Microchip device detects small populations of cancerous cells

The device, developed by a research team at Brigham and Women’s Hospital, could find broad therapeutic and diagnostic uses in the detection and capture of rare cell types, such as foetal and cancer cells, plus viruses and bacteria.

A study describing the work has been published online in Proceedings of the National Academy of Sciences.

According to a statement, the microchip device uses a three-dimensional DNA network made up of long DNA strands with repetitive sequences that can detect, bind and capture certain molecules.

The researchers, led by Dr Jeffrey Karp of the BWH Division of Biomedical Engineering, Department of Medicine, at Brigham and Women’s Hospital, senior study author, and Prof Rohit Karnik of the Massachusetts Institute of Technology, co-author, created the chip using a microfluidic surface and methods that allowed them to rapidly replicate long DNA strands with multiple targeting sites that can bind to cancer cells, but also custom tailor critical characteristics such as DNA length and sequence, which would allow them to target various cell types.

In this study, Karp and his team are said to have tested the chip using a DNA sequence that had a specific affinity to a cell-surface protein found abundantly in human cancer cells.

The researchers engineered the device to efficiently capture a higher quantity of cancer cells from whole-blood patient samples at much higher flow rates compared with other methods that use shorter DNA strands or antibodies.

‘The chip we have developed is highly sensitive. From just a tiny amount of blood, the chip can detect and capture the small population of cancer cells responsible for cancer relapse,’ said Dr Weian Zhao, a postdoctoral fellow from the Karp lab who is now faculty at the University of California, Irvine, and first study author.

The device could also be utilised to isolate cells that break away from solid tumours and travel through the bloodstream.

‘What most people don’t realise is that it is the metastasis that kills, not the primary tumour,’ said Karp. ‘Our device has the potential to catch these cells in the act with its “tentacles” before they may seed a new tumour in a distant organ.’

Moreover, unlike other methods, the device was able to maintain a high purity of the captured cells that could easily be released and cultured in the laboratory.

‘One of the greatest challenges in the treatment of cancer patients is to know which drug to prescribe,’ said Karp. ‘By isolating circulating tumour cells before and after the first round of chemotherapy is given, we can determine the biology behind why certain cells are resistant to chemotherapy. We can also use the isolated cells to screen drugs for personalised treatments that could boost effectiveness and hopefully prevent cancer relapse.’