Investigating Fibroblast-Induced Collagen Gel Contraction Using a Dynamic Microscale Platform

• Main Authors: Tianzi Zhang, John H. Day, Xiaojing Su, Arthur G. Guadarrama, Nathan K. Sandbo, Stephane Esnault, Loren C. Denlinger, Erwin Berthier, Ashleigh B. Theberge
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2019-08-01
• Series: Frontiers in Bioengineering and Biotechnology
• Subjects: mechanobiology; collagen gel contraction; microfluidics; dynamic; coculture; paracrine signaling
• Online Access: https://www.frontiersin.org/article/10.3389/fbioe.2019.00196/full

Mechanical forces have long been recognized as fundamental drivers in biological processes, such as embryogenesis, tissue formation and disease regulation. The collagen gel contraction (CGC) assay has served as a classic tool in the field of mechanobiology to study cell-induced contraction of extracellular matrix (ECM), which plays an important role in inflammation and wound healing. In a conventional CGC assay, cell-laden collagen is loaded into a cell culture vessel (typically a well plate) and forms a disk-shaped gel adhering to the bottom of the vessel. The decrement in diameter or surface area of the gel is used as a parameter to quantify the degree of cell contractility. In this study, we developed a microscale CGC assay with an engineered well plate insert that uses surface tension forces to load and manipulate small volumes (14 μL) of cell-laden collagen. The system is easily operated with two pipetting steps and the microscale device moves dynamically as a result of cellular forces. We used a straightforward one-dimensional measurement as the gel contraction readout. We adapted a conventional lung fibroblast CGC assay to demonstrate the functionality of the device, observing significantly more gel contraction when human lung fibroblasts were cultured in serum-containing media vs. serum-free media (p ≤ 0.05). We further cocultured eosinophils and fibroblasts in the system, two important cellular components that lead to fibrosis in asthma, and observed that soluble factors from eosinophils significantly increase fibroblast-mediated gel contraction (p ≤ 0.01). Our microscale CGC device provides a new method for studying downstream ECM effects of intercellular cross talk using 7- to 35-fold less cell-laden gel than traditional CGC assays.