nan Yoshiteru

Photodynamic Therapy Using a Diode Laser with Mono-l-aspartyl Chlorin e6 for Implanted Fibrosarcoma in Mice

We have developed a new high‐power red (664 nm) laser diode system for photodynamic therapy (PDT) with mono‐L‐aspartyl chlorin e6 (NPe6). Meth‐A fibrosarcoma cells (1X106) were implanted subcutaneously in the right hind leg of 4‐week‐old BALB/c female mice. One week later, diode laser irradiation was applied 5 h after the intravenous administration of NPe6 to each tumor‐bearing mouse. In the first study, the time course of intratumor temperature increase during PDT was measured by using a 23‐guage thermocouple hypodermic needle at a depth of 2 mm from the tumor surface. In the second study, 6 groups of 10 to 17 tumor‐bearing mice were treated with the diode laser 5 h after intravenous administration of NPe6 at the dose of 1.25, 2.5, 5.0 or 7.5 mg/kg i.v. per mouse. Total photoirradiation ranged from 0 to 150 J/cm2 and the dose rate was adjusted to 100 mW/cm2. Percentages of cures were determined from numbers of mice apparently disease‐free 50 days after treatment. The results showed that this diode laser is effective in PDT of implanted fibrosarcoma after NPe6 administration. It also confirmed that the therapeutic effects of PDT were not due to hyperthermia. Moreover, the diode laser beam was demonstrated by CCD technology to be uniform in intensity throughout the photoirradiated field.

Photodynamic therapy using a diode laser with mono-L-aspartyl chlorin e6 (NPe6)

The authors developed a new high-power red laser diode system (Matsushita Industrial Equipment Co., Ltd., Osaka) for photodynamic therapy (PDT) with mono-L-aspartyl chlorin e6 (NPe6, Meiji Seika Kaisha LTD.). The laser wavelength was adjusted to 664 nm and the power output could be varied in the range of 50-500 mW at the fiber tip in a continuous wave (cw) mode. The delivered energy could be adjusted from 50 - 1000 J. The system has a size of 49 by 20 by 40 cm, weighs 20 kg, and is readily portable. It runs on 100 V current. The laser power is easily controlled and the wavelength is stable (less than plus or minus 0.2 nm). The output beam is delivered via a quartz fiber. Furthermore, the full width at half-maximum power is less than 2 nm, which enables uniform, high-density photoirradiation. The power density distribution of the laser, analyzed by a CCD camera, was uniform throughout the photoirradiated field. In an animal study, tumor-bearing Balb/c mice were treated with the diode laser 5 hours after intravenous administration of NPe6 at a dose of 1.25 to 12.5 mg/kg i.v.. Total photoirradiation ranged from 3.13 to 250 J/cm2 which the energy density was adjusted to 100 mW/cm2. Percentages of cures were determined histopathologically from numbers of mice apparently disease-free 1 week after treatment. The results show that a laser energy of more than 12.5 J/cm2 was necessary to obtain 90% tumor cure rate at a maximum dose of NPe6 (12.5 mg/kg) and NPe6 dose of more than 2.5 mg/kg was necessary to obtain 90% cure rate at high laser energy of 200 J/cm2.

Effectiveness of photodynamic therapy with a diode laser using mono-L-aspartyl chlorin e6 for implanted fibrosarcoma in mice

The authors developed a new high power red laser diode system for photodynamic therapy (PDT) with Mono-L-aspartyl Chlorin e6 (NPe6). The laser beam has a low wavelength (664 nm) and relatively high power. Our results suggest that a certain increase in the tumor tissue level of NPe6 and a certain increase of laser light dose reaching a deeper layer of tumor caused an increase in percent cure. In addition, the effectiveness of PDT and also tumor recurrence following PDT depend to some extent on the total laser dose reaching deeper layers of tumors. Furthermore, the effectiveness of PDT tends to correlate with the amount of photobleaching by PDT.