Project description:The advent of human induced pluripotent stem (iPS) cells enables for the first time the derivation of unlimited numbers of patient-specific stem cells and holds great promise for regenerative medicine. However, realizing the full potential of iPS cells requires robust, precise and safe strategies for their genetic modification. Safe human iPS cell engineering is especially needed for therapeutic applications, as stem cell-based therapies that rely on randomly integrated transgenes pose oncogenic risks. Here we describe a strategy to genetically modify iPS cells from patients with beta-thalassemia in a potentially clinically relevant manner. Our approach is based on the identification and selection of âsafe harborâ sites for transgene expression in the human genome. We show that thalassemia patient iPS cell clones harboring a transgene can be isolated and screened according to chromosomal position. We next demonstrate that iPS cell clones that meet our âsafe harborâ criteria resist silencing and allow for therapeutic levels of beta-globin expression upon erythroid differentiation without perturbation of neighboring gene expression. Combined bioinformatics and functional analyses thus provide a robust and dependable approach for achieving desirable levels of transgene expression from selected chromosomal loci. This approach may be broadly applicable to introducing therapeutic or suicide genes into patient specific iPS cells for use in cell therapy. iPS cell clones were derived from beta-thalassemia patients. A single copy of beta-globin transgene cis-linked to locus control region (LCR) elements and an excisable Neo-eGFP transcription unit were inserted into these cell clones. beta-globin expression was induced by erythroid differentiation.
Project description:The advent of human induced pluripotent stem (iPS) cells enables for the first time the derivation of unlimited numbers of patient-specific stem cells and holds great promise for regenerative medicine. However, realizing the full potential of iPS cells requires robust, precise and safe strategies for their genetic modification. Safe human iPS cell engineering is especially needed for therapeutic applications, as stem cell-based therapies that rely on randomly integrated transgenes pose oncogenic risks. Here we describe a strategy to genetically modify iPS cells from patients with beta-thalassemia in a potentially clinically relevant manner. Our approach is based on the identification and selection of “safe harbor” sites for transgene expression in the human genome. We show that thalassemia patient iPS cell clones harboring a transgene can be isolated and screened according to chromosomal position. We next demonstrate that iPS cell clones that meet our “safe harbor” criteria resist silencing and allow for therapeutic levels of beta-globin expression upon erythroid differentiation without perturbation of neighboring gene expression. Combined bioinformatics and functional analyses thus provide a robust and dependable approach for achieving desirable levels of transgene expression from selected chromosomal loci. This approach may be broadly applicable to introducing therapeutic or suicide genes into patient specific iPS cells for use in cell therapy.
Project description:Reactivation of gamma-globin is considered a promising approach for the treatment of beta-thalassaemia and sickle cell disease. Therapeutic induction of gamma-globin expression is fraught with lack of suitable therapeutic targets. In order to identify new potential targets we analysed the changes in the proteome of human primary erythroid progenitor cells by treatment with decitabine, a known, yet not clinically safe, gamma-globin inducer. Significant differentially expressed proteins were identified which were involved in various biological pathways and functional categories.
Project description:Clinical application of induced pluripotent stem (iPS) cells is limited by low efficiency of iPS derivation, and protocols that permanently modify the genome to effect cellular reprogramming. Moreover, safe and effective means of directing the fate of patient-specific iPS cells towards clinically useful cell types are lacking. Here we describe a simple, non-mutagenic strategy for reprogramming cell fate based on administration of synthetic mRNA modified to overcome innate anti-viral responses. We show that this approach can reprogram multiple human cell types to pluripotency with efficiencies that greatly surpass established protocols. We further show that the same technology can be used to efficiently direct the differentiation of RNA-induced pluripotent stem (RiPS) cells into terminally differentiated myogenic cells. Our method represents a safe, efficient strategy for somatic cell reprogramming and directing cell fates that has broad applicability for basic research, disease modeling and regenerative medicine. We isolated RNA from human RNA derived iPS cells, viral derived iPS cells, different human fibroblasts and human embryonic stem cells for hybridization to the Affymetrix gene expression microarrays.
Project description:Robust β-globin expression in erythroid cells derived from induced pluripotent stem cells (iPSCs) would increase the resolution with which red blood cell disorders such as sickle cell disease and β thalassemia can be modeled in vitro. To better quantify efforts in augmenting β-globin expression, we report the creation of a β-globin reporter iPSC line through the insertion of a GFP cassette after the endogenous β-globin promoter, allowing for the mapping of β-globin expression throughout erythroid development in real time at single cell resolution. Sorting live GFP+ and GFP- cells at the most mature stage of erythroid differentiation, followed by single cell RNA sequencing (scRNAseq), identifies features that distinguish GFP- from GFP+ β-globin expressing cells and allows for the dissection of the developmental and maturational status of iPSC-derived erythroid cells. Co-expression of embryonic, fetal and adult globins in individual cells indicates a yolk sac erythro-myeloid progenitor (EMP) stage of hematopoietic development, representing the onset of definitive erythropoiesis. Within this developmental program, scRNAseq analysis identifies a gradient of erythroid maturation with GFP+ β-globin expressing cells showing increased maturation. In addition, scRNAseq analysis reveals that definitively patterned iPSC-derived erythroblasts resemble their postnatal counterparts in terms of gene expression and essential biological processes, confirming their potential for disease modeling and regenerative medicine applications.
Project description:Induced pluripotent stem (iPS) cells give rise to neural stem cells, which are applicable for therapeutic transplantation in treatment of neural diseases. However, generation of neural stem cells from iPS cells requires a careful selection of safe iPS clones. We sought to determine whether direct induction of neural stem cells from partially reprogrammed somatic cells is able to generate safer cells rapidly. We have successfully established direct induction system from fibroblast to neural stem cells. To characterize these directly induced neural stem cells, Gene expression profiles were compared with iPS cell or ES cell-derived neurosphere. We used affymetrix microarrays to compare the global gene expression of neurospheres prepared several method. RNA extracted from neurospheres was hybridized to Affymetrix microarrays. The mouse strain used in this study except ES/iPS cells was C57BL/6.
Project description:Human induced pluripotent stem cells (hIPSCs) represent a unique opportunity for regenerative medicine since they offer the prospect of generating unlimited quantities of cells for autologous transplantation as a novel treatment for a broad range of disorders. However, the use of hIPSCs in the context of genetically inherited human disease will require correction of disease-causing mutations in a manner that is fully compatible with clinical applications. Genomic instability induced by reprogramming or genetic modification would be a main issue for the safe use of these cells. We analyzed primary hIPSC lines and genetically modified derivatives by array-based comparative genomic hybridization.
Project description:Background: The thalassemias are highly diverse at both the molecular and clinical levels. Many of the HBB mutations that result in β-thalassemia are missense mutations in the coding region of the β-globin gene, but a few cause alternative splicing, and interfere with normal processing of the β-globin transcripts. Transcriptome profiling in individuals affected with β-thalassemia, especially in individuals who carry novel mutations in the HBB, may improve our understanding of the heterogeneity and molecular mechanisms of the disease. Methods: Members of a family with a daughter affected with thalassemia intermedia, although her mother was not clinically affected, were examined for physical characteristics, hematological parameters and β-globin gene sequences. We also characterized genome-wide gene expression in the family using RT-qPCR and high-throughput RNA-sequencing mRNA expression profiling of blood. Results: Clinical findings, hematological indices, DNA and RNA sequence analysis of individuals with β-thalassemia, including the description of a novel mutation in the β-globin gene, which introduces a cryptic donor splice site. More than 300 genes are differentially expressed in β-thalassemic blood with many of the DEGs involved in pathways relevant to the clinical management of β-thalassemia. β-thalassemia shows important similarities and differences with sickle cell disease at the transcriptome level. Conclusions: We described the down-regulation of the β-globin gene in β-thalassemia by RNA-sequencing analysis using a sample from an affected individual and her mother, who have a novel mutation in the HBB that creates a cryptic donor splice site. The daughter has a typical β-thalassemia allele as well, and an unexpectedly severe phenotype. The DEGs are enriched in pathways that are directly or indirectly related to β-thalassemia such as hemopoiesis, heme biosynthesis, response to oxidative stress, inflammatory responses, immune responses, control of circadian rhythm, apoptosis, and other cellular activities. We compare our findings with published results of RNA-Sequencing analysis of sickle cell disease (SCD) and erythroblasts from a KLF1-null neonate with hydrops fetalis, and recognize similarities and differences in their transcriptional expression patterns.