Changes in optical properties of cells and tissue after induction of apoptosis

Apoptosis is the effector of regulated cell death and plays a role in many physiologic and pathologic processes. It is characterized by a highly regulated condensation and fragmentation of the cell nucleus, and breakup of the entire cell into vesicles, (apoptotic bodies) containing cell organelles and fragments of the nucleus. Previous experiments indicate that changes in optical properties after induction of apoptosis might be detected using optical imaging systems, such as optical coherence tomography (OCT), due to an increase in scattering of apoptotic cells. The previous in vitro experiments are extended to ex vivo and in vivo experiments. A nearly two-fold increase in attenuation coefficient is observed in a tissue culture of porcine carotid artery, in which apoptosis is induced by balloon dilation, and a significant 20 % increase in an in vivo setup. The preliminary results of this study indicate that the apoptotic process may also be detected ex vivo and in vivo using optical imaging systems, such as optical coherence tomography (OCT), due to an increase in scattering by the typical disintegration of cellular material.