Characterization and comparison of human and mouse milk cells

Recent data has characterized human milk cells with unprecedented detail and provided insight into cell populations. While such analysis of freshly expressed human milk has been possible, studies of cell functionality within the infant have been limited to animal models. One commonly used animal model for milk research is the mouse; however, limited data are available describing the composition of mouse milk. In particular, the maternal cells of mouse milk have not been previously characterized in detail, in part due to the difficulty in collecting sufficient volumes of mouse milk. In this study, we have established a method to collect high volumes of mouse milk, isolate cells, and compare the cell counts and types to human milk. Surprisingly, we found that mouse milk cell density is three orders of magnitude higher than human milk. The cell types present in the milk of mice and humans are similar, broadly consisting of mammary epithelial cells and immune cells. These results provide a basis of comparison for mouse and human milk cells and will inform the most appropriate uses of mouse models for the study of human phenomena.近期已有研究以空前细致的精度对人乳细胞（human milk cells）进行了全面表征，并为乳细胞群体的研究提供了新见解。尽管目前已可对新鲜采集的人乳开展此类分析，但针对婴儿体内乳细胞功能的研究仍仅局限于动物模型。乳研究领域常用的动物模型为小鼠，但目前关于小鼠乳（mouse milk）组成的公开数据仍较为有限。具体而言，小鼠乳中的母体来源细胞此前尚未得到细致表征，这在一定程度上源于小鼠乳采集量不足的技术难题。本研究建立了一种可高效采集大量小鼠乳的方法，能够分离乳细胞并将其细胞计数与细胞类型与人乳细胞进行对比分析。令人意外的是，我们发现小鼠乳的细胞密度比人乳高出三个数量级。小鼠与人类乳中的细胞类型整体相似，大致可分为乳腺上皮细胞（mammary epithelial cells）与免疫细胞（immune cells）两类。本研究结果为小鼠与人类乳细胞的对比分析提供了参照基准，同时可为小鼠模型在人类相关生理现象研究中的合理应用提供科学指导。