Light Intensity Effect in Fibroblasts Proliferation

Abstract

There has been much interest in the biological effects of low energy laser irradiation. Most of the experiments show that low energy lasers do have specific bioeffects which seem to change from stimulatory to damaging with increasing doses. In a recent paper⁽¹⁾ we irradiated fibroblasts with various lasers and found that at specific, relatively low energy dose there was acceleration of mitosis, while at higher doses the cells were destroyed. We then suggested^(1,2) that the effect of low energy laser irradiation in the visible and in the near infrared region was due to light absorption by either endogeneous porphyrins in the mitochondria or by cytochromes. As the effect does not seem to be unique to lasers or to coherent irradiation, we irradiated fibroblasts with non laser, non monochromatic light sources and found that accelerated cell mitosis does occur at certain wavelengths and at a specific energy dose of non coherent light. Moreover, we have found that the effect was not only dose dependent but also non-linearly intensity-dependent. These results have very important implications in phototherapy.