Bone Abstracts

The lactation has been considered a cause of bone loss in humans and animals. Studies have shown that during lactation, there is a significant reduction of bone mineral density. Rats at the end of lactation show reduced bone mass. The objective of this study was to verify the effect of lactation under osteogenic potential of bone marrow mesenchymal stem cells (BMMSCs) of female rats. Twelve Wistar rats were distributed among the control and lactating groups. The experiment was approved by the ethics committee on animal experimentation. BMMSCs were grown in osteogenic medium. At 7, 14, and 21 days of osteogenic differentiation of BMMSCs, 3-4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) conversion, gene expression for collagen I, osteocalcin, osteopontin, BMP-2, osterix, alkaline phosphatase were analyzed. The number of mineralized nodules per field was analyzed at 21 days. The lactation increased reduction of MTT in formazan crystals and alkaline phosphatase activity in all experimental periods. The lactating group showed significantly increased the expression of gene transcripts for alkaline phosphatase, collagen I and sialoprotein at 7, 14, 21 days of differentiation. The BMP-2 expression was significantly higher in cell culture of the lactating rats only at 21 days of differentiation. The expression of osteocalcin, osteopontin and osterix did not differ between lactating and control groups. The number of mineralized nodules per field was significantly higher in the lactating group compared to the control group. It was concluded that the BMMSCs from lactating rats have higher osteogenic differentiation potential when compared to BMMSCs of the non-lactating rats (control). In addition, the bone loss observed in lactating rats is not due to reduced osteogenic differentiation of bone marrow mesenchymal stem cells.

Acknowledgment: CNPq and FAPEMIG of the non-lactating rats (control). In addition, the bone loss observed in lactating rats is not due to reduced osteogenic differentiation of bone marrow mesenchymal stem cells.