Scientists have devised a way of testing urine for markers of disease that could reduce the need for
blood samples.
Their new way of purifying proteins in urine samples could reduce the need to draw blood for tests, the researchers say.
The new test promises to be faster and cheaper than current urine tests, say researchers from Clemson
University in South Carolina, who write about it in the journal Proteomics –
Clinical Applications.
Protein byproducts of diseases and drugs can end up in trace amounts in urine. For instance, they can reveal
early signs of heart disease, whether a person has sleeping sickness, and even whether a transplant recipient’s
body is rejecting their new kidney.
Currently, it is not easy to find these proteins because of the high amount of salt in urine, as senior
author Kenneth Marcus, a professor of analytical chemistry, explains:
“You’ve got almost seawater coming out of you, and I’m trying to find something far smaller than a
needle in a haystack. The concentrations of these proteins would be one part in a billion.”
At the heart of the new test is a material called “capillary-channeled polymer fiber” or C-CP fiber that
helps to extract the proteins in an efficient way prior to screening.
The proteins stick to the fibers when the salt is washed away
In their study paper, the team describes how they packed the C-CP fibers into plastic tubes and then passed
urine samples through them in a centrifuge spinning for 30 seconds.
They then rinsed the tubes with de-ionized water to wash off the salt and other contaminants. Because the
proteins do not dissolve in water, they remain stuck to the fibers.
The researchers then ran a solvent through the tubes in a centrifuge for 30 seconds to extract the purified
proteins from the C-CP fibers.
At the end of the process, the purified proteins can then be stored in plastic vials and kept cold until it
is time for them to be analyzed with a mass spectrometer.
The researchers were able to extract 12 samples in around 5 minutes. It would be possible to extract more
samples in that time with more centrifuge capacity, they say.
Fiber method is ‘smaller, faster, cheaper’ than using polymer beads
Current methods of purifying the proteins prior to mass spectrometer screening uses polymer beads. But Prof.
Marcus says the use of C-CP fibers, makes their method “smaller, faster and cheaper.”
In a review of the study, Youhe Gao, a professor in biochemistry and molecular biology at Beijing Normal
University, says the findings’ implications may go further than the researchers are anticipating, “simply because urine is more important than most
biomarker researchers realize.”
He explains that urine “accumulates all kinds of changes and should be a better biomarker source than
blood,” because various processes in the body limit changes in the blood. Also, urine is the easiest body fluid
to sample.
Prof. Markus says another advantage of their method is it would be easier to use urine samples from infants.
Current methods need large samples of urine, but theirs only uses a few microliters.
Meanwhile, Medical News Today recently reported how the discovery of a genetic biomarker may lead to
a blood test that predicts cancer years in advance.
Writing in the journal
EBioMedicine, researchers from Northwestern and Harvard Universities describe how they found blood
telomeres – the protective ends of DNA strands that stop them unraveling – age faster and then stop aging for a
few years in the period leading up to a cancer diagnosis.