Fucoidan has attracted attention as a potential drug because of its biological activities, which include osteogenesis. However, the molecular mechanisms involved in the osteogenic activity of fucoidan in human alveolar bone marrow-derived mesenchymal stem cells (hABM-MSCs) remain largely unknown. We investigated the action of fucoidan on osteoblast differentiation in hABM-MSCs and its impact on signaling pathways. Its effect on proliferation was determined using the crystal violet staining assay. Osteoblast differentiation was evaluated based on alkaline phosphatase (ALP) activity and the mRNA expression of multiple osteoblast markers. Calcium accumulation was determined by Alizarin red S staining. We found that fucoidan induced hABM-MSC proliferation. It also significantly increased ALP activity, calcium accumulation and the expression of osteoblast-specific genes, such as ALP, runt-related transcription factor 2, type I collagen-α 1 and osteocalcin. Moreover, fucoidan induced the expression of bone morphogenetic protein 2 (BMP2) and stimulated the activation of extracellular signal-related kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase by increasing phosphorylation. However, the effect of fucoidan on osteogenic differentiation was inhibited by specific inhibitors of ERK (PD98059) and JNK (SP600125) but not p38 (SB203580). Fucoidan enhanced BMP2 expression and Smad 1/5/8, ERK and JNK phosphorylation. Moreover, the effect of fucoidan on osteoblast differentiation was diminished by BMP2 knockdown. These results indicate that fucoidan induces osteoblast differentiation through BMP2–Smad 1/5/8 signaling by activating ERK and JNK, elucidating the molecular basis of the osteogenic effects of fucoidan in hABM-MSCs.

The purpose of this study was to describe an approach that aims to provide fundamental information for the application of natural cuttlefish bone. Before applying cuttlefish bone as a bone defect filling material, we evaluated proliferation, adhesion, and cell viability of human mesenchymal stem cells (hMSCs) cultured on cuttlefish bone. Cuttlefish bone was separated into two parts (dorsal shield and lamellar region) and each part was used. Cell proliferation and viability were assessed using the MTS assay and live/dead fluorescence staining method. The morphology was observed using scanning electron microscopy (SEM). hMSCs were stimulated with osteogenic medium and osteoblast differentiation was evaluated. The fluorescence images showed that the seeded cells grew well and that cell distribution was in accordance with the surface morphology of the cuttlefish bone. Compared with the dorsal shield, cells penetrated deeper into the three‐dimensional inner space of the lamellar part. Furthermore, under osteogenic differentiation conditions, alkaline phosphatase activity increased and the mRNA expression of ALP, runt‐related transcription factor 2, and collagen type I α1 was increased in hMSCs cultured on both the dorsal shield and lamellar block. These results indicate the potential of cuttlefish bone as an ideal scaffold for bone regenerative materials. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.