Cell attachment to extracellular matrices is modulated by pulsed radiation at 820 nm and chemicals that modify the activity of enzymes in the plasma membrane.

BACKGROUND AND OBJECTIVES: Adhesive interactions between cells and extracellular matrices play a regulative role in wound repair processes. The objective of this investigation is to study action mechanisms of pulsed radiation at 820 nm on cellular adhesion in vitro. Light emitting diodes (LED) at 820 nm are widely used for treatment of wounds of various etiology. STUDY DESIGN/MATERIALS AND METHODS: The LED (820 +/- 10 nm, 10 Hz, 16-120 J/m(2)) is used for the irradiation of HeLa cell suspension. In parallel experiments, amiloride (5 x 10(-4) M), ouabain (7 x 10(-5) M, 7 x 10(-4) M), quinacrine (6 x 10(-4) M), arachidonic acid (1 x 10(-5) M), glucose (2 x 10(-4) M), and ATP (5 x 10(-5) M) are added to the cell suspension before or after the irradiation procedure. The cell-glass adhesion is studied using the adhesion assay technique described in Lasers Surg Med 1996; 18:171. RESULTS: Cell-glass adhesion increases in a dose-dependent manner following the irradiation. Preirradiation eliminates the inhibition of cell attachment caused by ouabain, arachidonic acid, and ATP. The inhibitive effect of quinacrine on the cell attachment is eliminated by the irradiation performed after the treatment with the chemical. Irradiation and amiloride have a synergetic stimulative effect on the cell attachment. The threshold dose for the cell attachment stimulation by the irradiation is decreased by the treatment of the cell suspension with amiloride or ouabain. CONCLUSIONS: The results obtained indicate that pulsed IR radiation at 820 nm increases the cell-matrix attachment. It is the modulation of the monovalent ion fluxes through the plasma membrane and not the release of arachidonic acid that is involved in the cellular signaling pathways activated by irradiation at 820 nm. Preirradiation has a protective effect against the inhibitive action of ouabain, arachidonic acid, ATP, and quinacrine on cell attachment process. It is supposed that irradiation activates those signaling pathways in cells which attenuate the inhibitive action of these chemicals.

Donors of NO and pulsed radiation at lambda = 820 nm exert effects on cell attachment to extracellular matrices.

The adhesion of HeLa cells to a glass matrix was evaluated after the irradiation of the cell suspension with a pulsed near-infrared light-emitting diode (lambda = 820 nm, frequency 10 Hz, dose 8-120 J/m(2)) and treatment with two donors of nitric oxide, sodium nitroprusside (SNP, 5 x 10(-4) M) and NaNO(2) (4 x 10(-4) M). It was found that in an irradiated cell suspension, the cell-glass adhesion increases in a dose-dependent manner (a bell-shaped curve with a maximum at 60 J/m(2)). The treatment of cells with SNP or NaNO(2) before the irradiation eliminates the radiation-induced attachment stimulation. Pretreatment of cells with SNP not only eliminates the radiation-induced attachment stimulation but inhibits the attachment of irradiated (but not non-irradiated) cells. It is suggested that a modulation of the activity of respiratory chain (probably the alteration of the activity of cytochrome c oxidase) is involved in radiation-induced increase of cell attachment.

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

BACKGROUND AND OBJECTIVE: Adhesive interactions between cells and extracellular matrices play a regulative role in wound repair processes. The objective of this investigation is to study the mechanisms of light action on cellular adhesion in vitro. The adhesion of HeLa cells to a glass matrix is evaluated after irradiation with a pulsed near-infrared (IR) diode and treatment with various chemicals. STUDY DESIGN/MATERIALS AND METHODS: A semiconductor diode (820 +/- 10 nm, 10Hz, 16--120 J/m(2)) is used for irradiation of the cell suspension. In parallel 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 before or after the irradiation procedure. The cell-glass adhesion is studied 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-dependent manner after irradiation. The treatment of the cells with antioxidants (free radical scavengers), e.g., mannitol, melatonin, ethanol, and ascorbic acid, as well as with the ionophore DNP, eliminated the light effect. The respiratory chain inhibitors rotenone and azide strongly modified the light effect, depending on the dose. The oxidative agents hydrogen peroxide (in a low concentration) and methylene blue increased the cell adhesion. Superoxide dismutase did not modify the light effect. The effect of the catalase (stimulative or suppressive) was dependent on its concentration and treatment sequence. Preirradiation was found to decrease (or normalize to the control level) the suppressive effects of some chemicals. CONCLUSION: The results obtained are evidence that first, pulsed IR radiation with certain parameters modulates the cell-matrix attachment. second, free radical and redox processes are involved in the cell-matrix interaction, probably at some stage(s) of the photosignal transduction. Third, both types 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.

Nonmonotonic behavior of the dose dependence of the radiation effect on cells in vitro exposed to pulsed laser radiation at lambda = 820 nm.

BACKGROUND AND OBJECTIVE: In recent years, clinical low-intensity laser therapy practice has used pulsed radiation, mainly from semiconductor lasers. Experimental works devoted to the study of relationships between biological and clinical effects and parameters of pulsed radiation are practically absent. STUDY DESIGN/MATERIALS AND METHODS: The radiation source was a laser diode emitting at 820 nm (292 and 700 Hz, duty factor 80%; doses from 7 J/m2 to 5 x 10(5) J/m2; intensities 4, 12, 51, 152, 633, and 1,900 W/m2; irradiation time from 1 to 30 s). Four biological models were used: nucleated cells of murine spleen (splenocytes) and bone marrow (karyocytes), murine blood, and HeLa cells cultivated in vitro. The intensity of luminol-amplified chemiluminescence (in case of murine models) and the adhesion of HeLa cell membranes were measured as a function of the irradiation dose. RESULTS: Within the wide exposure dose range used we obtained seven maxima in the dose vs. biological effect curves: at fluences near 20, 1 x 10(2), 3 x 10(2), 8 x 10(2), 3 x 10(3), 1 x 10(4), and 3 x 10(4) J/m2. The peaks coincided for all four models. CONCLUSION: The dose curves obtained with different cellular systems are of the same type and are characterized by seven peaks in the dose interval studied (7 J/m2 to 5 x 10(5) J/m2).

Effects of monochromatic low-intensity light and laser irradiation on adhesion of HeLa cells in vitro.

BACKGROUND AND OBJECTIVE: The adhesion of HeLa cells was evaluated after irradiation with monochromatic low-intensity light or laser irradiation. It is well known that the cell-cell and cell-matrix adhesion changes during wound repair. For better understanding of low-power laser light action on the wound healing process, it would be of interest to study the light action on cellular adhesion in vitro. STUDY DESIGN/MATERIALS AND METHODS: The monochomatic light was in the range 580-860 nm (bandwidth 10 nm, 5-150 J/m2 1.3 W/m2) and the He-Ne laser irradiation was 632.8 nm (100 J/m2, 10 W/m2). Cell-cell and cell-glass adhesion were evaluated after irradiation of HeLa cells. RESULTS: It was found that cell-cell and cell-glass adhesion increased following irradiation depending on the irradiation conditions (wavelength, dose) and the time elapsed after the irradiation. The cell attachment to glass surface increased after irradiation of samples of HeLa cells in suspension. CONCLUSION: The adhesion was stimulated in the wavelength ranges 600-625, 645-700, and 720-850 nm with maxima at 620, 680, 750, and 820-830 nm, respectively.