Posted on September 24th, 2012 by
The University of New Mexico Cancer Center will receive its new flow cytometer in a matter of weeks, making available cancer research techniques that weren’t feasible just five years ago. The technology allows researchers to analyze and sort very large numbers of cells quickly, a process that previously was cumbersome and time- consuming. The new tool will have advanced safety features as well.
“The new instrument will allow us to look quantitatively at 16 features of each cell as it goes through the flow cytometer interrogation point—at a rate of fifty to seventy thousand cells per second,” says Bruce Edwards, PhD, UNM Research Professor, Department of Pathology. The new tool, encased in a biosafety cabinet to protect the operator, will also be able to sort the cells as it analyzes them thus making certain kinds of research—like cancer stem cell investigations— possible. Researchers will even be able to operate the instrument remotely.
Researchers have used flow cytometry for years. It works by flowing a stream of cells in solution through a laser beam. Because the cells pass individually through the laser light and because the laser light is monochromatic, coherent and directional, the detectors can precisely measure the directional light scattering intensity patterns each cell causes. The laser light can also excite fluorescent molecules used to label the cells. Cells with different characteristics cause different fluorescent and light scatter intensity patterns.
The new flow cytometer will have five lasers and 16 detectors. For each laser, Dr. Edwards can use biological probes in up to six different fluorescent colors, so he’ll be able to discern a great number of features for each cell. For certain research questions, though, even this capability isn’t enough.
“The distinguishing feature of this particular flow cytometry technology is that during inspection we can program the computer to recognize a particular cell subset that has characteristics based on those 16 parameters and to isolate that subset into a separate tube or well,” says Dr. Edwards. Inspired by ink jet technology, the cell-sorter on the new flow cytometer can separate cells into as many as five different groups. It works by charging the solution stream containing the cells and then vibrating the stream rapidly so that a tiny droplet containing a single cell breaks off. Each droplet retains the charge the stream had at the time of its separation. The cell-sorter then deflects each charged droplet into the appropriate vessel. “We calibrate the tool so we know where the cell will be in the stream,” says Dr. Edwards. That way, the cell-sorter applies the correct charge to the stream just before the cell’s droplet breaks off. At seventy thousand cells per second, though, Dr. Edwards says, “it’s a real timing challenge.”
An additional challenge is protecting the people who use the tool. “In doing these sorting experiments, you’re creating aerosols,” says Dr. Edwards. Especially in experiments with cancer or pathogens, it’s important to keep the experimenter away from such hazards. “This particular set-up is integrated into a very sophisticated biosafety cabinet,” Dr. Edwards says. “It also protects the cells from contamination. It serves both purposes.” Additionally, the tool features multiple cameras and an advanced interface allowing an experimenter to stay even safer by operating it remotely.
These safety, speed and sorting capabilities enable researchers to investigate questions they couldn’t examine previously. One example is the cancer stem cell theory. Stem cells can become virtually any cell in the body but cancer stem cells, as the theory explains, enable cancer tumors to keep coming back. “So, you may kill a lot of the other cancer cells but these cancer stem cells are isolated in the body. Ultimately, they regenerate the cancer,” says Dr. Edwards. He adds, “stem cells represent a very small fraction of total cells. To identify cancer stem cells, where they hide, how they operate, we need to be able to purify them. That’s where this technology can help us.”
At incredibly high speeds, the new flow cytometer will be able to isolate cells that represent only a tenth of a percent of the total population in a reasonable amount of time. Previously, getting enough cells on which to do a statistically valid evaluation was nearly impossible. Now, researchers will be able to find and study, among other things, cancer stem cells. As Dr. Edwards says, “we’ll be able to do experiments on cells that represent extremely small fractions of the cell population. That’s the critical thing.”
About the UNM Cancer Center
The UNM Cancer Center is the Official Cancer Center of New Mexico and the only National Cancer Institute (NCI)-designated cancer center in the state. One of just 67 NCI-designated cancer centers nationwide, the UNM Cancer Center is recognized for its scientific excellence, contributions to cancer research and delivery of medical advances to patients and their families. It is home to New Mexico’s largest team of board-certified oncology physicians and research scientists, representing every cancer specialty and hailing from prestigious institutions such as MD Anderson, Johns Hopkins and the Mayo Clinic. The UNM Cancer Center treats more than 65 percent of the adults and virtually all of the children in New Mexico affected by cancer, from every county in the state. In 2010, it provided care to more than 15,800 cancer patients. The Center’s research programs are supported by nearly $60 million annually in federal and private funding. Learn more at http://cancer.unm.edu.
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