Cell attachment modulation by radiation from a pulsed light diode (lambda=820 nm) and various chemicals

Background and Objective: Adhesive interactions between cells and extracell ular matrices play a regulative role in wound repair processes. The objecti ve of this investigation is to study the mechanisms of light action on cell ular adhesion in vitro. The adhesion of HeLa cells to a glass matrix is eva luated after irradiation with a pulsed near-infrared (IR) diode and treatme nt with various chemicals. Study Design/Materials and Methods: A semiconductor diode (820 +/- 10 nm, 1 0Hz, 16-120 J/m(2)) is used for irradiation of the cell suspension. In para llel experiments, various chemicals (mannitol, melatonin, ethanol, ascorbic acid, superoxide dismutase, catalase, rotenone, azide, dinitrophenol (DNP) , methylene blue, and hydrogen peroxide) are added to the cell suspension b efore or after the irradiation procedure. The cell-glass adhesion is studie d by using the adhesion assay technique (Lasers Surg. Med. 1996;18:171), Results: It has been found that cell-glass adhesion increases in a dose-dep endent manner after irradiation. The treatment of the cells with antioxidan ts (free radical scavengers), e.g., mannitol, melatonin, ethanol, and ascor bic acid, as well as with the ionophore DNP, eliminated the light effect. T he respiratory chain inhibitors rotenone and azide strongly modified the li ght effect, depending on the dose. The oxidative agents hydrogen peroxide t in a low concentration) and methylene blue increased the cell adhesion. Sup eroxide dismutase did not modify the light effect. The effect of the catala se (stimulative or suppressive) was dependent on its concentration and trea tment sequence. Preirradiation was found to decrease (or normalize to the c ontrol level) the suppressive effects of some chemicals. Conclusion: The results obtained are evidence that first, pulsed IR radiati on with certain parameters modulates the cell-matrix attachment, second, fr ee radical and redox processes are involved in the cell-matrix interaction, probably at some stage(s) of the photosignal transduction. Third, both typ es of the primary reactions in the respiratory chain, namely, the increase of the electron flow and production of the reactive oxygen species, cause a transient oxidative stress in the cytoplasm. (C) 2001 Wiley-Liss, Inc.