Growth Inhibition of Mesenchymal Stem Cells by Laminarin: Impact on Chondrocyte Differentiation

Beta-(1 → 3)-glucans constitute highly promising biomolecules as evidenced by their immunostimulating ability which were first used as folk medicine in Chinese populations and further identified in fungi, yeasts and seaweeds. Previous investigations showed that glucans proteins interaction mediate cell growth pathways. We have adopted this approach to study the effect of laminarin, a beta-(1 → 3)-D-glucan, on Mesenchymal Stem Cells (MSCs) proliferation and differentiation. MSCs were cultured in MSC growth and chondrogenic differentiation mediums. Proliferation rate and apoptosis were explored by cell count, MTT assays and Annexin V staining. mRNA and protein expression of specifics markers for MSCs and chondrocytes were studied using qPCR and immunofluorescence. Results showed that laminarin treatment reduced MSCs proliferation in both growth and chondrogenic mediums (p<0.05). Annexin V staining showed no apoptosis. MSC cells in growth medium showed no impact of laminarin for Thy1, nucleostemin and endoglin mRNA analysis. Conversely, in chondrogenetic medium, laminarin had a negative effect on Thy1 levels and no change in nucleostemin and endoglin. Collagen II responded positively in chondrogenitic medium in absence of laminarin and significantly reduced when laminarin was added (p<0.05). These results indicate that laminarin inhibited both cells proliferation and chondrogenic differentiation suggesting potential clinical applications in MSC therapy.