Le Provost, F. | bioRxiv Science

bioRxiv2023

Sorted stem/progenitor epithelial cells of pubertal bovine mammary gland present limited potential to reconstitute an organised mammary epithelium after transplantation

The development and maintenance of mammary gland tissue depend on the proliferation and differentiation of mammary stem and progenitor cells. Here, we investigated populations of mammary epithelial cells that are potential candidates for bovine mammary gland development using xenotransplantation into mice cleared mammary fat pad. Transplanted mammary explants from 17-month-old Holstein heifers developed outgrowths exhibiting the archetypal morphology and molecular marker distributions of the bovine gland. Xenotransplantation of sorted mammary epithelial cells (CD49fpos) into bovinised fat pads using inactivated bovine fibroblasts resulted in outgrowth developments with 50% take rate, but these lacked the ductal or alveolar epithelial structures of the normal mammary gland. Similar results were obtained with xenografts of candidate bovine mammary epithelial stem cells (CD49fhighCD24pos) or epithelial cells of the basal lineage (CD49fhighCD24neg) which also developed as clumps of cells surrounded by stromal stretches within the mouse adipose tissue. These results provide further evidence for the existence of cells with self-renewing capacities in the bovine mammary gland. Sorted cells, however, showed compromised regenerative potential for epithelial morphogenesis. Further work is therefore needed to identify mammary stem/progenitor cells with full regenerative capabilities for biogenesis of normal mammary gland structure, with milk-secreting function.

cell biology↗

bioRxiv2022

Impact of pre-breeding feeding practices on rabbit mammary gland development at mid-pregnancy.

AO_SCPLOWBSTRACTC_SCPLOWOptimizing rabbit does preparation during early life to improve reproductive potential is a major challenge for breeders. Does selected for reproduction have specific nutritional needs, which may not be supplied with the common practice of feed restriction during rearing in commercial rabbit production. Nutrition during early life was already known to influence metabolism, reproduction and mammary gland development later in life, in particular during pregnancy. The aim of this study was to analyze the impact of four different feeding strategies in the early life of rabbit females (combination of high or moderate feed restriction from 5 to 9 weeks of age with restricted or ad libitum feeding regime from 9 to 12 weeks of constituting the pubertal period) on their growth, reproductive capacities and mammary development at mid-pregnancy. Unlike food intake, which remains regular, mean body weight gain was inversely proportional to the dietary restriction applied over the considered periods. The feeding strategies in place for the four groups had no effect on the reproductive parameters of the females at mid-pregnancy, as opposed to certain metabolic parameters such as cholesterolemia, that decreased with dietary intake at puberty (p[≤]0.05). Furthermore, restriction programs have impacted mammary tissular structures at mid-pregnancy. The expression of lipid metabolism enzymes (Fatty acid synthase N and Stearoyl co-A desaturase) is also increased in mammary epithelial tissue at mid-pregnancy by the dietary strategies implemented (p[≤]0.05). Moreover, milk gene expression, used as differentiation markers, indicates a better mammary epithelial development regarding further lactation, in the case of the less restrictive strategies during early life period, especially the higher feeding allowance. Our results highlight the importance of investigating feeding conditions of young female rabbits and nutrition in early life rearing, in order to provide specific recommendations for optimizing lactation and thus preventing neonatal mortality of the offspring.

physiology↗