Breast milk MSCs: An explanation of tissue growth and maturation of offspring.

Exciting advances are revealing that breast milk harbors populations of stem and progenitor cells, and much attention is now intensified on delineating their properties and functions. The aim of this study is to isolate a mesenchymal stem cell (MSC)-like population from rabbit breast milk and track their integration into the different organs of the breastfed rabbits after taken by oral route and to explore the functional role of stem cells in the breastfed newborn babies. Ten newborn rabbits 2 weeks old fed on 2 × 106 PKH26-labeled rabbit milk derived-MSCs suspended in 2 mL Dulbecco's modified Eagle's medium (DMEM) and 10 newborn baby rabbits fed with 2 mL DMEM solution or with rabbit fibroblasts as a control group were used in the study. All rabbits were sacrificed after 1 week. We found that PKH26-labeled MSCs were engrafted into the offspring organs as liver, cartilage, bone and duodenum. Histologically, there was proliferation of cells in some organs. Moreover, there was overexpression of both PCNA and cyclin D1 genes in all organs from milk derived MSCs fed rabbits compared to the control group. Our results confirmed the presence of MSC-like population in the breast milk. We first showed that milk derived-MSCs were engrafted into the offspring organs when were taken orally. Milk derived-MSCs may elucidate the functional benefits to the newborn babies by increasing cell proliferation and growth.