Comprehensive characterization of cell and tissue responses toward high hydrostatic pressure treatment: Molecular feedback and structural integrity in bone graft processing

In the field of tissue reconstruction, the development and improvement of suitable bone grafts is of increasing importance. The implementation of bone banks enables the international distribution of suitable allografts that can be used for defect reconstruction. Currently used procedures have significant drawbacks, especially regarding biomechanical and structural properties. These can be overcome by using the technique of high hydrostatic pressure (HHP) processing. To date, little is known about the impact of HHP protocol alterations including pressure-transmitting medium or temperature regarding bone graft integrity. Data of the present study show that a low-temperature and medium-pressure treatment using isotonic sodium chloride solution as the pressure-transmitting medium generated devitalized bone tissue with preserved extracellular matrix. Specifically, efficient devitalization of human primary osteoblasts (hOBs) was found starting from 150 MPa with cell death being a complex interaction between different mechanisms. Furthermore, protein denaturation in response to HHP treatment that was predominantly observed at 600 MPa led to non-significant impairment of biomechanical properties. Effects of HHP treatment on the bone tissue did not lead to any noticeable compromise in biocompatibility. Accordingly, the presented protocol may be applied as a medical device to improve the outcome of patients undergoing bone defect reconstruction with allogenic grafts.