Unknown,Transcriptomics,Genomics,Proteomics

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Genetic correction and analysis of induced pluripotent stem cells from a patient with gyrate atrophy

ABSTRACT: Gene-corrected patient-specific induced pluripotent stem (iPS) cells offer a novel approach to gene therapy. Yet it is unknown whether selective pressures during prolonged culture and multiple clonal events would introduce a mutational load incompatible with therapeutic use. Here we begin to assess whether the mutational load of gene-corrected iPS cells is compatible with use in the treatment of genetic causes of retinal degenerative disease. We isolated iPS cells free of transgene sequences from a patient with gyrate atrophy caused by a point mutation in the gene encoding ornithine-δ-aminotransferase (OAT) and used homologous recombination to correct the genetic defect. Cytogenetic analysis, array comparative genomic hybridization (aCGH), and exome sequencing were performed to assess the genomic integrity of an iPS cell line after three sequential clonal events: initial reprogramming, gene targeting, and subsequent removal of a selection cassette. No abnormalities were detected following standard G-band metaphase analysis. However, aCGH and exome sequencing identified two deletions, one amplification, and nine point mutations in protein-coding regions in the initial iPS cell clone. Except for the targeted correction of the single nucleotide in the OAT locus and a single synonymous base pair change, no additional mutations or copy number variation were identified in iPS cells following the two subsequent clonal events. These findings confirm that iPS cells themselves may carry a significant mutational load at initial isolation, but that the clonal events and prolonged cultured required for correction of a genetic defect can be accomplished without a substantial increase in mutational burden. Array comparative genomic hybridization (aCGH) were performed to assess the genomic integrity of an iPS cell line after three sequential clonal events: initial reprogramming, gene targeting, and subsequent removal of a selection cassette. Human CGH 2.1M Whole-Genome Tiling v2.0D Array plus 4633 custom-designed probes which cover the gene targeting construct and the reprogramming plasmid vectors. Comparison of patient iPS cell with full skin fibroblast cells was performed on this design.

ORGANISM(S): Homo sapiens

SUBMITTER: jeff Nie

PROVIDER: E-GEOD-26773 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Genomic analysis of many cancers has led to the identification of novel targets and the development of personalized, targeted therapies. Unfortunately, in the majority of rare tumors, this type of analysis can be particularly challenging. Large series of specimens for analysis are simply not available, allowing recurring patterns to remain hidden. Clinical specimens typically contain variable degrees of non-tumor cells that can mask a potentially critical genomic signature, leaving important clinically relevant events undetected. When analysis is limited to a smaller number of specimens, the effects of heterogeneity within each sample is magnified. In light of these challenges, we used DNA content based flow cytometry to isolate clonal tumor populations from a series of rare cancers for genomic analysis: intrahepatic cholangiocarcinoma, anal carcinoma, adrenal leiomyosarcoma, and pancreatic neuroendocrine tumors. These purified clonal populations are then subject to high definition measurement of copy number aberrations by objectively measuring the height and boundaries of amplicons and by discriminating homozygous from partial deletions. Ranking of these events by copy number facilitates the identification of highly selected aberrations. This approach can garner useful information from a single biopsy. In the cases we describe, several potential therapeutic targets were identified and genomic aberrations correlated with the phenotypic behavior. We propose that clonal genomic analysis can generate unique hypotheses and guide the development of clinical advances for these and other rare tumors. We applied DNA content based flow sorting to isolate the nuclei of clonal populations from tumor biopsies. We coupled this strategy with oligonucleotide array CGH (aCGH) thereby obtaining high definition genomic profiles of clonal populations from different rare tumors including pancreatic neuroendocrine cancers, adrenal leiomyosarcoma, anal carcinoma, and cholangiocarcinoma.

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Genetic correction and analysis of induced pluripotent stem cells from a patient with gyrate atrophy

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