gms | German Medical Science

Introduction: The marine origin polysaccharide fucoidan combines multiple biological activities. As demonstrated in a large number of studies in vitro and in vivo, fucoidans shows anti-viral, anti-tumor anti-oxidant, anti- inflammatory and anti-coagulant properties, although the detailed molecular action remains to be elucidated. The aim of this present study is to assess the impact of fucoidan, on the formation of vascular structures in co-culture models relevant for bone vascularization during bone repair but also for vascularization processes in osteosarcoma. The co-cultures consisted of bone marrow derived mesenchymal stem cells, respectively the osteosarcoma cell line MG63, and human blood derived endothelial cells (Outgrowth endothelial cells (OEC).

Methods: Human MSCs and OECs were isolated and cultured as previously described. MSCs differentiated in osteogenic medium were seeded in 24-well-plates to establish MSC mono-cultures grown in the osteogenic differentiation medium (ODM). After one day, OECs were seeded to the MSC to setup co-culture systems in the endothelial growth medium (EGM-2). Fucoidan was applied 24h after establishing the MSC mono- or MSC/OEC co-cultures, respectively. Co-cultures with MG63 were established in the same way. On day 7 and day 10 the surface marker of endothelial cells VE-Cadherin, angiogenesis related marker CXCR-4 and nuclei were used to depict OECs in the co-cultures and to quantify angiogenesis by quantitative image analysis. Cellular DNA quantification was used to analyse cell proliferation, Elisa and RT-PCR were used to evaluate the effect of fucoidan on several classes of molecules involved in angiogenesis and bone formation. Finally calcification was quantified by alizarin based calcification assay.

Results and Conclusion: Fucoidan significantly reduced angiogenesis in MSC/OEC but also in MG63/OEC co-cultures suggesting a potential application of fucoidan to lower the vascularization in bone tumors such as osteosarcoma. This was associated with a decrease in VEGF (Vascular endothelial growth factor) but also SDF-1 (Stromal derived factor) both related to the control of angiogenesis and discussed to play a role in osteosarcoma progression and metastasis. VEGF, is a key regulatory molecule in angiogenesis promoting adhesion, migration, proliferation and survival of endothelial cells. Thus it serves as a common target to control angiogenesis in general and specifically to control tumor growth. This CXCR4/SDF-1 pathway is relevant for attraction of stem cells but also many other cells relevant in tumor progression and control of angiogenesis in general. In terms of bone formation, fucoidan slightly lowered on the calcification process in MSC monocultures and MSC/OEC co-cultures

Acknowledgement: This work is supported by the Interreg project FucoSan.