Compression instrument for tissue experiments (cite) at the meso-scale: device validation - biomed 2011

Liver sinusoidal endothelial cells (LSECs) are the primary site of numerous transport and exchange processes essential for liver function. LSECs rest on a sparse extracellular matrix layer housed in the space of Disse, a 0.5-1LSECs from hepatocytes. To develop bioengineered liver tissue constructs, it is important to understand the mechanical interactions among LSECs, hepatocytes, and the extracellular matrix in the space of Disse. Currently the mechanical properties of space of Disse matrix are not well understood. The objective of this study was to develop and validate a device for performing mechanical tests at the meso-scale (100nm-100m), to enable novel matrix characterization within the space of Disse. The device utilizes a glass micro-spherical indentor attached to a cantilever made from a fiber optic cable. The 3-axis translation table used to bring the specimen in contact with the indentor and deform the cantilever. A position detector monitors the location of a laser passing through the cantilever and allows for the calculation of subsequent tissue deformation. The design allows micro-newton and nano-newton stress-strain tissue behavior to be quantified. To validate the device accuracy, 11 samples of silicon rubber in two formulations were tested to experimentally confirm their Young's moduli. Prior macroscopic unconfined compression tests determined the formulations of EcoFlex030 (n-6) and EcoFlex010 (n-5) to posses Young's moduli of 92.67+-6.22 and 43.10+-3.29 kPa respectively. Optical measurements taken utilizing CITE's position control and fiber optic cantilever found the moduli to be 106.4 kPa and 47.82 kPa.