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Cell growth modulation of human cells
irradiated in vitro with low-level laser therapy.
Photomedicine and laser surgery; VOL: 22 (6);
p. 523-6 /200412/
Dipartimento di Biologia, Università degli Studi di
Padova, Padova, Italy.
OBJECTIVE: The aim of this study was to investigate
the effects of different wavelengths and doses of
laser radiation on in vitro cell proliferation. We
evaluated the biological effects of low-level laser
therapy (LLLT) on two human cancer cell lines: HeLa
(epithelial adenocarcinoma) and TK6 (lymphoblast).
Our attention was focused on the combination of the
two laser emissions as it could have a synergic
effect greater than the single emission applied
separately. BACKGROUND DATA: The effects of LLLT on
human cells are still poorly understood and
unexplained. Several cell types were found non
responsive to laser bio stimulation; in other cases,
only a partial activation was observed. METHODS: A
laser device was used for cell irradiation with a
continuous wave diode (lambda = 808 nm), a pulsed
wave diode (lambda = 905 nm), and a combined wave
diodes (lambda = 808 nm + 905 nm), in the dose range
of 1-60 J/cm(2). RESULTS: The effect of the combined
low-level 808-905-nm diode laser irradiation were
slightly superior to those achieved with either
laser alone in HeLa cells. TK6 cellular
proliferation was not found to be significantly
affected by any of the energy levels and varying
exposure doses investigated.
CONCLUSIONS: Our results are a confirmation of
previous observations carried out on human cells,
where only the proliferation of slowly growing cell
populations appeared to be stimulated by laser
light.
Does LLLT stimulate laryngeal
carcinoma cells?
An in vitro study.
Brazilian dental journal; VOL: 13 (2); p. 109-12 /2002/
Faculty of Dentistry, Federal University of Bahia,
Salvador, BA, Brazil. albp@ufba.br
Low level laser therapy (LLLT) has been used
successfully in biomedicine and some of the results
are thought to be related to cell proliferation. The
effects of LLLT on cell proliferation is debatable
because studies have found both an increase and a
decrease in proliferation of cell cultures. Cell
culture is an excellent method to assess both
effects and dose of treatment.
The aim of this study was to assess the effect of
635nm and 670 nm laser irradiation of H.Ep.2 cells
in vitro using MTT
(3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium
bromide). The cells were obtained from squamous cell
carcinoma (SCC) of the larynx and were routinely
processed from defrost to the experimental
condition. Twenty-four hours after transplantation
the cells were irradiated with doses ranging from
0.04 to 0.48J/cm2 for seven consecutive days (5 mW
diode lasers: 635nm or 670 nm, beam cross-section
approximately 1 mm) at local light doses between
0.04 and 0.48 J/cm2.
The results showed that 635nm laser light did not
significantly stimulate the proliferation of H.Ep.2
cells at doses of 0.04 J/cm2 to 0.48 J/cm2,
However, 670nm laser irradiation led to an increased
cell proliferation when compared to both control and
635nm irradiated cells.
The best cell proliferation was found with 670nm
laser irradiated cultures exposed to doses of doses
of 0.04 to 0.48 J/cm2. We conclude that both dose
and wavelength are factors that may affect cell
proliferation of H.Ep.2 cells.
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