Fracture healing continues to pose challenges for researchers and clinicians in the field of trauma and orthopaedic surgery. The future treatment strategies for fracture healing will most likely focus on the use of biologic and biochemical methods in combination with established fixation and mechanical methods. In this study, heparanase (HPSE), a mammalian endo-glycuronidase that promotes angiogenesis through cleavage of the extra cellular matrix (ECM)-heparan sulphate and mobilization of ECM resident growth factors, was investigated for its osteoblasts-stimulating effect.

Osteoblast cells, originated from osteoporotic and healthy human subjects who underwent total knee replacement, were cultured and exposed to HPSE at a series of final concentrations of 1, 3, and 6μg/mL. The cell density, proliferation, alkaline phosphatase (ALP) production and specific activity, and expression of osteogenic genes were examined.

A marked stimulating effect of HPSE in cell density and proliferation was observed in the osteoblastic cultures from both osteoporotic and healthy subjects. The ALP level and its specific activity, a classical osteoblastic marker, were also increased at the presence of HPSE in a dose-dependant manner. The expression of osteogenic pathway genes, particularly bone morphogenic proteins (BMPs), transcription factors SMDs, vascular endothelial growth factor and tissue inhibitor of metallopeptidase (TIMP) were up- or down-regulated, which correlated with the doses of HPSE.

This study is the first to show that HPSE increases cell proliferation and stimulates differentiation in human osteoblasts suggesting that the potential of HPSE as a new biofactor for the treatment of fractures. Further research on HPSE in co-culture of osteoblasts and osteoclasts is under investigation in our laboratory.