Efficient human iPS cell derivation by a non-integrating plasmid from blood cells with unique epigenetic and gene expression signatures

HMGA1 acts as an epigenetic gatekeeper of ASCL2 and Wnt signaling during colon tumorigenesis

Mutated tumor cells undergo changes in chromatin accessibility and gene expression, resulting in aberrant proliferation and differentiation, although how this occurs is unclear. HMGA1 chromatin regulators are abundant in stem cells and oncogenic in diverse tissues; however, their role in colon tumorigenesis is only beginning to emerge. Here, we uncover a previously unknown epigenetic program whereby HMGA1 amplifies Wnt signaling during colon tumorigenesis driven by inflammatory microbiota and/or Adenomatous polyposis coli (Apc) inactivation. Mechanistically, HMGA1 "opens" chromatin to upregulate the stem cell regulator, Ascl2, and downstream Wnt effectors, promoting stem and Paneth-like cell states while depleting differentiated enterocytes. Loss of just one Hmga1 allele within colon epithelium restrains tumorigenesis and Wnt signaling driven by mutant Apc and inflammatory microbiota. However, HMGA1 deficiency has minimal effects in colon epithelium under homeostatic conditions. In human colon cancer cells, HMGA1 directly induces ASCL2 by recruiting activating histone marks. Silencing HMGA1 disrupts oncogenic properties, whereas reexpression of ASCL2 partially rescues these phenotypes. Further, HMGA1 and ASCL2 are coexpressed and upregulated in human colorectal cancer. Together, our results establish HMGA1 as an epigenetic gatekeeper of Wnt signals and cell state under conditions of APC inactivation, illuminating HMGA1 as a potential therapeutic target in colon cancer.

Human organoids and organ-on-chips in coeliac disease research

Coeliac disease (CeD) is an immune-mediated disorder characterised by gluten-triggered inflammation and damage in the small intestine, with lifelong gluten-free diet (GFD) as the only treatment. It is a multifactorial disease, involving genetic and environmental susceptibility factors, and its complexity and lack of comprehensive human model systems have hindered understanding of its pathogenesis and development of new treatments. Therefore, it is crucial to establish systems that recapitulate patient genetic background and the interactions between the small intestinal epithelial barrier, immune cells, and environment that contribute to CeD. In this review, we discuss disease complexity, recent advances in stem cell biology, organoids, tissue co-cultures, and organ-on-chip (OoC) systems that facilitate the development of comprehensive human model systems, and model applications in preclinical studies of potential treatments.

Human iPSC Reprogramming Success: The Impact of Approaches and Source Materials

Since their discovery, human induced pluripotent stem cells (hiPSCs) have been instrumental in biomedical research, particularly in the fields of disease modelling, drug screening and regenerative therapies. Their use has significantly increased over recent years driven by the ability of hiPSCs to provide differentiated cell models without requiring embryonic stem cells. Furthermore, the transition from integrating to non-integrating reprogramming methodologies has contributed to the increase in utilisation. This shift minimises the risk of genomic alterations, enhancing the safety and reliability of hiPSCs. However, the factors that contribute to reprogramming success are still not well understood. In this study, we conducted a comparative analysis of the most prevalent non-integrating reprogramming methods across a range of starting source materials to assess their impact on reprogramming success rates. We found that while source material does not significantly impact success rates, the Sendai virus reprogramming method yields significantly higher success rates relative to the episomal reprogramming method. Our findings offer important insights from a biobanking perspective, for which long-term reliability, integrity and reproducibility of hiPSCs are crucial.

Subtype-specific neurons from patient iPSCs display distinct neuropathological features of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by massive neuronal loss in the brain. Both cortical glutamatergic neurons and basal forebrain cholinergic neurons (BFCNs) in the AD brain are selectively vulnerable. The degeneration and dysfunction of these two subtypes of neurons are closely associated with the cognitive decline of AD patients. The determination of cellular and molecular mechanisms involved in AD pathogenesis, especially in the early stage, will largely facilitate the understanding of this disease and the development of proper intervention strategies. However, due to the inaccessibility of living neurons in the brains of patients, it remains unclear how cortical glutamatergic neurons and BFCNs respond to pathological stress in the early stage of AD. In this study, we established in vitro differentiation systems that can efficiently differentiate patient-derived iPSCs into BFCNs. We found that AD-BFCNs secreted less Aβ peptide than cortical glutamatergic neurons did, even though the Aβ42/Aβ40 ratio was comparable to that of cortical glutamatergic neurons. To further mimic the neurotoxic niche in AD brain, we treated iPSC-derived neurons with Aβ42 oligomer (AβO). BFCNs are less sensitive to AβO induced tau phosphorylation and expression than cortical glutamatergic neurons. However, AβO could trigger apoptosis in both AD-cortical glutamatergic neurons and AD-BFCNs. In addition, AD iPSC-derived BFCNs and cortical glutamatergic neurons exhibited distinct electrophysiological firing patterns and elicited different responses to AβO treatment. These observations revealed that subtype-specific neurons display distinct neuropathological changes during the progression of AD, which might help to understand AD pathogenesis at the cellular level.

An Optimized Human Erythroblast Differentiation System Reveals Cholesterol-Dependency of Robust Production of Cultured Red Blood Cells Ex Vivo

The generation of cultured red blood cells (cRBCs) ex vivo represents a potentially unlimited source for RBC transfusion and other cell therapies. Human cRBCs can be generated from the terminal differentiation of proliferating erythroblasts derived from hematopoietic stem/progenitor cells or erythroid precursors in peripheral blood mononuclear cells. Efficient differentiation and maturation into cRBCs highly depend on replenishing human plasma, which exhibits variable potency across donors or batches and complicates the consistent cRBC production required for clinical translation. Hence, the role of human plasma in erythroblast terminal maturation is investigated and uncovered that 1) a newly developed cell culture basal medium mimicking the metabolic profile of human plasma enhances cell growth and increases cRBC yield upon erythroblast terminal differentiation and 2) LDL-carried cholesterol, as a substitute for human plasma, is sufficient to support erythroid survival and terminal differentiation ex vivo. Consequently, a chemically-defined optimized medium (COM) is developed, enabling robust generation of cRBCs from erythroblasts of multiple origins, with improved enucleation efficiency and higher reticulocyte yield, without the need for supplementing human plasma or serum. In addition, the results reveal the crucial role of lipid metabolism during human terminal erythropoiesis.

Generation of iPSC lines (KAIMRCi003A, KAIMRCi003B) from a Saudi patient with Dravet syndrome carrying homozygous mutation in the CPLX1 gene and heterozygous mutation in SCN9A

The most prevalent form of epileptic encephalopathy is Dravet syndrome (DRVT), which is triggered by the pathogenic variant SCN1A in 80% of cases. iPSCs with different SCN1A mutations have been constructed by several groups to model DRVT syndrome. However, no studies involving DRVT-iPSCs with rare genetic variants have been conducted. Here, we established two DRVT-iPSC lines harboring a homozygous mutation in the CPLX1 gene and heterozygous mutation in SCN9A gene. Therefore, the derivation of these iPSC lines provides a unique cellular platform to dissect the molecular mechanisms underlying the cellular dysfunctions consequent to CPLX1 and SCN9A mutations.

Novel Approaches to Studying SLC13A5 Disease

The role of the sodium citrate transporter (NaCT) SLC13A5 is multifaceted and context-dependent. While aberrant dysfunction leads to neonatal epilepsy, its therapeutic inhibition protects against metabolic disease. Notably, insights regarding the cellular and molecular mechanisms underlying these phenomena are limited due to the intricacy and complexity of the latent human physiology, which is poorly captured by existing animal models. This review explores innovative technologies aimed at bridging such a knowledge gap. First, I provide an overview of SLC13A5 variants in the context of human disease and the specific cell types where the expression of the transporter has been observed. Next, I discuss current technologies for generating patient-specific induced pluripotent stem cells (iPSCs) and their inherent advantages and limitations, followed by a summary of the methods for differentiating iPSCs into neurons, hepatocytes, and organoids. Finally, I explore the relevance of these cellular models as platforms for delving into the intricate molecular and cellular mechanisms underlying SLC13A5-related disorders.

Engineered T cells from induced pluripotent stem cells: from research towards clinical implementation

Induced pluripotent stem cell (iPSC)-derived T (iT) cells represent a groundbreaking frontier in adoptive cell therapies with engineered T cells, poised to overcome pivotal limitations associated with conventional manufacturing methods. iPSCs offer an off-the-shelf source of therapeutic T cells with the potential for infinite expansion and straightforward genetic manipulation to ensure hypo-immunogenicity and introduce specific therapeutic functions, such as antigen specificity through a chimeric antigen receptor (CAR). Importantly, genetic engineering of iPSC offers the benefit of generating fully modified clonal lines that are amenable to rigorous safety assessments. Critical to harnessing the potential of iT cells is the development of a robust and clinically compatible production process. Current protocols for genetic engineering as well as differentiation protocols designed to mirror human hematopoiesis and T cell development, vary in efficiency and often contain non-compliant components, thereby rendering them unsuitable for clinical implementation. This comprehensive review centers on the remarkable progress made over the last decade in generating functional engineered T cells from iPSCs. Emphasis is placed on alignment with good manufacturing practice (GMP) standards, scalability, safety measures and quality controls, which constitute the fundamental prerequisites for clinical application. In conclusion, the focus on iPSC as a source promises standardized, scalable, clinically relevant, and potentially safer production of engineered T cells. This groundbreaking approach holds the potential to extend hope to a broader spectrum of patients and diseases, leading in a new era in adoptive T cell therapy.

Avian iPSC Derivation to Recover Threatened Wild Species: A Comprehensive Review in Light of Well-Established Protocols

Induced pluripotent stem cells (iPSCs) were first generated by Yamanaka in 2006, revolutionizing research by overcoming limitations imposed by the use of embryonic stem cells. In terms of the conservation of endangered species, iPSC technology presents itself as a viable alternative for the manipulation of target genetics without compromising specimens. Although iPSCs have been successfully generated for various species, their application in nonmammalian species, particularly avian species, requires further in-depth investigation to cover the diversity of wild species at risk and their different protocol requirements. This study aims to provide an overview of the workflow for iPSC induction, comparing well-established protocols in humans and mice with the limited information available for avian species. Here, we discuss the somatic cell sources to be reprogrammed, genetic factors, delivery methods, enhancers, a brief history of achievements in avian iPSC derivation, the main approaches for iPSC characterization, and the future perspectives and challenges for the field. By examining the current protocols and state-of-the-art techniques employed in iPSC generation, we seek to contribute to the development of efficient and species-specific iPSC methodologies for at-risk avian species. The advancement of iPSC technology holds great promise for achieving in vitro germline competency and, consequently, addressing reproductive challenges in endangered species, providing valuable tools for basic research, bird genetic preservation and rescue, and the establishment of cryobanks for future conservation efforts.

Advances in Genetic Reprogramming: Prospects from Developmental Biology to Regenerative Medicine

The foundations of cell reprogramming were laid by Yamanaka and co-workers, who showed that somatic cells can be reprogrammed into pluripotent cells (induced pluripotency). Since this discovery, the field of regenerative medicine has seen advancements. For example, because they can differentiate into multiple cell types, pluripotent stem cells are considered vital components in regenerative medicine aimed at the functional restoration of damaged tissue. Despite years of research, both replacement and restoration of failed organs/ tissues have remained elusive scientific feats. However, with the inception of cell engineering and nuclear reprogramming, useful solutions have been identified to counter the need for compatible and sustainable organs. By combining the science underlying genetic engineering and nuclear reprogramming with regenerative medicine, scientists have engineered cells to make gene and stem cell therapies applicable and effective. These approaches have enabled the targeting of various pathways to reprogramme cells, i.e., make them behave in beneficial ways in a patient-specific manner. Technological advancements have clearly supported the concept and realization of regenerative medicine. Genetic engineering is used for tissue engineering and nuclear reprogramming and has led to advances in regenerative medicine. Targeted therapies and replacement of traumatized , damaged, or aged organs can be realized through genetic engineering. Furthermore, the success of these therapies has been validated through thousands of clinical trials. Scientists are currently evaluating induced tissue-specific stem cells (iTSCs), which may lead to tumour-free applications of pluripotency induction. In this review, we present state-of-the-art genetic engineering that has been used in regenerative medicine. We also focus on ways that genetic engineering and nuclear reprogramming have transformed regenerative medicine and have become unique therapeutic niches.

Optimized and Scalable Precoating-Free Reprogramming of Human Peripheral Blood Mononuclear Cells into iPSCs

Human disease modeling has been profoundly transformed by the introduction of human induced pluripotent stem cells (iPSCs), marking the onset of a new era. This ground-breaking development offers a tailored framework for generating pluripotent cells from any individual, effectively enabling the development of cellular models for the study of human physiology and diseases on an unprecedented scale. Although technologies for iPSCs generation have advanced rapidly over the past two decades, protocols for reprogramming patient-derived somatic cells into stem cells still pose a major challenge for the development of automated pipelines capable of generating iPSCs at scales that are cost-effective, reproducible, and easy to implement. Most methods commonly rely on extracellular matrix protein mixtures or synthetic substrates to promote efficient proliferation of iPSCs. Nonetheless, employing these substances entails a laborious and time-consuming process, as the culture surface requires coating treatments before cell seeding. Here we describe a method for reprogramming blood-derived mononucleated cells that eliminates the need to precoat culture surfaces for the entire experimental flow. This procedure is suitable for fresh or frozen purified peripheral blood mononuclear cells (PBMCs) and allows seeding of reprogrammed cells in a culture medium containing a fragment of laminin-511, regardless of the method of reprogramming employed. Our protocol incorporates a streamlined workflow that optimizes key factors, including cell density, culture medium composition, and iPSC culture propagation techniques. Using a precoating-free approach, we eliminate the time-consuming steps, while our optimized subcloning method improves the scalability of the protocol, making it suitable for large-scale applications. Additionally, the automation-friendly nature of our protocol allows for high-throughput processing, reducing the labor and costs associated with manual handling. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Miniaturized and time efficient precoating-free reprogramming of fresh or frozen PBMCs Alternate Protocol: Erythroid progenitor cells (EPCs) enrichment and reprogramming into iPSCs using Sendai viral vectors Basic Protocol 2: Picking and precoating-free optimized expansion of iPSC clones.

HLA-based banking of induced pluripotent stem cells in Saudi Arabia

BACKGROUND

Human iPSCs' derivation and use in clinical studies are transforming medicine. Yet, there is a high cost and long waiting time associated with autologous iPS-based cellular therapy, and the genetic engineering of hypo-immunogenic iPS cell lines is hampered with numerous hurdles. Therefore, it is increasingly interesting to create cell stocks based on HLA haplotype distribution in a given population. This study aimed to assess the potential of HLA-based iPS banking for the Saudi population.

METHODS

In this study, we interrogated the HLA database of the Saudi Stem Cell Donor Registry (SSCDR), containing high-resolution HLA genotype data from 64,315 registered Saudi donors at the time of analysis. This database was considered to be a representative sample of the Saudi population. The most frequent HLA haplotypes in the Saudi population were determined, and an in-house developed iterative algorithm was used to identify their HLA matching percentages in the SSCDR database and cumulative coverage. Subsequently, to develop a clinically relevant protocol for iPSCs generation, and to illustrate the applicability of the concept of HLA-based banking for cell therapy purposes, the first HLA-based iPS cell line in Saudi Arabia was generated. Clinically relevant methods were employed to generate the two iPS clones from a homozygous donor for the most prevalent HLA haplotype in the Saudi population. The generated lines were then assessed for pluripotency markers, and their ability to differentiate into all three germ layers, beating cardiomyocytes, and neural progenitors was examined. Additionally, the genetic stability of the HLA-iPS cell lines was verified by comparing the mutational burden in the clones and the original blood sample, using whole-genome sequencing. The standards set by the American College of Medical Genetics and Genomics (ACMG) were used to determine the clinical significance of identified variants.

RESULTS

The analysis revealed that the establishment of only 13 iPSC lines would match 30% of the Saudi population, 39 lines would attain 50% coverage, and 596 lines would be necessary for over 90% coverage. The proof-of-concept HLA-iPSCs, which cover 6.1% of the Saudi population, successfully demonstrated pluripotency and the ability to differentiate into various cell types including beating cardiomyocytes and neuronal progenitors. The comprehensive genetic analysis corroborated that all identified variants in the derived iPSCs were inherently present in the original donor sample and were classified as benign according to the standards set by the ACMG.

CONCLUSIONS

Our study sets a road map for introducing iPS-based cell therapy in the Kingdom of Saudi Arabia. It underscores the pragmatic approach of HLA-based iPSC banking which circumvents the limitations of autologous iPS-based cellular therapies. The successful generation and validation of iPSC lines based on the most prevalent HLA haplotype in the Saudi population signify a promising step toward broadening the accessibility and applicability of stem cell therapies and regenerative medicine in Saudi Arabia.

Generation and Characterization of a Human-Derived and Induced Pluripotent Stem Cell (iPSC) Line from an Alzheimer's Disease Patient with Neuropsychiatric Symptoms

Agitation is one of the most eminent characteristics of neuropsychiatric symptoms (NPS) affecting people living with Alzheimer's and Dementia and has serious consequences for patients and caregivers. The current consensus is that agitation results, in part, from the disruption of ascending monoamine regulators of cortical circuits, especially the loss of serotonergic activity. It is believed that the first line of treatment for these conditions is selective serotonin reuptake inhibitors (SSRIs), but these are effective in only about 40% of patients. Person-specific biomarkers, for example, ones based on in vitro iPSC-derived models of serotonin activity, which predict who with Agitation responds to an SSRI, are a major clinical priority. Here, we report the generation of human-induced pluripotent stem cells (iPSCs) from a 74-year-old AD patient, the homozygous APOE ε4/ε4 carrier, who developed Agitation. His iPSCs were reprogrammed from peripheral blood mononuclear cells (PBMCs) using the transient expression of pluripotency genes. These display typical iPSC characteristics that are karyotypically normal and attain the capacity to differentiate into three germ layers. The newly patient-derived iPSC line offers a unique resource to investigate the underlying mechanisms associated with neuropsychiatric symptom progression in AD.

The Emerging Role of Induced Pluripotent Stem Cells as Adoptive Cellular Immunotherapeutics

Adoptive cell therapy (ACT) has transformed the treatment landscape for cancer and infectious disease through the investigational use of chimeric antigen receptor T-cells (CAR-Ts), tumour-infiltrating lymphocytes (TILs) and viral-specific T-cells (VSTs). Whilst these represent breakthrough treatments, there are subsets of patients who fail to respond to autologous ACT products. This is frequently due to impaired patient T-cell function or "fitness" as a consequence of prior treatments and age, and can be exacerbated by complex manufacturing protocols. Further, the manufacture of autologous, patient-specific products is time-consuming, expensive and non-standardised. Induced pluripotent stem cells (iPSCs) as an allogeneic alternative to patient-specific products can potentially overcome the issues outlined above. iPSC technology provides an unlimited source of rejuvenated iPSC-derived T-cells (T-iPSCs) or natural killer (NK) cells (NK-iPSCs), and in the context of the growing field of allogeneic ACT, iPSCs have enormous potential as a platform for generating off-the-shelf, standardised, "fit" therapeutics for patients. In this review, we evaluate current and future applications of iPSC technology in the CAR-T/NK, TIL and VST space. We discuss current and next-generation iPSC manufacturing protocols, and report on current iPSC-based adoptive therapy clinical trials to elucidate the potential of this technology as the future of ACT.

Establishment of induced pluripotent stem cell line SDPHi003-A from a healthy male donor

Peripheral blood mononuclear cells (PBMCs) were derived from a 67-year-old Chinese male. We used non-integrating episomal vectors containing OCT4, SOX2, KLF4 and c-MYC to reprogram PBMCs into induced pluripotent stem cell (iPSCs). This iPSC line, SDPHi003-A, have a normal karyotype, expressed pluripotent markers and have the potential for trilineage differentiation. This iPSC line can be used as a control for disease modeling studies and contribute to the research exploring disease pathogenesis.

Induced pluripotent stem cells for cardiovascular therapeutics: Progress and perspectives

The discovery of methods for reprogramming adult somatic cells into induced pluripotent stem cells (iPSCs) opens up prospects of developing personalized cell-based therapy options for a variety of human diseases as well as disease modeling and new drug discovery. Like embryonic stem cells, iPSCs can give rise to various cell types of the human body and are amenable to genetic correction. This allows usage of iPSCs in the development of modern therapies for many virtually incurable human diseases. The review summarizes progress in iPSC research in the context of application in the cardiovascular field including modeling cardiovascular disease, drug study, tissue engineering, and perspectives for personalized cardiovascular medicine.

Excitatory Neurons Derived from Human-Induced Pluripotent Stem Cells Show Transcriptomic Differences in Alzheimer's Patients from Controls

The recent advances in creating pluripotent stem cells from somatic cells and differentiating them into a variety of cell types is allowing us to study them without the caveats associated with disease-related changes. We generated induced Pluripotent Stem Cells (iPSCs) from eight Alzheimer's disease (AD) patients and six controls and used lentiviral delivery to differentiate them into excitatory glutamatergic neurons. We then performed RNA sequencing on these neurons and compared the Alzheimer's and control transcriptomes. We found that 621 genes show differences in expression levels at adjusted p < 0.05 between the case and control derived neurons. These genes show significant overlap and directional concordance with genes reported from a single-cell transcriptome study of AD patients; they include five genes implicated in AD from genome-wide association studies and they appear to be part of a larger functional network as indicated by an excess of interactions between them observed in the protein-protein interaction database STRING. Exploratory analysis with Uniform Manifold Approximation and Projection (UMAP) suggests distinct clusters of patients, based on gene expression, who may be clinically different. Our research outcomes will enable the precise identification of distinct biological subtypes among individuals with Alzheimer's disease, facilitating the implementation of tailored precision medicine strategies.

Wnt3a-Loaded Extracellular Vesicles Promote Alveolar Epithelial Regeneration after Lung Injury

Compromised regeneration resulting from the deactivation of Wnt/β-catenin signaling contributes to the progression of chronic obstructive pulmonary disease (COPD) with limited therapeutic options. Extracellular cytokine-induced Wnt-based signaling provides an alternative option for COPD treatment. However, the hydrophobic nature of Wnt proteins limits their purification and use. This study devises a strategy to deliver the membrane-bound wingless-type MMTV integration site family, member 3A (Wnt3a) over a long distance by anchoring it to the surface of extracellular vesicles (EVs). The newly engineered Wnt3aWG EVs are generated by co-expressing Wnt3a with two genes encoding the membrane protein, WLS, and an engineered glypican, GPC6ΔGPI -C1C2. The bioactivity of Wnt3aWG EVs is validated using a TOPFlash assay and a mesoderm differentiation model of human pluripotent stem cells. Wnt3aWG EVs activate Wnt signaling and promote cell growth following human alveolar epithelial cell injury. In an elastase-induced emphysema model, impaired pulmonary function and enlarged airspace are greatly restored by the intravenous delivery of Wnt3aWG EVs. Single-cell RNA sequencing-based analyses further highlight that Wnt3aWG EV-activated regenerative programs are responsible for its beneficial effects. These findings suggest that EV-based Wnt3a delivery represents a novel therapeutic strategy for lung repair and regeneration after injury.

Promoting the Differentiation of Neural Progenitor Cells into Oligodendrocytes through the Induction of Olig2 Expression: A Transcriptomic Study Using RNA-seq Analysis

Oligodendrocytes are the myelinating cells of the central nervous system that facilitate efficient signal transduction. The loss of these cells and the associated myelin sheath can lead to profound functional deficits. Moreover, oligodendrocytes also play key roles in mediating glial-neuronal interactions, which further speaks to their importance in health and disease. Neural progenitor cells (NPCs) are a promising source of cells for the treatment of oligodendrocyte-related neurological diseases due to their ability to differentiate into a variety of cell types, including oligodendrocytes. However, the efficiency of oligodendrocyte differentiation is often low. In this study, we induced the expression of the Olig2 transcription factor in tripotent NPCs using a doxycycline-inducible promoter, such that the extent of oligodendrocyte differentiation could be carefully regulated. We characterized the differentiation profile and the transcriptome of these inducible oligodendrogenic NPCs (ioNPCs) using a combination of qRT-PCR, immunocytochemistry and RNA sequencing with gene ontology (GO) and gene set enrichment analysis (GSEA). Our results show that the ioNPCs differentiated into a significantly greater proportion of oligodendrocytes than the NPCs. The induction of Olig2 expression was also associated with the upregulation of genes involved in oligodendrocyte development and function, as well as the downregulation of genes involved in other cell lineages. The GO and GSEA analyses further corroborated the oligodendrocyte specification of the ioNPCs.

Induced pluripotent stem cells in companion animals: how can we move the field forward?

Following a one medicine approach, the development of regenerative therapies for human patients leads to innovative treatments for animals, while pre-clinical studies on animals provide knowledge to advance human medicine. Among many different biological products under investigation, stem cells are among the most prominent. Mesenchymal stromal cells (MSCs) are extensively investigated, but they present challenges such as senescence and limited differentiation ability. Embryonic stem cells (ESCs) are pluripotent cells with a virtually unlimited capacity for self-renewal and differentiation, but the use of embryos carries ethical concerns. Induced pluripotent stem cells (iPSCs) can overcome all of these limitations, as they closely resemble ESCs but are derived from adult cells by reprogramming in the laboratory using pluripotency-associated transcription factors. iPSCs hold great potential for applications in therapy, disease modeling, drug screening, and even species preservation strategies. However, iPSC technology is less developed in veterinary species compared to human. This review attempts to address the specific challenges associated with generating and applying iPSCs from companion animals. Firstly, we discuss strategies for the preparation of iPSCs in veterinary species and secondly, we address the potential for different applications of iPSCs in companion animals. Our aim is to provide an overview on the state of the art of iPSCs in companion animals, focusing on equine, canine, and feline species, as well as to identify which aspects need further optimization and, where possible, to provide guidance on future advancements. Following a "step-by-step" approach, we cover the generation of iPSCs in companion animals from the selection of somatic cells and the reprogramming strategies, to the expansion and characterization of iPSCs. Subsequently, we revise the current applications of iPSCs in companion animals, identify the main hurdles, and propose future paths to move the field forward. Transferring the knowledge gained from human iPSCs can increase our understanding in the biology of pluripotent cells in animals, but it is critical to further investigate the differences among species to develop specific approaches for animal iPSCs. This is key for significantly advancing iPSC application in veterinary medicine, which at the same time will also allow gaining pre-clinical knowledge transferable to human medicine.

Reprogramming of human peripheral blood mononuclear cells into induced mesenchymal stromal cells using non-integrating vectors

Mesenchymal stromal cells (MSCs) have great value in cell therapies. The MSC therapies have many challenges due to its inconsistent potency and limited quantity. Here, we report a strategy to generate induced MSCs (iMSCs) by directly reprogramming human peripheral blood mononuclear cells (PBMCs) with OCT4, SOX9, MYC, KLF4, and BCL-XL using a nonintegrating episomal vector system. While OCT4 was not required to reprogram PBMCs into iMSCs, omission of OCT4 significantly impaired iMSC functionality. The omission of OCT4 resulted in significantly downregulating MSC lineage specific and mesoderm-regulating genes, including SRPX, COL5A1, SOX4, SALL4, TWIST1. When reprogramming PBMCs in the absence of OCT4, 67 genes were significantly hypermethylated with reduced transcriptional expression. These data indicate that transient expression of OCT4 may serve as a universal reprogramming factor by increasing chromatin accessibility and promoting demethylation. Our findings represent an approach to produce functional MSCs, and aid in identifying putative function associated MSC markers.

Evaluation of 2D and 3D Erythroid Differentiation Protocols Using Sickle Cell Disease and Healthy Donor Induced Pluripotent Stem Cells

BACKGROUND

Sickle cell disease (SCD) is a highly prevalent genetic disease caused by a point mutation in the HBB gene, which can lead to chronic hemolytic anemia and vaso-occlusive events. Patient-derived induced pluripotent stem cells (iPSCs) hold promise for the development of novel predictive methods for screening drugs with anti-sickling activity. In this study, we evaluated and compared the efficiency of 2D and 3D erythroid differentiation protocols using a healthy control and SCD-iPSCs.

METHODS

iPSCs were subjected to hematopoietic progenitor cell (HSPC) induction, erythroid progenitor cell induction, and terminal erythroid maturation. Differentiation efficiency was confirmed by flow cytometry analysis, colony-forming unit (CFU) assay, morphological analyses, and qPCR-based gene expression analyses of HBB and HBG2.

RESULTS

Both 2D and 3D differentiation protocols led to the induction of CD34⁺/CD43⁺ HSPCs. The 3D protocol showed good efficiency (>50%) and high productivity (45-fold) for HSPC induction and increased the frequency of BFU-E, CFU-E, CFU-GM, and CFU-GEMM colonies. We also produced CD71⁺/CD235a⁺ cells (>65%) with a 630-fold cell expansion relative to that at the beginning of the 3D protocol. After erythroid maturation, we observed 95% CD235a⁺/DRAQ5- enucleated cells, orthochromatic erythroblasts, and increased expression of fetal HBG2 compared to adult HBB.

CONCLUSION

A robust 3D protocol for erythroid differentiation was identified using SCD-iPSCs and comparative analyses; however, the maturation step remains challenging and requires further development.

Establishment of an induced pluripotent stem cell (SIAISi016-A) line from a 62-years old Chinese Han patient with Alzheimer's disease

A 62-years old Alzheimer's disease (AD) male patient donated his Peripheral blood mononuclear cells. The non-integrating episomal vector system used to reprogram PBMCs with Oct3/4, Klf4, Sox2 and c-Myc transcription factors. The pluripotency of transgene-free pluripotent stem cell (iPSC) was confirmed by immunocytochemistry for pluripotency markers-SOX2, NANOG, OCT3/4, SSEA4, TRA1-60, and TRA1-81. The differentiation capacity of the iPSCs into endoderm, mesoderm and ectoderm was assessed by AFP, SMA and βIII-TUBULIN, respectively. In addition, the iPSC line displayed a normal karyotype. This iPSC line might offer a good cell model to explore the pathological mechanisms and treatment strategies for AD.

HMGA1 induces FGF19 to drive pancreatic carcinogenesis and stroma formation

High mobility group A1 (HMGA1) chromatin regulators are upregulated in diverse tumors where they portend adverse outcomes, although how they function in cancer remains unclear. Pancreatic ductal adenocarcinomas (PDACs) are highly lethal tumors characterized by dense desmoplastic stroma composed predominantly of cancer-associated fibroblasts and fibrotic tissue. Here, we uncover an epigenetic program whereby HMGA1 upregulates FGF19 during tumor progression and stroma formation. HMGA1 deficiency disrupts oncogenic properties in vitro while impairing tumor inception and progression in KPC mice and subcutaneous or orthotopic models of PDAC. RNA sequencing revealed HMGA1 transcriptional networks governing proliferation and tumor-stroma interactions, including the FGF19 gene. HMGA1 directly induces FGF19 expression and increases its protein secretion by recruiting active histone marks (H3K4me3, H3K27Ac). Surprisingly, disrupting FGF19 via gene silencing or the FGFR4 inhibitor BLU9931 recapitulates most phenotypes observed with HMGA1 deficiency, decreasing tumor growth and formation of a desmoplastic stroma in mouse models of PDAC. In human PDAC, overexpression of HMGA1 and FGF19 defines a subset of tumors with extremely poor outcomes. Our results reveal what we believe is a new paradigm whereby HMGA1 and FGF19 drive tumor progression and stroma formation, thus illuminating FGF19 as a rational therapeutic target for a molecularly defined PDAC subtype.

Characterization of human induced pluripotent stems cells: Current approaches, challenges, and future solutions

Human induced pluripotent stem cells (iPSC) have demonstrated massive potentials for use in regenerative and personalized medicine due to their ability to expand in culture and differentiate into specialized cells with therapeutic benefits. However, in order to industrialize iPSC-derived therapies, it is necessary to address the existing challenges surrounding the analytics implemented in the manufacturing process to evaluate and monitor cell expansion, differentiation, and quality of the final products. Here, we review some of the key analytical methods used as part of identity, potency, or safety for in-process or final product release testing and highlighted the challenges and potential solutions for consideration in the Chemistry, Manufacturing and Controls (CMC) strategy for iPSC-based therapies. Some of the challenges associated with characterization and testing of iPSC-based products are related to the choice of analytical technology (to ensure fit-for-purpose), assay reliability and robustness. Automation of analytical methods may be required to reduce hands on time, and improve reliability of the methods through reducing assay variability. Indeed, we have shown that automation of analytical methods is feasible (evaluated using an ELISA based assay) and would result in more precise measurements (demonstrated by lower co-efficient of Variation and standard deviation), less hands-on time, and swift compared to a manually run assay. Therefore, in order to support commercialization of iPSC-based therapies we suggest a well-designed testing strategy to be established in the development phase while incorporating robust, reproducible, reliable, and potentially automated analytics in the manufacturing process.

iPSC-based model of Vogt-Koyanagi-Harada disease for phenotype recapitulation and drug screening

Vogt-Koyanagi-Harada (VKH) disease, a major blinding eye disease, is characterized by an autoimmune response against melanocytes in multiple organs throughout the body. Currently, the aetiology and pathogenesis of VKH disease are unclear, and the treatment strategy needs to be further optimized. The retinal pigment epithelium (RPE), a monolayer of pigmented cells of the fundus, is essential for maintaining normal visual function and is involved in both the acute and chronic stages of VKH disease. Therefore, the functions of the RPE may play a critical role in the aetiology and treatment of VKH disease. Herein, we established a human induced pluripotent stem cell (hiPSC) RPE model of VKH disease by reprogramming peripheral blood mononuclear cells (PBMCs) into iPSCs and then differentiating them into RPE cells. Patient-derived RPE cells exhibited barrier disruption, impaired phagocytosis, and depigmentation compared with those from normal controls, which was consistent with the features of VKH disease. Furthermore, a small molecular compound targeting EGR2 was found to rescue the barrier and phagocytic functions of the hiPSC-RPE cells through high-throughput virtual screening and functional studies, suggesting a promising strategy for the treatment of VKH disease.

PEAR1 is a potential regulator of early hematopoiesis of human pluripotent stem cells

Hemogenic endothelial (HE) cells are specialized endothelial cells to give rise to hematopoietic stem/progenitor cells during hematopoietic development. The underlying mechanisms that regulate endothelial-to-hematopoietic transition (EHT) of human HE cells are not fully understand. Here, we identified platelet endothelial aggregation receptor-1 (PEAR1) as a novel regulator of early hematopoietic development in human pluripotent stem cells (hPSCs). We found that the expression of PEAP1 was elevated during hematopoietic development. A subpopulation of PEAR1⁺ cells overlapped with CD34⁺ CD144⁺ CD184⁺ CD73^- arterial-type HE cells. Transcriptome analysis by RNA sequencing indicated that TAL1/SCL, GATA2, MYB, RUNX1 and other key transcription factors for hematopoietic development were mainly expressed in PEAR1⁺ cells, whereas the genes encoding for niche-related signals, such as fibronectin, vitronectin, bone morphogenetic proteins and jagged1, were highly expressed in PEAR1^- cells. The isolated PEAR1⁺ cells exhibited significantly greater EHT capacity on endothelial niche, compared with the PEAR1^- cells. Colony-forming unit (CFU) assays demonstrated the multilineage hematopoietic potential of PEAR1⁺ -derived hematopoietic cells. Furthermore, PEAR1 knockout in hPSCs by CRISPR/Cas9 technology revealed that the hematopoietic differentiation was impaired, resulting in decreased EHT capacity, decreased expression of hematopoietic-related transcription factors, and increased expression of niche-related signals. In summary, this study revealed a novel role of PEAR1 in balancing intrinsic and extrinsic signals for early hematopoietic fate decision.

Using liver models generated from human-induced pluripotent stem cells (iPSCs) for evaluating chemical-induced modifications and disease across liver developmental stages

The liver is a pivotal organ regulating critical developmental stages of fetal metabolism and detoxification. Though numerous studies have evaluated links between prenatal/perinatal exposures and adverse health outcomes in the developing fetus, the central role of liver to health disruptions resulting from these exposures remains understudied, especially concerning early development and later-in-life health outcomes. While numerous in vitro methods for evaluating liver toxicity have been established, the use of iPSC-derived hepatocytes appears to be particularly well suited to contribute to this critical research gap due to their potential to model a diverse range of disease phenotypes and different stages of liver development. The following key aspects are reviewed: (1) an introduction to developmental liver toxicity; (2) an introduction to embryonic and induced pluripotent stem cell models; (3) methods and challenges for deriving liver cells from stem cells; and (4) applications for iPSC-derived hepatocytes to evaluate liver developmental stages and their associated responses to insults. We conclude that iPSC-derived hepatocytes have great potential for informing liver toxicity and underlying disease mechanisms via the generation of patient-specific iPSCs; implementing large-scale drug and chemical screening; evaluating general biological responses as a potential surrogate target cell; and evaluating inter-individual disease susceptibility and response variability.

Generation of transgene-free human induced pluripotent stem cells from erythroblasts in feeder-free conditions

This protocol describes the generation and characterization of human induced pluripotent stem cells (hiPSCs) from erythroblasts. A key difference with classical protocols is the reprogramming of erythroblasts from a simple blood draw as opposed to fibroblasts/keratinocytes, which requires a biopsy. Moreover, working with erythroblasts ensures that no recombination of the TCR/BCR genes occurs, as opposed to T cells and whole peripheral blood mononuclear cells-based approaches. Last, this approach uses non-integrative episomes ensuring no integration of transgenes into the hiPSCs genome.

For complete details on the use and execution of this protocol, please refer to Perriot et al. (2018).

•

Generation of human iPSCs from only 10 mL of blood

•

An approach that is completely feeder free and transgene free

•

Quality controls following the guidelines edited by the European Bank for iPSCs (EBiSC)

•

Absence of TCR/BCR genomic recombination attributed to erythroblast reprogramming

Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

Establishment of SIAISi021-A, an induced pluripotent stem cell (iPSC) line from a 71-year-old Chinese Han male with Alzheimer's Disease (AD) having two copies of APOE4/4 allele

A 71-year-old Han male from China contributed peripheral blood mononuclear cells (PBMCs). Non-integrative Sendai viral vectors containing reprogramming factors OCT4, KLF4, SOX2 and C-MYC were used to reprogram PBMCs. Pluripotency makers confirmed the pluripotency of transgene-free induced pluripotent stem cell (iPSC). The ability of iPSC to spontaneously differentiate three germ layers in vitro confirmed the pluripotency of iPSC. The iPSC line displayed a normal karyotype. The newly generated human iPSC SIAISi021-A can be used for studying further disease mechanisms of Alzheimer's Disease (AD).

Generation of two iPSC cell lines (SIAISi020-A and SIAISi019-A) from an 82-year-old mild cognitive impairment (MCI) and her unaffected child from Chinese Han population

IPSCs have great potential value in cell replacement therapy, pathogenesis research, screening for new drugs, and treatment of clinical disease. An 82-year-old woman with mild cognitive impairment (MCI) and her unaffected child donated their peripheral blood mononuclear cells (PBMC). Their PBMCs were reprogrammed using human OKSM transcription factors (SOX2, OCT3/4, KLF4 and C-MYC) via a non-integrated complementary vector system. In the newly developed hiPSC series SIAISi019-A and SIAISi020-A, immunocytochemistry and the ability to spontaneously differentiate into 3 germ layers in vitro confirmed the pluripotency of transgene-free iPSCs. And their karyotypes were normal.

Different Transcriptomic Response to T. cruzi Infection in hiPSC-Derived Cardiomyocytes From Chagas Disease Patients With and Without Chronic Cardiomyopathy

Chagas disease is a tropical zoonosis caused by Trypanosoma cruzi. After infection, the host present an acute phase, usually asymptomatic, in which an extensive parasite proliferation and intense innate immune activity occurs, followed by a chronic phase, characterized by low parasitemia and development of specific immunity. Most individuals in the chronic phase remain without symptoms or organ damage, a state called indeterminate IND form. However, 20 to 40% of individuals develop cardiac or gastrointestinal complications at any time in life. Cardiomyocytes have an important role in the development of Chronic Chagas Cardiomyopathy (CCC) due to transcriptional and metabolic alterations that are crucial for the parasite survival and replication. However, it still not clear why some infected individuals progress to a cardiomyopathy phase, while others remain asymptomatic. In this work, we used hiPSCs-derived cardiomyocytes (hiPSC-CM) to investigate patterns of infection, proliferation and transcriptional response in IND and CCC patients. Our data show that T. cruzi infection and proliferation efficiency do not differ significantly in PBMCs and hiPSC-CM from both groups. However, RNA-seq analysis in hiPSC-CM infected for 24 hours showed a significantly different transcriptional response to the parasite in cells from IND or CCC patients. Cardiomyocytes from IND showed significant differences in the expression of genes related to antigen processing and presentation, as well as, immune co-stimulatory molecules. Furthermore, the downregulation of collagen production genes and extracellular matrix components was significantly different in these cells. Cardiomyocytes from CCC, in turn, showed increased expression of mTORC1 pathway and unfolded protein response genes, both associated to increased intracellular ROS production. These data point to a differential pattern of response, determined by baseline genetic differences between groups, which may have an impact on the development of a chronic outcome with or without the presentation of cardiac symptoms.

Cell–Cell Contact Mediates Gene Expression and Fate Choice of Human Neural Stem/Progenitor Cells

Transplantation of Neural Stem/Progenitor Cells (NPCs) is a promising regenerative strategy to promote neural repair following injury and degeneration because of the ability of these cells to proliferate, migrate, and integrate with the host tissue. Precise in vitro control of NPC proliferation without compromising multipotency and differentiation ability is critical in stem cell maintenance. This idea was highlighted in recent clinical trials, where discrepancies in NPC culturing protocols produced inconsistent therapeutic benefits. Of note, cell density plays an important role in regulating the survival, proliferation, differentiation, and fate choice of stem cells. To determine the extent of variability produced by inconsistent culturing densities, the present study cultured human-induced pluripotent NPCs (hiPSC-NPCs) at either a low or high plating density. hiPSC-NPCs were then isolated for transcriptomic analysis or differentiation in vitro. Following sequencing analysis, genes involved in cell–cell contact-mediated pathways, including Hippo-signaling, NOTCH, and WNT were differentially expressed. Modulation of these pathways was highly associated with the regulation of pro-neuronal transcription factors, which were also upregulated in response to higher-density hiPSC-NPC culture. Moreover, higher plating density translated into a greater neuronal and less astrocytic differentiation in vitro. This study highlights the importance of precisely controlling culture conditions during the development of NPC transplantation therapies.

Spatial and Temporal Development of Müller Glial Cells in hiPSC-Derived Retinal Organoids Facilitates the Cell Enrichment and Transcriptome Analysis

Müller glial cells (MGCs) play important roles in human retina during physiological and pathological conditions. However, the development process of human MGCs in vivo remains unclear, and how to obtain large numbers of human MGCs with high quality faces technical challenges, which hinder the further study and application of MGCs. Human induced pluripotent stem cell (hiPSC)-derived retinal organoids (ROs) with all retinal cell subtypes provide an unlimited cell resource and a platform for the studies of retinal development and disorders. This study explored the development of human MGCs in hiPSC-derived ROs and developed an approach to select and expand the induced MGCs (iMGCs). In ROs, retinal progenitor cells progressively differentiated into SOX9+ Ki67– MGC precursors during differentiation day (D) 60 to D90, while mature MGCs expressing markers CRALBP and GS gradually appeared since D120, which spanned the entire thickness of the neural retina layer. Cells isolated from ROs aged older than 120 days was an optimal source for the enrichment of iMGCs with high purity and expansion ability. They had typical features of human MGCs in morphological, structural, molecular and functional aspects, and could be passaged serially at least 10 times, yielding large numbers of cells in a short period. The transcriptome pattern of the expanded iMGCs was also revealed. This study firstly clarified the timecourse of human MGC development in the RO model, where the iMGCs could be enriched and expanded, paving the way for downstream investigation and application in MGC-related retinal disorders.

HMGA1 chromatin regulators induce transcriptional networks involved in GATA2 and proliferation during MPN progression

Myeloproliferative neoplasms (MPNs) transform to myelofibrosis (MF) and highly lethal acute myeloid leukemia (AML), although the actionable mechanisms driving progression remain elusive. Here, we elucidate the role of the high mobility group A1 (HMGA1) chromatin regulator as a novel driver of MPN progression. HMGA1 is upregulated in MPN, with highest levels after transformation to MF or AML. To define HMGA1 function, we disrupted gene expression via CRISPR/Cas9, short hairpin RNA, or genetic deletion in MPN models. HMGA1 depletion in JAK2V617F AML cell lines disrupts proliferation, clonogenicity, and leukemic engraftment. Surprisingly, loss of just a single Hmga1 allele prevents progression to MF in JAK2V617F mice, decreasing erythrocytosis, thrombocytosis, megakaryocyte hyperplasia, and expansion of stem and progenitors, while preventing splenomegaly and fibrosis within the spleen and BM. RNA-sequencing and chromatin immunoprecipitation sequencing revealed HMGA1 transcriptional networks and chromatin occupancy at genes that govern proliferation (E2F, G2M, mitotic spindle) and cell fate, including the GATA2 master regulatory gene. Silencing GATA2 recapitulates most phenotypes observed with HMGA1 depletion, whereas GATA2 re-expression partially rescues leukemogenesis. HMGA1 transactivates GATA2 through sequences near the developmental enhancer (+9.5), increasing chromatin accessibility and recruiting active histone marks. Further, HMGA1 transcriptional networks, including proliferation pathways and GATA2, are activated in human MF and MPN leukemic transformation. Importantly, HMGA1 depletion enhances responses to the JAK2 inhibitor, ruxolitinib, preventing MF and prolonging survival in murine models of JAK2V617F AML. These findings illuminate HMGA1 as a key epigenetic switch involved in MPN transformation and a promising therapeutic target to treat or prevent disease progression.

Generation of an RCVRN-eGFP Reporter hiPSC Line by CRISPR/Cas9 to Monitor Photoreceptor Cell Development and Facilitate the Cell Enrichment for Transplantation

Stem cell-based cell therapies are considered to be promising treatments for retinal disorders with dysfunction or death of photoreceptors. However, the enrichment of human photoreceptors suitable for transplantation has been highly challenging so far. This study aimed to generate a photoreceptor-specific reporter human induced pluripotent stem cell (hiPSC) line using CRISPR/Cas9 genome editing, which harbored an enhanced green fluorescent protein (eGFP) sequence at the endogenous locus of the pan photoreceptor marker recoverin (RCVRN). After confirmation of successful targeting and gene stability, three-dimensional retinal organoids were induced from this reporter line. The RCVRN-eGFP reporter faithfully replicated endogenous protein expression of recoverin and revealed the developmental characteristics of photoreceptors during retinal differentiation. The RCVRN-eGFP specifically and steadily labeled photoreceptor cells from photoreceptor precursors to mature rods and cones. Additionally, abundant eGFP-positive photoreceptors were enriched by fluorescence-activated cell sorting, and their transcriptome signatures were revealed by RNA sequencing and data analysis. Moreover, potential clusters of differentiation (CD) biomarkers were extracted for the enrichment of photoreceptors for clinical applications, such as CD133 for the positive selection of photoreceptors. Altogether, the RCVRN-eGFP reporter hiPSC line was successfully established and the first global expression database of recoverin-positive photoreceptors was constructed. These achievements will provide a powerful tool for dynamically monitoring photoreceptor cell development and purification of human photoreceptors, thus facilitating photoreceptor cell therapy for advanced retinal disorders.

Defective hematopoietic differentiation of immune aplastic anemia patient-derived iPSCs

In acquired immune aplastic anemia (AA), pathogenic cytotoxic Th1 cells are activated and expanded, driving an immune response against the hematopoietic stem and progenitor cells (HSPCs) that provokes cell depletion and causes bone marrow failure. However, additional HSPC defects may contribute to hematopoietic failure, reflecting on disease outcomes and response to immunosuppression. Here we derived induced pluripotent stem cells (iPSCs) from peripheral blood (PB) erythroblasts obtained from patients diagnosed with immune AA using non-integrating plasmids to model the disease. Erythroblasts were harvested after hematologic response to immunosuppression was achieved. Patients were screened for germline pathogenic variants in bone marrow failure-related genes and no variant was identified. Reprogramming was equally successful for erythroblasts collected from the three immune AA patients and the three healthy subjects. However, the hematopoietic differentiation potential of AA-iPSCs was significantly reduced both quantitatively and qualitatively as compared to healthy-iPSCs, reliably recapitulating disease: differentiation appeared to be more severely affected in cells from the two patients with partial response as compared to the one patient with complete response. Telomere elongation and the telomerase machinery were preserved during reprogramming and differentiation in all AA-iPSCs. Our results indicate that iPSCs are a reliable platform to model immune AA and recapitulate clinical phenotypes. We propose that the immune attack may cause specific epigenetic changes in the HSPCs that limit adequate proliferation and differentiation.

Label-Free Imaging to Track Reprogramming of Human Somatic Cells

The process of reprogramming patient samples to human-induced pluripotent stem cells (iPSCs) is stochastic, asynchronous, and inefficient, leading to a heterogeneous population of cells. In this study, we track the reprogramming status of patient-derived erythroid progenitor cells (EPCs) at the single-cell level during reprogramming with label-free live-cell imaging of cellular metabolism and nuclear morphometry to identify high-quality iPSCs. EPCs isolated from human peripheral blood of three donors were used for our proof-of-principle study. We found distinct patterns of autofluorescence lifetime for the reduced form of nicotinamide adenine dinucleotide (phosphate) and flavin adenine dinucleotide during reprogramming. Random forest models classified iPSCs with ∼95% accuracy, which enabled the successful isolation of iPSC lines from reprogramming cultures. Reprogramming trajectories resolved at the single-cell level indicated significant reprogramming heterogeneity along different branches of cell states. This combination of micropatterning, autofluorescence imaging, and machine learning provides a unique, real-time, and nondestructive method to assess the quality of iPSCs in a biomanufacturing process, which could have downstream impacts in regenerative medicine, cell/gene therapy, and disease modeling.

Human organotypic brain model as a tool to study chemical-induced dopaminergic neuronal toxicity

Oxidative stress is caused by an imbalance between the generation and detoxification of reactive oxygen and nitrogen species (ROS/RNS). This imbalance plays an important role in brain aging and age-related neurodegenerative diseases. In the context of Parkinson’s disease (PD), the sensitivity of dopaminergic neurons in the substantia nigra pars compacta to oxidative stress is considered a key factor of PD pathogenesis. Here we study the effect of different oxidative stress-inducing compounds (6-OHDA, MPTP or MPP⁺) on the population of dopaminergic neurons in an iPSC-derived human brain 3D model (aka BrainSpheres). Treatment with 6-OHDA, MPTP or MPP⁺ at 4 weeks of differentiation disrupted the dopaminergic neuronal phenotype in BrainSpheres at (50, 5000, 1000 μM respectively). 6-OHDA increased ROS production and decreased mitochondrial function most efficiently. It further induced the greatest changes in gene expression and metabolites related to oxidative stress and mitochondrial dysfunction. Co-culturing BrainSpheres with an endothelial barrier using a transwell system allowed the assessment of differential penetration capacities of the tested compounds and the damage they caused in the dopaminergic neurons within the BrainSpheres In conclusion, treatment with compounds known to induce PD-like phenotypes in vivo caused molecular deficits and loss of dopaminergic neurons in the BrainSphere model. This approach therefore recapitulates common animal models of neurodegenerative processes in PD at similarly high doses. The relevance as tool for drug discovery is discussed.

Non-Integrating Lentiviral Vectors in Clinical Applications: A Glance Through

Lentiviral vectors (LVs) play an important role in gene therapy and have proven successful in clinical trials. LVs are capable of integrating specific genetic materials into the target cells and allow for long-term expression of the cDNA of interest. The use of non-integrating LVs (NILVs) reduces insertional mutagenesis and the risk of malignant cell transformation over integrating lentiviral vectors. NILVs enable transient expression or sustained episomal expression, especially in non-dividing cells. Important modifications have been made to the basic human immunodeficiency virus (HIV) structures to improve the safety and efficacy of LVs. NILV-aided transient expression has led to more pre-clinical studies on primary immunodeficiencies, cytotoxic cancer therapies, and hemoglobinopathies. Recently, the third generation of self-inactivating LVs was applied in clinical trials for recombinant protein production, vaccines, gene therapy, cell imaging, and induced pluripotent stem cell (iPSC) generation. This review discusses the basic lentiviral biology and the four systems used for generating NILV designs. Mutations or modifications in LVs and their safety are addressed with reference to pre-clinical studies. The detailed application of NILVs in promising pre-clinical studies is also discussed.

Bone regeneration of induced pluripotent stem cells derived from peripheral blood cells in collagen sponge scaffolds

Stem cell-based regeneration therapy offers new therapeutic options for patients with bone defects because of significant advances in stem cell research. Although bone marrow mesenchymal stem cells are the ideal material for bone regeneration therapy using stem cell, they are difficult to obtain. Induced pluripotent stem cells (iPSCs) are now considered an attractive tool in bone tissue engineering. Recently, the efficiency of establishing iPSCs has been improved by the use of the Sendai virus vector, and it has become easier to establish iPSCs from several type of somatic cells. In our previous study, we reported a method to purify osteogenic cells from iPSCs.

Single-cell RNA sequencing reveals that BMPR2 mutation regulates right ventricular function via ID genes

Mutations in bone morphogenetic protein type II receptor (BMPR2) have been found in patients with congenital heart disease-associated pulmonary arterial hypertension (CHD-PAH). Our study aimed to clarify whether deficient BMPR2 signalling acts through downstream effectors, inhibitors of DNA-binding proteins (IDs), during heart development to contribute to the progress of PAH in CHD patients. To confirm that IDs are downstream effectors of BMPR2 signalling in cardiac mesoderm progenitors (CMPs) and contribute to PAH, we generated Cardiomyocytes (CMs)-specific Id 1/3 knockout mice (Ids cDKO), and 12/25 developed mild PAH with altered haemodynamic indices and pulmonary vascular remodelling. Moreover, we generated ID1 and ID3 double-knockout (IDs KO) human embryonic stem cells that recapitulated the BMPR2 signalling deficiency of CHD-PAH iPSCs. CMs differentiated from induced pluripotent stem cells (iPSCs) derived from CHD-PAH patients with BMPR mutations exhibited dysfunctional cardiac differentiation and reduced Ca²⁺ transients, as evidenced by confocal microscopy experiments. Smad1/5 phosphorylation and ID1 and ID3 expression were reduced in CHD-PAH iPSCs and in Bmpr2 ^+/- rat right ventricles. Moreover, Ultrasound revealed that 33% of Ids cDKO mice had detectable defects in their ventricular septum and pulmonary regurgitation. CMs isolated from the mouse right ventricles also showed reduced Ca²⁺ transients and shortened sarcomeres. Single-cell RNA(scRNA)-seq analysis revealed impaired differentiation of CMPs and downregulated USP9X expression in IDs KO cells compared with wild-type (WT) cells. We found that BMPR2 signals through IDs and USP9X to regulate cardiac differentiation, and the loss of ID1 and ID3 expression contributes to CM dysfunction in CHD-PAH patients with BMPR2 mutations.

Generation of Primordial Germ Cell-like Cells from iPSCs Derived from Turner Syndrome Patients

Turner syndrome (TS) is a genetic disorder in females with X Chromosome monosomy associated with highly variable clinical features, including premature primary gonadal failure leading to ovarian dysfunction and infertility. The mechanism of development of primordial germ cells (PGCs) and their connection with ovarian failure in TS is poorly understood. An in vitro model of PGCs from TS would be beneficial for investigating genetic and epigenetic factors that influence germ cell specification. Here we investigated the potential of reprogramming peripheral mononuclear blood cells from TS women (PBMCs-TS) into iPSCs following in vitro differentiation in hPGCLCs. All hiPSCs-TS lines demonstrated pluripotency state and were capable of differentiation into three embryonic layers (ectoderm, endoderm, and mesoderm). The PGCLCs-TS recapitulated the initial germline development period regarding transcripts and protein marks, including the epigenetic profile. Overall, our results highlighted the feasibility of producing in vitro models to help the understanding of the mechanisms associated with germ cell formation in TS.

Tissue-Restricted Stem Cells as Starting Cell Source for Efficient Generation of Pluripotent Stem Cells: An Overview

Induced pluripotent stem cells (iPSCs) have vast biomedical potential concerning disease modeling, drug screening and discovery, cell therapy, tissue engineering, and understanding organismal development. In the year 2006, a groundbreaking study reported the generation of iPSCs from mouse embryonic fibroblasts by viral transduction of four transcription factors, namely, Oct4, Sox2, Klf4, and c-Myc. Subsequently, human iPSCs were generated by reprogramming fibroblasts as a starting cell source using two reprogramming factor cocktails [(i) OCT4, SOX2, KLF4, and c-MYC, and (ii) OCT4, SOX2, NANOG, and LIN28]. The wide range of applications of these human iPSCs in research, therapeutics, and personalized medicine has driven the scientific community to optimize and understand this reprogramming process to achieve quality iPSCs with higher efficiency and faster kinetics. One of the essential criteria to address this is by identifying an ideal cell source in which pluripotency can be induced efficiently to give rise to high-quality iPSCs. Therefore, various cell types have been studied for their ability to generate iPSCs efficiently. Cell sources that can be easily reverted to a pluripotent state are tissue-restricted stem cells present in the fetus and adult tissues. Tissue-restricted stem cells can be isolated from fetal, cord blood, bone marrow, and other adult tissues or can be obtained by differentiation of embryonic stem cells or trans-differentiation of other tissue-restricted stem cells. Since these cells are undifferentiated cells with self-renewal potential, they are much easier to reprogram due to the inherent characteristic of having an endogenous expression of few pluripotency-inducing factors. This review presents an overview of promising tissue-restricted stem cells that can be isolated from different sources, namely, neural stem cells, hematopoietic stem cells, mesenchymal stem cells, limbal epithelial stem cells, and spermatogonial stem cells, and their reprogramming efficacy. This insight will pave the way for developing safe and efficient reprogramming strategies and generating patient-specific iPSCs from tissue-restricted stem cells derived from various fetal and adult tissues.

Leukocyte reduction filters as an alternative source of peripheral blood leukocytes for research

INTRODUCTION

Peripheral blood leukocytes are a suitable cell model for science research. However, blood samples from healthy volunteers are limited in volume and difficult to obtain due to the complexity of volunteer recruitment.

OBJECTIVE

Therefore, it is urgent to find an alternative source of peripheral blood leukocytes.

METHOD

One of the possibilities is the use of leukocyte reduction filters (LRFs) in blood banks that is used for preparation of leukoreduced blood products. More than 90% of the leukocytes are trapped in the leukofilters allowing the desired blood product to pass through.

RESULTS

It has been reported that the biological function of leukocytes collected from the filters are no different from those isolated from buffy coats, leukapheresis products and whole blood (WB) cells. Moreover, LRFs are waste products that are discarded after leukoreduction.

CONCLUSION

Thus, leukofilters represent an economic source of human cell populations that can be used for a variety of investigative purposes, with no cost. In the present study, we reviewed the different usage of LRFs in the research, clinical and commercial applications.

Generation of a SIAISi004-A hiPSC line from PBMCs of a 74 year-old Alzheimer's disease woman by non-integrating sendai virus mediated reprogramming

A 74-year-old Alzheimer's Disease (AD) woman patient donated her peripheral blood mononuclear cells (PBMC). Non-integrating episomal vector system were used to reprogram their PBMCs with human OKSM (OCT3/4, KLF4, SOX2, and c-MYC) transcription factors. Immunocytochemistry and flow cytometry for pluripotency makers confirmed the pluripotency of transgene-free iPSCs. Pluripotency was confirmed by the ability of iPSCs to spontaneously differentiate three germ layers in vitro as well. The newly generated human iPSC from PBMCs of a 74 year-old Alzheimer's disease woman can be used for studying further disease mechanisms of Alzheimer's Disease (AD).

Dense optical flow software to quantify cellular contractility

Cell membrane deformation is an important feature that occurs during many physiological processes, and its study has been put to good use to investigate cardiomyocyte function. Several methods have been developed to extract information on cardiomyocyte contractility. However, no existing computational framework has provided, in a single platform, a straightforward approach to acquire, process, and quantify this type of cellular dynamics. For this reason, we develop CONTRACTIONWAVE, high-performance software written in Python programming language that allows the user to process large data image files and obtain contractility parameters by analyzing optical flow from images obtained with videomicroscopy. The software was validated by using neonatal, adult-, and human-induced pluripotent stem-cell-derived cardiomyocytes, treated or not with drugs known to affect contractility. Results presented indicate that CONTRACTIONWAVE is an excellent tool for examining changes to cardiac cellular contractility in animal models of disease and for pharmacological and toxicology screening during drug discovery.