How Scientists Develop New Laser For Destroying Cancer Cells
Cancer cells can spread to other parts of the body through the blood. But this do not mean that Cancer sickness can be “catch” through sex. This is because a healthy immune system immediately identifies cancerous cells and gets rid of them before they can grow and spread.
In previous study, researchers could successfully programmed nanorobots to find tumors and cut off their blood supply while leaving healthy tissue unharmed.
The researchers in this study used a mouse tumor model. Human breast, melanoma, ovarian, and lung cancer cells were injected into mice to spur tumor growth. Once the tumors grew, the nanorobots were injected into the mice.
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The nanorobots were made from flat, rectangular DNA origami sheets 90 nanometers by 60 nanometers. They were outfitted with an enzyme called thrombin, which helps blood to clot. The nanorobots traveled the bloodstream carrying a DNA aptamer. The DNA aptamers targeted a protein called nucleolin, high amounts of which are found only on the surface of tumor endothelial cells. This particular protein is not found on the surface of healthy cells.
After locating and binding to the tumor blood vessel surface, the nanorobots opened up and delivered the thrombin. This caused clotting in blood vessels that feed tumor growth, cutting off the blood supply and killing tumor tissue.
But according to the now, researchers have developed a new kind of laser that can find and zap those tumor cells from the outside of the skin.
Though it may still be a ways away from becoming a commercial diagnostic tool, the laser is up to 1,000 times more sensitive than current methods used to detect tumor cells in blood, the researchers reported June 12 in the journal Science Translational Medicine.
To test for cancer spread, doctors typically take blood samples, but often the tests fail to find tumor cells even if they are present in a single sample, especially if the patient has an early form of cancer, said senior author Vladimir Zharov, director of the nanomedicine center at the University of Arkansas for Medical Sciences.
If the tests do come back positive, that typically means there’s a high concentration of circulating tumor cells in the blood; at that point, the cancer has likely spread widely to other organs and it’s often “too late to effectively treat patients,” Zharov added.
Years ago, Zharov and his team came up with the idea of an alternate, noninvasive method to test larger quantities of blood with a greater sensitivity. Taking the familiar route, they tested it in the lab, then on animals and recently brought it to clinical trials in humans.
The new technology, dubbed the Cytophone, uses pulses of laser light on the outside of the skin to heat up cells in the blood. But the laser only heats up melanoma cells — not healthy cells — because these cells carry a dark pigment called melanin, which absorbs the light. The Cytophone then uses an ultrasound technique to detect the teensy, tiny waves emitted by this heating effect.
Killing Tumor Cells
The device didn’t return any false positives on the healthy volunteers, and it didn’t cause safety concerns or side effects, they said. Melanin is a pigment that is normally present in the skin, but skin cells aren’t harmed, Zharov said. Even though the skin produces melanin naturally, this laser technique doesn’t harm those cells. That’s because the laser light exposes a relatively a large area on the skin (so it’s not focused enough on individual skin cells to damage them), while the laser energy is more concentrated on the blood vessels and circulating tumor cells, he added.
Unexpectedly, the team also found that after the treatment, the cancer patients had fewer circulating tumor cells. “We used a relatively low energy” with the primary purpose of diagnosing rather than treating the cancer, Zharov said. Yet, even at that low energy, the laser beam seemed able to destroy the cancer cells.
According to Zharov, “Our goal is by killing these cells, we can help prevent the spreading of metastatic cancer.” But he hopes to conduct more research to optimize the device further to kill more tumor cells, while still being harmless to other cells.
They also haven’t yet tested the device on people with darker skin, who have higher levels of melanin. Even so, only a very small percentage of African Americans get melanoma.