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The differentiation of human embryonic stem cells (hESCs) and human-induced pluripotent stem cells (hiPSCs) towards functional neurons particularly hold great potential for the cell-based replacement therapy in neurodegenerative diseases. Here,we describe a stepwise differentiation protocol that mimics the early stage of neural development in human to promote the generation of neuroprogenitors at a high yield. Both the hESCs and hiPSCs are initially cultured in an optimized feeder-free condition,which offer an efficient formation of aggregates. To specify the neuroectodermal specification,these aggregates are differentiated in a defined neural induction medium to develop into neural rosettes-like structures. The rosettes are expanded into free-floating sphere and can be further propagated or developed into variety of neuronal subtypes. View Publication

Basal forebrain cholinergic neurons (BFCNs) are believed to be one of the first cell types to be affected in all forms of AD,and their dysfunction is clinically correlated with impaired short-term memory formation and retrieval. We present an optimized in vitro protocol to generate human BFCNs from iPSCs,using cell lines from presenilin 2 (PSEN2) mutation carriers and controls. As expected,cell lines harboring the PSEN2 N141I mutation displayed an increase in the A$\beta$42/40 in iPSC-derived BFCNs. Neurons derived from PSEN2 N141I lines generated fewer maximum number of spikes in response to a square depolarizing current injection. The height of the first action potential at rheobase current injection was also significantly decreased in PSEN2 N141I BFCNs. CRISPR/Cas9 correction of the PSEN2 point mutation abolished the electrophysiological deficit,restoring both the maximal number of spikes and spike height to the levels recorded in controls. Increased A$\beta$42/40 was also normalized following CRISPR/Cas-mediated correction of the PSEN2 N141I mutation. The genome editing data confirms the robust consistency of mutation-related changes in A$\beta$42/40 ratio while also showing a PSEN2-mutation-related alteration in electrophysiology. View Publication

Human induced pluripotent stem cells (iPSCs) derived cardiomyocytes (iCMCs) would provide an unlimited cell source for regenerative medicine and drug discoveries. The objective of our study is to generate functional cardiomyocytes from human iPSCs and to develop a novel method of measuring contractility of CMCs. In a series of experiments,adult human skin fibroblasts (HSF) and human umbilical vein endothelial cells (HUVECs) were treated with a combination of pluripotent gene DNA and mRNA under specific conditions. The iPSC colonies were identified and differentiated into various cell lineages,including CMCs. The contractile activity of CMCs was measured by a novel method of frame-by-frame cross correlation (particle image velocimetry-PIV) analysis. Our treatment regimen transformed 4% of HSFs into iPSC colonies at passage 0,a significantly improved efficiency compared with use of either DNA or mRNA alone. The iPSCs were capable of differentiating both in vitro and in vivo into endodermal,ectodermal and mesodermal cells,including CMCs with<88% of cells being positive for troponin T (CTT) and Gata4 by flow cytometry. We report a highly efficient combination of DNA and mRNA to generate iPSCs and functional iCMCs from adult human cells. We also report a novel approach to measure contractility of iCMCs. View Publication

The discovery of induced pluripotent stem cells (iPSCs) and their application to patient-specific disease models offers new opportunities for studying the pathophysiology of neurological disorders. However,current methods for culturing iPSC-derived neuronal cells result in clustering of neurons,which precludes the analysis of individual neurons and defined neuronal networks. To address this challenge,cultures of human neurons on micropatterned surfaces are developed that promote neuronal survival over extended periods of time. This approach facilitates studies of neuronal development,cellular trafficking,and related mechanisms that require assessment of individual neurons and specific network connections. Importantly,micropatterns support the long-term stability of cultured neurons,which enables time-dependent analysis of cellular processes in living neurons. The approach described in this paper allows mechanistic studies of human neurons,both in terms of normal neuronal development and function,as well as time-dependent pathological processes,and provides a platform for testing of new therapeutics in neuropsychiatric disorders. View Publication

A renewable source of human monocytes and macrophages would be a valuable alternative to primary cells from peripheral blood (PB) in biomedical research. We developed an efficient protocol to derive monocytes and macrophages from human induced pluripotent stem cells (hiPSCs) and performed a functional comparison with PB-derived cells. hiPSC-derived monocytes were functional after cryopreservation and exhibited gene expression profiles comparable with PB-derived monocytes. Notably,hiPSC-derived monocytes were more activated with greater adhesion to endothelial cells under physiological flow. hiPSC-derived monocytes were successfully polarized to M1 and M2 macrophage subtypes,which showed similar pan- and subtype-specific gene and surface protein expression and cytokine secretion to PB-derived macrophages. hiPSC-derived macrophages exhibited higher endocytosis and efferocytosis and similar bacterial and tumor cell phagocytosis to PB-derived macrophages. In summary,we developed a robust protocol to generate hiPSC monocytes and macrophages from independent hiPSC lines that showed aspects of functional maturity comparable with those from PB. View Publication

Type 1 interferons (IFN-Is) exhibit significant antiviral,antitumor,and immunoregulatory properties,demonstrating substantial therapeutic potential. However,IFN-Is are pleiotropic cytokines,and the available data on their effect under specific pathological conditions are inconclusive. Furthermore,the systemic administration of IFN-Is can result in side effects. Generating cells that can migrate to the pathological focus and provide regulated local production of IFN-Is could overcome this limitation and provide a model for an in-depth analysis of the biological and therapeutic effects of IFN-Is. Induced pluripotent stem cells (iPSCs) are a valuable source of various differentiated cell types,including human immune cells. In this study,we describe the generation of genetically modified human iPSCs with doxycycline-controlled overexpression of interferon β (IFNB1). Three IFNB1-overexpressing iPSC lines (IFNB-iPSCs) and one control line expressing the transactivator M2rtTA (TA-iPSCs) were generated using the CRISPR/Cas9 technology. The pluripotency of the generated cell lines has been confirmed by the following: (i) cell morphology; (ii) the expression of the pluripotency markers OCT4,SOX2,TRA 1-60,and NANOG; and (iii) the ability to spontaneously differentiate into the derivatives of the three germ layers. Upon the addition of doxycycline,all IFNB-iPSCs upregulated IFNB1 expression at RNA (depending on the iPSC line,126-816-fold) and protein levels. The IFNB-iPSCs and TA-iPSCs generated here represent a valuable cellular model for studying the effects of IFN-β on the activity and differentiation trajectories of different cell types,as well as for generating different types of cells with controllable IFN-β expression. View Publication

Human induced pluripotent stem cell (hiPSC) derived neurons are powerful tools to model disease biology in the drug development space. Here we leveraged a spectrum of neurophysiological tools to characterize iPSC-derived NGN2 neurons. Specifically,we applied these technologies to detect phenotypes associated with presynaptic dysfunction and rescue in NGN2 neurons lacking a synaptic vesicle associated protein MUNC18-1,encoded by syntaxin binding protein 1 gene (STXBP1). STXBP1 homozygous knock out NGN2 neurons lacked miniature post synaptic currents and demonstrated disrupted network bursting as assayed with multielectrode array and calcium imaging. Furthermore,knock out neurons released less glutamate into culture media,consistent with a presynaptic deficit. These synaptic phenotypes were rescued by reconstitution of STXBP1 protein by AAV transduction in a dose-dependent manner. Our results identify a complementary suite of physiological methods suitable to examine the modulation of synaptic transmission in human neurons. View Publication

The delicate “Excitatory/Inhibitory balance” between neurons holds significance in neurodegenerative and neurodevelopmental diseases. With the ultimate goal of creating a faithful in vitro model of the human brain,in this study,we investigated the critical factor of heterogeneity,focusing on the interplay between excitatory glutamatergic (E) and inhibitory GABAergic (I) neurons in neural networks. We used high-density Micro-Electrode Arrays (MEA) with 2304 recording electrodes to investigate two neuronal culture configurations: 100% glutamatergic (100E) and 75% glutamatergic / 25% GABAergic (75E25I) neurons. This allowed us to comprehensively characterize the spontaneous electrophysiological activity exhibited by mature cultures at 56 Days in vitro,a time point in which the GABA shift has already occurred. We explored the impact of heterogeneity also through electrical stimulation,revealing that the 100E configuration responded reliably,while the 75E25I required more parameter tuning for improved responses. Chemical stimulation with BIC showed an increase in terms of firing and bursting activity only in the 75E25I condition,while APV and CNQX induced significant alterations on both dynamics and functional connectivity. Our findings advance understanding of diverse neuron interactions and their role in network activity,offering insights for potential therapeutic interventions in neurological conditions. Overall,this work contributes to the development of a valuable human-based in vitro system for studying physiological and pathological conditions,emphasizing the pivotal role of neuron diversity in neural network dynamics. View Publication

Establishing robust models of human myelinating Schwann cells is critical for studying peripheral nerve injury and disease. Stem cell differentiation has emerged as a key human cell model and disease motivating development of Schwann cell differentiation protocols. Human embryonic stem cells (hESCs) are considered the ideal pluripotent cell but ethical concerns regarding their use have propelled the popularity of human induced pluripotent stem cells (hiPSCs). Given that the equivalence of hESCs and hiPSCs remains controversial,we sought to compare the molecular and functional equivalence of hESC- and hiPSC-derived Schwann cells generated with our previously reported protocol. We identified only modest transcriptome differences by RNA sequencing and insignificant proteome differences by antibody array. Additionally,both cell types comparably improved nerve regeneration and function in a chronic denervation and regeneration animal model. Our findings demonstrate that Schwann cells derived from hESCs and hiPSCs with our protocol are molecularly comparable and functionally equivalent. Subject areas: Neuroscience,Cell biology,Stem cells research,Transcriptomics View Publication

A hexanucleotide GGGGCC repeat expansion in the C9orf72 gene is the most frequent genetic cause of amyotrophic lateral sclerosis (ALS) and frontal temporal dementia (FTD). C9orf72 repeat expansions are currently identified with long-range PCR or Southern blot for clinical and research purposes,but these methods lack accuracy and sensitivity. The GC-rich and repetitive content of the region cannot be amplified by PCR,which leads traditional sequencing approaches to fail. We turned instead to PacBio single-molecule sequencing to detect and size the C9orf72 repeat expansion without amplification. We isolated high molecular weight genomic DNA from patient-derived iPSCs of varying repeat lengths and then excised the region containing the C9orf72 repeat expansion from naked DNA with a CRISPR/Cas9 system. We added adapters to the cut ends,capturing the target region for sequencing on PacBio’s Sequel,Sequel II,or Sequel IIe. This approach enriches the C9orf72 repeat region without amplification and allows the repeat expansion to be consistently and accurately sized,even for repeats in the thousands. Key features • This protocol is adapted from PacBio’s previous “no-amp targeted sequencing utilizing the CRISPR-Cas9 system.” • Optimized for sizing C9orf72 repeat expansions in patient-derived iPSCs and applicable to DNA from any cell type,blood,or tissue. • Requires high molecular weight naked DNA. • Compatible with Sequel I and II but not Revio. View Publication

Alzheimer's Disease (AD) is a neurodegenerative disorder characterized by the accumulation of pathological proteins and synaptic dysfunction. This study aims to investigate the molecular and functional differences between human induced pluripotent stem cells (hiPSCs) derived from patients with sporadic AD (sAD) and age-matched controls (healthy subjects,HS),focusing on their neuronal differentiation and synaptic properties in order to better understand the cellular and molecular mechanisms underlying AD pathology. Skin fibroblasts from sAD patients ( n = 5) and HS subjects ( n = 5) were reprogrammed into hiPSCs using non-integrating Sendai virus vectors. Through karyotyping,we assessed pluripotency markers (OCT4,SOX2,TRA-1–60) and genomic integrity. Neuronal differentiation was evaluated by immunostaining for MAP2 and NEUN. Electrophysiological properties were measured using whole-cell patch-clamp,while protein expression of Aβ,phosphorylated tau,Synapsin-1,Synaptophysin,PSD95,and GluA1 was quantified by western blot. We then focused on PAK1-LIMK1-Cofilin signaling,which plays a key role in regulating synaptic structure and function,both of which are disrupted in neurodegenerative diseases such as AD. sAD and HS hiPSCs displayed similar stemness features and genomic stability. However,they differed in neuronal differentiation and function. sAD-derived neurons (sAD-hNs) displayed increased levels of AD-related proteins,including Aβ and phosphorylated tau. Electrophysiological analyses revealed that while both sAD- and HS-hNs generated action potentials,sAD-hNs exhibited decreased spontaneous synaptic activity. Significant reductions in the expression of synaptic proteins such as Synapsin-1,Synaptophysin,PSD95,and GluA1 were found in sAD-hNs,which are also characterized by reduced neurite length,indicating impaired differentiation. Notably,sAD-hNs demonstrated a marked reduction in LIMK1 phosphorylation,which could be the underlying cause for the changes in cytoskeletal dynamics that we found,leading to the morphological and functional modifications observed in sAD-hNs. To further investigate the involvement of the LIMK1 pathway in the morphological and functional changes observed in sAD neurons,we conducted perturbation experiments using the specific LIMK1 inhibitor,BMS-5. Neurons obtained from healthy subjects treated with the inhibitor showed similar morphological changes to those observed in sAD neurons,confirming that LIMK1 activity is crucial for maintaining normal neuronal structure. Furthermore,administration of the inhibitor to sAD neurons did not exacerbate the morphological alterations,suggesting that LIMK1 activity is already compromised in these cells. Our findings demonstrate that although sAD- and HS-hiPSCs are similar in their stemness and genomic stability,sAD-hNs exhibit distinct functional and structural anomalies mirroring AD pathology. These anomalies include synaptic dysfunction,altered cytoskeletal organization,and accumulation of AD-related proteins. Our study underscores the usefulness of hiPSCs in modeling AD and provides insights into the disease's molecular underpinnings,thus highlighting potential therapeutic targets. The online version contains supplementary material available at 10.1186/s13195-024-01632-3. View Publication