The lowly jellyfish, a gelatinous, free-swimming Cnidarian, is an unlikely source of scientific inspiration. Yet, in an article published in this week’s issue of Proceedings of the National Academy of Science, researchers from Harvard, MIT, and the Xi’an Jiaotong University of China reported an innovative method, inspired by jellyfish tentacles, of isolating and removing tumor cells from blood samples.
This novel technology has the potential to transform cancer diagnostis by facilitating efficient retrieval and analysis of cancer cells from the bloodstream. The study developed microfluidic devices coated in a network of dangling DNA aptamers, or stable strands of synthetic DNA, that can identify and capture particles and cells. Like the tentacles of a jellyfish, which extend into water surrounding the animal to capture food particles, the protruding DNA aptamers were designed to extend into blood samples and bind to a surface protein called tyrosine kinase-7 (PTK-7). Because PTK-7 is overexpressed in cancer cells, this allows DNA aptamers to target them.
DNA aptamer-based capture devices have several advantages over prior cell adhesion technologies. While previous methods involved complicated processes like flow cytometric cell sorting, using the jellyfish-inspired DNA networks is a simple two-step procedure. Furthermore, the restriction enzymes used to separate the cancer cells from the aptamers do not damage the tumor cells; other cell capture techniques often bind to the intended target with high specificity but the extraction of the particles damages the specimen, thus hindering further analysis. The stability of the aptamers also allows for longer DNA tentacles that can withstand blood flowing through the microfluidic channels at high velocities; longer DNA chains and faster blood flow through the channels increase the frequency of DNA-cancer cell interactions and improve the capture rate.
In addition to possibilities in diagnosing cancer, cellular capture devices using DNA aptamers have the potential to improve drug discovery and monitoring therapy for a wide range of illnesses. The targets of the devices can be altered by modifying the DNA aptamers, and they even can be engineered to bind to specific bacteria or viruses present in a peripheral blood sample. Furthermore, these DNA networks can be exploited to isolate and preserve rare cell types, such as CD4 T cells and stem cells, for analysis in research laboratories.