Development of Dual-Scale Fluorescence Endoscopy for In Vivo Bacteria Imaging in an Orthotopic Mouse Colon Tumor Model

Abstract

Colorectal cancer is a representative cancer where early diagnosis and proper treatment monitoring are important. Recently, cancer treatment using bacteria has actively progressed and has been successfully monitored using fluorescence imaging techniques. However, because subcutaneous tumor models are limited in reflecting the actual colorectal cancer situation, new imaging approaches are needed to observe cancers growing in the colon. The fluorescence endoscopic approach is an optimal monitoring modality to evaluate the therapeutic response of bacteria in orthotopic colon cancer. In this study, we developed dual-scaled fluorescence endoscopy (DSFE) by combining wide-field fluorescence endoscopy (WFE) and confocal fluorescence endomicroscopy (CFEM) and demonstrated its usefulness for evaluating bacterial therapy. Firstly, the endoscopic probe of DSFE was developed by integrating the CFEM probe into the guide sheath of WFE. Secondly, colorectal cancer tumor growth and tumors infiltrating the fluorescent bacteria were successfully monitored at the multi-scale using DSFE. Finally, the bacterial distribution of the tumor and organs were imaged and quantitatively analyzed using CFEM. DSFE successfully exhibited fluorescent bacterial signals in an orthotopic mouse colon tumor model. Thus, it can be concluded that the DSFE system is a promising modality to monitor bacterial therapy in vivo.

Multicolor fluorescence imaging using a single RGB-IR CMOS sensor for cancer detection with smURFP-labeled probiotics

“…Conventional concentration quenching is a manifestation of the Forster nonradiative energy transfer phenomenon, and it is characterized by a decrease in the fluorescence quantum yield as the fluorophore concentration is increased [22]. However, the fluorescence intensity of FITC and Cy5 demonstrated a linear increment in this concentration [23].…”

Phthalocyanine-Blue Nanoparticles for the Direct Visualization of Tumors with White Light Illumination

“…However, it should be noted that ZnPC­(TB)-loaded micelles also exhibit strong photoacoustic and fluorescent signals within tumors 24 h post-intravenous injection (Figure S11). The use of photoacoustic and fluorescence imaging could further improve the sensitivity of tumor detection and aid in the identification of deeper-seeded tumors. ,− Both fluorescent and photoacoustic endoscopy devices are already being developed and are currently being tested in clinical trials. − …”

Optical-Mechanical Configuration of Imaging Operation for Endoscopic Scanner: A Review

“…Fig. 2 summarizes tissue images reconstructed using information obtained from confocal microscopy [23], fluorescence microscopy [17], [24], and OCT [25]. Confocal microscopy offers the elimination of out-of-focus glare by using pinhole aperture to produce a high-resolution image but at a shallow penetration depth (<100 µm) [26].…”