Combined photodynamic and photothermal induced injury enhances damage to in vivo model blood vessels

Background and objectives: The degree of port wine stain (PWS) blanching following pulsed dye laser (PDL) therapy remains variable and unpredictable. Because of the limitations of current PDL therapy, alternative treatment approaches should be explored. The objective was to evaluate a novel methodology for selective vascular damage, combined photodynamic (PDT) and photothermal (PDL) treatment, using the in vivo chick chorioallantoic membrane (CAM) model.

Study design/materials and methods: Thirty microliters of benzoporphyrin derivative monoacid ring A (BPD) solution was administered intraperitoneally into chick embryos at day 12 of development. Study groups were: (1) control (no BPD, no light); (2) BPD alone; (3) continuous wave irradiation (CW) alone (576 nm, 60 mW/cm2, 125 seconds); (4) CW + PDL; (5) BPD+PDL; (6) PDT (BPD+CW); (7) PDL alone (585 nm, 4 J/cm(2)); and (8) PDT+PDL (BPD + CW followed immediately by PDL). Vessels were videotaped prior to, and at 1 hour post-intervention and then assessed for damage based on the following scale: 0, no damage; 1, coagulation; 1.5, vasoconstriction; 2.0, coagulation+vasoconstriction; 2.5, angiostasis; 3.0, hemorrhage. Damage scores were weighted by vessel "order."

Results: PDT + PDL resulted in significantly (P < 0.01) more severe vascular damage than was observed in any other study group: 127% more than PDT, 47% more than PDL alone.

Conclusions: PDT + PDL is a novel and promising approach for selective vascular damage and may offer a more effective method for treatment of PWS and other vascular skin lesions.