Targeted beta-globin gene conversion in human hematopoietic CD34+ and Lin−CD38− cells

Liu, H.; Agarwal, Sheba; Kmiec, Eric B.; Davis, Brian R.

doi:10.1038/sj.gt.3301610

Cited by 25 publications

(13 citation statements)

References 25 publications

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“…Such a phenomenon had been noticed previously but the data were not completely revealing and no clear explanation was offered to explain this observation. 49 However, if one considers the experimental protocols used to introduce the Non-specific oligo-Kan/LD50C Specific oligo for eGFP mutation-EGFP3S/47NT…”

Section: The Dna Replication Process Regulates Gene Repair Activitymentioning

confidence: 99%

“…Interestingly, Davis and co-workers introduced several types of synthetic molecules, including the chimeric RNA/DNA oligonucleotide into CD34-positive cells using microinjection and succeeded in demonstrating that the targeted gene was altered precisely. 49 More importantly, the inheritance of the alteration persists as the cells were expanded in culture; a requirement of this approach is to be brought forward into clinic.…”

Section: The Dna Replication Process Regulates Gene Repair Activitymentioning

confidence: 99%

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Gene therapy progress and prospects: targeted gene repair

et al. 2005

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The capacity to correct a mutant gene within the context of the chromosome holds great promise as a therapy for inherited disorders but fulfilling this promise has proven to be challenging. However, steady progress is being made and the development of gene repair as a viable and robust approach is underway. Here, we present some of the recent advances that are helping to shape our thinking about the feasibility and the limitations of this technique. For the most part, these advances center on understanding the regulation of the reaction and validating its application in animal models. Gene Therapy (2005) 12, 639-646.

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Section: The Dna Replication Process Regulates Gene Repair Activitymentioning

confidence: 99%

Section: The Dna Replication Process Regulates Gene Repair Activitymentioning

confidence: 99%

Gene therapy progress and prospects: targeted gene repair

et al. 2005

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“…Microinjection or nuclear injection of corrective molecules has also been used to overcome the natural cell barriers (cytoplasmic and/or nuclear membranes) with additional control over the amount of nucleic acid molecules incorporated into individual cells, although presently its widespread and clinical application is impractical due to the low number of cells that can be modified using this technically-demanding methodology. Nevertheless, this strategy has also served to incorporate chimeraplasts [Zhang et al, 1998], [Liu et al, 2002a], [Tran et al, 2003], [Tagalakis et al, 2005], small DNA fragments [Kunzelmann et al, 1996], , phosphorothioate antisense oligonucleotides [Shoeman et al, 1997], [Lorenz et al, 1998], and triplex-forming oligonucleotides into the nucleus of target cells. Finally, ultrasound through cavitating gas bodies such as microbubbles may also prove a very useful alternative for in vivo enhanced delivery of genetic material [Pitt et al, 2004].…”

Section: Cellular and Nuclear Membranes As Physiological Barriersmentioning

confidence: 99%

Targeted Gene Repair: The Ups and Downs of a Promising Gene Therapy Approach

Semir¹,

Aran

2006

CGT

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As a novel form of molecular medicine based on direct actions over the genes, targeted gene repair has raised consideration recently above classical gene therapy strategies based on genetic augmentation or complementation. Targeted gene repair relies on the local induction of the cell's endogenous DNA repair mechanisms to attain a therapeutic gene conversion event within the genome of the diseased cell. Successful repair has been achieved both in vitro and in vivo with a variety of corrective molecules ranging from oligonucleotides (chimeraplasts, modified single-stranded oligonucleotides, triplex-forming oligonucleotides), to small DNA fragments (small fragment homologous replacement (SFHR)), and even viral vectors (AAV-based). However, controversy on the consistency and lack of reproducibility of early experiments regarding frequencies and persistence of targeted gene repair, particularly for chimeraplasty, has flecked the field. Nevertheless, several hurdles such as inefficient nuclear uptake of the corrective molecules, and misleading assessment of targeted repair frequencies have been identified and are being addressed. One of the key bottlenecks for exploiting the overall potential of the different targeted gene repair modalities is the lack of a detailed knowledge of their mechanisms of action at the molecular level. Several studies are now focusing on the assessment of the specific repair pathway(s) involved (homologous recombination, mismatch repair, etc.), devising additional strategies to increase their activity (using chemotherapeutic drugs, chimeric nucleases, etc.), and assessing the influence of the cell cycle in the regulation of the repair process. Until therapeutic correction frequencies for single gene disorders are reached both in cellular and animal models, precision and undesired side effects of this promising gene therapy approach will not be thoroughly evaluated.

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“…Previous attempts to do so have been made using 'chimeraplasty', that takes advantage of cellular mismatch repair coupled to homologous recombination using chimeric RNA-DNA strands. [4][5][6][7] However, the resultant frequency of mutation correction has been highly variable; 8,9 more consistent results were obtained when deoxyoligonucleotides instead of chimeric strands were used to induce sitespecific base changes. 10 We have been exploring an alternative approach to correct a mutant base pair directly on the chromosome.…”

Section: Introductionmentioning

confidence: 99%

Third strand-mediated psoralen-induced correction of the sickle cell mutation on a plasmid transfected into COS-7 cells

2006

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A significant level of correction of the mutation responsible for sickle cell anemia has been achieved in monkey COS-7 cells on a plasmid containing a b-globin gene fragment. The plasmid was treated in vitro with a nucleic acid 'third strand' bearing a terminal photoreactive psoralen moiety that binds immediately adjacent to the mutant base pair. Following covalent attachment of the psoralen by monoadduct or diadduct formation to the mutant T-residue on the coding strand, the treated plasmid was transfected into the cells, which were then incubated for 48 h to allow the cellular DNA repair mechanisms to remove the photoadducts. Upon reisolation and amplification of the transfected plasmid, sickle cell mutation correction, as determined by sequence analysis of both complementary strands, was established in a full 1%. This result encourages extension of the approach to correct the mutation directly on the chromosome.

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Targeted beta-globin gene conversion in human hematopoietic CD34+ and Lin−CD38− cells

Cited by 25 publications

References 25 publications

Gene therapy progress and prospects: targeted gene repair

Gene therapy progress and prospects: targeted gene repair

Targeted Gene Repair: The Ups and Downs of a Promising Gene Therapy Approach

Third strand-mediated psoralen-induced correction of the sickle cell mutation on a plasmid transfected into COS-7 cells

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