RESUMEN
<p><b>OBJECTIVE</b>To explore the inhibitory effect of He-Ne laser irradiation on fibroblast growth of hypertrophic scars in culture.</p><p><b>METHODS</b>He-Ne laser with wavelength of 632.8 nm, power density of 50 mW/cm(2) and doses of 3 J/cm(2), 30 J/cm(2), 90 J/cm(2) and 180 J/cm(2) was used to irradiate human scar fibroblasts in culture 1, 3 and 5 times respectively, and then the cell count and cell cycle analysis were done.</p><p><b>RESULTS</b>Repeated irradiation with He-Ne laser at dose of 180 J/cm(2) three and five times led to an evident decrease in total cell number compared with that of the control group and there was a significant difference (P<0.05). The cell cycle analysis showed after three and five times of irradiation with 180 J/cm(2) He-Ne laser the cell number in S-phase decreased from 51% to 20% and 14% respectively, the cell number in G(0)/G(1) phase increased from 28% to 55% and 60% respectively, and the cell percentage in Sub-G1 phase was 6.7% and 9.8% respectively.</p><p><b>CONCLUSIONS</b>Repeated irradiation with 180 J/cm(2) He-Ne laser can inhibit scar fibroblasts growth in culture. It may be that He-Ne laser irradiation causes cell stagnation in G(0)/G(1) phase and apoptosis.</p>