The minimum influences for murine normal joint tissue by novel bactericidal treatment and photodynamic therapy using na-pheophorbide a for septic arthritis.

OBJECTIVE

In this study, we examined the effect of photodynamic therapy (PDT) using Na-pheophorbide a (Na-Phde a) on normal joint tissue.

BACKGROUND DATA: The treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection is a serious issue. Recently, an experimental in vivo and in vitro model for the inactivation of MRSA by PDT using a photosensitizer, Na-Phde a, has been developed.

MATERIALS AND

METHODS

The knee joints of mice were injected with 560 or 280 micromol/L of Na-Phde a. Thirty minutes after injection, percutaneous laser irradiation was applied for 5 min using a semiconductor laser (power: 125 mW; wavelength: 664 nm; total energy: 12 J/cm2). The joint perimeter and body weight of the treated mice were monitored, and histological evaluation was also done.

RESULTS

Joint swelling was observed up to 3 wk after PDT (p < 0.05). On histology 1 wk post-PDT, the treated knees were found to have inflammatory changes, primarily in synovial tissue. Eight weeks after PDT, the synovitis was no longer present. No significant effects were observed on cartilage, bone marrow, or menisci.

CONCLUSIONS

The results of this experiment showed that PDT with Na-Phde a induced arthritis for a short time after treatment. However, this arthritis was reversible, and the PDT did not appear to induce osteoarthritic changes in normal joint tissue. These findings indicate that PDT using Na-Phde a caused minimal but reversible changes in joint tissue, suggesting that it would be a safe and useful treatment for bacterial septic arthritis.