We report here the development of fluorescence laparoscopy to image green fluorescent protein (GFP)-expressing pancreatic tumors in an orthotopic mouse model.

An orthotopic mouse model of human pancreatic cancer was established by injecting GFP-expressing MiaPaca-2 human pancreatic cancer cells into the pancreas of 6-week old female athymic mice. On post-operative day 14, the animals underwent a diagnostic laparoscopy using both white and fluorescent light. The fluorescence laparoscope was constructed by modifying a standard laparoscopic system in the following manner: a 480-nm short pass excitation filter was placed between the light cable and the laparoscope, and a 2-mm thick emission filter that allows leakage of 1% of the background light was placed between the laparoscope and the camera. The camera and recording system were replaced with a MultiCam 310C (UVP, Upland, CA) that allows variable exposure time and gain setting in the controlling software. The exposure time was set to 110 msec and the gain to 97. A 3-mm 0-degree laparoscope was used in the mice. The mouse's abdomen was gently insufflated to 2 mm Hg via a 22-gauge angiocatheter that was secured via a suture. After fluorescence laparoscopy, the animals were sacrificed, and the identified tumors were collected and processed for histology. The experiments were performed in triplicate.

Fluorescence laparoscopy allowed facile and rapid identification of the bright fluorescent tumors in the pancreatic body. By employing the specific parameters above mentioned, a clear background was visible along with the fluorescent tumor under the fluorescent light mode. This could proffer an advantage in allowing exact localization of the lesions, eliminating the need to flip back and forth between white and fluorescent lighting, under which the background is usually so darkened that it is difficult to maintain spatial orientation.

In summary, the use of fluorescence laparoscopy permits the facile, clear, and rapid identification and localization of tumors that are labeled with fluorescent proteins or other fluorophores. Fluorescence laparoscopy may thus play a useful role in the diagnosis and staging of pancreatic and other aggressive gastrointestinal cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4336.