iPSC Clones Research Articles

Modeling Acute Megakaryoblastic Leukemia of Down Syndrome Using Induced Pluripotent Stem Cells

Introduction Development of Acute megakaryoblastic leukemia in Down syndrome children (DS-AMKL) is a multi-step process. Acquired GATA1s mutation during fetal hematopoiesis is responsible of a transient myeloproliferative disorder (TMD) characterized by an accumulation of megakaryoblasts. Although most of TMD regress around birth, some TMD can progress from the initial GATA1s clone to AMKL through the acquisition of additional mutations, including in (i) the cohesin complex (i.e: SMC3), (ii) the JAK/STAT signaling pathway, such as MPL and (iii) the polycomb repressive complex 2 (EZH2). How these mutations cooperate to deregulate megakaryocyte (MK) differentiation and to induce a full-blown AMKL, along with the precise role of trisomy 21 (T21) during this transformation process remain unclear. Because modeling of DS-AMKL is particularly difficult in mice, we performed a step-wise introduction of GATA1s, a gain of function mutation of MPL (MPLW515K) and a heterozygous loss of function mutation in a cohesin (SMC3), separately or in combination, in T21 and isogenic disomic 21 (Dis21) human induced Pluripotent Stem Cells (iPSCs). Methods Trisomy 21 iPSCs were kindly provided by M. Weiss (Memphis, TN). CRISPR/Cas 9 genome editing of GATA1 or SMC3 allowed the generation of GATA1s T21, SMC3+/- T21 and GATA1s SMC3+/- T21 iPSC clones. CRISPR/Cas9-mediated knock-in of MPLW515K was performed in T21 GATA1s iPSCs. The subsequent T21 GATA1sMPLW515K/W515Kclones were selected as well as a revertant Dis21 GATA1sMPLW515K/W515Kclone. Finally, SMC3 insertion/deletion were obtained in isogenic T21 and Dis21 GATA1s MPLW515K/W515K SMC3+/-iPSCs clones. Hematopoietic differentiation was induced in 2D cultures in presence of a matrix and a cocktail of cytokines followed by a MK differentiation with SCF and TPO. MK differentiation was studied by clonogenic assays, flow cytometry, confocal microscopy and ultrastructural studies. Gene expression analyses were performed by RNA-seq on highly purified MK from all genotypes. Results GATA1s alone blocked MK maturation characterized by a persistent CD34 expression, an accumulation of abnormal large granules, a defect in the development of demarcation membranes (DMS), and a marked decrease in proplatelet formation. The typical GATA1s MK were large megakaryoblasts with numerous large granules and rare DMS. However, GATA1s alone had no effect on the clonogenic activity in CFU-MK assays and MK numbers. The introduction of the MPLW515K mutation did not modify this phenotype either in Dis21 or T21 GATA1s MK, but induced a complete TPO independence. SMC3+/- alone enhanced the MK maturation allowing the generation of a higher number of proplatelets-generating MK. Importantly, the combination of GATA1s and SMC3+/- mutations had a marked cooperative effect that worsened the MK maturation defect, led to the generation of abnormal megakaryoblasts with only a pre-DMS and resulted in enhanced proliferation and ploidization both in Dis21 and T21 iPSCs. Interestingly, the proliferation was markedly higher in T21 clones compared to Dis21 counterparts. RNA-seq and GSEA analyses showed that T21 GATA1s SMC3+/- mutant MK exhibited transcriptional signatures consistent with a dramatic decrease in the expression of maturation genes, including GATA1 target genes, while DNA replication gene markers were increased compared with GATA1s alone. T21 GATA1s MPLW515K/W515K SMC3+/- MK were enriched for AMKL signatures as compared to isogenic Dis21 GATA1sMPLW515K/W515K SMC3+/- MK. Ongoing ATAC-seq analyses will define the consequence of the different mutations on chromatin accessibility. Conclusion Using iPSC modeling, we analyzed in a human cell-context the consequences of the different combination of mutations associated with DS-AMKL that would be difficult to model using human primary cells. Our data demonstrate that GATA1s expression cooperates with SMC3+/- to enhance proliferation of megakaryoblasts from T21 iPSCs and isogenic Dis21 iPSCs hence reproducing the abnormalities observed in DS-AMKL. T21 is not directly involved in the MK differentiation defects but rather give a proliferative advantage supporting its role in leukemia development. Disclosures No relevant conflicts of interest to declare.

CGMP Mass Production of FT538, a First-of-Kind, Off-the-Shelf, Multiplexed Engineered Natural Killer Cell Cancer Immunotherapy Derived from a Clonal Master Induced Pluripotent Stem Cell Line

FT538 is an investigational, off-the-shelf, multiplexed engineered natural killer (NK) cell cancer immunotherapy that is derived from a clonal master induced pluripotent stem cell (iPSC) line engineered with three functional components to enhance innate immunity: a novel high-affinity, non-cleavable CD16 (hnCD16) Fc receptor; an IL-15/IL-15 receptor fusion (IL-15RF); and the elimination of CD38 expression. The use of a clonal master engineered iPSC line as a starting cell source enables routine mass production of FT538 and supports off-the-shelf product availability to reach many patients. The clonal master iPSC line for the manufacture of FT538 was made by reprogramming and engineering donor-consented human fibroblasts to induce pluripotency using a proprietary non-integrating system and to integrate a bicistronic cassette containing hnCD16 and IL-15RF into the CD38 locus, which resulted in complete disruption of the CD38 gene. The engineered iPSC population was then sorted to isolate single clones, and each engineered iPSC clone was screened for multiple critical quality attributes including pluripotency, identity, genomic stability, cassette integration, and off-target effects of engineering. Accordingly, a single engineered iPSC clone was selected as the FT538 clonal master iPSC line. The clonal master engineered iPSC line serves as a renewable source for the routine cGMP mass production of FT538 drug product. Routine cGMP manufacture of FT538 drug product consists of three stages: 1) differentiation of the clonal master engineered iPSC line to CD34-expressing hematopoietic progenitor cells; 2) further differentiation to and expansion of NK cells; and 3) fill/finish and cryopreservation of the FT538 drug product. A cGMP manufacturing campaign yielded sufficient CD34-expressing hematopoietic progenitor cells to support at least 15 batches of NK cell differentiation, the first batch of which was used to produce a total of 3 × 1011 FT538 NK cells filled into over 300 units of cryopreserved drug product. The cGMP campaign had a theoretical yield of 4.5 x 1012 FT538 NK cells. The FT538 drug product was characterized and found to be comprised of uniformly engineered CD56+ NK cells with homogeneous expression of hnCD16 and lacking expression of CD38. Importantly, there were no residual iPSCs detected in the FT538 drug product. Additionally, the FT538 drug product exhibited potent effector function in a candidate potency assay measuring IFN-γ release in response to RPMI 8226 target cells in the presence of daratumumab. An Investigational New Drug application for FT538 has been cleared by the U.S. Food and Drug Administration (FDA) for the conduct of a multicenter, multi-dose Phase I clinical trial for the treatment of patients with relapsed/refractory (r/r) acute myelogenous leukemia (AML) and multiple myeloma (MM). The dose-escalation utilizes a 3+3 design to identify the maximum tolerated dose of three doses of FT538 on Days 1, 8, and 15 as a monotherapy in r/r AML (Regimen A) and in combination with daratumumab (Regimen B) or elotuzumab (Regimen C) in r/r MM. The trial will test up to five FT538 dose levels ranging from 50 million to 1.5 billion cells, and up to 105 patients will be enrolled. The trial is expected to begin patient enrollment in 2020. Disclosures Rezner: Fate Therapeutics, Inc: Current Employment, Current equity holder in publicly-traded company. Solchaga:Fate Therapeutics, Inc: Current Employment. Reyes:Fate Therapeutics, Inc: Current Employment. Lin:Fate Therapeutics, Inc: Current Employment. Abujarour:Fate Therapeutics, Inc: Current Employment. Lee:Fate Therapeutics, Inc.: Current Employment. Valamehr:Fate Therapeutics, Inc: Current Employment, Current equity holder in publicly-traded company. Wang:Fate Therapeutics, Inc: Current Employment.

Generation of Multiplexed Engineered, Off-the-Shelf CAR T Cells Uniformly Carrying Multiple Anti-Tumor Modalities to Prevent Tumor Relapse

The development of chimeric antigen receptor (CAR) T cell therapeutics is widely recognized as a significant advancement for the treatment of cancer. However, several obstacles currently impede the broad use of CAR T cells, including the inherent process variability, cost of manufacturing, the absolute requirement for precise and uniform genetic editing in the allogeneic setting, and the challenge to keep pace with clonal heterogeneity and tumor growth. Utilizing our previously described induced pluripotent stem cell (iPSC)-derived T (iT) cell platform, we illustrate here the unique ability to address these challenges by creating a consistent CAR iT cell product that can be repeatedly manufactured in large quantities from a renewable iPSC master cell bank that has been engineered to mitigate the occurrence of graft versus host disease (GvHD), antigen escape and tumor relapse. Utilizing our proprietary cellular reprogramming and engineering platform and stage-specific T cell differentiation protocol, we demonstrate that iPSC can be engineered at the single cell level to generate a fully characterized clonal iPSC line, which can then be accessed routinely to yield CAR iT cells in a highly scalable manufacturing process (>100,000 fold expansion). Through bi-allelic targeting of a CAR into the T cell receptor alpha constant (TRAC) region, we generated CAR iT cells with uniform CAR expression (99.0 ± 0.5% CAR+) and complete elimination of T cell receptor (TCR) expression to avoid GvHD in the allogeneic setting. We elected to utilize the 1XX-CAR configuration, which has demonstrated superior anti-tumor performance relative to other CAR designs and when introduced into iT cells displayed enhanced antigen specificity (% specific cytotoxicity at E:T=10:1, antigen positive group: 86.4 ± 7.8; antigen null group: 8.9 ± 3.5). To enhance persistence without reliance on exogenous cytokine support, we engineered signaling-fusion complexes, including IL-7 receptor fusion (RF), into iPSC and studied its impact on iT phenotype, persistence, and efficacy. In vitro, IL-7RF clones demonstrated improved anti-tumor activity in a serial antigen dependent tumor challenge assay (Day 10, relative tumor counts, IL-7RF group: 1.95 ± 0.01; control group: 57.56 ± 4.55, P<0.000001). In a preclinical in vivo model of disseminated leukemia, IL-7RF clones demonstrate enhanced tumor growth inhibition (Day 34, Log [BLI], IL-7RF group: 6.68 ± 1.93; control group: 9.99 ± 0.23, P=0.0143). We next investigated a unique strategy to incorporate multi-antigen targeting potential into anti-CD19 1XX CAR iT cells with the addition of a high-affinity non-cleavable CD16 (hnCD16) Fc receptor. The combination of hnCD16 with anti-CD19 1XX CAR culminated in iT cells capable of multi-antigen specificity through combinatorial use with monoclonal antibodies to tackle antigen escape. Utilizing CD19 negative leukemia cells as targets, superior antibody-dependent cellular cytotoxicity (ADCC) was demonstrated by the combination of hnCD16 CAR iT and Rituximab (% specific cytotoxicity at E:T=1:1, hnCD16 group + Rituximab: 75.64 ± 2.12; control group + Rituximab: 16.98 ± 3.87, P<0.001). To address T cell fitness, the role of CD38 knockout (KO) in T cells was investigated, which we have previously shown to mediate NK cell resistance to oxidative stress induced apoptosis. CD38 gene was disrupted at the iPSC stage to generate 1XX-CAR T cells that lack CD38 expression (% CD38+ population, CD38WT group: 69.67 ± 24.34; CD38KO group: 0.12 ± 0.11) and upon antigen mediated stimulation, CD38KO CAR iT cells showed higher percentages of degranulation (2.3-fold increase in CD107a/b), and IFNγ (4.1-fold increase) and TNFα (2.5-fold increase) production. Antigen specific in vitro tumor killing also was enhanced in CD38KO CAR iT cells (EC50, 3.2-fold decrease). Lastly, to avoid the potential host-mediated rejection, the inclusion of allogeneic defense receptor (ADR) which has been shown to significantly reduce host-mediated rejection will be discussed. Collectively, the described studies demonstrate that iPSCs are an ideal cellular source to generate large-quantities of uniformly multi-edited off-the-shelf CAR T cell products that include a best-in-class CAR design, enhanced product modalities, and complete elimination of TCR expression to avoid the potential of GvHD while maintaining high anti-tumor efficacy in allogeneic setting. Disclosures Hsia: Fate Therapeutics Inc.: Current Employment. Clarke:Fate Therapeutics Inc.: Current Employment, Current equity holder in publicly-traded company. Lee:Fate Therapeutics, Inc.: Current Employment. Robbins:Fate Therapeutics, Inc.: Current Employment. Denholtz:Fate Therapeutics, Inc: Current Employment. Hanok:Fate Therapeutics, Inc.: Current Employment. Carron:Fate Therapeutics, Inc.: Current Employment. Navarrete:Fate Therapeutics, Inc.: Current Employment. ORourke:Fate Therapeutics, Inc.: Current Employment. Sung:Fate Therapeutics, Inc.: Current Employment. Gentile:Fate Therapeutics, Inc.: Current Employment. Nguyen:Fate Therapeutics, Inc.: Current Employment. Valamehr:Fate Therapeutics, Inc: Current Employment, Current equity holder in publicly-traded company.

Regulation of breast cancer oncogenesis by the cell of origin's differentiation state.

Human breast cancer which affects 1/8 women is rare at a cellular level. Even in the setting of germline BRCA1/BRCA2, which is present in all breast cells, solitary cancers or cancers arising at only several foci occur. The overwhelming majority of breast cells (109–1012 cells) resist transformation. Our hypothesis to explain this rareness of transformation is that mammary oncogenesis is regulated by the cell of origin’s critical window of differentiation so that target cells outside of this window cannot transform. Our novel hypothesis differs from both the multi-hit theory of carcinogenesis and the stem/progenitor cell compartmental theory of tumorigenesis and utilizes two well established murine transgenic models of breast oncogenesis, the FVB/N-Tg (MMTV-PyVT)634Mul/J and the FVB-Tg (MMTV-ErbB2) NK1Mul/J. Tail vein fibroblasts from each of these transgenics were used to generate iPSCs. When select clones were injected into cleared mammary fat pads, but not into non-orthotopic sites of background mice, they exhibited mammary ontogenesis and oncogenesis with the expression of their respective transgenes. iPSC clones, when differentiated along different non-mammary lineages in vitro, were also not able to exhibit either mammary ontogenesis or oncogenesis in vivo. Therefore, in vitro and in vivo regulation of differentiation is an important determinant of breast cancer oncogenesis.

Generation of five induced pluripotent stem cell lines with DMD/c.497G>T mutation from renal epithelial cells of a Duchenne muscular dystrophy patient and a recessive carrier parent.

Duchenne muscular dystrophy (DMD), an inherited disease caused by the dystrophin gene mutation, is the most common muscular dystrophy in children and is clinically characterized by progressive muscle degeneration and severe cardiomyopathy. In this study, renal epithelial cells were obtained from urine samples of a DMD patient (4years old) and his recessive carrier parent (35years old). The cells were reprogrammed with non-integrating Sendai virus to generate three induced pluripotent stem cell (iPSC) clones for the patient and two clones for non-manifesting mutation carrier parent. The iPSC lines had normal karyotypes, iPSC morphology, pluripotency expression markers, and were capable of differentiating into the three germ layers.

Establishment of integration free iPSC clones, NCCSi011-A and NCCSi011-B from a liver cirrhosis patient of Indian origin with hepatic encephalopathy.

Liver cirrhosis accompanied with hepatic encephalopathy commonly causes cognitive impairment in patients. To model this disease, two independent patient specific induced pluripotent stem cell-line (iPSC) clones, NCCSi011-A and NCCSi011-B were generated by reprogramming the CD4+ T cells of an Indian male patient suffering from this chronic condition. Both clones expressed the stemness markers, formed embryoid bodies (EBs) with potential for spontaneous differentiation in to all the three lineages, exhibited normal karyotype (46, XY) and demonstrated alkaline phosphatase activity. These generated iPSC lines have potential for use in understanding biology of the disease and evaluation of drugs.

Using High-Content Screening to Generate Single-Cell Gene-Corrected Patient-Derived iPS Clones Reveals Excess Alpha-Synuclein with Familial Parkinson's Disease Point Mutation A30P.

The generation of isogenic induced pluripotent stem cell (iPSC) lines using CRISPR-Cas9 technology is a technically challenging, time-consuming process with variable efficiency. Here we use fluorescence-activated cell sorting (FACS) to sort biallelic CRISPR-Cas9 edited single-cell iPSC clones into high-throughput 96-well microtiter plates. We used high-content screening (HCS) technology and generated an in-house developed algorithm to select the correctly edited isogenic clones for continued expansion and validation. In our model we have gene-corrected the iPSCs of a Parkinson’s disease (PD) patient carrying the autosomal dominantly inherited heterozygous c.88G>C mutation in the SNCA gene, which leads to the pathogenic p.A30P form of the alpha-synuclein protein. Undertaking a PCR restriction-digest mediated clonal selection strategy prior to sequencing, we were able to post-sort validate each isogenic clone using a quadruple screening strategy prior to generating footprint-free isogenic iPSC lines, retaining a normal molecular karyotype, pluripotency and three germ-layer differentiation potential. Directed differentiation into midbrain dopaminergic neurons revealed that SNCA expression is reduced in the gene-corrected clones, which was validated by a reduction at the alpha-synuclein protein level. The generation of single-cell isogenic clones facilitates new insights in the role of alpha-synuclein in PD and furthermore is applicable across patient-derived disease models.

Generation of two induced pluripotent stem cell lines from a patient with Stargardt Macular Dystrophy caused by the c.768G>T and c.6079C>T mutations in ABCA4.

Autosomal recessive Stargardt disease is the most common cause of inherited retinal disease. In this report, we describe the generation and characterization of two human induced pluripotent stem cell (iPSC) lines from a patient with compound heterozygous mutations in the ABCA4 gene (c.[768G>T];[6079C>T]). Patient dermal fibroblasts were reprogrammed using episomal plasmids encoding OCT4, SOX2, KLF4, L-MYC, LIN28, mir302/367 microRNA and shRNA for P53. The clonal iPSC lines LEIi012-A and LEIi012-B were established. Both lines had a normal karyotype, displayed iPSC morphology, expressed pluripotency genes at similar levels to control iPSC and displayed trilineage differentiation potential during embryoid body differentiation.

Abstract 325: The Regulation of Endothelial Function Through Hmgcr/mevalonate Pathway Mediated Yap Activity

Background: Cardiovascular diseases (CVD) are the leading cause of death in the United States. Statins, a class of hydroxy-methylglutaryl-coenzyme A reductase (HMGCR) inhibitors, have been proven to be effectively prevent and treat CVD by improving vascular functions independent of their cholesterol-lowering effect. However, the molecular mechanisms by which statins improve cardiovascular functions remain elusive. In this study, we used human induced pluripotent stem cells-derived endothelial cells (hiPSC-ECs) to explore the protective role of statins in the vascular system. Methods and Results: hiPSCs were generated from 3 healthy individuals and differentiated into endothelial cells using two different iPSC clones and two batches (4 biological replicates for each individual). hiPSC-ECs of each individual were treated with simvastatin or a vehicle control. The RNA-sequencing analysis was performed on 12 control and 12 statin-treated hiPSC-ECs. A total number of 2,580 differentially expressed genes (DEGs) were found in simvastatin-treated hiPSC-ECs. Gene enrichment analysis revealed that statin-upregulated DEGs were highly enriched in angiogenesis and anti-inflammation pathways. Interestingly, statin-downregulated DEGs were significantly enriched in epigenetic regulation and nucleosome assembly pathways, suggesting an epigenetic regulatory role of stains in vascular gene expression. To test this hypothesis, we further performed the Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) analysis on vehicle or simvastatin treated hiPSC-ECs. Transcription factor (TF) binding motif analyses of ATAC-seq peaks using HOMER revealed that YAP/TEAD binding was the most significantly downregulated TF after statin treatment. Furthermore, we observed that statin can improve endothelial functions (e.g., angiogenesis and nitric oxide production) after the YAP activity was inhibited. The ChIP-seq analysis showed that statin downregulated the expression levels of genes associated with the endothelial-to-mesenchymal transition (EndoMT) by attenuating the binding capacity of YAP. As such, simvastatin effectively rescued diabetic vascular dysfunction mainly through inhibiting EndoMT. Conclusion: We found that statins can improve endothelial functions through attenuating the chromatin accessibility of EndoMT-related genes, a process tightly regulated by the activity of YAP. These findings will provide novel insights into the protective mechanisms of statins in the cardiovascular system beyond their cholesterol-lowering effects.

Abstract 530: Mechanisms Underlying Phospholamban L39 Stop (PLN L39X) Cardiomyopathy

Background: Defective calcium (Ca++) handling is a hallmark of HF across species. Together with the Sarco/Endoplasmic Reticulum Ca-ATPase (SERCA2a), Phospholamban (PLN) has emerged as a critical regulator of Ca++homeostasis. Worldwide, PLN mutations are identified with increasing frequency in patients with dilated, hypertrophic and arrhythmogenic cardiomyopathy (CMPs) but the causative defects leading to the CMP remain incompletely understood. While preclinical studies have unequivocally shown that absence of PLN (PLNKO) is therapeutic in rodent HF models, the discovery of a human pathogenic mutation (L39X) presumed to be the human equivalent of the PLNKO lead to the conclusion that PLN ablation was lethal in human, mitigating any enthusiasm in targeting PLN inhibition in PLN-associated disease or HF treatment. The objective of this proposal is to levarge the use of “induced-pluripotent” stem cells (iPSCs) derived cardiomyocytes (CM) from homozygote L39X carriers to elucidate the role of PLN (L39) in human pathophysiology. Methodology and Results: We obtained mononuclear cells from Homozygotes (Hom) L39 carriers and generated 11 iPSC clones. To derive CMs, we used the direct differentiation method temporally modulating the Wnt/β-catenin signaling. Immunocytostaining revealed positive expression of cardiac troponin T as well as PLN. In Hom L39 derived CMs, PLN showed an abnormal cytoplasmic distribution, formed intracellular aggregates and there was loss of perinuclear localization when compared to matched WT iPSC-CMs. Using fura-2AM, we observed decreased calcium transient amplitude in iPSC-CMs from L39 compared to WT with prolongation of the time constant of relaxation and early after depolarization (EAD). Lastly, we saw a 70% and 50% reduction in the protein and mRNA expression of PLN and SERCA2a respectively. Conclusions: Our data suggest that the L39 PLN mutant is expressed but mis-located within the cardiomyocytes. The mis-location of PLN was associated to decreased SERCA2a expression impaired Ca++ handling and increased arrhythmogenicity. Further studies will be required to fully elucidate the impact of the mutation in HF pathophysiology

Development and characterization of two independent integration free iPSC clones NCCSi010-A and NCCSi010-B from a patient with alcoholic liver cirrhosis of Indian ethnicity.

We generated two human induced pluripotent stem cell-line (iPSC) clones, NCCSi010-A and NCCSi010-B, from a 32-year-old alcoholic cirrhosis patient with minimal hepatic encephalopathy of Indian origin by reprogramming his CD4+ T cells with integration free Sendai viral vector system. The generated iPSC clones showed high alkaline phosphatase activity, expressed pluripotency markers, possessed potential for multi-lineage differentiation and exhibited a normal karyotype (46, XY). These two-patient specific iPSC clones of alcoholic liver cirrhosis can potentially serve as models for disease modeling, drug development and organoid generation (Shah and Bataller, 2016).

Generation of Induced Pluripotent Stem Cells from a Female Patient with a Xq27.3-q28 Deletion to Establish Disease Models and Identify Therapies.

Since it is extremely difficult to establish an animal model for human chromosomal abnormalities, induced pluripotent stem cells (iPSCs) provide a powerful alternative to study underlying mechanisms of these disorders and identify potential therapeutic interventions. In this study we established iPSCs from a young girl with a hemizygous deletion of Xq27.3-q28 who exhibited global developmental delay and intellectual disability from early in infancy. The deletion site on the X chromosome includes Fragile X Mental Retardation 1 (FMR1), the gene responsible for fragile X syndrome, which likely contributes to the patient's neurodevelopmental abnormalities. The FMR1 gene was expressed in approximately half of the iPSC clones we generated while it was absent in the other half due to the random inactivation of normal and abnormal X chromosomes. The normal or absent expression pattern of the FMR1 gene was not altered when the iPSCs were differentiated into neural progenitor cells (NPCs). Moreover, chromosome reactivating reagents such as 5-aza-2-deoxycytidine, trichostatin A, and UNC0638, were tested in an attempt to reactivate the suppressed FMR1 gene in affected iPSC-NPCs. The affected and control isogenic iPSCs developed in this study are ideal models with which to identify downstream consequences caused by the Xq27.3-q28 deletion and also to provide tools for high-throughput screening to identify compounds potentially improving the well-being of this patient population.

2050-P: A Multiomics Investigation of a Patient-Derived HNF-1A MODY IPSC Disease Model Reveals Insights into Its Role in Pancreatic Islet Development and Function

Heterozygous loss of function mutations in HNF1A, encoding the transcription factor hepatocyte nuclear factor 1 alpha (HNF-1A) are the most common cause of monogenic diabetes. HNF-1A is involved in both beta cell development and mature cell function. However, model organisms have often failed to faithfully recapitulate the human phenotypes. As such, we used a patient-derived HNF1A Pro291fsinsC iPSC model and CRISPR-Cas9 genome editing to correct the mutation and generate an isogenic control. iPSC clones (n=6) were differentiated towards the endocrine lineage in triplicate, with RNA-seq (bulk and single-cell) and ATAC-seq performed at definitive endoderm (DE), pancreatic endoderm (PE) and beta-like cells (BLC) stages. RNA-seq data confirmed HNF1A haploinsuffiency in the patient cell lines, with corrected cell lines demonstrating restored HNF1A expression at both transcript and protein level. At the BLC stage, there was a significant overlap in differentially expressed genes and HNF1A targets identified in an independent HNF1A knock-down experiment in the EndoC-βh1 cell line (p=4.4e-132). Corrected clones demonstrated a higher expression of INS (p=7.2e-03), insulin secretion genes and effects on pancreas progenitor cell genes indicating that HNF1A may mediate the cellular composition of the pancreatic islet. Bulk RNA-seq data were also supported in the preliminary analysis of the single-cell RNA-seq data. Open chromatin, assessed by ATAC-seq was significantly different between patient and corrected lines, with >90% of the sites being more accessible at both PE and BLC stages in the corrected clones. These sites were enriched for HNF1A binding motifs, implicating HNF1A in the establishment of open chromatin. In conclusion, our patient-derived HNF1A-MODY iPSC model recapitulates a number of features of HNF1A-MODY, as well as providing insights into the cellular and molecular phenotypes caused by HNF-1A deficiency. Disclosure C. Duff: Research Support; Self; Novo Nordisk A/S. R. Jensen: None. M. Perez-Alcantara: None. M. Rasmussen: None. A. Grotz: None. M. Jansen: None. B. Holst: None. C. Clausen: None. N.A.J. Krentz: None. M. Hansson: Employee; Self; Novo Nordisk A/S. M.I. McCarthy: Advisory Panel; Self; Illumina. Consultant; Self; Eli Lilly and Company, Novo Nordisk Inc., Zoe Global Ltd. Employee; Self; Genentech, Inc. Research Support; Self; AbbVie Inc., Merck & Co., Inc., Sanofi-Aventis, Servier, Takeda UK. A.L. Gloyn: Consultant; Self; Merck Sharp & Dohme Corp. Employee; Spouse/Partner; Genentech, Inc. Research Support; Self; Novo Nordisk A/S. A. Wesolowska-Andersen: None. C. Honore: Employee; Self; Novo Nordisk A/S. Stock/Shareholder; Self; Novo Nordisk A/S. Funding Innovative Medicines Initiative (115439)

Crisponi syndrome/cold-induced sweating syndrome type 2: Reprogramming of CS/CISS2 individual derived fibroblasts into three clones of one iPSC line.

Crisponi syndrome/cold-induced sweating syndrome type 2 (CS/CISS2) is a rare disease with severe dysfunctions of thermoregulatory processes. CS/CISS2 individuals suffer from recurrent episodes of hyperthermia in the neonatal period and paradoxical sweating at cold ambient temperatures in adolescence. Variants in CLCF1 (cardiotrophin-like-cytokine 1) cause CS/CISS2. Here, we summarize the generation of three clones of one stem cell line (iPSC) of a CS/CISS2 individual carrying the CLCF1 variant c.321C>G on both alleles. These patient derived iPSC clones show a normal karyotype, several pluripotency markers, and the ability to differentiate into the three germ layers.

Generation and genetic repair of 2 iPSC clones from a patient bearing a heterozygous c.1120del18 mutation in the ACVRL1 gene leading to Hereditary Hemorrhagic Telangiectasia (HHT) type 2.

Fibroblasts from a patient carrying a heterozygous 18bp deletion in exon 8 of the ACVRL1 gene (c.1120del18) were reprogrammed using episomal vectors. The in-frame deletion in ACVRL1 causes the loss of 6 amino acids of the protein, which is associated with Hereditary Hemorrhagic Telangiectasia (HHT) type 2 (Letteboeretal., 2005). CRISPR-Cas9 editing was used to genetically correct the mutation in the induced pluripotent stem cells (iPSCs). The top5-predicted off-target sites were not altered. Patient and isogenic iPSCs showed high pluripotent marker expression, in vitro differentiation capacity into all three germ layers and displayed a normal karyotype. The obtained isogenic pairs will enable proper in vitro disease modelling of HHT (Romanand Hinck,2017).

Quantitative proteomic analysis of Rett iPSC-derived neuronal progenitors

BackgroundRett syndrome (RTT) is a progressive neurodevelopmental disease that is characterized by abnormalities in cognitive, social, and motor skills. RTT is often caused by mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MeCP2). The mechanism by which impaired MeCP2 induces the pathological abnormalities in the brain is not understood. Both patients and mouse models have shown abnormalities at molecular and cellular level before typical RTT-associated symptoms appear. This implies that underlying mechanisms are already affected during neurodevelopmental stages.MethodsTo understand the molecular mechanisms involved in disease onset, we used an RTT patient induced pluripotent stem cell (iPSC)-based model with isogenic controls and performed time-series of proteomic analysis using in-depth high-resolution quantitative mass spectrometry during early stages of neuronal development.ResultsWe provide mass spectrometry-based quantitative proteomic data, depth of about 7000 proteins, at neuronal progenitor developmental stages of RTT patient cells and isogenic controls. Our data gives evidence of proteomic alteration at early neurodevelopmental stages, suggesting alterations long before the phase that symptoms of RTT syndrome become apparent. Significant changes are associated with the GO enrichment analysis in biological processes cell-cell adhesion, actin cytoskeleton organization, neuronal stem cell population maintenance, and pituitary gland development, next to protein changes previously associated with RTT, i.e., dendrite morphology and synaptic deficits. Differential expression increased from early to late neural stem cell phases, although proteins involved in immunity, metabolic processes, and calcium signaling were affected throughout all stages analyzed.LimitationsThe limitation of our study is the number of RTT patients analyzed. As the aim of our study was to investigate a large number of proteins, only one patient was considered, of which 3 different RTT iPSC clones and 3 isogenic control iPSC clones were included. Even though this approach allowed the study of mutation-induced alterations due to the usage of isogenic controls, results should be validated on different RTT patients to suggest common disease mechanisms.ConclusionsDuring early neuronal differentiation, there are consistent and time-point specific proteomic alterations in RTT patient cells carrying exons 3–4 deletion in MECP2. We found changes in proteins involved in pathway associated with RTT phenotypes, including dendrite morphology and synaptogenesis. Our results provide a valuable resource of proteins and pathways for follow-up studies, investigating common mechanisms involved during early disease stages of RTT syndrome.

Generation of two clonal iPSC lines, ICGi019-A and ICGi019-B, by reprogramming peripheral blood mononuclear cells of a patient suffering from hypertrophic cardiomyopathy and carrying a heterozygous p.M659I mutation in MYH7.

Hypertrophic cardiomyopathy (HCM) is one of the most frequent cardiovascular diseases but no methods to prevent its progression have been developed. Cardiomyocytes derived from patient-specific induced pluripotent stem cells can become a platform to study pathogenesis of the disease and to search for more effective therapy methods. We generated two iPSC lines from peripheral blood mononuclear cells of an HCM patient with heterozygous p.M659I mutation in MYH7 using episomal vectors. The iPSC lines expressed pluripotency markers, demonstrated ability to spontaneously differentiate into derivatives of three germ layers, and retained the mutation.

Developing human cellular tools for studying and understanding jordan's syndrome

Background & Aim Jordan's Syndrome (JS), also known as PPP2R5D-related intellectual disability (ID), is a neurodevelopmental disorder that is caused primarily by de novo missense mutations in the PPP2R5D gene. PPP2R5D encodes a 602-amino acid protein PPP2R5D (also known as the B56δ subunit), which is a regulatory subunit of the heterotrimeric enzyme serine/threonine-protein phosphatase 2A (PP2A). Mutations in phosphatases are known to cause human overgrowth due to their involvement in cellular regulation. With the recent identification of Jordan's Syndrome using Whole Exome Sequencing, PPP2R5D mutations specifically have been associated with various patient intellectual disabilities (IDs), malformations, autism spectrum disorders, seizures, and behavioral challenges. The wide range of the severity of patient IDs, along with the association of PPP2R5D to Alzheimer's, autism, Parkinson's-like symptoms, and cancer, has generated an impetus for further research to elucidate the specific cellular pathways that are affected by PPP2R5D. In order to study JS in vitro, various biological tools need to be generated including neural cellular models. Methods, Results & Conclusion Induced pluripotent stem cells (iPSC) are highly proliferative cells that can differentiate into all three germ layers in vitro. Reprogramming patient somatic cells in to iPSC offers a means of generating difficult to source neural stem cells and neurons to study PPP2R5D mutations. Our team has generated five chromosomally stable iPSC clones from JS patient-derived skin fibroblasts representing four of the most common PPP2R5D disease-causing mutations. We have also generated chromosomally stable isogenic clones of these iPSC lines using precision CRISPR editing to provide genetically matched unmutated cells as controls. Neural stem cell (NSC) lines and neurons have been derived from each line to help study disease biology and novel therapeutic agents in a disease relevant cell type, as well. iPSC and NSC provide a theoretically unlimited supply of disease-specific cells that can be used to study JS. They are important and necessary tools for advancing the field of JS research and developing therapies for this debilitating disorder.

Generation of two control iPSC clones NCCSi008-A and NCCSi008-B from an individual of Indian ethnicity.

Two iPSC clones, NCCSi008-A and NCCSi008-B, were generated from a healthy male individual of Indian origin by reprogramming his CD4+ T cells with an integration free Sendai viral vector. The established iPSC clones showed high alkaline phosphatase (ALP) activity, expression of pluripotency markers, a normal male karyotype consistent with the donor gender (46, XY) and has potential for multi-lineage differentiation. These iPSC lines of Indian origin would serve as valuable resources for disease modeling, drug development and screening.

Induced pluripotency and spontaneous reversal of cellular aging in supercentenarian donor cells

Supercentenarians (≥110-year-old, SC) are a uniquely informative population not only because they surpass centenarians in age, but because they appear to age more slowly with fewer incidences of chronic age-related disease than centenarians. We reprogramed donor B-lymphoblastoid cell lines (LCL) derived from a 114-year-old (SC), a 43-year-old healthy disease-free control (HDC) and an 8-year-old with a rapid aging disease (Hutchinson-Gilford progeria syndrome (HGPS)) and compared SC-iPSC to HDC-iPSC and HGPS-iPSCs. Reprogramming to pluripotency was confirmed by pluripotency marker expression and differentiation to 3 germ-layers. Each iPSC clone differentiated efficiently to mesenchymal progenitor cells (MPC) as determined by surface marker expression and RNAseq analysis. We identified supercentenarian and HGPS associated gene expression patterns in the differentiated MPC lines that were not evident in the parental iPSC lines. Importantly, telomere length resetting occurred in iPSC from all donors albeit at a lower incidence in supercentenarian iPSCs. These data indicate the potential to use reprogramming to reset both developmental state and cellular age in the “oldest of the old.” We anticipate that supercentenarian iPSC and their differentiated derivatives will be valuable tools for studying the underlying mechanisms of extreme longevity and disease resistance.