Lab-on-a-chip device could combat cancer

Scientists at the University of Kansas (UOK), US have made a breakthrough in the detection and testing possibilities of nanoscale biomarkers known as exosomes.

Exosomes are relatively ambiguous microvesicles ranging from 30-150nm in size and are released from most, if not all, cell types, including cancer cells, scientists claim.

Yong Zeng, assistant professor of chemistry at the University of Kansas, said: “First described in the mid-’80s, they were once thought to be ’cell dust,’ or trash bags containing unwanted cellular contents. However, in the past decade scientists realised that exosomes play important roles in many biological functions through capsuling and delivering molecular messages in the form of nucleic acids and proteins from the donor cells to affect the functions of nearby or distant cells.

“Our blood-based test is minimally invasive, inexpensive, and more sensitive, thus suitable for large population screening to detect early-stage tumours

UOK professor Yong Zeng

“In other words, this forms a crucial pathway in which cells talk to others.”

According to Zeng, there are currently very few technologies that are suitable for efficient isolation and sensitive molecular profiling of exosomes.

Fortunately, Zeng and his colleagues at UOK claim to have invented a miniaturised biomedical testing device for exosomes.

The researchers say their ’lab-on-a-chip’ device will offer faster result times, reduced costs, minimal sample demands and better sensitivity of analysis when compared to the conventional bench-top instruments now used to examine nanoscale biomarkers.

“A lab-on-a-chip shrinks the pipettes, test tubes and analysis instruments of a modern chemistry lab onto a microchip-sized wafer,” Zeng said.

In its research, the UOK team has developed the lab-on-a-chip technology to help advance lung cancer diagnosis, suggesting it could be used to detect cancer earlier using only a small drop of a patient’s blood.

“Diagnosis of lung cancer requires removing a piece of tissue from the lung for molecular examination. Tumour biopsy is often impossible for early cancer diagnosis as the developing tumour is too small to see by the current imaging tools,” Zeng said.

“In contrast, our blood-based test is minimally invasive, inexpensive, and more sensitive, thus suitable for large population screening to detect early-stage tumours.”

To create its prototype, the UOK team used silicone rubber called polydimethylsiloxane alongside a technique called ’on-chip immunoisolation’.

“We used magnetic beads of three micrometres in diameter to pull down the exosomes in plasma samples,” Zeng said.

“In order to avoid other interfering species present in plasma, the bead surface was chemically modified with an antibody that recognises and binds with a specific target protein - for example, a protein receptor - present on the exosome membrane. The plasma containing magnetic beads then flows through the microchannels on the diagnostic chip in which the beads can be readily collected using a magnet to extract circulating exosomes from the plasma.”

In perfecting this technology, Zeng said it could be used to detect a range of potentially deadly forms of cancer.