines to determine if increased expression of Syn affects neural induction and neuronal differentiation. Clonal hESC lines with significantly different levels of Syn expression proliferated normally and maintained expression of pluripotent markers, such as OCT4. All cell lines efficiently produced PAX6+ neuroectoderm and there was no correlation between Syn expression and neural induction efficiency. Finally, global transcriptomic analysis of cortical differentiation of hESC lines with low or high levels of Syn expression demonstrated robust and similar induction of cortical neuronal expression profiles. Gene expression differences observed were unrelated to neural induction and neuronal differentiation. We conclude that elevated expression of Syn in human pluripotent stem cells does not adversely affect their neuronal differentiation potential and that collections of isogenic cell lines with differing levels of Syn expression are valid and suitable models to investigate synucleinopathies.

The field of human induced pluripotent stem cells (hiPSCs) has seen significant progress since the discovery of reprogramming somatic cells using the transcription factors Oct4, Sox2, Klf4, and c-Myc. hiPSCs are similar to embryonic stem cells in a primed state of pluripotency and has the potential to differentiate into any adult human cell type, offering a versatile tool for research and potential therapeutic applications. However, the efficiency of differentiation protocols for generating complex structures with multiple cell types, like kidney organoids, remains a challenge. This study investigates the impact of treating hiPSCs with a low-dose dimethyl sulfoxide to enhance kidney organoid differentiation using a well-established protocol from literature. We found that treating hiPSCs with 1-2% DMSO affects gene expression of pluripotent transcription factors, hiPSC colony morphology, and enhances the expression of key metanephric mesenchyme nephron progenitor marker, SIX2 after 9 days of kidney organoid differentiation. Our findings also suggest that DMSO treatment helps improve hiPSC differentiation protocol efficiency toward the development of tubular kidney organoids. Further research is needed to elucidate the mechanisms underlying these effects and to refine the differentiation process for potential in vitro research applications in biomedical research and drug development.

Genetic backgrounds contribute to cellular phenotypes, drug responsiveness, and health outcomes. However, the majority of human induced pluripotent stem cell (iPSC) lines are derived from individuals of European descent. Thus, there is a major, unmet need in the generation, characterisation, and distribution of iPSCs from diverse ancestries. To begin to address this need, we have generated iPSCs from dermal fibroblasts isolated from a healthy 60-year-old indigenous Nigerian male belonging to the Babur ethnic group. The iPSCs were generated using Sendai virus, and copy number variation (CNV) analysis revealed no new major abnormalities compared to the parental fibroblasts. The iPSCs have been characterised for pluripotency markers and morphology and successfully differentiated into neural progenitor cells and astrocytes. This iPSC line could serve as a healthy control in comparative studies and can be used in disease modelling, toxicity assessments, genetic analyses, and drug discovery processes within an African genetic background. To bolster the inclusion of African models in biomedical research, this iPSC line will be made available to the broader scientific community. Ongoing efforts focus on generating more lines from diverse indigenous populations towards creating a dedicated open-access African iPSC biobank.

Embryonic epicardium is a major source of cardiac fibroblasts (CFs), which play essential roles in heart development and response to heart injury. In this study, we developed a novel mouse model to identify distinct populations of epicardium-derived CFs. Our Wt1GFP/+;Wt1Cre;ROSA26-tdRFP model enables lineage tracing of WT1Cre-labeled (RFP+) fibroblasts and the identification of cells actively expressing WT1 (GFP+). Flow cytometry at early postnatal stages showed that RFP+ cells form a heterogeneous stromal population, with 20.13% co-expressing GFP, indicating persistent WT1 expression in a subset. We successfully immortalized RFP+ cardiac stromal cells, highly enriched in fibroblasts, by excluding other Wt1Cre-active cell types. Through culture condition optimization, we could selectively expand or differentiate specific fibroblast subpopulations, increasing the models utility. These immortalized cells, carrying an integrated WT1 reporter system, provide a robust in vitro platform to study fibroblast activation, differentiation, and plasticity under defined conditions. Summary blurbThis study presents a novel in vitro mouse model for investigating the activation, identity, and functional properties of epicardium-derived cardiac fibroblasts.

BackgroundThe progressive skeletal muscle degeneration observed in Duchenne Muscular Dystrophy (DMD) patients requires multiple cycles of satellite cells (SCs) activation to promote tissue regeneration. Dystrophic SCs present intrinsic defects, and the disrupting fibrotic niche hinders appropriate muscle recovery. Traditional 2D culture systems face challenges in modeling the DMD muscle niche and SCs behavior. Our aim was to validate a 3D culture of skeletal muscle spheroids (iSMS) for DMD modeling, as compared to the traditional 2D culture, while investigating the pathophysiological mechanisms of dystrophin deficiency in vitro. MethodsTo compare iSMS with traditional 2D myogenic differentiation, we differentiated PAX7 reporter wild-type (WT), dystrophic (DMD) isogenic induced pluripotent stem cells (iPSCs), and patients iPSCs, characterized myogenic markers levels and assessed differences in proliferation and differentiation using RT-qPCR, immunofluorescence, and flow cytometry. ResultsOur data showed that although both 2D and iSMS culture systems generated myogenic progenitors positive for MYOD, MYOG, MYF5, and MYH3, iSMS improved PAX7 expression in vitro. Moreover, we identified a differential regulation of canonical Notch signaling genes between iSMS and 2D, which may influence the comparison between WT and DMD. We also characterized the differentiation of myogenic progenitors derived from 2D and iSMS towards elongated myofibers, providing a valuable comparison with muscle fibers differentiated from human primary myoblasts. Additionally, DMD iSMS derived progenitors proliferated at reduced levels compared with WT iSMS, a characteristic not observed in progenitors derived from 2D cultures. Finally, we performed iSMS and 2D myogenic differentiation of iPSC lines from three patients with DMD, thus validating the iSMS protocol for DMD modeling. ConclusionOur results highlight the important advantages of using the iSMS differentiation platform over 2D for disease modeling. Exploring these 3D systems may help to gain a deeper understanding of SCs behavior to advance in novel treatments for DMD, which might be applicable to other forms of muscular disorders.

Numerous strategies exist to isolate hematopoietic stem cells (HSCs) using complex combinations of markers and flow cytometry. However, robust identification of HSCs using imaging techniques is substantially more challenging which has prompted the recent development of HSC reporter mice. To date, none of the molecules used in these reporters have been useful for human HSC identification. Here we report that PLXDC2 is a useful marker for both mouse and human HSCs. Using a green fluorescent protein (GFP) knock-in at the Plxdc2 locus in mice (hereafter denoted as Plxdc2-GFP), we showed that Plxdc2-GFP is highly expressed in HSCs with 1 in 2.8 Plxdc2-GFP+CD150+ cells giving long-term multi-lineage reconstitution in transplantation. Moreover, we developed a novel human PLXDC2 antibody and showed that human PLXDC2+ HSCs have stronger long-term multilineage reconstitution ability compared with PLXDC2- HSCs in a xenograft model. Thus, our study identifies PLXDC2 as a highly relevant molecule in HSC identification, potentially allowing greater purity and live in vivo tracking of these cells. SummaryTo date, few molecules are available for isolation of HSCs across species. The present study shows that PLXDC2 is a highly useful molecule for isolation of HSCs, which works across mouse and human.

Maturity-onset diabetes of the young type 3 (MODY3) disorder is characterized by an autosomal dominant type of inheritance and highly heterogeneous clinical phenotype influenced by type and position of mutation in the HNF1A gene. We reprogrammed dermal fibroblasts derived from a patient with MODY3 carrying a heterozygous mutation in the site encoding the transactivation domain of the HNF1A protein (c. 864delGinsCC, p.Gly292ArgfsTer25) into iPSCs using transfection with self-replicating RNA vector. Obtained iPSCs (ERCi004-A line) proliferate in dense monolayer cell colonies, have a normal karyotype (46,XX), express pluripotency markers (OCT4, SOX2, TRA-1-60). The functional pluripotency of iPSCs was confirmed by their ability to form embryoid bodies and differentiate into the three germ layers (ecto-, endo-, and mesoderm). Sanger sequencing of iPSCs confirmed the presence of pathogenic heterozygous mutation in the HNF1A gene. This cell line could be useful to modeling of MODY3 pathology to improve understanding of the mechanism of the transactivation domain mutation, as well as a potential source for autologous cell-based therapy.

BackgroundCompetitive transplantation is essential for defining intrinsic repopulating capacity of murine hematopoietic stem and progenitor cells (HSPCs), yet comparable assays for human cells have been limited by the lack of a robust in vivo platform. MethodsHere, we describe a novel competitive transplantation method in humanized NOD.Cg-KitW-41J Tyr + Prkdcscid Il2rgtm1Wjl/ThomJ (NBSGW) mice that enables simultaneous engraftment and longitudinal tracking of distinct human grafts within a shared microenvironment. ResultsUsing human leukocyte antigen-mismatched donor CD34+ cells, this method facilitates standard flow cytometry panels to track multiple donor cell chimerism, lineage output, and HSPC composition. The experimental framework may be adapted to different mouse models, conditioning strategies, donor sources, and treatments. ConclusionsOverall, this humanized competitive repopulation assay fills a critical translational gap and offers a flexible foundation for advancing mechanistic discovery in human hematopoietic biology and improving clinical strategies for stem cell transplantation.

BackgroundiPSCs generated from healthy individuals constitute an important control resource for disease modelling applications but existing biobanks are highly skewed towards populations of European ancestry while well characterized control lines from Indian populations remain limited. Given the extensive genetic diversity of the Indian subcontinent, the availability of ethnically relevant healthy control lines is important for developing accurate disease models and reducing population specific confounding effects. MethodologyWe used peripheral blood mononuclear cells (PBMNCs) of a healthy female donor of Eastern Indian origin for the generation a wild type iPSC line using non-integrating episomal reprogramming vectors. Established colonies were expanded and characterized through morphological assessment, expression of pluripotency and trilineage markers, episomal vector clearance analysis, and chromosomal stability evaluation and mycoplasma contamination analysis. ResultsThe line generated exhibited characteristic pluripotent stem cell morphology and also showed strong expression of pluripotency markers, was free from any contamination and free from the reprogramming vectors confirming an integration free system. The cells maintained a normal diploidy number during characterization. Expression of lineage specific markers associated with ectoderm, mesoderm and endoderm confirmed the developed iPSCs functional capacity to undergo trilineage differentiation. ConclusionWe have developed and validated an iPSC line from an underrepresented Indian population. This well characterized, ethnicity specific iPSC line provides a valuable cell line for establishing a high quality, well characterized control baseline, which is a major missing element in South Asian stem cell repositories and thus will provide a solid foundation for future disease specific modelling and screening.

Immune checkpoint inhibitor-associated myocarditis (ICIM) is an uncommon but potentially fatal inflammatory heart disease triggered by cancer immunotherapy, with up to 40% mortality. The underlying mechanisms are still elusive, partly due to the lack of appropriate human disease models. Here, we report the generation of three induced pluripotent stem cell (iPSC) lines derived from an ICIM patient, an ICI-treated patient without myocarditis, and a healthy donor. These lines exhibit typical pluripotent stem cell morphology, express pluripotency markers, maintain normal karyotypes, and differentiate into derivatives of the three germ layers, providing a valuable platform for mechanistic studies and therapeutic discovery.

BackgroundMegalencephalic leukoencephalopathy with subcortical cysts (MLC), a rare and progressive neurodegenerative disorder involving the white matter, is not adequately recapitulated by current disease models. Somatic cell reprogramming, along with advancements in genome engineering, may allow the establishment of in-vitro human models of MLC for disease modeling and drug screening. In this study, we utilized cellular reprogramming and gene-editing techniques to develop induced pluripotent stem cell (iPSC) models of MLC to recapitulate the cellular context of the classical MLC-impacted nervous system. MethodsSomatic cell reprogramming of peripheral patient-derived blood mononuclear cells (PBMCs) was used to develop iPSC models of MLC. CRISPR-Cas9 system-based genome engineering was also utilized to create the MLC1 knockout model of the disease. Directed differentiation of iPSCs to neural stem cells (NSCs) and astrocytes was performed in a 2D cell culture format, followed by various cellular and molecular biology approaches, to characterize the disease model. ResultsMLC iPSCs established by somatic cell reprogramming and genome engineering were well characterized for pluripotency. iPSCs were subsequently differentiated to disease-relevant cell types: neural stem cells (NSCs) and astrocytes. RNA sequencing profiling of MLC NSCs revealed a set of differentially expressed genes related to neurological disorders and epilepsy, a common clinical finding within MLC disease. This gene set can serve as a target for drug screening for the development of a potential therapeutic for this disease. Upon differentiation to the more disease relevant cell type-astrocytes, MLC-characteristic vacuoles were clearly observed, which were distinctly absent from controls. This emergence recapitulated a distinguishing phenotypic marker of the disease. ConclusionThrough the creation and analyses of iPSC models of MLC, our work addresses a critical need for relevant cellular models of MLC for use in both disease modeling and drug screening assays. Further investigation can utilize MLC iPSC models, as well as generated transcriptomic data sets and analyses, to identify potential therapeutic interventions for this debilitating disease.

hPSCs can acquire chromosomal aberrations such as copy number variations during prolonged maintenance in vitro, conferring growth advantages. However, the effect of these culture-acquired mutations on the phenotypes of the differentiated hPSCs is largely unstudied. Here, we identified mosaicism in a hPSC line in which some cells showed a gain of chromosome 1q31.3. We subcloned the wild-type and variant hPSCs and could maintain both as stable lines. While both variant and wildtype lines differentiated efficiently to cardiomyocytes (hPSC-CMs), molecular analysis revealed the variant hPSC-CMs had increased expression of TNNT2, a gene encoding one of the major sarcomere proteins mediating cardiomyocyte contractility and located within the gained chromosome 1q region. Moreover, the variant hPSC-CMs showed altered contraction kinetics. Together these results highlight the importance of careful monitoring of chromosome aberrations in hPSC lines as these could have confounding effects in various applications such as disease modelling and drug discovery.