Photodynamic ablation of a selected rat embryo: a model for the treatment of extrauterine pregnancy.

BACKGROUND To test the feasibility of photodynamic therapy (PDT)-based ablation of rat embryos as a model for PDT of extrauterine pregnancy (EUP) in humans. METHODS A controlled pre-clinical study. Selected rat embryos [one per litter, n = 30, embryonic day 14 (E14)] were subjected to placental injection of a Palladium-bacteriochlorophyll derivative and illuminated to achieve selective photo-ablation. Histopathology studies were performed 48 h after treatment (E16). Parturition (E21) and breeding (approximately 12 weeks) after treatment were also evaluated. RESULTS Using direct placental injection, nearly 80% of the treated rat embryos were selectively photo-ablated, leaving the remaining litter unharmed to achieve normal parturition. Treated animals retained fertility and normally implanted in both treated and untreated uterine horns attesting to the confined toxicity inherent to this approach. CONCLUSIONS Although requiring respective adaptation to clinical application in terms of treatment protocols and designated hardware, photodynamic interventions using novel bacteriochlorophyll-based photosensitizers may prove applicable to treatment of EUP, as well as other gynecological pathologies and malignancies in a safe, minimally invasive manner.