10x scRNA-seq analysis of a human milk cell sample compared to a non-lactating breast tissue sample

Breast cancer risk is influenced by parity in an age-dependant manner, however human tissue remodelling induced by pregnancy and lactation is not well understood. In most cases, it is difficult to acquire human breast tissue during these key stages of development. Here, we present an approach to overcome this using single-cell RNA sequencing to examine viable primary mammary epithelial cells isolated from human milk (n=1, LMC) compared to resting, non-lactating human breast tissue (n=1, NMC, ran over 3 lanes of a 10x Genomics chip). We identified all documented mammary subpopulations within our breast tissue samples and found that milk contains distinct secretory luminal cells together with myeloid and lymphocytic hematopoietic lineage cells. Comparing the luminal transcriptional profiles of cells isolated from the resting and lactating state identified differences in mammary cell function and metabolism between these maturation states. This data may be used to provide an insight into how parity influences human luminal cell metabolism and breast cancer risk.