Researchers at Max Planck Institute in Germany have used a new nano-sized imaging tool to capture the first-ever movies of cells transmitting the messages that control genes. The breakthrough is expected to help pharmaceutical companies speed and enhance the process of screening candidate cancer drugs.
In a study published in the February issue of the respected science journal Nature Biotechnology, the researchers reported they used quantum dots developed and manufactured by Hayward-based Quantum Dot Corporation (QDC) to provide prolonged, real-time visualizations in living cells of the signalling mechanisms of the erbB family of receptors, the targets of many cancer drugs. Quantum dots are nano-scale crystals of semiconductor material - up to ten-billionths of a meter in size - that glow in several different colours, depending on their size, when excited by a light source such as a laser. The dramatic video-clip images mark the first time researchers have been able to see moving images of a cell's basic means of communication with its environment.
"The in vivo measurements reported in our study revealed new insights into cellular processes and interactions that could previously only be studied on fixed (dead) cells," wrote the researchers, led by Prof. Thomas M. Jovin, chairman of the department of molecular biology at the Max Planck Institute for Biophysical Chemistry in Goettingen, Germany. "An understanding of receptor-mediated transduction mechanisms is essential for rational receptor-targeted therapeutics. Quantitative approaches based on multiple combinations of quantum dots and ligands will be invaluable for such investigations."
In a commentary on the study that appeared in the same issue of Nature Biotechnology, two leading experts in live cell imaging welcomed the Jovin team's breakthrough. "Semiconductor nanocrystals can track movements of individual receptors on the surface of living cells with unmatched spatial and temporal resolution," wrote Drs. Gal Gur and Yosef Yarden of the Weizmann Institute of Science in Rehovot, Israel. "(Other) imaging methodologies have limited spatial resolution and either require complex manipulation or are able to provide only very brief snapshots of receptor dynamics."
"This significant study again validates the importance of quantum dots for biomolecular imaging and drug development," said Carol Lou, president of QDC. "Our Qdot conjugates give researchers a powerful set of tools in the quest to develop new drugs that can successfully treat cancer and other diseases."
Older imaging tools such as fluorescent dyes or polymer spheres fade too quickly - within a matter of seconds - to capture lengthy video images of living cells, the scientists wrote. QDC's Qdot conjugates, by contrast, let the researchers see multiple cell elements for minutes or hours at a time. Length of observation time is critical to studying cellular processes, which change rapidly over a span of several minutes. Previous observations using dyes have produced only quick snapshots of the process.
The study is one of several recent reports to validate the superior imaging qualities of QDC's Qdot conjugates. Researchers at Carnegie Mellon University and QDC announced in January they had developed Qdot particles that are compatible with prolonged, non-invasive imaging in living animals with unparalleled brightness, paving the way for direct detection and tracking of molecules within the animal models that are the basis of drug development in almost every major pharmaceutical company. That report was published in the science journal Bioconjugate Chemistry.