Optical coherence tomography of cell dynamics in three-dimensional tissue models

Abstract

Three-dimensional cell-based tissue models have been increasingly useful in the fields of tissue engineering, drug discovery, and cell biology. While techniques for building these tissue models have been advanced, there have been increasing demands for imaging techniques that are capable of assessing complex dynamic three-dimensional cell behavior in real-time and at larger depths in highly-scattering scaffolds. Understanding these cell behaviors requires advanced imaging tools to progress from characterizing two-dimensional cell cultures to complex, highly-scattering, thick three-dimensional tissue constructs. Optical coherence tomography (OCT) is an emerging biomedical imaging technique that can perform cellular-resolution imaging in situ and in real-time. In this study, we demonstrate that it is possible to use OCT to evaluate dynamic cell behavior and function in a quantitative fashion in four dimensions (three-dimensional space plus time). We investigated and characterized in thick tissue models a variety of cell processes, such as chemotaxis migration, proliferation, de-adhesion, and cell-material interactions. This optical imaging technique was developed and utilized in order to gain new insights into how chemical and/or mechanical microenvironments influence cellular dynamics in multiple dimensions. With deep imaging penetration and increased spatial and temporal resolution in three-dimensional space, OCT will be a useful tool for improving our understanding of complex biological interactions at the cellular level.

Three‐ and four‐dimensional visualization of cell migration using optical coherence tomography

“…Fluorescent confocal and multiphoton microscopy, commonly used for analysis of cell-substrate interactions and 3D cell behavior, can penetrate only about 300 mm into tissue and the exogenous fluorophores used may interfere with the biological processes taking place within the cell [2,5,16,20,24]. Additionally high laser intensities used in fluorescence imaging can cause photodamage to living tissue [5,20,24].…”

“…The noninvasive interferometric imaging technology of frequency-domain optical coherence tomography (OCT) overcomes these problems [2,5,16,20,[25][26][27]. In OCT, refractive-index variations caused by membranes or vacuoles of cells eliminates the need for staining and sample processing, reducing artefacts and increasing cell viability [2,5].…”

“…In OCT, refractive-index variations caused by membranes or vacuoles of cells eliminates the need for staining and sample processing, reducing artefacts and increasing cell viability [2,5]. This is of particular significance when imaging over long periods of time.…”

“…In adult health, related processes are an important aspect of new clinical technologies for tissue engineering, repair and replacement of damaged organs [4][5][6][7]. Conventional studies of cell migration have largely relied on the …”

Artefact reduction for cell migration visualization using spectral domain optical coherence tomography

“…Substrates involved are often opaque which causes difficulties for conventional cellular imaging modalities such as differential interference contrast (DIC) microscopy. Therefore optical coherence tomography (OCT) has been proposed to be used for time lapse cell imaging in 3D scaffolds [1][2][3][4][5]. Difficulties arise since OCT signals from cell samples exhibit high dynamic range.…”