Light Against Light

Experiments were based on mouse cell culture (fibroblasts). Irradiation by ultraviolet with wave-length of 365 nanometers in the 1.8 joule per cubic centimeter dose suppressed their division. As a source of the vermeil red light, the researchers did not use laser but applied a matrix with the Luxeon Star LEDs, their wave-length being 625 nanometers.

The influence of this irradiation on cells depends on the dose. When the dose makes 0.9 joule per cubic centimeter, the vermeil red light stimulated cell division, the irradiation effect remaining even 72 hours afterwards. The twofold and fourfold increased dose suppressed cell division. This effect is similar to the action that the helium-neon laser has on human cells: certain doses of it stimulate cell division, but further radiation intensity increase inhibits it.

Having determined the influence of each type of irradiation on mouse fibroplasts, the researchers set about studying their joint action. They chose the division suppressing dose of the vermeil red light. In case of consecutive irradiation by ultra-violet and vermeil red light or vice versa (first, by vermeil red light and then – by ultraviolet), cell division rate was lower than that in case of only ultra-violet irradiation and several times lower than that in the reference.

However, although simultaneous irradiation suppressed cell division, still it did so to a much lower extent than consecutive irradiation. This phenomenon means that under certain doses of ultra-violet and vermeil red light the latter protects cells from the negative ultra-violet action. It is well-known that the red light of 70 nanometer wave-length also possesses the same protective effect.

The researchers assume that the vermeil red light activates respiratory enzyme – terminal cytochrome-c-oxidase, which increases concentration of active forms of oxygen, and this increase, for its part, stimulates cell division. Nevertheless, cell division stimulation occurs in a very narrow dosage range. The researchers also emphasize that they did not use a low intensity radiation laser as a source of visible light, but applies ordinary LEDs which also have a rather narrow emission band but they are more affordable and economical.

The effect described by the Puschino researchers explains the effective action of light-converting materials, which transform part of the ultra-violet radiation into additional light in the 580 to 750-nanometer range. These materials are now starting to be applied in medicine. The sunlight cures patients with trophic ulcers, cutaneous wounds and burns. It contains the ulter-violet component, which, passing through the light-converting film, accelerates injured skin regeneration.