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All procedures involving animal models have been reviewed by the local institutional animal care committee and the JoVE veterinary review board.
1. Colonoscopy and wound induction
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	<li>Pre-assemble the components of the endoscope by first inserting the 1.9 mm rigid bore endoscope into the sheath (Figure 1A-B). Attach the air pump (to provide colonic insufflation) using the tubing provided, to the gas valve on the left side of the sheath next to the working channel (<str...

colonoscopic guided pinch biopsy in a mouse model: a technique to visualize and extract tissue samples from mouse colon

Source: Montrose, D. C., et al. <a href="https://www.jove.com/v/60949">Performing Colonoscopic-Guided Pinch Biopsies in Mice and Evaluating Subsequent Tissue Changes.</a> J. Vis. Exp. (2021)
This video demonstrates the protocol for performing colonoscope-guided pinch biopsy in the mouse. This technique helps visually analyze the colon lumen and collect tissue samples for detailed studies.

<img alt="Figure 1" src="/files/ftp_upload/20810/20810_Figure1.jpg" /> 
Figure 1: Items needed to carry out biopsies. (A) Image of lens (a), sheath (b) and biopsy forceps (c). (B) Insertion of the lens into the sheath. (C) Insertion of forceps through the working channel of the sheath (solid arrow). Dashed arrow indicates correct location for attachment of air pump.

Colonoscopic Guided Pinch Biopsy in a Mouse Model: A Technique to Visualize and Extract Tissue Samples from Mouse Colon

Source: Montrose, D. C., et al. Performing Colonoscopic-Guided Pinch Biopsies in Mice and Evaluating Subsequent Tissue Changes. J. Vis. Exp. (2021)
This ...

Under pathological conditions, colonoscopy enables visualization of the colon and tissue extraction by pinch biopsy for detailed analysis of inflammatory wounds.
To perform colonoscopic-guided pinch biopsy in a mouse, begin with a biopsy assembly. The assembly contains a connector unit, an endoscope sheath with a pre-inserted colonoscope of optimal diameter. The colonoscope is connected to a light source, a video source, a gas port, and an instrument port for biopsy forceps.
Next, prepare an anesthetized mouse in the prone position on the colonoscopy platform. Pull the tail upward and use a gavage needle to infuse the anus with a suitable buffer to flush any fecal matter. Then, insert the colonoscope into the anus and advance it into the rectum. Continue moving the colonoscope further toward the colon while pumping gas to keep the colon inflated.
Next, steer the forceps out of the instrument port and open the jaws. Rotate the forceps at a right angle to induce a wound of optimal depth. Wounds that are too shallow or too deep result in a superficial wound or colon perforation, respectively. Thereafter, using biopsy forceps, pinch off the colon tissue. The extracted tissue and the induced wound can be further analyzed to understand the pathophysiology.

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Research

JoVE Encyclopedia of Experiments

Biology

Rodent Models

Adult

Non-invasive Assessment of the Efficacy of New Therapeutics for Intestinal Pathologies Using Serial Endoscopic Imaging of Live Mice

Animal models of inflammatory bowel disease (IBD) and colorectal cancer (CRC) have provided significant insight into the cell intrinsic and extrinsic mechanisms that contribute to the onset and progression of intestinal diseases. The identification of new molecules that promote these pathologies has led to a flurry of activity focused on the development of potential new therapies to inhibit their function. As a result, various pre-clinical mouse models with an intact immune system and stromal microenvironment are now heavily used. Here we describe three experimental protocols to test the efficacy of new therapeutics in pre-clinical models of (1) acute mucosal damage, (2) chronic colitis and/or colitis-associated colon cancer, and (3) sporadic colorectal cancer. We also outline procedures for serial endoscopic examination that can be used to document the therapeutic response of an individual tumor and to monitor the health of individual mice. These protocols provide complementary experimental platforms to test the effectiveness of therapeutic compounds shown to be well tolerated by mice.

We describe methods for longitudinal monitoring of the efficacy of therapeutics for the treatment of colonic pathologies in mice using a rigid endoscope. This protocol can be readily used for the characterization of the therapeutic response of an individual tumor in live mice and also for monitoring potential disease relapse.

Animal models of inflammatory bowel disease (IBD) and colorectal cancer (CRC) have provided significant insight into the cell intrinsic and extrinsic ...

JoVE Journal

Medicine

Drug-Induced Sleep Endoscopy (DISE) with Target Controlled Infusion (TCI) and Bispectral Analysis in Obstructive Sleep Apnea

The aim of this study was to establish a standardized protocol for drug-induced sleep endoscopy (DISE) to differentiate obstruction patterns in obstructive sleep apnea (OSA). Target-controlled infusion (TCI) of the sedative propofol was combined with real-time monitoring of the depth of sedation using bispectral analysis.
In an observational study 57 patients (mean age 44.8 years, &#177; SD 10.5; mean apnea hypopnea Index (AHI) 30.8/hr, &#177; SD 21.6, mean BMI 28.2 kg/m2, &#177; SD 5.3) underwent cardiorespiratory polysomnography followed by DISE with TCI and bispectral analysis. Sleep was induced solely by the intravenous infusion of propofol with a TCI-pump, with an initial target plasma level of 2.0 &#181;g/ml. Under continuous monitoring of the patient&#39;s respiration, state of consciousness and value of the bispectral analysis, the target plasma propofol level was raised in steps of 0.2 &#181;g/ml/2 min until the desired depth of sedation was reached. The mean value of the bispectral analysis at the target depth of sedation was determined and the obstruction patterns during DISE-TCI-bispectral analysis then classified according to the VOTE-system. Subsequently the results were analyzed according to polysomnographic and anthropometric data. The occurrence of multilevel obstruction sites across all degrees of severity of OSA clarifies the need for sleep endoscopy prior to upper airway surgery.
The advantage of this technique is the reproducibility of the protocol even for heterogeneous groups of patients. In addition, the gradual controlled and standardized increase of the plasma level of propofol with real-time control of the bispectral index leads to a precisely controllable depth of sedation. The DISE-TCI-bispectral analysis procedure is a step towards a required reproducible protocol of sleep endoscopy &#8212; capable of standardization. However it is not yet known whether these observed obstruction patterns also correspond to findings in natural sleep.

Drug-Induced Sleep Endoscopy DISE with Target Controlled Infusion TCI and Bispectral Analysis in Obstructive Sleep Apnea

The aim of this study was to establish a standardized protocol for sleep endoscopy to differentiate obstruction patterns in obstructive sleep apnea (OSA). Target-controlled infusion (TCI) of the sedative was combined with real-time monitoring of the depth of sedation using bispectral analysis.

The aim of this study was to establish a standardized protocol for drug-induced sleep endoscopy (DISE) to differentiate obstruction patterns in ...

Induction of Intestinal Graft-versus-host Disease and Its Mini-endoscopic Assessment in Live Mice

Acute graft-versus-host disease (GvHD) represents the most severe complication that patients previously undergoing allogeneic hematopoietic stem cell transplantation (allo-HCT) face and is frequently associated with a poor clinical outcome. While, for instance, GvHD manifestations of the skin are usually responsive to established immune-suppressive therapies and are, hence, not taking a fatal course, the presence and the intensity of intestinal GvHD, especially of the mid-to-lower parts of the gut, strongly influence the outcome and overall survival of patients with acute GvHD. Therapeutic options are essentially limited to the classic immune-suppressive agents yielding only moderate disease-mitigating effects. Hence, detailed knowledge about the tissue-resident immune cascade, changes in the intestinal microbiota, and the stromal response prior, upon, and after intestinal GvHD onset are urgently needed to understand the events and mechanisms underlying its pathogenesis and to develop innovative therapeutic options. Murine models of GvHD are frequently employed to identify and functionally assess molecules and pathways putatively driving intestinal GvHD. However, means to specifically monitor and evaluate intestinal inflammation over time are essentially lacking since established scores to assess and grade acute GvHD are routinely comprised of various parameters which rather reflect&#160;systemic GvHD manifestations. The detailed evaluation of intestinal GvHD has been restricted to studies using euthanized mice, thereby essentially excluding longitudinal (i.e., kinetic) analyses of the colonic compartment under a given experimental condition (e.g., antibody-mediated blockade of a proinflammatory cytokine) in live mice (i.e., in vivo). The mini-endoscopic in situ assessment of the distal colon of allo-HCT-treated mice described here allows a) a detailed macroscopic evaluation of different aspects of intestinal inflammation and b) the option to collect tissue samples for downstream analyses at various time points over the course of the observation period. Overall, the mini-endoscopic approach provides a major advance in preclinical noninvasive monitoring and assessment of intestinal GvHD.

Here, we present a protocol that describes allogeneic hematopoietic stem cell transplantation and allows repetitive mini-endoscopic evaluations of the distal colon in situ for the presence, characteristics, and severity of colonic inflammation within live mice suffering from intestinal graft-versus-host disease.

Acute graft-versus-host disease (GvHD) represents the most severe complication that patients previously undergoing allogeneic hematopoietic stem cell ...

Colonoscopic Guided Pinch Biopsy in a Mouse Model: A Technique to Visualize and Extract Tissue Samples from Mouse Colon

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