Anti-CD117 monoclonal antibody (mAb) agents have emerged as exciting alternative conditioning strategies to traditional genotoxic irradiation or chemotherapy conditioning for both allogeneic and autologous gene-modified hematopoietic stem cell transplantation. Further, these agents are concurrently being explored in the treatment of mast cell disorders. Despite promising results in animal models and more recently in patients, the short-term and long-term effects of these treatments have not been fully explored. We conducted rigorous assessments to evaluate the effects of antagonistic anti-mCD117 mAb, ACK2, on hematopoiesis in wild-type (WT) and Fanconi Anemia (FA) mice. Importantly, we found no evidence of short-term DNA damage in either setting following this treatment suggesting that ACK2 does not induce immediate genotoxicity, providing crucial insights into its safety profile. Surprisingly, FA mice exhibited an increase in colony formation post-ACK2 treatment without accompanying DNA damage, indicating a potential targeting of hematopoietic stem cells (HSCs) and expansion of hematopoietic progenitor cells. Moreover, the long-term phenotypic and functional changes in hematopoietic stem and progenitor cells did not significantly differ between the ACK2-treated and control groups, in either setting, supporting that ACK2 does not adversely affect hematopoietic capacity. These finding underscore the safety of these agents when utilized as a short-course treatment in the conditioning context, as they did not induce significant changes in DNA damage amongst hematopoietic stem or progenitor cells. However, through a comparison of gene expression via single-cell RNA sequencing between untreated and treated mice, it was revealed that the ACK2 mAb, via c-Kit downregulation, effectively modulated the MAPK pathway with Fos down-regulation in WT and FA mice. Importantly, this modulation was achieved without causing prolonged disruptions. These findings validate the safety of the treatment and also enhance our understanding of its intricate mode of action at the molecular level.

中文翻译：

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野生型和范可尼贫血环境中抗 CD117 单克隆抗体治疗后的造血作用。

抗 CD117 单克隆抗体 (mAb) 药物已成为异体和自体基因修饰造血干细胞移植中传统基因毒性放射或化疗调理的令人兴奋的替代调理策略。此外，这些药物正在同时探索用于治疗肥大细胞疾病。尽管在动物模型和最近在患者中取得了有希望的结果，但这些治疗的短期和长期效果尚未得到充分探索。我们进行了严格的评估，以评估拮抗性抗 mCD117 mAb ACK2 对野生型 (WT) 和范可尼贫血 (FA) 小鼠造血的影响。重要的是，我们在这种治疗后的任何一种情况下都没有发现短期 DNA 损伤的证据，这表明 ACK2 不会立即引起遗传毒性，这为其安全性提供了重要的见解。令人惊讶的是，FA 小鼠在 ACK2 治疗后表现出集落形成的增加，但没有伴随 DNA 损伤，这表明造血干细胞 (HSC) 和造血祖细胞的扩增具有潜在的靶向作用。此外，无论在哪种情况下，造血干细胞和祖细胞的长期表型和功能变化在ACK2治疗组和对照组之间都没有显着差异，这支持ACK2不会对造血能力产生不利影响。这些发现强调了这些药物在调理环境中用作短期治疗时的安全性，因为它们不会引起造血干细胞或祖细胞 DNA 损伤的显着变化。然而，通过单细胞 RNA 测序对未治疗和治疗小鼠之间的基因表达进行比较，发现 ACK2 mAb 通过 c-Kit 下调，有效地调节 WT 和 FA 小鼠中的 MAPK 通路以及 Fos 下调。重要的是，这种调制是在没有造成长时间中断的情况下实现的。这些发现验证了治疗的安全性，并增强了我们对其复杂的分子水平作用模式的理解。