Gene expression in breastmilk cells changes with the stage of lactation (732.2)

Abstract

Breastmilk contains a cellular hierarchy including pluripotent stem cells, progenitor cells, and differentiated epithelial cells and leukocytes. The latter are strongly associated with the health status of the mother/infant dyad. Little is known about the variation in the content of non‐leukocytic breastmilk cells. In this study, we used RT‐PCR to examine expression of genes representative of different cell types in breastmilk from over 50 healthy dyads from Australia and the USA, and the effects of lactation stage. Pluripotency genes were expressed at varying levels, with higher expression earlier in lactation. Expression of ESRRB, a pluripotency marker and reprogramming factor, was consistently higher than the other pluripotency genes, and than embryonic stem cells. The mammary stem cell marker CD49f was also highly expressed across all lactation stages. Expression of all stem cell genes tested was minimal in resting breast cells. These findings reinforce reports of stem cell gene expression in breastmilk cells across lactation, and suggest that some, but not all, of these genes are differentially regulated during lactation. These data now begin to elucidate developmental changes occurring in the breast during different lactation stages. They also ascertain an optimal window for accessing different breastmilk stem cell subpopulations for use in lactation research and regenerative medicine.