Pictured: A pen-size microscope could be used to detect dyed circulating tumor cells.
A tumor growing in the prostate gland, breast or any other organ can shed cancerous cells into the blood. These cancerous seeds travel the body and can take root nearly anywhere, growing into a new cancer threat even after the initial cancer is treated.
The rule of thumb with cancer is that the earlier you can detect the disease, the more effective the treatment and increased likelihood of better outcomes.
Currently, doctors draw a patient's blood and analyze it using special antibodies to detect the presence of the seeds, called circulating tumor cells. This works well if CTCs are present in large numbers, but may fail to detect smaller numbers released by earlier tumors.
Now, a team of engineers, scientists and doctors from Stanford is developing a mini-microscope that may be able to noninvasively detect the CTCs earlier than ever, allowing for earlier interventions.
IN focus: The clark center and bio-x
"There has been a huge push to increase sensitivity," said Bonnie King, PhD, an instructor in neonatal medicine. "We suspect that CTCs often circulate in numbers below our current threshold of detectability."
A major advantage with the microscopic technique, King said, is the ability to screen much larger volumes of blood, rather than just a small vial collected from a patient. This will be done using a method called in vivo flow cytometry - a laser-based technology for counting cells in a live subject.
Christopher Contag, PhD, professor of pediatrics and of microbiology and immunology, envisions that a doctor would inject a patient with a dye that will cause the CTCs to fluoresce. The doctor would then use the pen-size microscope to focus a low-power laser light on a blood vessel just a few hair-widths below the patient's skin.
As the dyed cancer cells pass through the laser, the light excites them and causes them to stand out from normal cells. The microscope registers each of these cells and a computer logs each observation. The improved sensitivity of the technology and the ability to noninvasively scan blood for long periods will help create a fuller picture of the number of CTCs in a person's body.
"At present we will not screen all of a person's blood [with the microscope], but we are aiming to increase the amount of blood screened compared to a 7-milliliter blood draw," Contag said.
The work is a collaborative effort of Olav Solgaard, PhD, professor of electrical engineering; Geoffrey Gurtner, MD, a professor of surgery; and Michael Clarke, MD, a professor of oncology. It began last fall, when the proposed project was awarded a seed grant by Stanford's Bio-X Interdisciplinary Initiatives Program.
To date, the blood-scan group has focused on developing the method in mice, taking advantage of the thin transparent tissue of the ear to image fluorescent cells traversing the small blood vessels below the skin.
Soon the researchers will move the microscope to a clinical setting to conduct a proof-of-principle test of the technique in humans. Gurtner is currently conducting a clinical trial to evaluate the Food and Drug Administration-approved green dye for defining skin vasculature during postmastectomy breast reconstruction surgeries. The researchers are piggybacking on this trial to test the miniature microscope's ability to detect blood vessels and circulating cells.
Bjorn Carey is a science writer for the Stanford News Service.
Stanford Medicine integrates research, medical education and patient care at its three institutions - Stanford University School of Medicine, Stanford Hospital & Clinics and Lucile Packard Children's Hospital. For more information, please visit the Office of Communication & Public Affairs site at http://mednews.stanford.edu/.
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