Holographic Images Show Cellular Response to Anticancer Drug

The new digital holographic imaging system uses a laser and a charged couple device (CCD), the same microchip used in household digital cameras, to see inside tumor cells. The device also may have applications in drug development and medical imaging.

"This is the first time holography has been used to study the effects of a drug on living tissue,” said Dr. David D. Nolte, lead investigator and professor of physics from Purdue University (West Lafayette, IN, USA). "We have moved beyond achieving a 3D image to using that image for a direct physiological measure of what the drug is doing inside cancer cells. This provides valuable information about the effects of various doses of the drug and the time it takes each dose to become significantly effective.”

The laser is gentle and does not harm living tissue, according to Dr. Nolte. The cancer cells utilized for the research were grown independently in a bioreactor in the laboratory. Holography uses the full spectrum of information available from light, more than what the human eye can detect, to create a 3D image called a hologram. By shining a laser on both the object and directly on the CCD chip of the digital camera, the system screens the pattern of light reflected from the object and allows the camera to record very detailed data, including depth and motion on a scale of microns, or 0.0001 cm.

The findings of this study were presented on March 6, 2007, at the American Physical Society Meeting, held in Denver, CO, USA. The Purdue researchers detected the motion of organelles inside cancer cells. Organelles are tiny specialized structures that perform internal cell functions and are a common target of anticancer drugs because they play a critical role in the uncontrolled cell division that makes cancer deadly.

Colchicine, the anticancer drug studied by the group, limits the ability of organelles to move throughout the cell and perform their functions. The drug disrupts the growth of microtubules, the highways of the internal cellular structure, and leaves organelles stuck at dead ends unable to move.
This reduction in motion translates to less shimmer in the screen image that can be quantitatively analyzed by a computer program, according to Dr. Nolte.

The investigators now plan to make measurements of the cytoskeleton, the support structure of cells, and to additionally determine what types of motion influence the shimmer effect. "What we have seen is just the tip of the iceberg,” Dr. Nolte said.


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