High-throughput measurements of hydrogel tissue construct mechanics.

Engineered tissues represent a natural environment for studying cell physiology, mechanics, and function. Cellular interactions with the extracellular matrix proteins are important determinants of cell physiology and tissue mechanics. Dysregulation of these parameters can result in diseases such as cardiac fibrosis and atherosclerosis. In this report we present a novel system to produce hydrogel tissue constructs (HTCs) and to characterize their mechanical properties. HTCs are grown in custom chambers and a robotic system is used to indent them and measure the resulting forces. Force measurements are then used to estimate HTC pretension (cellular contractility). Pretension was reduced in a dose-dependent manner by cytochalasin D (CD) treatment; the highest concentration (2microM) resulted in 10-fold decrease. On the other hand, treatment with fetal bovine serum (20%) resulted in approximately threefold increase in pretension. Excellent repeatability and precision were observed in measurements from replicate HTCs. The coefficient of statistical variance of quantified pretension ranged from 7% to 15% (n=4). Due to the small size (4x4x0.8mm) of the HTCs, this system of profiling HTC mechanics can readily be used in high-throughput applications. In particular, it can be used for screening chemical libraries in search of drugs that can alter tissue mechanics.