The advent of next-generation genome engineering tools like CRISPR-Cas9 has transformed the field of gene therapy, rendering targeted treatment for several incurable diseases. Hematopoietic stem and progenitor cells (HSPCs) continue to be the ideal target cells for gene manipulation due to their long-term repopulation potential. Among the gene manipulation strategies such as lentiviral gene augmentation, non-homologous end joining (NHEJ)-mediated gene editing, base editing and prime editing, only the homology-directed repair (HDR)-mediated gene editing provides the option of inserting a large transgene under its endogenous promoter or any desired locus. In addition, HDR-mediated gene editing can be applied for the gene knock-out, correction of point mutations and introduction of beneficial mutations. HSPC gene therapy studies involving lentiviral vectors and NHEJ-based gene-editing studies have exhibited substantial clinical progress. However, studies involving HDR-mediated HSPC gene editing have not yet progressed to the clinical testing. This suggests the existence of unique challenges in exploiting HDR pathway for HSPC gene therapy. Our review summarizes the mechanism, recent progresses, challenges, and the scope of HDR-based gene editing for the HSPC gene therapy.

中文翻译：

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用于造血干细胞和祖细胞基因治疗的同源定向基因编辑方法

CRISPR-Cas9等下一代基因组工程工具的出现改变了基因治疗领域，为多种疑难杂症提供了靶向治疗。造血干细胞和祖细胞 (HSPC) 由于其长期增殖潜力，仍然是基因操作的理想靶细胞。在慢病毒基因增强、非同源末端连接（NHEJ）介导的基因编辑、碱基编辑和引物编辑等基因操作策略中，只有同源定向修复（HDR）介导的基因编辑提供了插入大片段的选项。转基因位于其内源启动子或任何所需基因座下。此外，HDR介导的基因编辑可用于基因敲除、点突变的校正和有益突变的引入。涉及慢病毒载体的 HSPC 基因治疗研究和基于 NHEJ 的基因编辑研究已显示出实质性的临床进展。然而，涉及HDR介导的HSPC基因编辑的研究尚未进展到临床测试。这表明利用 HDR 途径进行 HSPC 基因治疗存在独特的挑战。我们的综述总结了 HSPC 基因治疗基于 HDR 的基因编辑的机制、最新进展、挑战和范围。