Optimization Study Of Photosensitizer Dose During Rose Bengal-mediated Vascular-targeted Photodynamic Therapy

Vascular-targeted photodynamic therapy(V-PDT)is an optical therapy technique,which through the energy exchange of oxygen molecules(3O2)and photosensitizer,generating cytotoxic singlet oxygen(1O2)which could damage to the vessels of pathological tissue during an excitation of specific wavelength laser.1O2 yield has a direct influence on the clinical therapeutic effect of V-PDT,meanwhile it closely related to the laser power density,blood oxygen level and photosensitizer.In order to establish the preliminary dose-effect relationship between photosensitizer and V-PDT response,the responses of blood flow and vasoconstriction of dorsal skinfold window chamber(DSWC)which impacted by concentration of photosensitizer before and after V-PDT were discussed in this study,moreover,1O2 luminescence was also monitoring by near infrared CCD during V-PDT.Rose Bengal(RB)was selected as photosensitizer in this study,and total light dose of 30 J/cm2 was used with irradiation of 100 mW/cm2 for V-PDT treatment.As well as,laser speckle imaging(LSI)and Leica fluorescence stereomicroscope were used to evaluate the V-PDT responses of blood flow and vasoconstriction,respectively.The obtained results indicate that blood flow would have a certain decrease,and the vessel diameter also have an obvious change,which shows a complete shutdown of arteries and a partly constriction of veins during V-PDT.And the optimal RB concentration is 25 mg/kg.Meanwhile,with the increasement of injected RB concentration,a rise would be observed in the signal of 1270 nm detected by near infrared CCD,which means 1O2 yield also has some increase.The 1215 and 1315 nm luminescence intensity were subtracted from the intensity recorded at 1270 nm filter to produce initial 1O2 luminescence intensity in this study.With the increase of 1O2luminescence intensity,a rise would be observed in the vascular responses.It is preliminarily obtained that 25 mg/kg is the optimal RB concentration during V-PDT treatment of total light dose of 30 J/cm2 used with irradiation of 100 mW/cm2 in this paper.