MicroRNA hails simple cancer blood test
21 Oct 2011 by Evoluted New Media
Genetic snippets known as microRNA often go haywire in cancer cells and contribute to a tumour’s uncontrollable growth, and they could be the key to a simple blood test to diagnose the disease.
A team from MIT has engineered a way to detect abnormal microRNA levels in the blood of cancer patients, with each type of cancer having its own microRNA signature.
“While measuring microRNA levels has clear potential benefits, there are many challenges to detecting microRNA,” said researcher leader Patrick Doyle, a professor of chemical engineering. “There’s not an accepted gold standard. Everybody has their own favourite one.”
The new technique consists of an array of tiny hydrogel particles each designed to latch onto a specific type of microRNA. By exposing a blood sample – or purified RNA – to these particles, researchers can generate a microRNA profile that reveals whether cancer is present.
Doyle’s previous research suggested that tiny hydrogel particles – about 200 micrometers in length –could rapidly detect microRNA dysregulation patterns in RNA taken from four individuals with four different types of cancer. The new research – published in Analytical Chemistry – successfully detected microRNA in the blood serum of a prostate cancer patient.
The water-loving particles are decorated with millions of identical strands of DNA that are complementary to a specific microRNA target sequence, and a fluorescent probe. When mixed with a blood sample, the microRNA binds to its complementary DNA, and fluoresces.
Using a custom-build microfluidic scanner, researchers were able to rapidly measure each particle’s fluorescence, revealing how much microRNA was present. The scanner also reads the chemical barcode imprinted on each particle, which reveals the type of microRNA being detected.
The researchers also improved the particles’ sensitivity by amplifying the fluorescence generated by each particle by attaching multiple DNA label sequences to each microRNA target.
The approach is 100 times more sensitive than other particle technologies for detecting microRNA, and can detect as few as 10,000 copies of a particular microRNA.
Doyle is now working with medical researchers to investigate microRNA detection as a means of studying other diseases such as cardiovascular disease and HIV.
