Photosensitization of the rat endometrium following 5-aminolevulinic acid induced photodynamic therapy

Background and Objective: The impact of photodynamic therapy (PDT) on the endometrium following topical application of 5-aminolevulinic acid (ALA) was studied in a rat model. Study Design/Materials and Methods: Fluorescence microscopy revealed peak ALA to protoporphyrin IX (Pp IX) conversion 3-6 hours after application. Significantly higher Pp IX level were observed in the endometrial glands compared with endometrial stroma and myometrium. Results: Histological studies showed PDT-induced endometrial destruction with atrophy 7-10 weeks after treatment, Reproductive performance studies demonstrated significant implantation failure in the treated uterine horns compared with controls. The number of implantation sacs in the treated and untreated horns was 0.4 +/- 0.3 and 8.9 +/- 1.0, respectively (P < 0.01). Conclusion: We conclude that the high rate of Pp IX conversion in the endometrial glands can be exploited to treat dysfunctional uterine bleeding with PDT. In addition, this concept may also be applied to study endometrial regeneration and embryo implantation mechanisms. (C) 1996 Wiley-Liss, Inc.