Flexible Colonoscopy in Mice to Evaluate the Severity of Colitis and Colorectal Tumors Using a Validated Endoscopic Scoring System

Hi.I am Tomohiro Kani, a visiting pH from Nintendo University in Tokyo, And I'm Fabio Elli, director of the Digestive Health Research Center, a case Western Reserve University School of Medicine. In this video, we will describe our methodology to perform colonoscopy in mice. Highlight the importance of becoming familiar with the normal endoscopic anatomy.

Describe how to effectively troubleshoot problems during endoscopy to minimize trauma and image artifact. And finally, describe our scoring system for the assessment of intestinal inflammation in mu eye model of colitis and colitis associated cancer. Thank you for your attention.

First, set up the endoscopy System at attach the scope to the video system center and light source. Sterilize the scope and attach a syringe for air insufflation. Then turn on the system and adjust The white balance With the animal.

Properly anesthetized and restrained start the endoscopic examination. Biopsy samples can be Obtained as necessary. After scoping, warm the mouse with a light for recovery at the end.

The scoring system for evaluation of colonic inflammation and colonic associated colon cancer is explained. Setting up the endoscopy system. The endoscopy system includes the video system center, a xenon light source, and a video recorder.

We use a human ureteroscope for colonoscopy in mice. Our scope URFV is a flexible video scope that uses a CCD sensor. The insertion tube outer diameter is 3.3 millimeters and the distal end is 2.8 millimeters in diameter.

To begin, attach the scope to the video system center and light source. Next, sterilize the scope and lens surface with 70%ethanol. Then attach a three millimeter syringe to the working channel.

This is used to regulate the amount of intraluminal air with insufflation or aspiration. Turn on the main switch and set up the white balance. Also, do not forget to set up in NBI mode Two, anesthetizing the mouse.

First, I will demonstrate inhalation anesthesia Using isof fluorine, we use four to 5%of isof fluorine for induction. After the mouse ceases movement, reduce the concentration to the maintenance dose of one to 2%Restrain the mouse on the table by taping the tail and lower extremities. Tail taping is especially important to keep the mouse stationary during the scoping.

Also, Intraperitoneal injection of tri bromo. Ethanol can be used for the anesthesia.Three. Endoscopy Perianal lesions are not part of the endoscopic evaluation, but are an important finding and should be observed prior to the insertion and not to be confused with traumatic bleeding.

Before insertion coat the scope with surgical lubricant, be sure not to coat the CCD sensor. Insert the scope through the anus. This initial insertion should be as gentle as possible as blind insertion may damage the colon colonic mucosa.

Turn the light on and start recording. Push the air syringe slowly and carefully to get a field of view. Too much air insufflation may kill the mouth.

The presence of spontaneous bleeding should be judged when the endoscope is inserted into the rectum or colon angle. Handling adjusts the view vertically and the torque control is for horizontal adjustment. The coordination between these two controls is very important.

Observe the transparency. In normal colon, the wall is transparent with normal vascularity and without any thickness. Transparency is defined as a transmural visibility of the vessels or extramural organs.

The repetitive motion of insertion and pulling out helps the evaluation in normal colon. Both small and large vessels are visible during the examination. You can take pictures or biopsy samples as necessary.

Check the presence of contact bleeding. When withdrawing the endoscope, it is not necessary to scrape the mucosa intentionally. The narrow band imaging mode emphasizes the fine structures of vessels in mucus membranes.

The rectum is surrounded by muscles whereas the colon is not fixed by the surrounding tissues. Because of this anatomical difference, extramural viscera are not visible in the rectum. Fecal pellets Are sometimes present close to the anus.

They can be removed with air insufflation, however, sometimes they can persist and obstruct the endoscopic view. In these cases, we will use up to one mil of PBS enema to wash out stool. Feces are usually excreted after a couple of minutes.

Blurry View caused by the presence of smears on the lens is also a common problem, especially in the case of colitis or bleeding. In this situation, we tried to clean the lens with insufflation of air. This procedure may be successful at clearing the lens without withdrawal of The scope.

Peristaltic Movement is one of the normal physiological activities of the gut. Because air insufflation is not successful at dilating the lumen during peristalsis, you should wait until the peristaltic wave passes. Number four, biopsy biopsy specimens are obtained using flexible biopsy cup forceps.

The cups are opened and closed by the handle. Insert the forceps into the working channel. Be careful not to pierce the intestine.

Open The cups to a suitable size and place the tip onto the area of interest. Gently close the cups and pull firmly. Remove the specimen by flushing with suitable solution.

Number five, recovery. After the examination, warm the mouse until it recovers. We use an electric light for warming six scoring for colonic inflammation.

Our scoring system consists of four parameters, one perianal lesions, two, transparency of the colonic wall, three intestinal bleeding, and four focal lesions. Each parameter can be scored from zero to three. The maximum total score is 12.

Additionally, we have included a scale of decimal units that can be used to highlight specific endoscopic findings. The detailed description of each parameter is available in the accompanying manuscript. Here is a summary number one, perianal lesion.

This finding should be observed prior to introducing the scope into the rectum. This avoids confusion with traumatic bleeding. A score of zero is normal.

Score two is for bloody discharge. Score three is for granulation tissue or rectal prolapse.Two.Transparency. This represents the ability to visualize the blood vessels in the colonic wall and the surrounding viscera.

A score of zero indicates blood vessels are clearly visible. Score one. Small vessels are invisible partially, but large vessels are visible.

Score two. Small vessels are invisible generally and even large vessels are not clear. Score three the same as in score two and thickened appearance of the colon.Three.

Bleeding, spontaneous bleeding should be differentiated from contact bleeding. Judge it accordingly. Score one indicates contact bleeding is induced by the gentle standard scoping procedure score three.

Spontaneous bleeding notice upon entering the colon. Number four, focal lesion. These findings reflect local conditions that often accompany inflammation.

Score one. Plaque is a flat elevation covered by seemingly normal mucosa. Score two.

Red end area erosions score three. Ulceration erosions covered by fibrin like material. NBI is helpful to recognize this.

Decimal descriptors. We added three additional parameters and gave them decimal scores.0.1. For stricture score 0.2 for intestinal tear or perforation score 0.5 for tumorous lesion case presentation case one.

Mouse with clostridium difficile infection. It has normal transparency but early erosion. Small erosion is seen, But the background mucosa is normal.

Upon close observation, slight edema surrounding this lesion is revealed.Also. In other parts, there are no findings indicating the presence of inflammation. Case two.

Mouse with DSS induced colitis on a high fat diet. Non-transparency, spontaneous bleeding and stricture are seen in this case. At the beginning, bleeding is seen.

It is spontaneous. Here is a stricture. It is not dilated by air insufflation and the endoscope cannot pass through.

Background mucosa is Reddened and thickened. Also, contact beating occurs here and there. It indicates the fragility of the colon case.Three.

Mouse with chronic DSS colitis, non-transparency, wall thickness and tumor like protrusions are seen. Generally white collared wall thickness is seen and wall is not transparent. This is an Ulceration around the splenic flexor protrusions are remarkable.

Case four. Mouse with colitis associated cancer induced with azoxymethane and DSS. It has multiple tumors and ulceration.

A large flat type protruded lesion is on the right Wall and at a little more proximal Area, another lower flat type lesion is seen. The structure of the surface is apparently different from normal mucosa. NBI is useful for the detection and diagnosis in such a lesion.

There is a geographic large ulceration covered by fibrous material In the rectum. Thank you for watching.