Diagnosing deadly cancers earlier with 'lab-on-a-chip'

Date: Oct-08-2014 At present, diagnosis of lung cancer relies

on an invasive biopsy that is only effective after tumors are bigger than 3 cm or even

metastatic. Earlier detection would vastly improve patients' chances of survival. Now a team of

researchers is developing a "lab-on-a-chip" that promises to detect lung cancer - and possibly

other deadly cancers - much earlier, using only a small drop of a patient's blood.

The blood-based test is minimally invasive, inexpensive and "offers a general platform for detecting exosomes from cancer cells."

In the Royal Society of Chemistry journal, Yong Zeng, assistant professor of

chemistry at the University of Kansas, and colleagues report a breakthrough study describing

their invention.

For some time, scientists have been excited by the idea of testing for disease biomarkers in

"exosomes" - tiny vesicles or bags of molecules that cells, including cancer cells - release now

and again. When they first spotted them, researchers thought exosomes were just for getting rid

of cell waste, but now they know they also do other important things such as carry messages to

other cells near and far.

The challenge, however, is developing a technology that is small enough to target and

analyze the contents of exosomes - mostly nucleic acids and proteins - to find unique

biomarkers of disease. This is because exosomes are tiny - around 30 to 150 nanometers (nm) in

diameter - much smaller, for example, than red blood cells.

Current methods for separating out and testing exosomes require several steps of

ultracentrifugation - a lengthy and inefficient lab procedure, as Prof. Zeng

explains:

"There aren't many technologies out there that are suitable for efficient isolation and

sensitive molecular profiling of exosomes. First, current exosome isolation protocols are

time-consuming and difficult to standardize. Second, conventional downstream analyses on

collected exosomes are slow and require large samples, which is a key setback in clinical

development of exosomal biomarkers."

Now, using microfluid technology, he and his colleagues have developed a lab-on-a-chip that

can analyze the contents of targeted exosomes and spot the early signs of deadly cancer. They

have already successfully tested it on lung cancer.

Lab-on-a-chip device uses smaller samples, is faster, cheaper and more sensitive

The new device, which uses much smaller samples, promises to produce results faster, more

cheaply, with better sensitivity compared to conventional benchtop instruments, as Prof. Zeng

continues to explain:

"A lab-on-a-chip shrinks the pipettes, test tubes and analysis instruments of a modern

chemistry lab onto a microchip-sized wafer."

The technology behind the device - known as microfluidics - came out of new semiconductor

electronics and has been under intensive development since the 1990s, he adds:

"Essentially, it allows precise manipulation of minuscule fluid volumes down to one

trillionth of a liter or less to carry out multiple laboratory functions, such as sample

purification, running of chemical and biological reactions, and analytical measurement."

Unlike breast and colon cancer, there is no widely accepted screening tool for lung cancer,

which in most cases is first diagnosed based on symptoms that normally indicate lung function is

already impaired.

To diagnose lung cancer, doctors have to perform a biopsy - remove a piece of tissue from the

lung and send it to a lab for molecular analysis. It is rarely possible to do this in the early

stages as tumors are too small to be spotted on scans.

"In contrast, our blood-based test is minimally invasive, inexpensive, and more sensitive,

thus suitable for large population screening to detect early-stage tumors," says Prof. Zeng,

adding that the technique offers a general platform for detecting exosomes from cancer cells. The team

has already used the device to test for ovarian cancer, and in theory, says Prof. Zeng, it

should also be applicable to other cancer types.

"Our long-term goal is to translate this technology into clinical investigation of the

pathological implication of exosomes in tumor development. Such knowledge would help develop

better predictive biomarkers and more efficient targeted therapy to improve the clinical

outcome," he adds.

The team has received further funding from the National Cancer Institute at the National

Institutes of Health to further develop the lab-on-a-chip.

In March 2013, Medical News Today learned how another team of scientists is

developing a lab-on-a-chip that is implanted under the skin

to track levels of substances in the blood and transmit the results wirelessly to a smartphone

or other receiving device.

Written by Catharine Paddock PhD

Not to be reproduced without permission.

Courtesy: Medical News Today Note: Any medical information available in this news section is not intended as a substitute for informed medical advice and you should not take any action before consulting with a health care professional.