Interleukin-1-mediated hyperinflammation in XIAP deficiency is associated with defective autophagy.

ABSTRACT: Deficiency of X-linked inhibitor of apoptosis protein (XIAP) is a rare genetic condition that can present with recurrent episodes of hemophagocytic lymphohistiocytosis (HLH), though the exact mechanisms leading to this hyperinflammatory disorder are unclear. Understanding its biology is critical to developing targeted therapies for this potentially fatal disease. Here, we report on a novel multiexonic intragenic duplication leading to XIAP deficiency with recurrent HLH that demonstrated complete response to interleukin (IL)-1ß blockade. We further demonstrate using both primary patient cells and genetically modified THP-1 monocyte cell lines that, contrary to what has previously been shown in mouse cells, XIAP-deficient human macrophages do not produce excess IL-1ß when stimulated under standard conditions. Instead, nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome-mediated hyperproduction of IL-1ß is observed only when the XIAP-deficient cells are stimulated under autophagy-promoting conditions and this correlates with defective autophagic flux as measured by decreased accumulation of the early autophagy marker LC3-II. This work, therefore, highlights IL-1ß blockade as a therapeutic option for patients with XIAP deficiency experiencing recurrent HLH and identifies a critical role for XIAP in promoting autophagy as a means of limiting IL-1ß-mediated hyperinflammation during periods of cellular stress.

Pancreatic Endoderm-Derived From Diabetic Patient-Specific Induced Pluripotent Stem Cell Generates Glucose-Responsive Insulin-Secreting Cells.

Human-induced pluripotent stem cells (hiPSCs) can potentially serve as an invaluable source for cell replacement therapy and allow the creation of patient- and disease-specific stem cells without the controversial use of embryos and avoids any immunological incompatibility. The generation of insulin-producing pancreatic ß-cells from pluripotent stem cells in vitro provides an unprecedented cell source for personal drug discovery and cell transplantation therapy in diabetes. A new five-step protocol was introduced in this study, effectively induced hiPSCs to differentiate into glucose-responsive insulin-producing cells. This process mimics in vivo pancreatic organogenesis by directing cells through stages resembling definitive endoderm, primitive gut-tube endoderm, posterior foregut, pancreatic endoderm, and endocrine precursor. Each stage of differentiation were characterized by stage-specific markers. The produced cells exhibited many properties of functional ß-cells, including expression of critical ß-cells transcription factors, the potency to secrete C-peptide in response to high levels of glucose and the presence of mature endocrine secretory granules. This high efficient differentiation protocol, established in this study, yielded 79.18% insulin-secreting cells which were responsive to glucose five times higher than the basal level. These hiPSCs-derived glucose-responsive insulin-secreting cells might provide a promising approach for the treatment of type I diabetes mellitus. J. Cell. Physiol. 232: 2616-2625, 2017. © 2016 Wiley Periodicals, Inc.

Signaling and Gene Regulatory Networks Governing Definitive Endoderm Derivation From Pluripotent Stem Cells.

The generation of definitive endoderm (DE) from pluripotent stem cells (PSCs) is a fundamental stage in the formation of highly organized visceral organs, such as the liver and pancreas. Currently, there is a need for a comprehensive study that illustrates the involvement of different signaling pathways and their interactions in the derivation of DE cells from PSCs. This study aimed to identify signaling pathways that have the greatest influence on DE formation using analyses of transcriptional profiles, protein-protein interactions, protein-DNA interactions, and protein localization data. Using this approach, signaling networks involved in DE formation were constructed using systems biology and data mining tools, and the validity of the predicted networks was confirmed experimentally by measuring the mRNA levels of hub genes in several PSCs-derived DE cell lines. Based on our analyses, seven signaling pathways, including the BMP, ERK1-ERK2, FGF, TGF-beta, MAPK, Wnt, and PIP signaling pathways and their interactions, were found to play a role in the derivation of DE cells from PSCs. Lastly, the core gene regulatory network governing this differentiation process was constructed. The results of this study could improve our understanding surrounding the efficient generation of DE cells for the regeneration of visceral organs. J. Cell. Physiol. 231: 1994-2006, 2016. © 2016 Wiley Periodicals, Inc.

Investigation of immunomodulatory properties of human Wharton's Jelly-derived mesenchymal stem cells after lentiviral transduction.

Human Wharton's Jelly-derived Mesenchymal Stem Cells (hWJ-MSCs) are considered as an alternative for bone-marrow-derived MSCs. These cells have immunosuppressive properties. It was unclear whether the WJ-MSCs would sustain their immunomodulatory characteristics after lentiviral transduction or not. In this study, we evaluated immunomodulatory properties of WJ-MSCs after lentiviral transduction. HWJ-MSCs were transduced with lentiviral particles. Expression of transduced and un-transduced hWJ-MSCs surface molecules and secretion of IL-10, HGF, VEGF and TGF-ß was analyzed. Cell proliferation and frequency of CD4(+)CD25(+) CD127(low/neg) Foxp3(+) T regulatory cells was measured. There was no difference between the surface markers and secretion of IL-10, HGF, VEGF and TGF-ß in transduced and un-transduced hWJ-MSCs. Both cells inhibited the proliferation of PHA stimulated PBMCs, and improved the frequency of T regulatory cells. These findings suggest that lentiviral transduction does not alter the immunomodulatory function of hWJ-MSCs. However, lentiviral transduction may have a wide range of applications in gene therapy.

Differential effect of Activin A and WNT3a on definitive endoderm differentiation on electrospun nanofibrous PCL scaffold.

The first step in the formation of hepatocytes and beta cells is the generation of definitive endoderm (DE) which involves a central issue in developmental biology. Human induced pluripotent stem cells (hiPSCs) have the pluripotency to differentiate into all three germ layers in vitro and have been considered potent candidates for regenerative medicine as an unlimited source of cells for therapeutic applications. In this study, we investigated the differentiating potential of hiPSCs on poly (ε-caprolactone) (PCL) nanofibrous scaffold into DE cells. Here, we demonstrate directed differentiation of hiPSCs by factors such as Activin A and Wnt3a. The differentiation was determined by immunofluoresence staining with Sox17, FoxA2 and Goosecoid (Gsc) and also by qRT-PCR analysis. The results of this study showed that hiPSCs, as a new cell source, have the ability to differentiate into DE cells with a high capacity and also demonstrate that three dimension (3D) culture provides a suitable nanoenviroment for growth, proliferation and differentiation of hiPSCs. PCL nanofibrous scaffold with essential supplements, stimulating factors and EB-derived cells is able to provide a novel method for enhancing functional differentiation of hiPSCs into DE cells.

Efficient programming of human eye conjunctiva-derived induced pluripotent stem (ECiPS) cells into definitive endoderm-like cells.

Due to pluripotency of induced pluripotent stem (iPS) cells, and the lack of immunological incompatibility and ethical issues, iPS cells have been considered as an invaluable cell source for future cell replacement therapy. This study was aimed first at establishment of novel iPS cells, ECiPS, which directly reprogrammed from human Eye Conjunctiva-derived Mesenchymal Stem Cells (EC-MSCs); second, comparing the inductive effects of Wnt3a/Activin A biomolecules to IDE1 small molecule in derivation of definitive endoderm (DE) from the ECiPS cells. To that end, first, the EC-MSCs were transduced by SOKM-expressing lentiviruses and characterized for endogenous expression of embryonic markers Then the established ECiPS cells were induced to DE formation by Wnt3a/Activin A or IDE1. Quantification of GSC, Sox17 and Foxa2 expression, as DE-specific markers, in both mRNA and protein levels revealed that induction of ECiPS cells by either Wnt3a/Activin A or IDE1 could enhance the expression level of the genes; however the levels of increase were higher in Wnt3a/Activin A induced ECiPS-EBs than IDE1 induced cells. Furthermore, the flow cytometry analyses showed no synergistic effect between Activin A and Wnt3a to derive DE-like cells from ECiPS cells. The comparative findings suggest that although both Wnt3a/Activin A signaling and IDE1 molecule could be used for differentiation of iPS into DE cells, the DE-inducing effect of Wnt3a/Activin A was statistically higher than IDE1.

Human endometrial stem cells differentiation into functional hepatocyte-like cells.

In spite of certain clinical limitations, such as teratoma formation, the use of stem cells is considered as an appropriate source in cell therapy and tissue engineering. This study shows human endometrial stem cells (hEnSCs) has exceptional differentiation ability in hepatocyte formation. hEnSCs have high purification rate and immune-tolerance, and can be used as an appropriate substitute for hepatocytes in liver disorders. Differentiation required hepatogenic medium. Quantitative reverse transcription-polymerase chain reaction and immunofluorescent staining of hepatic genes and proteins including cytokeratin 18 (ck18), alpha-fetoprotein (afp), and albumin (alb) were used to assess differentiation. Cells differentiated with a hepatocyte-like morphology and expressed hepatic markers on 30 days of differentiation. The Periodic Acid-Schiff (PAS) reaction showed storage of glycogen, and albumin and afp secretions were also detected. In vitro hEnSCs behave like hepatocyte after differentiation and may be a suitable source of cells in liver regeneration.

Bispecific immune cell engager enhances the anticancer activity of CD16+ NK cells and macrophages in vitro, and eliminates cancer metastasis in NK humanized NOG mice.

BACKGROUND: In a prior report, we detailed the isolation and engineering of a bispecific killer cell engager, referred to as BiKE:E5C1. The BiKE:E5C1 exhibits high affinity/specificity for the CD16a activating receptor on natural killer (NK) cells and human epidermal growth factor receptor 2 (HER2) on cancer cells. In vitro studies have demonstrated that BiKE:E5C1 can activate the NK cells and induce the killing of HER2+ ovarian and breast cancer cells, surpassing the performance of the best-in-class monoclonal antibody, Trazimera (trastuzumab). To advance this BiKE technology toward clinical application, the objective of this research was to demonstrate the ability of BiKE:E5C1 to activate CD16+ immune cells such as NK cells and macrophages to kill cancer cells, and eradicate metastatic HER2+ tumors in NK humanized NOG mice. METHODS: We assessed BiKE:E5C1's potential to activate CD16-expressing peripheral blood (PB)-NK cells, laNK92 cells, and THP-1-CD16A monocyte-macrophages through flowcytometry and antibody-dependent cell-mediated cytotoxicity/phagocytosis (ADCC) assays. Subsequently, laNK92 cells were selected as effector cells and genetically modified to express the nanoluciferase gene, enabling the monitoring of their viability in NK humanized NOG mice using quantitative bioluminescent imaging (qBLI). To evaluate the functionality of BiKE:E5C1 in vivo, we introduced firefly luciferase-expressing ovarian cancer cells via intraperitoneal injection into hIL-15 and hIL-2 NOG mice, creating a model of ovarian cancer metastasis. Once tumor establishment was confirmed, we treated the mice with laNK92 cells plus BiKE:E5C1 and the response to therapy was assessed using qBLI. RESULTS: Our data demonstrate that BiKE:E5C1 activates not only laNK92 cells but also PB-NK cells and macrophages, significantly enhancing their anticancer activities. ADCC assay demonstrated that IgG1 Fc region had no impact on BiKE:E5C1's anticancer activity. In vivo results reveal that both hIL-15 and hIL-2 NOG mouse models support the viability and proliferation of laNK92 cells. Furthermore, it was observed that BiKE:E5C1 activates laNK92 cells in mice, leading to eradication of cancer metastasis in both NK humanized hIL-15 and hIL-2 NOG mouse models. CONCLUSIONS: Collectively, our in vivo findings underscore BiKE:E5C1's potential as an immune cell engager capable of activating immune cells for cancer cell elimination, thereby expanding the arsenal of available BiKEs for cancer immunotherapy.

A Novel Tetravalent Bispecific Immune Cell Engager Activates Natural Killer Cells to Kill Cancer Cells without Mediating Fratricide.

We previously reported the structure, affinity, and anticancer activity of a bivalent bispecific natural killer cell engager (BiKE) composed of one anti-CD16a VHH and one anti-HER2 VHH fused via a linker. In this study, we explored the engineering of a tetravalent BiKE by fusing two anti-CD16a and two anti-HER2 VHHs in tandem, using bivalent BiKE as a template. The tetravalent BiKE was genetically engineered, and its tertiary structure was predicted using in silico modeling. The antigen binding and affinity of the tetravalent BiKE were assessed using ELISA, flow cytometry, and biolayer interferometry. The ability of the BiKEs to kill cancer cells was evaluated through classical and residual antibody-dependent cellular cytotoxicity (ADCC) assays. Additionally, we investigated the potential for NK cell fratricide via CD16a-CD16a crosslinking. Our results revealed that the tetravalent BiKE exhibited at least 100-fold higher affinity toward its target antigens compared to its bivalent counterpart. The residual ADCC assay indicated that the tetravalent BiKE was more effective in killing cancer cells than the bivalent BiKE, attributable to its lower Koff value, which prolonged its binding to NK cell surfaces. Fratricide assays demonstrated that neither the bivalent nor the tetravalent BiKE mediated fratricide. Notably, our findings showed that daratumumab-induced NK fratricide was restricted to CD38-CD38 crosslinking and was not related to ADCC via CD16a-CD38 crosslinking. This study is the first in the literature to show the successful engineering of a tetravalent immune cell engager composed of tandem VHH units, which achieves high affinity and anticancer activity without mediating fratricide.

Gene expression dynamics after murine pancreatitis unveils novel roles for Hnf1α in acinar cell homeostasis.

OBJECTIVES: During pancreatitis, specific transcriptional programmes govern functional regeneration after injury. The objective of this study was to analyse the dynamic regulation of pancreatic genes and the role of transcriptional regulators during recovery from pancreatitis. DESIGN: Wild-type and genetically modified mice (Hnf1α(-/-) and Ptf1a(+/-)) were used. After caerulein or L-arginine induced pancreatitis, blood or pancreata were processed for enzymatic assays, ELISA, histology, immunohistochemistry, western blotting and quantitative reverse transcriptase-PCR. Nr5a2 promoter reporter and chromatin immunoprecipitation assays for Hnf1α were also performed. RESULTS: After caerulein pancreatic injury, expression of acinar and endocrine genes rapidly decreased, but eventually recovered, depicting distinct cell-type-specific patterns. Pdx1 and Hnf1α mRNAs underwent marked downregulation, matching endocrine/exocrine gene expression profiles. Ptf1a, Pdx1 and Hnf1α protein levels were also reduced and recovered gradually. These changes were associated with transient impairment of exocrine and endocrine function, including abnormal glucose tolerance. On l-arginine pancreatitis, changes in Ptf1a, Pdx1 and Hnf1α gene and protein expression were recapitulated. Reduced Hnf1α and Ptf1a levels after pancreatitis coincided with increased acinar cell proliferation, both in Hnf1α(-/-) and Ptf1a(+/-) mice. Moreover, Hnf1α(-/-) mice had reduced Ptf1a protein as well as transcripts for Ptf1a and digestive enzymes. Dispersed acini from Hnf1α(-/-) mice showed suboptimal secretory responses to caerulein. Bioinformatics analysis did not support a role for Hnf1α as a direct regulator of digestive enzyme genes. Instead, it was found that Hnf1α binds to, and regulates, the promoter of Nr5a2, coding an orphan nuclear receptor that regulates acinar gene expression. CONCLUSIONS: Dynamic changes in gene expression occur on pancreatitis induction, determining altered exocrine and endocrine function. This analysis uncovers roles for Hnf1α in the regulation of acinar cell determination and function. This effect may be mediated, in part, through direct regulation of Nr5a2.

Immune-privileged tissues formed from immunologically cloaked mouse embryonic stem cells survive long term in allogeneic hosts.

The immunogenicity of transplanted allogeneic cells and tissues is a major hurdle to the advancement of cell therapies. Here we show that the overexpression of eight immunomodulatory transgenes (Pdl1, Cd200, Cd47, H2-M3, Fasl, Serpinb9, Ccl21 and Mfge8) in mouse embryonic stem cells (mESCs) is sufficient to immunologically 'cloak' the cells as well as tissues derived from them, allowing their survival for months in outbred and allogeneic inbred recipients. Overexpression of the human orthologues of these genes in human ESCs abolished the activation of allogeneic human peripheral blood mononuclear cells and their inflammatory responses. Moreover, by using the previously reported FailSafe transgene system, which transcriptionally links a gene essential for cell division with an inducible and cell-proliferation-dependent kill switch, we generated cloaked tissues from mESCs that served as immune-privileged subcutaneous sites that protected uncloaked allogeneic and xenogeneic cells from rejection in immune-competent hosts. The combination of cloaking and FailSafe technologies may allow for the generation of safe and allogeneically accepted cell lines and off-the-shelf cell products.

Derivation of islet-like cells from mesenchymal stem cells using PDX1-transducing lentiviruses.

Pancreatic duodenum homeobox protein-1 (PDX1) is a master regulatory gene in pancreatic development. Reprogramming of mesenchymal stem cells (MSCs) is a promising tool for producing insulin-producing cells. In this study, lentivirus harboring PDX1 (LV-PDX1) has been used for persistence gene expression in MSCs. The objective of this study was to evaluate the potential of lentivirus to introduce the PDX1 gene into MSCs to produce insulin-secreting cells and apply it for treatment of hyperglycemia in diabetic rats. MSCs were isolated from rat bone marrow, characterized, and transduced by LV-PDX1. Significant expressions of PDX1, neurogenin3, glucagon, glucose transporter2 (Glut2), and insulin were detected by quantitative reverse transcription-polymerase chain reaction (P < 0.05). PDX1 and insulin were detected at the protein level by immunofluorescence analysis. PDX1 could trigger a gene expression cascade that involved pancreatic endocrine differentiation and also revealed the glucose sensing ability by expressing Glut2 in high-glucose medium. The insulin secretion of MSCs(PDX1+) in the high-glucose medium was 1.75-fold higher than that secreted in the low-glucose medium (P < 0.05). MSCs(PDX1+) implanted into diabetic rats could decrease the blood glucose level from 485 mg/dL to the normal level in 3 days. This study showed MSCs(PDX1+) have the potential to be used as a viable resource in cell-based gene therapy of type 1 diabetes.

Murine embryonic stem cell-derived pancreatic acinar cells recapitulate features of early pancreatic differentiation.

BACKGROUND & AIMS: Acinar cells constitute 90% of the pancreas epithelium, are polarized, and secrete digestive enzymes. These cells play a crucial role in pancreatitis and pancreatic cancer. However, there are limited models to study normal acinar cell differentiation in vitro. The aim of this work was to generate and characterize purified populations of pancreatic acinar cells from embryonic stem (ES) cells. METHODS: Reporter ES cells (Ela-pur) were generated that stably expressed both beta-galactosidase and puromycin resistance genes under the control of the elastase I promoter. Directed differentiation was achieved by incubation with conditioned media of cultured fetal pancreatic rudiments and adenoviral-mediated co-expression of p48/Ptf1a and Mist1, 2 basic helix-loop-helix transcription factors crucial for normal pancreatic acinar development and differentiation. RESULTS: Selected cells expressed multiple markers of acinar cells, including digestive enzymes and proteins of the secretory pathway, indicating activation of a coordinated differentiation program. The genes coding for digestive enzymes were not regulated as a single module, thus recapitulating what occurs during in vivo pancreatic development. The generated cells displayed transient agonist-induced Ca(2+) mobilization and showed a typical response to physiologic concentrations of secretagogues, including enzyme synthesis and secretion. Importantly, these effects did not imply the acquisition of a mixed acinar-ductal phenotype. CONCLUSIONS: These studies allow the generation of almost pure acinar-like cells from ES cells, providing a normal cell-based model for the study of the acinar differentiation program in vitro.

Glucose-Responsiveness of Pancreatic ß-Like (GRP ß-L) Cells Generated from Human Pluripotent Stem Cells.

The International Diabetic Federation estimated that 415 million adults currently have diabetes and 318 million adults had impaired glucose tolerance, putting them at high risk of developing diabetes in the future. In Type 1 Diabetes (T1D), the ß cells are lost because of autoimmune reactions. Although islet transplantation has been a promising therapy for T1D, it is greatly limited by pancreatic donors. Here, we describe a protocol to generate glucose- responsive pancreatic ß-like (GRPß-L) cells from human-induced pluripotent stem (iPS) cells. We recapitulate in vivo pancreas development by in vitro induction of differentiating human (iPS) cells with stage-specific signaling molecules and proteins. Inhibition of Tyrosine Kinase receptor AXL, TGF-ß, and Notch signaling pathways in the final stage of the five-stage protocol could efficiently generate GRPß-L from the endocrine progenitor. Differentiation of human iPS cells through the protocol could result in functional GRPß-L cells, which could be used in pharmaceutical and ß cell biology studies. © 2018 by John Wiley & Sons, Inc.

An efficient method for isolation of murine bone marrow mesenchymal stem cells.

Mesenchymal stem cells (MSCs) have been isolated based on the ability of adherence to plastic surfaces. The potential of these cells to differentiate along multiple lineages is the key to identifying stem cell populations in the absence of molecular markers. Here we describe a homogenous population of MSCs from mouse bone marrow isolated using a relatively straightforward and novel approach. This method is based on the combination of frequent medium change (FMC) and treatment of the primary cultures with trypsin. Cells isolated using this method demonstrated the MSCs characteristics including their ability to differentiate into mesenchymal lineages. MSCs retained the differentiation potentials in expanded cultures up to 10 passages. Isolated MSCs were reactive to the CD44, Sca-1, and CD90 cell surface markers. MSCs were negative for the hematopoietic surface markers such as CD34, CD11b, CD45, CD31, CD106, CD117 and CD135. The data presented in this report indicated that this method can result in efficient isolation of homogenous populations of MSCs from mouse bone marrow.

Improved human endometrial stem cells differentiation into functional hepatocyte-like cells on a glycosaminoglycan/collagen-grafted polyethersulfone nanofibrous scaffold.

Liver tissue engineering (TE) is rapidly emerging as an effective technique which combines engineering and biological processes to compensate for the shortage of damaged or destroyed liver tissues. We examined the viability, differentiation, and integration of hepatocyte-like cells on an electrospun polyethersulfone (PES) scaffold, derived from human endometrial stem cells (hEnSCs). Natural polymers were separately grafted on plasma-treated PES nanofibers, that is, collagen, heparan sulfate (HS) and collagen-HS. Galactosilated PES (PES-Gal) nanofibrous were created. The engineering and cell growth parameters were considered and compared with each sample. The cellular studies revealed increased cell survival, attachment, and normal morphology on the bioactive natural polymer-grafted scaffolds after 30 days of hepatic differentiation. The chemical and molecular assays displayed hepatocyte differentiation. These cells were also functional, showing glycogen storage, α-fetoprotein, and albumin secretion. The HS nanoparticle-grafted PES nanofibers demonstrated a high rate of cell proliferation, differentiation, and integration. Based on the observations mentioned above, engineered tissue is a good option in the future, for the commercial production of three-dimensional liver tissues for clinical purposes. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2516-2529, 2017.

Enhanced Cardiac Differentiation of Human Cardiovascular Disease Patient-Specific Induced Pluripotent Stem Cells by Applying Unidirectional Electrical Pulses Using Aligned Electroactive Nanofibrous Scaffolds.

In the embryonic heart, electrical impulses propagate in a unidirectional manner from the sinus venosus and appear to be involved in cardiogenesis. In this work, aligned and random polyaniline/polyetersulfone (PANI/PES) nanofibrous scaffolds doped by Camphor-10-sulfonic acid (ß) (CPSA) were fabricated via electrospinning and used to conduct electrical impulses in a unidirectional and multidirectional fashion, respectively. A bioreactor was subsequently engineered to apply electrical impulses to cells cultured on PANI/PES scaffolds. We established cardiovascular disease-specific induced pluripotent stem cells (CVD-iPSCs) from the fibroblasts of patients undergoing cardiothoracic surgeries. The CVD-iPSCs were seeded onto the scaffolds, cultured in cardiomyocyte-inducing factors, and exposed to electrical impulses for 1 h/day, over a 15-day time period in the bioreactor. The application of the unidirectional electrical stimulation to the cells significantly increased the number of cardiac Troponin T (cTnT+) cells in comparison to multidirectional electrical stimulation using random fibrous scaffolds. This was confirmed by real-time polymerase chain reaction for cardiac-related transcription factors (NKX2.5, GATA4, and NPPA) and a cardiac-specific structural gene (TNNT2). Here we report for the first time that applying electrical pulses in a unidirectional manner mimicking the unidirectional wave of electrical stimulation in the heart, could increase the derivation of cardiomyocytes from CVD-iPSCs.

Involvement of Polycomb Repressive Complex 2 in Maturation of Induced Pluripotent Stem Cells during Reprogramming of Mouse and Human Fibroblasts.

Induced pluripotent stem cells (iPSCs) provide a reliable source for the study of regenerative medicine, drug discovery, and developmental biology. Despite extensive studies on the reprogramming of mouse and human fibroblasts into iPSCs, the efficiency of reprogramming is still low. Here, we used a bioinformatics and systems biology approach to study the two gene regulatory waves governing the reprogramming of mouse and human fibroblasts into iPSCs. Our results revealed that the maturation phase of reprogramming was regulated by a more complex regulatory network of transcription factors compared to the initiation phase. Interestingly, in addition to pluripotency factors, the polycomb repressive complex 2 (PRC2) members Ezh2, Eed, Jarid2, Mtf2, and Suz12 are crucially recruited during the maturation phase of reprogramming. Moreover, we found that during the maturation phase of reprogramming, pluripotency factors, via the expression and induction of PRC2 complex members, could silence the lineage-specific gene expression program and maintain a ground state of pluripotency in human and mouse naïve iPSCs. The findings obtained here provide us a better understanding of the gene regulatory network (GRN) that governs reprogramming, and the maintenance of the naïve state of iPSCs.

Efficient generation of dopaminergic-like neurons by overexpression of Nurr1 and Pitx3 in mouse induced Pluripotent Stem Cells.

Parkinson's disease (PD) is a neurodegenerative disorder, in which the nigro-striatal Dopaminergic (DAergic) neurons are selectively lost. Treatment of neurodegenerative diseases with Pluripotent Stem Cells (PSCs) is a big interest in cell therapy. Here, we used induced Pluripotent Stem Cells (iPSCs) expressing two master Dopaminergic (DAergic) transcription factors, i.e. Nurr1 and Pitx3, to generate functional in vitro DAergic-like neurons. After establishment and characterization of Doxycycline-inducible iPSCs from mouse fibroblasts, the cells were transduced by NURR1- and PITX3-harboring lentiviruses. The Nurr1/Pitx3 -iPSCs were differentiated through a five-stage protocol to generate DAergic-like neurons. The results confirmed the efficient expression of DAergic neuron markers in the end of protocol. Beside, the generated cells could exclusively synthesize and secrete Dopamine in response to secretagogues. In conclusion, overexpression of Nurr1 and Pitx3 in iPSCs could efficiently program iPSCs into functional DAergic-like neurons. This finding may have an impact on future stem cell therapy of PD.

An Abbreviated Protocol for In Vitro Generation of Functional Human Embryonic Stem Cell-Derived Beta-Like Cells.

The ability to yield glucose-responsive pancreatic beta-cells from human pluripotent stem cells in vitro will facilitate the development of the cell replacement therapies for the treatment of Type 1 Diabetes. Here, through the sequential in vitro targeting of selected signaling pathways, we have developed an abbreviated five-stage protocol (25-30 days) to generate human Embryonic Stem Cell-Derived Beta-like Cells (ES-DBCs). We showed that Geltrex, as an extracellular matrix, could support the generation of ES-DBCs more efficiently than that of the previously described culture systems. The activation of FGF and Retinoic Acid along with the inhibition of BMP, SHH and TGF-beta led to the generation of 75% NKX6.1+/NGN3+ Endocrine Progenitors. The inhibition of Notch and tyrosine kinase receptor AXL, and the treatment with Exendin-4 and T3 in the final stage resulted in 35% mono-hormonal insulin positive cells, 1% insulin and glucagon positive cells and 30% insulin and NKX6.1 co-expressing cells. Functionally, ES-DBCs were responsive to high glucose in static incubation and perifusion studies, and could secrete insulin in response to successive glucose stimulations. Mitochondrial metabolic flux analyses using Seahorse demonstrated that the ES-DBCs could efficiently metabolize glucose and generate intracellular signals to trigger insulin secretion. In conclusion, targeting selected signaling pathways for 25-30 days was sufficient to generate ES-DBCs in vitro. The ability of ES-DBCs to secrete insulin in response to glucose renders them a promising model for the in vitro screening of drugs, small molecules or genes that may have potential to influence beta-cell function.