Quantitative volume comparisons of methamphetamine-induced apoptosis by simultaneous digital holographic microscopy and transport of intensity phase-imaging techniques

Transport of intensity (TIE) and digital holographic microscopy (DHM) are imaging techniques capable of real-time high resolution phase reconstructions. DHM is a widely used technique that provides phase maps through numerical reconstruction of light propagation of captured hologram intensities generated by interference between an object and a reference beam. TIE is a bright-field compatible technique that yields phase reconstructions through intensity measurements of a single object beam at symmetric planes about the focal plane. A TIE setup is simpler than DHM due to its non-interferometric nature and may yield a higher resolution reconstruction than DHM. Since TIE is a somewhat less-mature technique, we have developed a setup capable of both TIE and DHM measurements and simultaneously measured the volume changes of biological cells using both techniques. The setup is based on a modified bright-field microscope, with the addition of laser illumination for the DHM measurements. Live C6 glial cells were monitored as a hydrogen peroxide solution was introduced to the sample media to produce a visible and measurable decrease in cell volume through apoptosis. This decrease in volume was simultaneously measured by TIE and DHM, and the results were directly compared. Additionally, volume changes in C6 glial cells undergoing methamphetamine-induced apoptosis were tracked and compared.