Neonatal Research Group, Health Research Institute Hospital La Fe, Avda Fernando Abril Martorell 106, 46026 Valencia, Spain.
Department of Analytical Chemistry, University of Valencia, Dr. Moliner 50, 46100 Burjassot, Spain.
Nutrients. 2023 Feb 22;15(5):1100. doi: 10.3390/nu15051100.
Human milk (HM) is a complex biofluid containing a wide cell variety including epithelial cells and leukocytes. However, the cellular compositions and their phenotypic properties over the course of lactation are poorly understood. The aim of this preliminary study was to characterize the cellular metabolome of HM over the course of lactation. Cells were isolated via centrifugation and the cellular fraction was characterized via cytomorphology and immunocytochemical staining. Cell metabolites were extracted and analyzed using ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-QqTOF-MS) in the positive and negative electrospray ionization modes. Immunocytochemical analysis revealed a high variability of the number of detected cells with relative median abundances of 98% of glandular epithelial cells, 1% of leukocytes, and 1% of keratinocytes. Significant correlations between the milk postnatal age with percentage of epithelial cells and leukocytes, and with total cell count were observed. Results from the Hierarchical Cluster Analysis of immunocytochemical profiles were very similar to those observed in the analysis of the metabolomic profiles. In addition, metabolic pathway analysis showed alterations in seven metabolic pathways correlating with postnatal age. This work paves the way for future investigations on changes in the metabolomic fraction of the cellular compartment of HM.
人乳（HM）是一种复杂的生物流体，含有多种细胞，包括上皮细胞和白细胞。然而，关于泌乳过程中细胞成分及其表型特性的了解甚少。本初步研究的目的是描述泌乳过程中人乳的细胞代谢组。通过离心分离细胞，通过细胞形态学和免疫细胞化学染色对细胞部分进行特征描述。使用超高效液相色谱-四极杆飞行时间质谱联用仪（UPLC-QqTOF-MS）在正、负离子模式下提取和分析细胞代谢物。免疫细胞化学分析显示，检测到的细胞数量具有很高的可变性，相对中位数丰度为 98%的腺上皮细胞、1%的白细胞和 1%的角质形成细胞。观察到乳后年龄与上皮细胞和白细胞百分比以及总细胞计数之间存在显著相关性。免疫细胞化学图谱的层次聚类分析结果与代谢组学图谱的分析结果非常相似。此外，代谢途径分析显示，与产后年龄相关的七个代谢途径发生了改变。这项工作为未来研究 HM 细胞区室的代谢组学部分的变化奠定了基础。
