title: A versatile technique for the in vivo imaging of human tumor xenografts using near-infrared fluorochrome-conjugated macromolecule probes.
abstract: Here, we present a versatile method for detecting human tumor xenografts in vivo, based on the enhanced permeability and retention (EPR) effect, using near-infrared (NIR) fluorochrome-conjugated macromolecule probes. Bovine serum albumin (BSA) and two immunoglobulins-an anti-human leukocyte antigen (HLA) monoclonal antibody and isotype control IgG2a-were labeled with XenoLight CF770 fluorochrome and used as NIR-conjugated macromolecule probes to study whole-body imaging in a variety of xenotransplantation mouse models. NIR fluorescent signals were observed in subcutaneously transplanted BxPC-3 (human pancreatic cancer) cells and HCT 116 (colorectal cancer) cells within 24 h of NIR-macromolecule probe injection, but the signal from the fluorochrome itself or from the NIR-conjugated small molecule (glycine) injection was not observed. The accuracy of tumor targeting was confirmed by the localization of the NIR-conjugated immunoglobulin within the T-HCT 116 xenograft (in which the orange-red fluorescent protein tdTomato was stably expressed by HCT 116 cells) in the subcutaneous transplantation model. However, there was no significant difference in the NIR signal intensity of the region of interest between the anti-HLA antibody group and the isotype control group in the subcutaneous transplantation model. Therefore, the antibody accumulation within the tumor in vivo is based on the EPR effect. The liver metastasis generated by an intrasplenic injection of T-HCT 116 cells was clearly visualized by the NIR-conjugated anti-HLA probe but not by the orange-red fluorescent signal derived from the tdTomato reporter. This result demonstrated the superiority of the NIR probes over the tdTomato reporter protein at enhancing tissue penetration. In another xenograft model, patient-derived xenografts (PDX) of LC11-JCK (human non-small cell lung cancer) were successfully visualized using the NIR-conjugated macromolecule probe without any genetic modification. These results suggested that NIR-conjugated macromolecule, preferably, anti-HLA antibody probe is a valuable tool for the detection of human tumors in experimental metastasis models using whole-body imaging.
authors.affiliation: Biomedical Research Department, Central Institute for Experimental Animals, Kawasaki, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suemizu
authors.affiliation: Pathology Research Department, Central Institute for Experimental Animals, Kawasaki, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kawai
authors.affiliation: Biomedical Research Department, Central Institute for Experimental Animals, Kawasaki, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Higuchi
authors.affiliation: Biomedical Research Department, Central Institute for Experimental Animals, Kawasaki, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Hashimoto
authors.affiliation: Animals Resource Department, Central Institute for Experimental Animals, Kawasaki, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Ogura
authors.affiliation: Marmoset Research Department, Central Institute for Experimental Animals, Kawasaki, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Itoh
authors.affiliation: Department of Applied Developmental Biology, Central Institute for Experimental Animals, Kawasaki, Japan.
authors.forename: Erika
authors.initials: E
authors.lastname: Sasaki
authors.affiliation: Pathology Research Department, Central Institute for Experimental Animals, Kawasaki, Japan ; Department of Pathology and Regenerative Medicine, Tokai University School of Medicine, Isehara, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Nakamura
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis / Q000473:pathology; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000473:pathology; D005456:Fluorescent Dyes; D045325:HCT116 Cells; D064593:Heterografts; D006801:Humans; D057054:Molecular Imaging / Q000379:methods*; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000175:diagnosis* / Q000473:pathology; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes