Improvement and Evaluation of a 3D Printable Bioreactor Chamber for Ex Vivo Trabecular Bovine Bone Core Testing with Mechanical Stimulation

Abstract

Better understanding of bone tissue mechanics is key in the development of more effective strategies to prevent bone fracture, regenerate, and repair bone pathologies like osteoporosis. Functioning as a bridge model between two-dimensional in vitroand in vivo studies, the ex vivobioreactor and loading systems allow the study of trabecular bone explants in a closed system that can be mechanically stimulated. Polycarbonate bioreactor chambers have been successfully used to study trabecular bone tissue mechanics in bone cores ex vivo. However, polycarbonate bioreactor chambers are difficult and expensive to fabricate, and the height-diameter ratio for bone cores is below the standard for mechanical compression tests.Three-dimensional (3D) printing, in contrast to subtractive fabrication methods, enables the fabrication of complex structures with high resolution and processing accuracy for diverse biomedical applications. Because of its adaptability and cost-effectiveness, a new bioreactor and loading system inspired by previous system like Zetos was developed using polyjet 3D printing and MED610™as printing material. The first version of the ex vivobioreactor chamber showed leakage and concerns regarding the material biological viability. Therefore, the overall aim of the current thesis research was to correct and improve the first version design limitations, by proposing and verifying a second design iteration. Biological viability of MED610™for complex constructs (like a bioreactor chamber) was evaluated. The findings support continuing developments of MED610™3D printed bioreactor chambers for organ culture and other complex 3D-printed structures for in vitro or ex vivo studies in biomedical applications.Finally, anex vivo bovine trabecular bone core study with the second versionof the3D printable bioreactor chamber confirmed thatprevious system issueswere addressed: neither system leakage nor loss of samples occurred throughout the study; andbone cores remained visibly viable during the 21-day period. Although contrasting bone behavior trends were observed when compared to previous similar studies, where mean apparent elastic modulus (Eₐₚₚ) decreased in the loading treatment groupby 14.7%,these results give valuable insights for the 3D printable bioreactor chamber and loading system’s continuing process validation.