Department of Bio Medical Engineering seminar 05.01.20
Biomedical Spectroscopic Imaging with Scattered Light
Abstract
Optical spectroscopy emerged as a valuable tool to study live biological tissue at various scales and detect early disease in the human body. While fluorescence and Raman spectra are sensitive to molecular properties of tissue, light scattering spectra, originating from the extracellular matrix, subcellular structures, and other tissue inhomogeneities, carry information about tissue microscopic and macroscopic organization. In this talk we will discuss how scattered light can be used for noninvasive detection of invisible pre-cancer in such diverse organs as the esophagus or pancreas that seem to have little in common. We will show, however, that since pre-cancer in many organs is characterized by certain microscopic changes in epithelial cells, such as increase in nuclear size and nuclear density, light scattering signatures of those precancers are quite similar, allowing early cancer imaging and detection without the need for external markers.
Light scattering signatures could also be used for sensing subnuclear and subcelluar structure of live cells, e.g. chromatin packing, organelle organization, and characterization of cell-derived exosomes. Nanoscale changes in the nuclear structure have been shown to play a critical role in genetic and transcriptional alterations and are a hallmark of neoplasia. However, due to the lack of technologies for label-free nanoscale-sensitive measurements in live cells, many aspects of these phenomena have remained an open problem. We will discuss how the approach based on the combination of confocal microscopy and spectroscopy of scattered light could help to solve this problem, providing several critical advantages over the existing methods.
Biography
Lev T. Perelman is Professor of Medicine at Harvard University and Director of the BIDMC Center for Advanced Biomedical Imaging and Photonics. His research interests are primarily focused on application of optics to medicine and biology. Perelman’s group pioneered biomedical light scattering spectroscopy for noninvasive detection of early precancerous changes in epithelial tissues and tissue characterization on a subcellular scale, and developed confocal light absorption and scattering spectroscopic (CLASS) microscopy for label-free functional imaging of live cells, recently employed, in collaboration with R. Kalluri, to demonstrate that subcellular exosomes perform cell-independent microRNA biogenesis and promote tumorigenesis. Working with K. Kneipp at MIT he demonstrated single molecule detection with surface-enhanced Raman scattering (SERS), and explained the role of stress confinement in short pulse laser ablation, a basic mechanism of laser surgery widely used now in neurosurgery and ophthalmology. He also developed, with J. Marshall, the first nonhydrostatic model of the ocean, the MIT General Circulation Model. Perelman has mentored 30+ graduate students and postdoctoral fellows, and 9 are now tenured professors at Princeton, Northwestern, and other universities.
