Fucoidan-Coated Silica Nanoparticles Promote the Differentiation of Human Mesenchymal Stem Cells into the Osteogenic Lineage

Silica nanoparticles (SiNPs) are widely used in biomedicalapplications,such as cancer therapy/diagnosis or tissue engineering and regenerativemedicine. Herein, we synthesized SiNPs and modified them with sulfonicacid groups (by organosilylation followed by oxidation) or a sulfatedpolysaccharide (i.e., fucoidan, a seaweed biopolymer, by using electrostaticsurface immobilization) due to the known capacity of the sulfonic/sulfatemoieties to stabilize proteins and promote stem cell differentiationtoward the osteogenic lineage. The developed pristine and functionalizednanoparticles were characterized by dynamic light scattering (DLS),scanning electron microscopy (SEM), transmission electron microscopy(TEM), and X-ray photoelectron spectroscopy (XPS), showing the monodispersesize distribution (between 360 and 450 nm) and the success of thecoating/functionalization with fucoidan or sulfonic groups. The developedSiNPs (at a concentration of 50 & mu;g/mL) were assessed throughtheir contact with SaOs2 cells evidencing their cytocompatibility.Furthermore, the osteogenic differentiation of bmMSCs was evaluatedby the quantification of ALP activity, as well as the expression profileof osteogenic-related genes, such as Runx2, ALP, and OP. We foundthat the coating of the SiNPs with fucoidan induced the osteogenicdifferentiation of bmMSCs, being an effective mediator of bone regeneration.