Optical coherence elastography of engineered and developing tissue

Biomechanical elastic properties are among the many variables used to characterize in vivo and in vitro tissues. Since these properties depend largely on the micro- and macroscopic structural organization of tissue, it is crucial to understand the mechanical properties and the alterations that occur when tissues respond to external forces or to disease processes. Using a novel technique called optical coherence elastography (OCE), we mapped the spatially distributed mechanical displacements and strains in a representative model of a developing, engineered tissue as cells began to proliferate and attach within a three-dimensional collagen matrix. OCE was also performed in the complex developing tissue of the Xenopus laevis (African frog) tadpole. Displacements were quantified by a cross-correlation algorithm on pre- and postcompression images, which were acquired using optical coherence tomography (OCT). The images of the engineered tissue were acquired over a 10-day development period to observe the relative strain differences in various regions. OCE was able to differentiate changes in strain over time, which corresponded with cell proliferation and matrix deposition as confirmed with histological observations. By anatomically mapping the regional variation of stiffness with micron resolution, it may be possible to provide new insight into the complex process by which engineered and natural tissues develop complex structures.