– THE NEW SCIENTIST, October 11-15, 2003
How laser light helps cells repair themselves CAN gentle doses of laser light help cells to heal? The technique is sometimes used to treat problems such as tinnitus and joint pain, but with no explanation for how these therapies work, there is scepticism over whether the effect is real. Now a physicist has come up with evidence that the physical forces generated by low-energy laser beams may switch on cells’ repair mechanisms.
This will support the growing body of evidence that laser therapy is beneficial. At the Joint International Laser Conference in Edinburgh, UK, last month, researchers reported promising results for fields as diverse as IVF and spinal injury. For example, rats with damaged spinal cords made a better recovery if their wound was illuminated with near-infrared laser light, reported Kimberly Byrnes of the Uniformed Services University of Health Sciences in Bethesda, Maryland.
Her team found that in light- treated rats, levels of interleukin-6, which is involved in inflammation, were only 1 per cent of the levels in a control group of rats. But Byrnes does not know how to explain the result. .’There are a million different theories,” she says.
One popular idea is that molecules within cells absorb the light, and the extra energy drives chemical reactions. Although this may be part of the answer, it does not explain why some studies have shown effects that are specific to laser light.
Anatoly Rubinov of the Stepanov Institute of Physics in Minsk, Belarus, is convinced that the unique properties of lasers offer an explanation. Unlike ordinary light, laser light is strongly ordered: its electromagnetic waves oscillate in step, with the peaks and troughs aligned. When a laser beam passes through a layer of cells, it splits into many components, which interfere with each other as they bounce about, creating a mottled pattern of light and dark regions.
To show the physical effect this might have on cells, Rubinov illuminated some cell-sized plastic beads with various interference patterns (Journal of Physics D: Applied Physics, vol 36, p 2317). The beads were moved around by the light, and became trapped in the bright regions. Rubinov says cells should be affected in the same way. It is well known that light can exert significant forces on small objects, but the effect of these forces in laser therapy has not been considered before.
Rubinov believes it is these forces that trigger a biological effect within the cells. When he exposed human white blood cells to uniform laser radiation, the number of cells that underwent apoptosis -a form of programmed death that eliminates mutated cells -increased with exposure time. When he used an interference pattern of the same laser light, the number of cells undergoing apoptosis also rose for a few minutes, but then dropped off sharply.
Rubinov concludes that while radiation itself can damage DNA, the forces exerted by the interference pattern trigger a repair mechanism within the cells. In another set of experiments, he showed that cells exposed to certain interference patterns showed fewer signs of DNA damage than those exposed to uniform radiation. “The gradient forces activate the repair system of the cell and increase the resistance of its genome to external factors and increase the resistance of its genome to external factors,” he says.
Harry Mosely, president of the British Medical Laser Association, says Rubinov’s work represents an important first step towards understanding the potential medical effects of lasers. “It is moving us on in our thinking, which is excellent,” he says.