A Lab-On-A-Chip Platform for Stimulating Osteocyte Mechanotransduction and Analyzing Functional Outcomes of Bone Remodeling.

Abstract

Bone remodeling is a tightly regulated process that is required for skeletal growth and repair as well as adapting to changes in the mechanical environment. During this process, mechanosensitive osteocytes regulate the opposing responses between the catabolic osteoclasts and anabolic osteoblasts. To better understand the highly intricate signaling pathways that regulate this process, our lab has developed a foundationary lab-on-a-chip (LOC) platform for analyzing functional outcomes (formation and resorption) of bone remodeling within a small scale system. As bone remodeling is a lengthy process that occurs on the order of weeks to months, we developed long-term cell culturing protocols within the system. Osteoblasts and osteoclasts were grown on functional activity substrates within the LOC and maintained for up to seven weeks. Afterward, chips were disassembled to allow for the quantification of bone formation and resorption. Additionally, we have designed a 3D printed mechanical loading device that pairs with the LOC platform and can be used to induce osteocyte mechanotransduction by deforming the cellular matrix. We have optimized cell culturing protocols for osteocytes, osteoblasts, and osteoclasts within the LOC platform and have addressed concerns of sterility and cytotoxicity. Here, we present the protocols for fabricating and sterilizing the LOC, seeding cells on functional substrates, inducing mechanical load, and disassembling the LOC to quantify endpoint results. We believe that these techniques lay the groundwork for developing a true organ-on-a-chip for bone remodeling.