Label-free monitoring of colorectal adenoma–carcinoma sequence based on multiphoton microscopy

Abstract

The monitoring and evaluation of colorectal adenoma–carcinoma sequence during endoscopy are important for endoscopic resection of precursor lesions to disrupt the adenoma–carcinoma sequence and halt progression to invasive neoplastic disease. In this study, multiphoton microscopy (MPM) was used to identify different stages during the development of colorectal adenocarcinoma including adenoma with low-grade and high-grade dysplasia, and adenocarcinoma invading the submucosa. It was found that by combining two-photon excited fluorescence (TPEF) imaging and second harmonic generation (SHG) imaging, MPM can reveal the morphological changes of the epithelial cells and glands, identify the invasive position and depth of atypical glands and quantitatively describe the change of the cellular nucleus and the nuclear-to-cytoplasmic ratio during the stepwise progression of colorectal adenocarcinoma. These are important pathological findings for pathologists when diagnosing colorectal lesions. With the advancement of a compact and flexible multiphoton endoscope for in vivo imaging and clinical applications, MPM has the potential to provide immediate histological diagnosis for the monitoring and evaluation of the colorectal adenoma–carcinoma sequence during endoscopy.

Nonlinear optical microscopy for label-free detection of gastrointestinal neuroendocrine tumors

“…The nuclear area in tumor tissues is 44.06 ± 1.66 μm 2 (Table 1), which is far smaller than other kinds of cancerous cells [15], and the small standard deviation further demonstrates that the neuroendocrine cells are uniform in shape with round nuclei and minimal cellular pleomorphism.…”

“…To be specific, the nuclear-to-cytoplasmic ratio in tumor tissues is 1.07 ± 0.27 instead of the normal 0.21 ± 0.02 (Table 1), indicating it may be used as a predictive factor for quantitatively monitoring the gastrointestinal tumor progression [15,19]. Figure 3 displays that submucosa is mainly made up of collagen fibers (blue arrow in Fig.…”

“…The nonlinear optical imaging system has been previously described [15,16]. In general, nonlinear optical images were obtained by an inverted microscope (LSM 510 META, Zeiss, Germany) equipped with a mode-locked femtosecond Ti: sapphire laser (Mira 900-F; Coherent, Inc.) at an excitation wavelength of 810 nm.…”

Assessment of Tumor Invasion Depth in Colorectal Carcinoma Using Multiphoton Microscopy

“…Collagen content alteration in the normal and cancerous tissue from colorectal submucosa and muscularis propria layers MPM has several unique advantages of being label-free, intrinsic optical sectioning ability, near-infrared excitation for deep penetration depth into tissue, reduced photobleaching and phototoxicity in the out-of-focus regions, and the capability of providing quantitative information. It has been used to examine the potential applications in the field of colorectal cancer including monitoring colorectal cancer progression [24], [25], detecting tumor metastasis and microenvironment [26]- [28], evaluating colorectal cancer therapy response [29], and visualizing and ablating preinvasive colorectal cancer cells [30]. In this paper, this technique was extended to assess colorectal carcinoma invasion depth in the colorectal submucosa or muscularis propria layers.…”

Applications of multiphoton microscopy in the field of colorectal cancer

“…It has been demonstrated that MPM can reveal the morphological changes of epithelial cells and glands at different stages during the development of colorectal adenocarcinoma including normal mucosa, low-grade dysplasia, high-grade dysplasia, and adenocarcinoma by combining 2PEF imaging and SHG imaging [9][10][11][12][13][14][15][16][17]. Representative images of colorectal cancer progression are demonstrated in figure 1.…”