RESUMO
<p><b>OBJECTIVE</b>To investigate the killing effect of photodynamic therapy (PDT) mediated by hematoporphyrin derivative (HpD) on human colon carcinoma LoVo and CoLo205 cells in vitro.</p><p><b>METHODS</b>LoVo and CoLo205 cells cultured in vitro were incubated in the presence of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 microg/ml HpD for 4 h and exposed to different light doses delivered using a semiconductor laser at 630 nm with the energy density of 2, 5, 10, and 20 J/cm(2). After further culture for 24 h, the survival rate of LoVo and CoLo205 cells were analyzed by MTT assay, and the cellular fluorescence intensities of HpD were measured with a luminescence spectrometer.</p><p><b>RESULTS</b>HpD-PDT resulted in effective cell killing to a comparable magnitude in LoVo and CoLo205 cells cultured in vitro (P>0.05). The killing effects were positively correlated with the concentration of HpD and the dosage of laser irradiation. Exposure to 20 J/cm(2) resulted in an IC(50) of LoVo and CoLo205 cells of 0.4 and 0.6 microg/ml respectively, which were not significantly different (P>0.05). The cellular HpD fluorescence intensities were also similar between the two cells.</p><p><b>CONCLUSION</b>HpD-PDT may effectively kill LoVo and CoLo205 cells cultured in vitro.</p>