Table 1 Characteristics of TGA-mediating methods
From: An update on targeted gene repair in mammalian cells: methods and mechanisms
| Method: | ssODNs | SDF | TFO | AAV | ZFN |
|---|---|---|---|---|---|
| Repair pathways involved | NER, HDR? (MMR and NHEJ are suppressive) | SFHR | NER, NHEJ? MMR? HDR? | HDR, NHEJ | HDR, NHEJ |
| Correction efficiency a | 0.1-5% (somatic cells) ~0.1% (ESCs) | 0.2-20% (somatic cells) 0.025% (ESCs) | 0.1-1.5% (somatic cells) | 9.86%-65% (somatic cells) ~1% (ESCs and iPSCs) | ~18-30% (somatic cells) 0.15-5% (iPSCs + ESCs) |
| Advantages | No integration of exogenous DNA, synthesis, stable, reproducible results | Reproducible results, potent episomal repair, artifacts can be circumvented | Synthesis, low toxicity, target specific, functional in hHPCs, stable target-complex formation | High efficiency and fidelity, effective in vivo delivery, broad cell type target field, low pathogenicity | High efficiency, known repair mechanism, normal cell cycle profiles, low background integrations, target silent genes |
| Disadvantages | Unknown repair mechanism, limited sequence size, PCR artifacts, genotoxicity, cell replication dependency | SFHR mechanism unknown, depend on HDR-like mechanism, synthesis (PCR) | Unknown repair mechanism, homopurine target restriction, G-C-rich sequences, weak DNA-binding, cellular death | Safety concerns, size limitation, integration of exogenous DNA, random integrations, cellular death | Synthesis, off-target cleavage, integration of exogenous DNA, multiple transductions |
| Targeted disease genes |
Dystrophin α-D-glucosidase β-PDE TYR |
CFTR DNA-PKcs Dystrophin β-globin SMN1 | β-globin |
COL1A1 COL1A2 FANCA Fah CFTR |
CCR5 IL2Rγ CFTR HoxB13 TYR |
| References b | [4, 9, 12, 14, 41, 46–49, 51, 52, 54, 62, 116, 117] | [4, 8, 35, 39, 40, 63, 64, 118–121] | [16, 66–69, 80, 84, 122] | [4, 11, 31, 54, 85, 88, 90, 92, 93, 123, 124] | [6, 10, 12, 13, 102, 104, 114, 125–127] |