2021 Annual Meeting

Tissue-Engineered 3D Trabecular Bone Model to Recapitulate Bone Remodeling

Trabecular bone is characterized by a 3D sponge-like porous structure, which undergoes bone remodeling in response to mechanical and chemical stimuli. Reproducing this process in vitro is imperative to understand trabecular bone metabolism in health and disease. Yet it remains a difficult task due to the lack of experimental models that can recapitulate key 3D structural and mechanical aspects of trabecular bone. We aimed to develop a model that can overcome this need. Here, we introduce a 3D trabecular bone tissue model using demineralized trabecular bone (DTB) scaffolds and a cyclic compressive bioreactor in a multi-well plate to induce mechanical stimulation. Our model represents an opportunity to provide new insight into how bone remodeling homeostasis is maintained and its role in diseases such as bone cancer and osteoporosis.

DTBs were prepared by demineralizing bone in 1.2N HCl solution. Osteoblasts were isolated from DsRed mice and seeded onto the DTBs. To induce chemical stimulation, vitamin D3 was used. To induce mechanical stimulation, we developed a multi-well plate-based mechano-culture platform consisting of three parts; (i) a pneumatic actuator moving a magnet array up-and-down, (ii) a magnetic spring-based insert to compress the DTB, and (iii) a microprocessor to control actuator movement.

Our DTB provides advantages, such as optical transparency with high porosity and surface area. Dsred osteoblasts adhered and proliferated well, coating the surface of the DTB within one week. In our platform, a pneumatic actuator receives air and pushes a magnet array closer to the well-plate, attracting a magnetic insert down, compressing the DTB. As air is removed, the array lowers, releasing the DTB. This is repeated in 1 min on/off cycles. In our proof-of-concept studies, osteoblasts were responsive to both chemical and mechanical stimulation, which was confirmed by the alteration of OPG and RANKL secretion profiles. Our ongoing study investigates four conditions to substantiate the relative impact of different stimuli; (1) mechanical, (2) chemical, (3) mechanical and chemical, and (4) no stimulation.

We have developed a 3D trabecular bone tissue model which incorporates both the mechanical and chemical aspects of trabecular bone remodeling to provide a reproducible and anatomically relevant model. Soon, bone marrow monocytes will be included to better simulate the bone remodeling cellular process. We envision a 3D dynamic bone tissue model that can provide better insight into bone metabolism and facilitate biomedical research into various bone remodeling associated diseases including bone metastasis and osteoporosis.