The aim of the present study was to investigate the accumulation of photosensitizer Photofrin II in the different organs as well as the placenta and embryos of pregnant rats and to determine during which stage of embryogenesis the photosensitizer is accumulated the most effectively.
Materials and methods: The experiments were carried out on 25 fetuses from 10 Wistar rats (weight 160-240 g). Female rats were mated with male rats in the evening. Vaginal smears were collected from each female rat next morning and were examined by microscope in order to determine the presence of sperm. The day when sperm was detected in the vagina was considered to be pregnancy day 0. Photofrin II (a dose of 5 mg/kg) was administered intravenously to pregnant rats on days 7, 14, 16, 18 and 20 of embryogenesis. Rats were euthanized 24 hours after intravenous injection of Photofrin II and the following organs were taken: brain, spleen, liver, kidneys, lungs, uterus, placenta, and embryos. The accumulation of the photosensitizer was observed in the samples prepared from these parts of body. Fluorescence measurements ex vivo were performed with an S2000-FI fluorescence spectrometer (Ocean Optics Inc., Florida, USA) by exciting the samples with a blue light emitting diode (lambda=400 nm).
Results: A comparative study of fluorescence spectra on days 7, 14, 16, 18 and 20 of embryogenesis showed that the most intense accumulation of Photofrin II in the embryo was on day 7, while on the other days of embryogenesis the accumulation of Photofrin II increased obviously in the uterus and placenta.
Conclusions: The obtained data show that the accumulation of Photofrin II in the embryo depended on the stage of embryogenesis as well as on permeability of the placental barrier. Further photodynamic therapy studies are necessary to determine the total effect of Photofrin II on the embryo.