Project description:Clinical application of somatic genome editing requires therapeutics that are generalizable to a broad range of patients. Targeted insertion of promoterless transgenes can ensure that edits are permanent, broadly applicable, while minimizing risks of off-target integration. In the liver, the Albumin locus is currently the only well characterized site for promoterless transgene insertion. Using an unbiased ChIP-seq approach, we here identify Apolipoprotein a1 (Apoa1) as one of the most highly expressed and accessible loci in mouse and human liver. We target the Apoa1 locus with Adeno-Associated Viral (AAV) delivery of CRISPR/Cas9, and achieve rates of 6 to 16% with no evidence of toxicity. We further show that the endogenous Apoa1 promoter can drive robust and sustained expression of therapeutic proteins such as factor IX (FIX) or apolipoprotein E (APOE). Finally, we demonstrate that Apoa1-targeted fumarylacetoacetate hydrolase (FAH) can correct and rescue the severe metabolic liver disease hereditary tyrosinemia type I. In summary, we identify and validate Apoa1 as novel safe harbor site for genome editing therapeutics.
Project description:X-CGD (X-linked chronic granulomatous disease) patient derived CD34+ cells were reprogrammed into two X-CGD iPSC clones (7 and 25) and subsequently corrected using ZFN (clone 7) and TALEN (clone 25) by integrating a therapeutic gp91phox expression cassette into the AAVS1 "safe harbor" locus Three condition experiment: before and after reprogramming and before and after genome editing.
Project description:Bulk RNA-sequencing experiments were performed to analyze the transcriptomic effects of such integrations into two newly established genomic safe harbor sites. Jurkat and HEK293T cells were edited to integrate CMV-mRuby expressing cassette into Rogi2 genomic safe harbor site using Cas9 RNP
Project description:Human iPSCs and NSCs were engineered by AAVS1 and/or C13 safe-harbor TALENs which mediated targeted integration of various reporter genes at single or dual safe-harbor loci. Multiple clones of targeted human iPSCs were used to compare with parental untargeted NCRM5 iPSCs. Polyclonal targeted human NSCs were used to compare with their parental untargeted NCRM1NSCs or H9NSCs. Total RNA obtained from targeted human iPSCs or NSCs compared to untargeted control iPSCs or NSCs.
Project description:Human iPSCs and NSCs were engineered by AAVS1 and/or C13 safe-harbor TALENs which mediated targeted integration of various reporter genes at single or dual safe-harbor loci. Multiple clones of targeted human iPSCs were used to compare with parental untargeted NCRM5 iPSCs. Polyclonal targeted human NSCs were used to compare with their parental untargeted NCRM1NSCs or H9NSCs.
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:X-CGD (X-linked chronic granulomatous disease) patient derived CD34+ cells were reprogrammed into two X-CGD iPSC clones (7 and 25) and subsequently corrected using ZFN (clone 7) and TALEN (clone 25) by integrating a therapeutic gp91phox expression cassette into the AAVS1 "safe harbor" locus