Hematopoietic stem/progenitor cell gene therapy (HSPC-GT) is proving successful to treat several genetic diseases. HSPCs are mobilized, harvested, genetically corrected ex vivo, and infused, after the administration of toxic myeloablative conditioning to deplete the bone marrow (BM) for the modified cells. We show that mobilizers create an opportunity for seamless engraftment of exogenous cells, which effectively outcompete those mobilized, to repopulate the depleted BM. The competitive advantage results from the rescue during ex vivo culture of a detrimental impact of mobilization on HSPCs and can be further enhanced by the transient overexpression of engraftment effectors exploiting optimized mRNA-based delivery. We show the therapeutic efficacy in a mouse model of hyper IgM syndrome and further developed it in human hematochimeric mice, showing its applicability and versatility when coupled with gene transfer and editing strategies. Overall, our findings provide a potentially valuable strategy paving the way to broader and safer use of HSPC-GT.

造血干/祖细胞基因疗法 (HSPC-GT) 被证明可以成功治疗多种遗传疾病。在施用毒性清髓性调理以消耗修饰细胞的骨髓 (BM) 后，HSPC 被动员、收获、离体基因校正和注入。我们表明，动员者为外源细胞的无缝植入创造了机会，这些细胞有效地超过了那些被动员的细胞，以重新填充耗尽的 BM。竞争优势源于离体抢救动员对 HSPC 的有害影响的培养，并且可以通过利用优化的基于 mRNA 的传递的植入效应器的瞬时过表达来进一步增强。我们在高 IgM 综合征小鼠模型中展示了治疗效果，并在人类血嵌合小鼠中进一步开发了它，在与基因转移和编辑策略相结合时显示了它的适用性和多功能性。总体而言，我们的研究结果提供了一种潜在有价值的策略，为更广泛和更安全地使用 HSPC-GT 铺平了道路。