A method previously developed for capturing and analyzing cancer cells that break away from patients'' tumors and circulate in the blood has been refined.
The device, which uses a Velcro-like nanoscale technology, can now detect and isolate single circulating tumor cells (CTCs) from patient blood samples which can provide doctors with critical information about the type of cancer a patient has, the characteristics of the individual cancer and the potential progression of the disease.
Scientists at the University of California (Los Angeles, CA, USA) developed a "NanoVelcro" chip. The device is based on polymer nanofiber-embedded microchips, which can detect, isolate, and perform molecular analysis of single circulating melanoma cells. When blood is passed through the chip, nanoscale wires or fibers coated with protein antibodies that match proteins on the surface of cancer cells, act like Velcro, trapping CTCs and isolating them for analysis. The CTCs trapped by the chip also act as a liquid biopsy of the tumor, providing convenient access to tumor cells and earlier information about potentially fatal metastases.
The investigators have improved the original NanoVelcro chip by replacing its previous nontransparent silicon nanowire substrate inside with a new type of transparent polymer nanofiber-deposited substrate, allowing the device''s nanowires an enhanced capture of cancer cells as blood passes by them. They were able to pick single CTCs immobilized on the new transparent substrate by using a miniaturized laser beam knife, a technique called laser micro-dissection, or LMD. The team was able to isolate and preserve single CMCs using the new assay on patients'' blood containing circulating melanoma cells.
The preservation of single captured CMCs in this proof-of-concept study also allowed the team to conduct single-cell genotyping to find within the cell a specific target, a mutation in the proto-oncogene B-Raf protein (BRAF V600E) that appears in approximately 60% of melanoma cases. Antoni Ribas, MD, PhD, a professor of medicine at the Jonsson Cancer Center (Los Angeles, CA, USA), said, "With this technology, we are getting closer to the goal of a widely clinically applicable liquid biopsy, where we can sample cancer cells by a simple blood draw and understand the genes that allow them to grow. With the NanoVelcro chips, we will be able to better personalize treatments to patients by giving the right treatment to stop what makes that particular cancer grow." The study was published on February 21, 2013, in the journalAngewandte Chemie International Edition.