Photodynamic therapy with intradermal administration of 5-aminolevulinic acid for port-wine stains

Objective: To investigate whether intradermal administration of 5-aminolevulinic acid (5-ALA) could achieve a sufficient amount of protoporphyrin IX (PpIX) to induce photochemical reaction in chicken comb, the animal model of port wine stains (PWSs). Methods: PpIX accumulation after 5-ALA administration through intradermal or intravenous injection was monitored for 24 hours. Localization of PpIX was observed under a confocal microscope. The comb was exposed to red light after intradermal 5-ALA injection, and the subsequent changes were observed grossly and microscopically. Results: In the comb, PpIX accumulation achieved the peak level at 5 and 4 hours after intravenous or intradermal injection of 5-ALA, respectively, and was almost completely eliminated within 24 hours. A similar amount of PpIX was observed in both groups. While in the body skin, a lower level of PpIX was observed after intradermal injection. A confocal microscope showed that PpIX distributed evenly in comb dermis without significant difference between the two groups. The vascular structure in comb was disrupted after laser irradiation based on intradermal administration of 5-ALA. Conclusions: Intradermal injection of 5-ALA is a safer administration route that could achieve the equivalent of PpIX accumulation and destroy vasculature after PDT. It might be applicable to the clinical treatment of PWSs.