Effects of lactoferrin on the differentiation of pluripotent mesenchymal cells.

Lactoferrin accelerates bone formation, but the precise cellular mechanism behind this is still unclear. We examined the effect of lactoferrin on the differentiation of pluripotent mesenchymal cells using a typical pluripotent mesenchymal cell line, C2C12. Cells were cultured in low-mitogen differentiation medium to induce cell differentiation, with or without the addition of lactoferrin. The cell lineage was determined by alkaline phosphatase (ALPase) activity, mRNA expression of cellular phenotype-specific markers using real-time polymerase chain reaction (PCR), and protein synthesis using Western blotting. The expression of low-density lipoprotein lipase receptor-related proteins (LRPs) 1 and 2, both lactoferrin receptors, was determined by reverse transcription-PCR. ALPase activity increased after the addition of lactoferrin. The mRNA expression of Runx2, osteocalcin, and Sox9 increased markedly as a result of lactoferrin treatment, whereas the expression of MyoD, desmin, and PPARgamma decreased significantly. Western blots showed that lactoferrin stimulation increased Runx2 and Sox9 proteins, whereas it decreased MyoD and PPARgamma synthesis. C2C12 cells expressed the LRP1 lactoferrin receptor. These results indicate that lactoferrin treatment converts the differentiation pathway of C2C12 cells into the osteoblastic and chondroblastic lineage.