Benefits of nanoencapsulation for the hypericin-mediated photodetection and photodynamic therapy of ovarian micrometastases

Ovarian cancer is the fourth most frequent cause of cancer-related death in women in the United States. The currently recommended treatment is a combination of surgery followed by chemotherapy. However, ovarian cancer is characterized by the development of peritoneal micrometastases. These latter, hardly detectable by conventional method, are therefore suboptimally treated by standard surgery. As a consequence, up to 50% of treated patients have a relapse and will inevitably die. A time-dependent fluorescence intensity increase in the tumour nodules was observed. However, whereas free Hy was distributed in both tumor and surrounding tissue, the fluorescence associated with Hy-loaded NPs was more specifically observed in tumor nodules. Thus, the incorporation of Hy in nanoparticles improves the selectivity of Hy for the tumor tissues. Hy is also evaluated as a potential tool for photodynamic therapy (PDT). Hy-loaded NPs have been shown to be active in vitro after irradiation of NuTu-19 ovarian cancer cells. A major concern with PDT for invasive cancers such as ovarian cancer is the high risk of normal tissue damage if the PS selectivity for malignant cells is not sufficient. Due to the high dissemination of ovarian tumor nodules, a selective irradiation of each abnormal lesion is impossible, although whole peritoneal cavity irradiation could be considered. To avoid collateral damage, a high selectivity for malignant tissues is crucial and the concept of PDT using Hy-loaded NPs could be promising.