Label-Free, Longitudinal Visualization of PDT Response In Vitro with Optical Coherence Tomography
ABSTRACT A major challenge in creating and optimizing therapeutics in the fight against cancer is visualizing and understanding the microscale spatiotemporal treatment response dynamics that occur in patients. This is especially true for photodynamic therapy (PDT), where therapeutic optimization relies on understanding the interplay between factors such as photosensitizer localization and uptake, in addition to light dose and delivery rate. In vitro 3D culture systems that recapitulate many of the biological features of human disease are powerful platforms for carrying out detailed studies on PDT response and resistance. Current techniques for visualizing these models, however, often lack accuracy due to the perturbative nature of the sample preparation, with light attenuation complicating the study of intact models. Optical coherence tomography (OCT) is an ideal method for the long-term, non-perturbative study of in vitro models and their response to PDT. Monitoring the response of 3D models to PDT by time-lapse OCT methods promises to provide new perspectives and open the way to cancer treatment methodologies that can be translated towards the clinic.
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ABSTRACT: In vitro three-dimensional models of cancer have the ability to recapitulate many features of tumors found in vivo, including cell-cell and cell-matrix interactions, microenvironments that become hypoxic and acidic, and other barriers to effective therapy. These model tumors can be large, highly complex, heterogeneous, and undergo time-dependent growth and treatment response processes that are difficult to track and quantify using standard imaging tools. Optical coherence tomography is an optical ranging technique that is ideally suited for visualizing, monitoring, and quantifying the growth and treatment response dynamics occurring in these informative model systems. By optimizing both optical coherence tomography and 3D culture systems, it is possible to continuously and non-perturbatively monitor advanced in vitro models without the use of labels over the course of hours and days. In this article, we describe approaches and methods for creating and carrying out quantitative therapeutic screens with in vitro 3D cultures using optical coherence tomography to gain insights into therapeutic mechanisms and build more effective treatment regimens.Methods 09/2013; 66(2). DOI:10.1016/j.ymeth.2013.08.028 · 3.22 Impact Factor
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ABSTRACT: Sebaceous glands perform complex functions, and are centrally involved in the pathogenesis of acne vulgaris. Current techniques for studying sebaceous glands are mostly static in nature, whereas the gland's main function - excretion of sebum via the holocrine mechanism - can only be evaluated over time. We present a longitudinal, real-time alternative - the in vivo, label-free imaging of sebaceous glands using Coherent Anti-Stokes Raman Scattering (CARS) microscopy, which is used to selectively visualize lipids. In mouse ears, CARS microscopy revealed dynamic changes in sebaceous glands during the holocrine secretion process, as well as in response to damage to the glands caused by cooling. Detailed gland structure, plus the active migration of individual sebocytes and cohorts of sebocytes were measured. Cooling produced characteristic changes in sebocyte structure and migration. This study demonstrates that CARS microscopy is a promising tool for studying the sebaceous gland and its associated disorders in three-dimensions in vivo.Journal of Investigative Dermatology accepted article preview online, 15 July 2014; doi:10.1038/jid.2014.293.Journal of Investigative Dermatology 07/2014; 135(1). DOI:10.1038/jid.2014.293 · 6.37 Impact Factor