Vital immunostaining of human gastric and colorectal cancers grafted into nude mice : a preclinical assessment of a potential adjunct to videoendoscopy

Videoendoscopy has not significantly advanced diagnostic accuracy beyond that attainable by conventional fiberscopy, with respect to microcarcinomas of the digestive tract. We suspected that after the labeling of these lesions with an agent detectable by videoendoscope, digital processing of the images could facilitate endoscopic diagnosis of microcarcinomas. We have developed a novel antibody labeled with an indocyanine green (ICG) derivative that is evident by videoendoscope. However, the binding of such an exogenous antibody in vivo to tumor surfaces has not been described. In this preliminary study, after transplanting human gastric cancer or colorectal cancer into nude mice, we successfully bound the tumors in vivo with an anti-MUC1 mucin antibody, as subsequently confirmed by the performing of immunohistochemistry with a secondary antibody. The antibody labeled with an ICG derivative may therefore be clinically useful in detecting gastrointestinal microcarcinoma by videoendoscopy.