This work is partially supported by Fundamental Research Funds for the Central University (G2018KY0302), University Fundamental Research Development Fund (KT00062), National Natural Science Foundation of China (81870380), and Clinical Research Award of the First Affiliated Hospital of Xi&#8217;an Jiaotong University in China (NO.XJTU1AF-CRF-2015-029). The authors thank Dr. Chengxin Shi for his technical suggestions during the early exploration phase of the murine appendectomy model, as well as the pathologist Dr. Xi Liu for evaluation of H&#38;E staining results of colitis and colorectal tumors. Y.L. performed the surgery demonstration,&#160;did data analysis, and wrote the draft of the manuscript; J.L., G.L., Z.P., and Y.M. took part in the surgical preparation, tissue collections, and video production; M.Z. performed the flow cytometry and ELISA; Q.W. and H.X. provided the technical support of generating a clinically relevant murine model; R.X.Z. designed the study, supervised the research, and wrote and proofed the manuscript; J.S. reviewed the manuscript.

All animal procedures were approved by the Institutional Animal Care and Use Committee of Xi&#8217;an Jiaotong University (No. XJTULAC2019-1023).
1. Mice appendectomy
<ol>
	<li>House 8&#8211;10-week-old C57BL/6 male mice in a certified specific-pathogen free (SPF) environment for 1 week prior to surgery.</li>
	<li>Prepare the following sterile surgical instruments: one pair of micro-scissors, one pair of micro-forceps, two sizes (4-0 and 8-0) of sterilized non-absorbable sutures, an electric coagulation pen with needle holder, 75% medical alcohol, iodine-based scrub (e.g., entoiodine), and a package of sterile cotton swabs.</li>
	<li>Fill a 10 mL syringe with pre-warmed 0.9% physiological saline for the abdominal flush and hydration during surgery.</li>
	<li>Anesthetize a non-fasted mouse intraperitoneally (i.p.) with 1% sodium pentobarbital at a dose of 100 mg/kg. Check for the depth of anesthesia by the lack of response to pedal reflexes. 
	NOTE: A single anesthetic dose is administered to ensure a full sedative effect in the mouse. Under the circumstance of short procedures, 50 mg/kg of sodium pentobarbital i.p. may be sufficient.</li>
	<li>Gently shave the abdominal hair with an electric shaver.</li>
	<li>Lay the mouse on the heating pad to prevent hypothermia.</li>
	<li>Secure the mouse on a platform in a supine position by placing four strips of medical adhesive tape across the limbs to prevent postural movement during the surgery.</li>
	<li>Gently touch the whole abdomen to find the feeling of a bump. 
	NOTE: In most cases, the feeling of a bump always indicates the exact position of the caecum. To avoid possible damage to the rest of the intestine, this pre-locating of the caecum prior to abdominal incision is important.</li>
	<li>Cover with a sterile drape and disinfect the shaved area of the abdomen by applying alternating surgical scrubs of iodine-based solution and 75% alcohol. Repeat the process 2x.</li>
	<li>Make a longitudinal incision ranging from 0.5&#8211;1.0 cm at the midline of the abdomen.</li>
	<li>According to the pre-determined location of the caecum, reach the caecum and gently exteriorize (~1 cm) to identify the caecal patch. Use a sterile, prewarmed saline solution of physiological pH to hydrate the intestine. 
	NOTE: The caecal patch of a mouse is part of the caecum and characterized by the presence of white ovoid follicles on the surface.</li>
	<li>To prevent potential complications of the post-operative bleeding and infection, ligate the mesenteric blood vessels of the caecum using the 8-0 suture. Hydrate the caecum with sterile saline.</li>
	<li>Mark the resection region using the 4-0 suture with an open loop near the apex of the caecum at the proximal colon. 
	NOTE: Marking the caecum with an open loop also prevents leakage of caecal content from the cut.</li>
	<li>Cut off the caecal patch below the marked resection using micro-scissors and wipe out the residual caecal content with medical cotton swabs. Then, disinfect the stump of caecum with iodine-based scrub.</li>
	<li>Close the stump with the running suture using the 8-0 suture.</li>
	<li>Carefully remove the 4-0 thread loop previously used for marking the resection at the stump of the caecum.</li>
	<li>Sterilize the sutured position with iodine-based scrub. Rehydrate the surgical site with saline again.</li>
	<li>Close the musculature layer with the running suture using 8-0 suture thread.</li>
	<li>Close the skin layers using interrupted sutures with 4-0 suture thread.</li>
	<li>Disinfect the surgical cut 2x with iodine-based scrub, then remove iodine using 75% medical alcohol.</li>
	<li>Gently flip the mouse back, subcutaneously (s.c.) inject 0.1 mg/kg body weight of buprenorphine and 0.4 mL of physiological saline and let the mouse rest on the heat pad until returning to consciousness.</li>
	<li>Put the mouse back to the sterile cage and closely monitor for signs of pain for 3 days post-surgery to ensure recovery. 
	NOTE: Post-operative application of 0.05 mg/kg buprenorphine may be needed for pain relief of the individual mouse. Allow mice to recover for 7 days after surgery for further induction of colitis-associated colorectal cancer.</li>
</ol>
2. Induction of chronic colitis-associated colorectal cancer with AOM and DSS
NOTE: Perform this procedure 7 days post-appendectomy.
<ol>
	<li>Prepare AOM stock solution by dissolving 25 mg of AOM in 2.5 mL of 0.9% sterile saline at a concentration of 10 mg/mL. 
	NOTE: AOM is light-sensitive.
	<ol>
		<li>Aliquot 2.5 mL of prepared AOM stock solution into 5 mL glass tubes wrapped with aluminum foil and store at -20 &#730;C each time upon use.</li>
		<li>Thaw one aliquot of AOM once and dilute it to a concentration of 1 mg/mL with 0.9% sterile saline (ratio 1:10). 
		CAUTION: AOM is extremely carcinogenic; hence, perform the entire preparation procedure in a fume hood.</li>
	</ol>
	</li>
	<li>Dissolve 4 g of DSS powder in 200 mL of autoclaved water to prepare 2% (w/v) DSS solution. 
	NOTE: The concentration of DSS may vary depending on the mouse strain, sex, and induction cycle; 3% DSS may be used for other mice strains.</li>
	<li>Simultaneously administer the freshly prepared AOM/DSS to the mice. To do so, follow the steps below.
	<ol>
		<li>Intraperitoneally inject 0.01 mL/g of freshly prepared AOM working solution for each mouse and replace the autoclaved water with 2% DSS solution for 5 days ad libitum. 
		NOTE: Each cage contains five mice; regularly check the DSS drinking bottle to ensure no precipitate occurs during the treatment period.</li>
		<li>Weight and closely monitor each mouse every day. 
		NOTE: During the administration, euthanize mice with up to 20% weight loss compared to its initial weight or signs of the huddle, squint, hypothermia, and poor activity.</li>
	</ol>
	</li>
	<li>Provide a fresh bottle of autoclaved water on the day 6 post-AOM/DSS administration until day 21 (Figure 1B). 
	NOTE: This is one complete cycle comprising of 21 days.</li>
	<li>Repeat steps 2.3&#8211;2.4 for an additional two cycles and sacrifice the mice on day 70.</li>
</ol>
3. Assessment of colonic inflammation and tumor (70 days post-AOM administration)
<ol>
	<li>Sacrifice the mice by CO2 inhalation at a fill rate of 10% in the euthanasia chamber followed by cervical dislocation.</li>
	<li>Harvest the entire colon from above the ileo-colic junction to the anus.</li>
	<li>Expose the lumen side by opening the colon longitudinally. Cut the whole colon into 10 cm long pieces and fix the colon tissue in 10% formalin for 72 h for hematoxylin and eosin (H&#38;E) staining.</li>
</ol>

The authors have nothing to disclose.

A murine appendectomy model of colitis-associated colorectal cancer was obtained using surgical steps with a high survival rate in mice. In most cases, since the caecum was positioned under the abdominal wall (Supplementary Table 1, Supplementary Table 2, and Figure 2), it was difficult to prejudge its location without laparotomy. In this surgical protocol, an easy step of touching the bump was introduced, and quantitative evaluation of the cecum location was also provided a...

The clinical appendectomy is a standard surgical procedure involving removal of the appendix mostly due to inflammation (e.g., appendicitis)1,2,3. However, the biological function of the vermiform human appendix remains controversial4,5,6. The appendix has been regarded as a vestigial remnant projecting from the cecum in the large bowel. Until recently, evolutionary, immunological, morphological, and microbiological studies have suggested that the appendix may possess distinct functions. These roles include the production of immunoglobins (e.g., IgA and IgG), a variety of B cells and T cells critical for adaptive immune responses within the gut-associated lymphoid tissues (GALTs), and replenishment of the large bowel with commensal microbiotas6,7,8,9,10,11,12.
Clinical epidemiological studies of patients with prior appendectomy or acute appendicitis have also revealed its potential roles in the pathogenesis of human diseases, such as inflammatory bowel disease (IBD), colorectal cancer, and non-gastrointestinal disorders (e.g., Parkinson&#8217;s disease and cardiovascular disease)13,14,15,16,17,18. For example, a large Asian population cohort study with 75,979 appendectomy patients recently showed a significant association between appendectomy and subsequent development of colorectal cancer, one of the most common malignancies with a high incidence and mortality14,19. Accordingly, establishing a suitable animal appendectomy model that resembles a human will be helpful to investigate the biological functions and molecular mechanisms of the appendix in the disease pathogenesis.
Many mammals possess an appendix or appendix-like organ, including primates, lagomorphs (e.g., rabbits), some rodents, and marsupials20. For small and commonly used laboratory animals, the rabbit possesses the vermiform appendix morphologically resembling the human21,22, but GALT in the rabbit is extremely large compared to that in humans, since the majority of lymphoid tissues are also found in Peyer&#8217;s patches located in both small and large intestines21. Additionally, the rabbit shows a different lymphoid follicular structure, T cell distribution, and immunoglobulin density from the human, which makes the studying of their appendices inappropriate21.
Mice are the most commonly used animal model to study human pathophysiology and test the various existing and novel therapuetics23,24,25. The single white large lymphoid cluster at the apex of the caecum in mice, known as the caecal patch, is thought to perform functions similar to the human appendix26,27,28. Yet, it is practically difficult to separate the caecal patch from caecum in mice. So far, the common surgical procedures for inducing appendicitis in a mouse model involve a relatively large incision (e.g., 1&#8211;2 cm) through the abdominal wall to gain access to the whole caecum (Supplemental Table 1)29,30,31,32,33,34,35,36.
Herein, to generate an appendectomy model associated with gastrointestinal disease, this report presents a facile surgical protocol for caecal patch removal in mice. This is followed by the combined administration of the genotoxic agent AOM and pro-inflammatory agent DSS for the induction of colitis-associated colorectal cancer similar to that seen in humans. IBD has been shown to be a risk factor of intestinal cancer37,38. The combination of AOM/DSS-induced chronic colitis-associated colorectal cancer has been well-established, and readers can refer to Neufert et al., and Thaker et al. for detailed procedures39,40. This reproducible and rapid murine appendectomy model can be used to study appendix-modulated bowel inflammation and colon microbiota, especially in the development and progression of IBD and colorectal cancer.

<table><tbody><tr><td>Azoxymethane(AOM)</td><td>Sigma-Aldrich,Inc.</td><td>A5486</td><td></td></tr><tr><td>Dextran Sulfate Sodium Salt(DSS)</td><td>MP Biomedicals,Inc.</td><td>160110</td><td></td></tr><tr><td>Entoiodine</td><td>Shanghai likon high technology disinfection co. LTD</td><td>310102</td><td></td></tr><tr><td>digital caliper</td><td>Ningbo yuanneng trading co. LTD</td><td>4859263</td><td></td></tr><tr><td>4-0 Silk Sutures</td><td>Yuanlikang co. LTD</td><td>20172650032</td><td></td></tr><tr><td>8-0 Prolene Sutures</td><td>Yuanlikang co. LTD</td><td>20172650032</td><td></td></tr><tr><td>Electric coagulation pen</td><td>Chuang mei medical equipment co. LTD</td><td>28221777292</td><td></td></tr><tr><td>disposable syringe 1ml</td><td>Shengguang medical products co. LTD</td><td>3262-2014</td><td></td></tr><tr><td>disposable syringe 10ml</td><td>Shengguang medical products co. LTD</td><td>3262-2014</td><td></td></tr><tr><td>75% Medicinal alcohol</td><td>Shandong anjie high-tech disinfection technology co. LTD</td><td>371402AAJ008</td><td></td></tr><tr><td>Pentobarbital sodium salt</td><td>Sigma-Aldrich,Inc.</td><td>57-33-0</td><td></td></tr><tr><td>Physiological Saline</td><td>Shandong qidu pharmaceutical co. LTD</td><td>H37020766</td><td></td></tr><tr><td>Absorbent Cotton Swab</td><td>Henan ruike medical co., LTD</td><td>RK051</td><td></td></tr><tr><td>Surgical Instruments-Ophthalmic</td><td>Jinzhong Shanghai co.LTD</td><td>WA3050</td><td></td></tr></tbody></table>

murine appendectomy model of chronic colitis associated colorectal cancer by precise localization of caecal patch

The human appendix has been recently implicated to play important biological roles in the pathogenesis of various complex diseases, such as colorectal cancer, inflammatory bowel disease, and Parkinson&#8217;s disease. To study the function of the appendix, a gut disease-associated murine appendectomy model has been established and its step-by-step protocol is described here. This report introduces a facile protocol for caecal patch removal in mice followed by the chemical induction of chronic colitis-associated colorectal cancer using a combination of dextran sulfate sodium (DSS) and azoxymethane (AOM). IgA specific cells and IgA concentration were significantly reduced upon removal of the caecal patch in male C57BL/6 mice&#160;compared to those in the sham group. Simultaneously administering 2% DSS and AOM resulted in nearly 80% mice survival in both sham and appendectomy groups without significant body weight loss. Histological results confirmed colonic inflammation and different degrees of adenocarcinoma. This model can be used for the study of the functional role of the appendix in maintaining gut microbiota homeostasis and pathogenesis of gut colitis and malignancies, as well as for the potential development of drug targeting therapies.

Establishment of murine appendectomy model
This murine appendectomy model of chronic colitis associated colorectal cancer can be generated by following the sequential surgical and induction steps as illustrated in Figure 1. The most frequent positions of caecum are in the left and right iliac fossa followed by the middle line of the abdomen (Figure 2). The successful rate of pre-localization of caecum prior to the abd...

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Murine Appendectomy Model of Chronic Colitis Associated Colorectal Cancer by Precise Localization of Caecal Patch

The presented protocol describes a facile surgical removal of the appendix (caecal patch) in a mouse followed by the induction of inflammatory bowel disease-associated colorectal cancer. This murine appendectomy model enables investigation of the biological role of the appendix in the pathogenesis of human gastrointestinal disease.

The human appendix has been recently implicated to play important biological roles in the pathogenesis of various complex diseases, such as colorectal ...

murine-appendectomy-model-chronic-colitis-associated-colorectal

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Medicine

9.9K Views.  Xi'an Jiaotong University. Het algemene protocol beschrijft gemakkelijk uitgevoerde chirurgische ingrepen van het verwijderen van de appendix bekend als caecal patch in muizen. Het murine appendectomiemodel kan worden gebruikt om de biologische rol van appendix in pathogenese van de menselijke maag-darmziekte te bestuderen. De menselijke bijlage is een betwistbaar orgaan.Recente studies hebben gesuggereerd dat de appendix een belangrijke rol speelt bij het behoud van de darmgezondheid. Om de biologische functie ...

Video: Murine Appendectomy Model of Chronic Colitis Associated Colorectal Cancer by Precise Localization of Caecal Patch

A Genetically Engineered Mouse Model of Sporadic Colorectal Cancer

Despite the advantages of easy applicability and cost-effectiveness, colorectal cancer mouse models based on tumor cell injection have severe limitations and do not accurately simulate tumor biology and tumor cell dissemination. Genetically engineered mouse models have been introduced to overcome these limitations; however, such models are technically demanding, especially in large organs such as the colon in which only a single tumor is desired.
As a result, an immunocompetent, genetically engineered mouse model of colorectal cancer was developed which develops highly uniform tumors and can be used for tumor biology studies as well as therapeutic trials. Tumor development is initiated by surgical, segmental infection of the distal colon with adeno-cre virus in compound conditionally mutant mice. The tumors can be easily detected and monitored via colonoscopy. We here describe the surgical technique of segmental adeno-cre infection of the colon, the surveillance of the tumor via high-resolution colonoscopy and present the resulting colorectal tumors.

A protocol for the establishment of a genetically engineered mouse model of colorectal cancer by segmental adeno-cre infection and its surveillance via high-resolution colonoscopy is presented.

Despite the advantages of easy applicability and cost-effectiveness, colorectal cancer mouse models based on tumor cell injection have severe limitations ...

Cancer Research

Modeling Colitis-Associated Cancer with Azoxymethane (AOM) and Dextran Sulfate Sodium (DSS)

Individuals with inflammatory bowel disease (IBD), such as Crohn's disease (CD) or ulcerative colitis (UC) are at increased risk of developing colorectal cancer (CRC) over healthy individuals. This risk is proportional to the duration and extent of disease, with a cumulative incidence as high as 30% in individuals with longstanding UC with widespread colonic involvement.1 Colonic dysplasia in IBD and colitis associated cancer (CAC) are believed to develop as a result of repeated cycles of epithelial cell injury and repair while these cells are bathed in a chronic inflammatory cytokine milieu.2 While spontaneous and colitis-associated cancers share the quality of being adenocarcinomas, the sequence of underlying molecular events is believed to be different.3 This distinction argues the need for specific animal models of CAC.
Several mouse models currently exist for the study of CAC. Dextran sulfate sodium (DSS), an agent with direct toxic effects on the colonic epithelium, can be administered in drinking water to mice in multiple cycles to create a chronic inflammatory state. With sufficient duration, some of these mice will develop tumors.4 Tumor development is hastened in this model if administered in a pro-carcinogenic setting. These include mice with genetic mutations in tumorigenesis pathways (APC, p53, Msh2), as well as mice pre-treated with genotoxic agents (azoxymethane [AOM], 1,2-dimethylhydrazine [DMH]).5 
The combination of DSS with AOM as a model for colitis associated cancer has gained popularity for its reproducibility, potency, low price, and ease of use. Though they have a shared mechanism, AOM has been found to be more potent and stable in solution than DMH. While tumor development in other models generally requires several months, mice injected with AOM and subsequently treated with DSS develop adequate tumors in as little as 7-10 weeks.6, 7 Finally, AOM and DSS can be administered to mice of any genetic background (knock out, transgenic, etc.) without cross-breeding to a specific tumorigenic strain. Here, we demonstrate a protocol for inflammation-driven colonic tumorigenesis in mice utilizing a single injection of AOM followed by three seven-day cycles of DSS over a 10 week period. This model induces tumors with histological and molecular changes closely resembling those occurring in human CAC and provides a highly valuable model for the study of oncogenesis and chemoprevention in this disease.8

Modeling Colitis-Associated Cancer with Azoxymethane AOM and Dextran Sulfate Sodium DSS

We demonstrate a protocol in which administration of the genotoxic agent azoxymethane (AOM) followed by three cycles of the pro-inflammatory agent dextran sulfate sodium (DSS) rapidly and consistently generates colon tumors in mice with morphologic and molecular similarities to those seen in human colitis-associated cancer.

Individuals with inflammatory bowel disease (IBD), such as Crohn's disease (CD) or ulcerative colitis (UC) are at increased risk of developing colorectal ...

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

The use of modern endoscopy for research purposes has greatly facilitated our understanding of gastrointestinal pathologies. In particular, experimental endoscopy has been highly useful for studies that require repeated assessments in a single laboratory animal, such as those evaluating mechanisms of chronic inflammatory bowel disease and the progression of colorectal cancer. However, the methods used across studies are highly variable. At least three endoscopic scoring systems have been published for murine colitis and published protocols for the assessment of colorectal tumors fail to address the presence of concomitant colonic inflammation. This study develops and validates a reproducible endoscopic scoring system that integrates evaluation of both inflammation and tumors simultaneously. This novel scoring system has three major components: 1) assessment of the extent and severity of colorectal inflammation (based on perianal findings, transparency of the wall, mucosal bleeding, and focal lesions), 2) quantitative recording of tumor lesions (grid map and bar graph), and 3) numerical sorting of clinical cases by their pathological and research relevance based on decimal units with assigned categories of observed lesions and endoscopic complications (decimal identifiers). The video and manuscript presented herein were prepared, following IACUC-approved protocols, to allow investigators to score their own experimental mice using a well-validated and highly reproducible endoscopic methodology, with the system option to differentiate distal from proximal endoscopic colitis (D-PECS).

Over the past few years, new generation endoscopes have emerged as important diagnostic research aids for evaluating murine colitis and colorectal tumors. We present herein a detailed protocol for endoscopic assessment of inflammation and colorectal tumors in mice, as well as a novel scoring system that uses decimal identifiers to document the endoscopic severity of colitis and colorectal tumors.

The use of modern endoscopy for research purposes has greatly facilitated our understanding of gastrointestinal pathologies. In particular, experimental ...

Murine Endoscopy for In Vivo Multimodal Imaging of Carcinogenesis and Assessment of Intestinal Wound Healing and Inflammation

Mouse models are widely used to study pathogenesis of human diseases and to evaluate diagnostic procedures as well as therapeutic interventions preclinically. However, valid assessment of pathological alterations often requires histological analysis, and when performed ex vivo, necessitates death of the animal. Therefore in conventional experimental settings, intra-individual follow-up examinations are rarely possible. Thus, development of murine endoscopy in live mice enables investigators for the first time to both directly visualize the gastrointestinal mucosa and also repeat the procedure to monitor for alterations. Numerous applications for in vivo murine endoscopy exist, including studying intestinal inflammation or wound healing, obtaining mucosal biopsies repeatedly, and to locally administer diagnostic or therapeutic agents using miniature injection catheters. Most recently, molecular imaging has extended diagnostic imaging modalities allowing specific detection of distinct target molecules using specific photoprobes. In conclusion, murine endoscopy has emerged as a novel cutting-edge technology for diagnostic experimental in vivo imaging and may significantly impact on preclinical research in various fields.

Murine Endoscopy for In Vivo Multimodal Imaging of Carcinogenesis and Assessment of Intestinal Wound Healing and Inflammation

Small animal imaging techniques allow serial diagnostic examinations and therapeutic interventions in vivo. Recently, the scope of applications has significantly widened and currently includes assessment of colonic tumor development, wound healing and monitoring of inflammation. This protocol illustrates these diverse potential applications of murine endoscopy.

Mouse models are widely used to study pathogenesis of human diseases and to evaluate diagnostic procedures as well as therapeutic interventions ...

Murine Ileocolic Bowel Resection with Primary Anastomosis

Intestinal resections are frequently required for treatment of diseases involving the gastrointestinal tract, with Crohn&#8217;s disease and colon cancer being two common examples. Despite the frequency of these procedures, a significant knowledge gap remains in describing the inherent effects of intestinal resection on host physiology and disease pathophysiology. This article provides detailed instructions for an ileocolic resection with primary end-to-end anastomosis in mice, as well as essential aspects of peri-operative care to maximize post-operative success. When followed closely, this procedure yields a 95% long-term survival rate, no failure to thrive, and minimizes post-operative complications of bowel obstruction and anastomotic leak. The technical challenges of performing the procedure in mice are a barrier to its wide spread use in research. The skills described in this article can be acquired without previous surgical experience. Once mastered, the murine ileocolic resection procedure will provide a reproducible tool for studying the effects of intestinal resection in models of human disease.

Ileocolic resection is commonly performed in several human diseases; however, little is known regarding the impact of intestinal resection on surgical illnesses. This article provides instruction on executing the procedure in mice with high success, providing a means to study the effects of ileocolic resection in models of disease.

Intestinal resections are frequently required for treatment of diseases involving the gastrointestinal tract, with Crohn&#8217;s disease and colon cancer ...

Murine Distal Colostomy, A Novel Model of Diversion Colitis in C57BL/6 Mice

Diversion colitis (DC) is a frequent clinical condition occurring in patients with bowel segments excluded from the fecal stream as a result of a diverting enterostomy. The etiology of this disease remains ill-defined but appears to differ from that of classical inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. Research aimed to decipher the pathophysiological mechanisms leading to the development of this disease has been severely hampered by the lack of an appropriate murine model. This protocol generates a murine model of DC that facilitates the study of the immune system's role and its interaction with the microbiome in the development of DC. In this model using C57BL/6 animals, distal parts of the colon are excluded from the fecal stream by creating a distal colostomy, triggering the development of mild to moderate inflammation in the excluded bowel segments and reproducing the hallmark lesions of human DC with a moderate systemic inflammatory response. In contrast to the rat model, a large number of genetically-modified murine models on the C57BL/6 background are available. The combination of these animals with our model allows the potential roles of individual cytokines, chemokines, or receptors of bioactive molecules (e.g., interleukin (IL)-17; IL-10, chemokine CXCL13, chemokine receptors CXCR5 and CCR7, and the sphingosine-1-phosphate receptor 4) to be assessed in the pathogenesis of DC. The availability of congenic mouse strains on the C57BL/6 background largely facilitates transfer experiments to establish the roles of distinct cell types involved in the etiology of DC. Finally, the model offers the opportunity to assess the influences of local interventions (e.g., modification of the local microbiome or local anti-inflammatory therapy) on mucosal immunity in affected and non-affected bowel segments and the on systemic immune homeostasis.

Murine distal colostomy provides a murine model for human diversion colitis, a predominantly lymphocytic colitis in colon segment excluded from the fecal stream.

Diversion colitis (DC) is a frequent clinical condition occurring in patients with bowel segments excluded from the fecal stream as a result of a ...

Creation of Colonic Anastomosis in Mice

Intestinal anastomoses are commonly performed in both elective and emergent operations. Even so, anastomotic leaks are a highly feared complications of colonic surgeries and can occur in up to 26% of surgical anastomoses, with mortality being up to 39% for patients with such a leak. Currently, there remains a paucity of data detailing the cellular mechanisms of anastomotic healing. Devising preventative strategies and treatment modalities for anastomotic leak could be greatly potentiated by a better understanding of appropriate anastomotic healing.
A murine model is ideal as previous studies have shown that the murine anastomosis is the most clinically similar to the human case as compared with other animal models. We offer an easily reproducible murine model of colonic anastomosis in mice that will allow for further illustration of anastomotic healing.

Anastomotic leak or breakdown after surgery is a major cause of postoperative morbidity and mortality. Our surgery for creating a colonic anastomosis is a reliable and reproducible method for studying the healing mechanisms of anastomoses.

Intestinal anastomoses are commonly performed in both elective and emergent operations. Even so, anastomotic leaks are a highly feared complications of ...

Liujunzi Decoction: An Effective Treatment for UC-CRC Prevention

Establishment of Coloproctitis Cancer Model in Mice and Evaluation of Therapeutic Effect of Chinese Medicine

Colorectal cancer (CRC) is a common malignancy of the digestive system and has become the third most common malignancy worldwide and the second leading cause of malignancy-related death. Ulcerative coloproctitis (UC) is a precancerous lesion, and UC-associated CRC (UC-CRC) is the most common subtype of CRC. Therefore, a reasonable UC-CRC model is the cornerstone and guarantee of new drug development. Traditional Chinese medicine (TCM) has been widely used in the treatment of UC-CRC due to its good efficacy. As a classic tonic prescription of TCM, Liujunzi decoction (LJZD) has been widely used in the treatment of UC-CRC. In this study, a UC-CRC model was established by combining azomethane and dextran sulfate sodium, and the LJZD was administered. The data confirmed that LJZD can effectively inhibit cancer transition in UC-CRC by using mouse body weight, colorectal length, pathological and inflammatory factors, colorectal barrier function, and cancer markers. This protocol provides a system for evaluating the efficacy of TCM in the prevention and treatment of UC-CRC.

Author Spotlight: Liujunzi Decoction as a Traditional Chinese Treatment for Coloproctitis Cancer

This protocol provides a mouse model of ulcerative coloproctitis-associated colorectal cancer induced by azomethane combined with dextran sulfate sodium. The model was used to evaluate the efficacy of traditional Chinese medicine compounds in the prevention and treatment of colorectal cancer.

Colorectal cancer (CRC) is a common malignancy of the digestive system and has become the third most common malignancy worldwide and the second leading ...

Experimental Rat Model of Pouchitis for Studying Ulcerative Colitis Pathogenesis and Treatment

A Rat Model of Pouchitis Following Proctocolectomy and Ileal Pouch-Anal Anastomosis Using Dextran Sulfate Sodium

Ulcerative colitis (UC) is a chronic immune-mediated disease that affects the entire colon and rectum with a relapsing and remitting course, causing lifelong morbidity. When medical treatment is ineffective, especially in cases of massive gastrointestinal bleeding, perforation, toxic megacolon, or carcinogenesis, surgery becomes the last line of defense to cure UC. Total colorectal resection and ileal pouch-anal anastomosis (IPAA) offer the best chance for long-term treatment. Pouchitis is the most common and troublesome postoperative complication. In this investigation, microsurgery is employed to create an ileal pouch model in experimental rats via IPAA surgery. Subsequently, a sustained rat model of pouchitis is established by inducing inflammation of the ileal pouch with dextran sulfate sodium (DSS). The successful establishment of rat pouchitis is validated through analysis of postoperative general status, weight, food and water intake, fecal data, as well as pouch tissue pathology, immunohistochemistry, and inflammatory factor analysis. This experimental animal model of pouchitis provides a foundation for studying the pathogenesis and treatment of the condition.

Author Spotlight: Developing a Rat Model for Pouchitis Research and Treatment

This protocol describes the method for establishing a rat model of pouchitis. The ileal pouch model was created by performing ileal pouch-anal anastomosis (IPAA) surgery using microsurgical techniques. After the surgery, the rat was treated with 4% dextran sulfate sodium (DSS) for 4 days.

Ulcerative colitis (UC) is a chronic immune-mediated disease that affects the entire colon and rectum with a relapsing and remitting course, causing ...

Mouse Ileal Loop Model: A Surgical Model to Study Intestinal Permeability in the Mouse

Source: Boerner, K., et al. <a href="https://www.jove.com/v/62093">Functional Assessment of Intestinal Permeability and Neutrophil Transepithelial Migration in Mice using a Standardized Intestinal Loop Model.</a> J. Vis. Exp. (2021)
This video demonstrates the generation of an ileal loop model to study intestinal permeability in a mouse model. This method provides a live model to understand the epithelial barrier function and consequent immune response.

Murine Appendectomy Model of Chronic Colitis Associated Colorectal Cancer by Precise Localization of Caecal Patch

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