Current capsule endoscopy (CE) provides minimally invasive technology for gastrointestinal imaging, but has limited ability to discriminate different polyp types. Near Infrared Fluorescent (NIRF) probes activated by biomarkers upregulated in adenomas (e.g., cathepsin B) are potentially powerful tools to distinguish premalignant or malignant lesions from benign or inflammatory lesions.
To examine whether CE can be integrated with NIRF probes to detect adenomas, and whether cathepsin B activated NIRF probes are activated by benign or inflammatory ones.
Design and Setting
Mouse models of adenomas, hyperplastic/lymphoid polyps, and acute or chronic intestinal inflammation were injected intravenously with a cathepsin B activated probe (Prosense™ 680). Dissected intestine was imaged with CE under white or NIRF light. For NIRF, excitation (680 nm), dichroic and emission (700 nm) filters were combined with CE when images were recorded. Prosense™ 680 samples with or without protease were used as positive and negative controls. CE based imaging data was verified using an independent imaging system (Xenogen IVIS system).
Main Outcome Measurements
Proof of principle that CE integrated with NIRF probes can detect and discriminate adenomas from other lesions.
CE based NIRF imaging with Prosense™ 680 readily visualized adenomas, including in the colitis model. NIRF signals of different intensities were detected. Prosense™ 680 was not activated by benign or inflammatory lesions.
Optical filters external to capsule were used.
We demonstrate proof of principle of biochromoendoscopy, CE combined with molecular probes, provides a novel approach that differentiates adenomas from benign polyps and inflammatory lesions.
Keywords: Capsule endoscopy, Near Infrared Fluorescent Imaging, Cathepsin B