Novel in vitro Microfluidic Platforms for Osteocyte Mechanotransduction Studies

Liangcheng Xu (1), Lidan You (1,2)

1. Institute of Biomaterials and Biomedical Engineering, University of Toronto.

2. Department of Mechanical and Industrial Engineering, University of Toronto.

Current research has focused on observing bone cell mechanotransduction under different simulated physiological conditions (e.g., shear stress, strain, pressure, etc.) using macro-scale devices. However, these devices often require large sample volumes and extensive setup protocol, as well as very limited designs only suitable for general cell culture. On the other hand, in vitro microfluidic devices provide an optimal tool to better understand this biological process with its flexible design, physiologically-relevant dimensions, and high-throughput capabilities. However, there lacks a robust system where multi-physiological flow conditions are applied to bone cells to study their intercellular communication.

This project aims to 1) design and fabricate a multi-shear stress, co-culture platform; 2) validate the platform by looking at the well-established osteocyte mechano-regulation of bone resorption; and 3) integrate on-chip chemical sensors that allow real-time tracking of osteocyte secretion factors.

Parallel multi-shear stress channels will be paired with corresponding osteoclast culturing chambers connected through perfusion pores. Through perfusion between the multi-shear stress channels and culturing chambers, different cell population can communicate to each other as they are stimulated by varying levels of shear stress. Standard soft lithography technique will be used for fabrication. Additionally, we aim to improve the analytics of cell behaviour by integrating on-chip nanowire-based chemical sensors. 

MLO-Y4 osteocyte-like cells seeded in the device are stimulated with oscillatory fluid flow with a custom in-house pump. Significant differences in RANKL levels are observed between channels, demonstrating that proper cellular response to flow can be elicit from each distinct shear stress channels as designed.