New 'Liquid Biopsy' Chip Can Detect Metastatic Cancer With a Drop of Blood

Engineers from the Worcester Polytechnic Institute (WPI) have developed a chip that uses just a drop of blood drawn from a cancer patient to "trap" and identify metastatic cancer cells.

However, perhaps the more surprising news is that they used a rather simple mechanical method in the breakthrough technology.

According to Science News Journal, the new technology has been demonstrated to be more effective in trapping cancer cells than current devices that use a microfluidic approach to trap cancer cells.

The WPI study explains that the new device uses antibodies attached to an array of carbon nanotubes at the bottom of a small well. The cancer cells settle to the bottom of the well and bind to the antibodies selectively based on the surface markers. They then make tiny structures called exosomes, which the WPI traps.

This new "liquid biopsy" was described in the recent issue of Nanotechnology and could become the basis of a simple lab test that can used to detect early signs of metastasis quickly. This helps doctors target specific treatments based on the identified cells.

It can be remembered that cancer can spread from one organ to other parts of the body through the metastasis process. This is done by the cancer entering the bloodstream. Different types of cancer prefer to spread to specific organs and tissues.

For instance, circulating breast cancer cells are more likely to take root in lungs, bones or the brain. The prognosis for metastatic cancer is generally poor and a patient's survival odds would be increased if these circulating tumor cells can be detected before they can form new colonies of tumors at distant sites.

Balaji Panchapakesan, the associate professor of mechanical engineering at WPI and director of its Small Systems Laboratory, said that focusing on capturing circulating tumor cells is a relatively recent development.

He added that the challenge is that there's only a small number of tumor cells floating among billions of red blood cells and tens of thousands of white blood cells.

However, the team has demonstrated that the tumor cells can be captured with high precision.

Panchapakesan's team have developed a device that has small elements, each about 3-millimeters across. These antibodies are attached to carbon nanotubes at the bottom of a well on each element. These antibodies are placed in each well, with antibodies selectively binding to one type of cancer cell based on the genetic markers.

Placing these antibodies allow the device to set up to use a single blood sample to capture a lot of different cancer cells types. Their capture efficiency ranged from 62-to-100-percent.

These carbon nanotubes perform as semiconductors, where an electrical signal can be detected where a cancer cell binds to one of the attached antibodies. 

The signals are then used to identify which of these elements in the array have captured cancer cells.

The specific arrays are taken to the lab for analysis, and the cells are stained and identified under a microscope. 

Since the electrical signature generation process takes only a few minutes, it can be possible to identify the kind of cancer on the same day.