A preliminary experimental in vivo study of the effect of photodynamic therapy on human pituitary adenoma implanted in mice

As surgery alone may prove inadequate to effecta cure for invasive pituitary adenomas, photodynamic therapy (PDT) was investigated as a possible adjuvant treatment for this group of tumours. Different subtypes of human pituitary adenoma cellswere implantedsubcutaneously intonude micetostudy the in vivo effectofPDT onsuchlesions.The photosensitizer used in this study was polyhaematoporphyrin at a dose of 10mg/kg b.w., followed by light irradiation at a wavelength of 630nm with varying light doses between 10 and 75J/cm2. Histopathological examination of the treated implants consistently showed tumour vascular changes with acute inflammatory reaction, interstitial haemorrhage, and evidence of cell death at higher doses of light. These changes were absent in the control groups. These findings indicate that the cytotoxic effect of PDT demonstrated in vitro in previous studies, is also present in vivo.