Comparison of in vitro and ex vivo osteogenic efficacy of fucoidans extracted from three brown macroalgae of the Pacific Ocean

Brown macroalgae possesses bioactive compounds including fucoidan, a sulfated polysaccharide that can affect bone cells based on its origin and composition. This study examined the potential of fucoidan isolated from three macroalgal species — Macrocystis pyrifera, Sargassum muticum, and Undaria pinnatifida — to modulate the bone remodeling process and evaluated their comparative effectiveness. Fucoidans were extracted under acidic media, and chemically and structurally characterized before comparing their bioactivity on bone cells at different stages. Fucoidans moderately decreased the survival of progenitor cells in a concentration-dependent manner, demonstrating their minimal toxicity to the cells. All fucoidans enhanced the mineralization of preosteoblast MC3T3-E1 or mouse bone marrow cells (BMCs), particularly at higher concentrations. While low concentrations of fucoidans stimulated osteoclastogenesis, higher concentrations inhibited osteoclast formation which could be due to a reduction in the RANKL/OPG ratio as indicated by gene expression analysis. Furthermore, in a 3D ex vivo calvaria culture, fucoidans increased the new bone formation area in a concentration-dependent manner. Although all three fucoidans showed comparable bioactivities, the fucoidan from U. pinnatifida was the most effective.

We found that fucoidans from marine algae can enhance bone growth and osteoclastogenesis depending on concentration. These findings suggest a dual biological activity in bone remodeling and highlight the need for in vivo studies to confirm their therapeutic potential for bone-loss diseases.