Exploration of inactivated bone using high hydrostatic pressurization for future oncologic application

Abstract High hydrostatic pressure (HHP) has emerged as a promising technique for inactivating tumor cells while preserving the structural integrity of biological tissues. This study investigated the potential of HHP-treated bone as a biologically compatible autograft material for oncological reconstruction. Bone morphogenetic protein-2 (BMP-2), a key osteoinductive factor, was subjected to various inactivation methods, including HHP, high-temperature heating, and liquid nitrogen, and its osteogenic activity was assessed through alkaline phosphatase (ALP) expression in MC3T3-E1 cells. BMP-2 activity was preserved following HHP and cryogenic treatment but was diminished by thermal methods. In a rat calvarial defect model, we compared the biological and structural performance of bone grafts processed using HHP, heating (Pasteur method), liquid nitrogen, and no treatment. Computed tomography and histological analyses demonstrated comparable bone healing and ossification in the HHP and liquid nitrogen-treated groups. Scanning electron microscopy and Vickers hardness testing revealed that the surface morphology and mechanical strength of the HHP-treated bone were similar to those of the untreated bone. These findings suggest that HHP treatment preserves both the osteogenic and biomechanical properties of autologous bone and should offer a clinically viable alternative to conventional tumor inactivation methods in bone reconstruction.