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

Abstract

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/cm 2 , 125 seconds); (4) CW þ PDL; (5) BPDþPDL; (6) PDT (BPDþCW); (7) PDL alone (585 nm, 4 J/cm 2 ); and (8) PDTþPDL (BPD þ CW followed immediately by PDL). Vessels were videotaped prior to, and at 1 hour postintervention and then assessed for damage based on the following scale: 0, no damage; 1, coagulation; 1.5, vasoconstriction; 2.0, coagulationþvasoconstriction; 2.5, angiostasis; 3.0, hemorrhage. Damage scores were weighted by vessel ''order.'' Results: PDT þ 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 þ 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.

Description and Analysis of Treatments for Port-wine Stain Birthmarks

“…Our group has demonstrated in animal models that photodynamic therapy (PDT) with benzoporphyrin derivative monoacid ring A and yellow light can be used to achieve selective vascular destruction. [42][43][44] Unlike PDL, which delivers short pulses at high irradiance, in PDT a laser or filtered noncoherent source provides low-power light at the desired wavelength to drive photochemical reactions that do not generate heat. Milliwatt light exposures used during PDT avoid epidermal thermal injury produced by high-peak-power PDL.…”

“…In 2 animal models this combined approach has demonstrated an enhanced effect compared with either PDT or PDL alone. 43,44 This protocol is experimental and requires clinical evaluation, which is under way.…”

Current treatment options for port wine stain birthmarks

“…For our experiments, we have used BPD as the photosensitizer in combination with 576 nm light for PDT and a 585 nm pulsed dye laser. In preliminary proof-ofconcept studies in a chick chorioallantoic membrane model, PDT + PDL intervention resulted in significantly more vascular damage than other study groups: 127% more than PDT (p < .01) and 47% more than PDL alone (p < .01) [6]. Further studies in a rodent dorsal skin fold model, achieved a reduction in perfusion in all intervention groups, with PDT + PDL resulting in the greatest reduction in vascular perfusion (56%) [7].…”

Selected Laser-based Therapies in Otolaryngology

“…Thus, the combined use of PDT and PDL shows promise in the treatment of PWS. An in vivo study using the chick chorioallantoic membrane model resulted in significantly more severe vascular damage following PDT plus PDL than with either treatment alone [21]. Prospective, comparative, and controlled clinical studies against accepted treatment regimes are required to confirm these results.…”