Tissue-specific stem cells persist for a lifetime and can differentiate to maintain homeostasis or transform to initiate cancer. Despite their importance, there are no described quality assurance mechanisms for newly formed stem cells. We observed intimate and specific interactions between macrophages and nascent blood stem cells in zebrafish embryos. Macrophage interactions frequently led to either removal of cytoplasmic material and stem cell division or complete engulfment and stem cell death. Stressed stem cells were marked by surface Calreticulin, which stimulated macrophage interactions. Using cellular barcoding, we found that Calreticulin knock-down or embryonic macrophage depletion reduced the number of stem cell clones that established adult hematopoiesis. Our work supports a model in which embryonic macrophages determine hematopoietic clonality by monitoring stem cell quality.

中文翻译：

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巨噬细胞对造血干细胞的质量保证决定了干细胞的克隆性

组织特异性干细胞终生存在，可以分化以维持体内平衡或转化以引发癌症。尽管它们很重要，但没有描述新形成的干细胞的质量保证机制。我们观察到斑马鱼胚胎中巨噬细胞和新生血液干细胞之间的密切和特异性相互作用。巨噬细胞相互作用经常导致细胞质物质去除和干细胞分裂或完全吞噬和干细胞死亡。受压的干细胞表面有钙网蛋白标记，可刺激巨噬细胞相互作用。使用细胞条形码，我们发现钙网蛋白敲除或胚胎巨噬细胞耗竭减少了建立成人造血功能的干细胞克隆的数量。