影像学的最新进展表明，造血细胞在骨髓微环境（生态位）中的空间组织调节细胞扩张，控制血液克隆疾病的进展和白血病转化。然而，我们在恶变前条件下探究生态位的能力受到限制，因为这些疾病的标准小鼠模型很大程度上依赖于将突变克隆移植到骨髓微环境受损的条件小鼠中。在这里，我们利用活体动物显微镜和超低剂量全身或局部照射来捕获单细胞，并在功能保留的微环境中早期扩增良性/癌前克隆。与非条件对照组相比，0.5 Gy 全身照射 (WBI) 可使细胞稳定植入超过 30 周。体内微环境跟踪和功能分析显示基质细胞的血管完整性、细胞活力和 HSC 支持功能没有变化，表明辐射损伤后炎症最小化。该方法能够对 Tet2/- 及其健康对应物进行体内成像，显示出在共享微环境中的优先定位，同时形成离散的微生态位。值得注意的是，与生态位的固定关联仅发生在细胞子集中，并且在没有实时成像的情况下无法被识别。该策略可广泛应用于研究空间背景下的克隆性疾病。© 2024。作者。

Recent advances in imaging suggested that spatial organization of hematopoietic cells in their bone marrow microenvironment (niche) regulates cell expansion, governing progression, and leukemic transformation of hematological clonal disorders. However, our ability to interrogate the niche in pre-malignant conditions has been limited, as standard murine models of these diseases rely largely on transplantation of the mutant clones into conditioned mice where the marrow microenvironment is compromised. Here, we leveraged live-animal microscopy and ultralow dose whole body or focal irradiation to capture single cells and early expansion of benign/pre-malignant clones in the functionally preserved microenvironment. 0.5 Gy whole body irradiation (WBI) allowed steady engraftment of cells beyond 30 weeks compared to non-conditioned controls. In-vivo tracking and functional analyses of the microenvironment showed no change in vessel integrity, cell viability, and HSC-supportive functions of the stromal cells, suggesting minimal inflammation after the radiation insult. The approach enabled in vivo imaging of Tet2+/- and its healthy counterpart, showing preferential localization within a shared microenvironment while forming discrete micro-niches. Notably, stationary association with the niche only occurred in a subset of cells and would not be identified without live imaging. This strategy may be broadly applied to study clonal disorders in a spatial context.© 2024. The Author(s).