SAN FRANCISCO, March 23 (Xinhua) -- A new study has taken a step forward to monitoring patients' response to cancer therapy by simply having their blood drawn and protein biomarkers measured.
The new probe starts with isolating cancer proteins in rare, individual tumor cells that float in the blood, and then using a microfluidic device to break the cells open and test the cellular contents for protein biomarkers, which are indicators of cancer.
In the study led by the University of California, Berkeley, researchers have isolated circulating tumor cells from the blood of breast cancer patients and used microscale physics to design a precision test for eight protein biomarkers while tring to expand the number of proteins identifiable with this technology.
"Tremendous advances have been made in DNA and RNA profiling in cells collected using a liquid biopsy. We extend those advances to highly selective measurement of proteins -- the 'molecular machines' of the cell," said Amy Herr, a UC Berkeley bioengineering professor. "We are working to create medicine that would allow a doctor to monitor a patient's treatment response through a blood draw, perhaps on a daily basis."
Circulating tumor cells are believed to be a potentially rich source of information about a person's cancer. These cells are thought to break off from the original tumor and circulate in the blood, and may be a sign of an aggressive tumor.
But studying these cells is difficult because the cells are rare, so few are collected even when enriched from the blood. The cells contain different proteins than the original tumor, so research is ongoing to unlock their secrets.
To better study these cells, the researchers collaborated with physician-scientists and industry engineers to develop a microfluidics system that separates these large cells into a concentrated sample.
A key advance made by the team headed by Herr was in devising a system to precisely handle and manipulate the concentrated cells from blood, according to a news release from UC Berkeley. The researchers then analyzed each circulating tumor cell for the specific panel of cancer proteins.
To be analyzed, each cell was place in a microwell with a diameter roughly half the width of a human hair. Once settled in the microwell, the circulating tumor cells were burst open and the proteins released from inside each cell were separated according to differences in size or mass.
The researchers were then able to identify cancer proteins by introducing fluorescent probes that bind to and light up a specific protein target. By sorting and probing the protein targets, the test is more selective than existing pathology tools.
Enhanced selectivity will be crucial in detecting subtle chemical modifications to biomarkers that can be important but difficult to measure, Herr was quoted as saying.
"Microfluidic design was key in this study. We were able to integrate features needed for each measurement stage into one process," she said. "Systems integration allowed us to do every single measurement step very, very quickly while the biomarkers are still concentrated. If not performed exceptionally fast, the cell's proteins diffuse away and become undetectable."
The study was published Thursday in the journal Nature Communications.