A method previously developed for capturing and analyzing cancer cells that break away from a tumor and circulates in the blood has been refined. With improvements to the device, which uses a Velcrolike nanoscale technology, single cancer cells from patient blood samples can now be detected and analyzed.
Circulating tumor cells (CTCs) play a crucial role in cancer metastasis, spreading from tumors to other parts of the body, where they form new tumors. When these cells are isolated from the blood early on, they can provide oncologists with critical information about the type of cancer a patient has, the characteristics of the individual cancer and the potential progression of the disease. Clinicians can also tell from these cells how to tailor a personalized treatment to a specific patient.
In recent years, a NanoVelcro chip that traps and isolates CTCs when blood is passed through the chip was developed. The CTCs are trapped by extremely small hairlike structures, which are nanoscale wires or fibers coated with protein antibodies that match proteins on the surface of cancer cells. CTCs trapped by the chip act as a liquid biopsy of the tumor, providing convenient access to tumor cells and earlier information about potentially fatal metastases.
Histopathology is currently considered the gold standard for determining tumor status, but in the early stages of metastasis, identifying a biopsy site is often difficult. By being able to extract viable CTCs from the blood with the NanoVelcro chip, however, doctors can perform a detailed analysis of the type and the various genetic characteristics of a patient’s cancer.
The NanoVelcro chip has been improved by replacing its original nontransparent silicon nanowire substrate inside with a new type of transparent polymer nanofiber-deposited substrate, allowing the device’s nanowires to better grab cancer cells as blood passes by them. Hsian-Rong Tseng, PhD, of the University of California, Los Angeles, and his colleagues 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 (LMD). Their research was published in Angewandte Chemie (2013; doi:10.1002/ange.2010005853).
“This paper summarizes a major milestone in the continuous development of NanoVelcro assays pioneered by our research group,” Tseng said. “We now can not only capture cancer cells from blood with high efficiency but also hand-pick single CTCs for in-depth characterization to provide crucial information that helps doctors make better decisions.”
Using the new assay on patients’ blood containing circulating melanoma cells (CMCs), Tseng’s team was able to isolate and preserve single CMCs. The ability to capture and preserve single CMCs allows doctors to analyze melanoma cells’ DNA structure, determine the genetic characteristics of the patient’s cancer and confirm that the circulating cells remain genetically similar to the tumor they came from.