Small Bowel and Colon Transplantation in Rats Using Porto-Portal Cuff Anastomosis

Arterial supply to the rat colon

Rats are often used as animal models in studies such as on intestinal transplantation and anastomosis healing, which require colectomy. Although detailed information regarding arterial supply is important to establish accurate and reproducible experimental procedures, this has not been studied in the rat colon. Therefore, we analysed the detailed arterial distribution pattern and its individual variations in the colon of 34 rats. The rat colon received colic branches of the ileocolic artery, and the right, middle and left colic arteries. The single left colic artery constantly arose from the caudal mesenteric artery and was distributed to the descending colon, whereas the others showed variations in number and distribution. The ileocolic artery gave rise to one (12%) or two (88%) colic branches supplying the proximal ascending colon, and these branches formed rich, mesh-like anastomoses along the initial portion of the ascending colon. One (74%) or two (26%) right colic arteries originated from the cranial mesenteric artery and supplied the ascending colon and right colic flexure. Moreover, one (38%), two (56%) or three (6%) middle colic arteries emerged from the cranial mesenteric artery and were distributed to the transverse colon, left colic flexure and proximal descending colon. In total, we categorized the individual variations in arterial branching and anastomosis into 11 patterns. Arterial supply to the rat colon showed a specific pattern and frequent individual variations. These findings thus provide essential information for establishing reproducible models of rat colic surgery.

A practical guide for small bowel transplantation in rats-review of techniques and models

BACKGROUND

Animal models are a central aspect in research on small bowel transplantation (SBTx). Among them, rats are the preferred species because of their widespread availability and cost effectiveness. Because the complexity of the surgical procedure could per se influence the outcome of an experiment, a standardized and comparable technique is important. Based on of the vast amount of different models and surgical techniques published to this point, a review seemed necessary to guide investigators when choosing the suitable model.

MATERIALS AND METHODS

A systematic literature search of original articles published between 1965 and 2016 using the Medline Database regarding techniques of SBTx in rats was conducted according to the Preferred reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles describing a new technique or evaluating different techniques were considered.

RESULTS

A total of 38 publications fulfilled the selection criteria and were included. Data from these publications were regarded as too heterogeneous for statistical analysis. Depending on graft length and placement, full-length and reduced length heterotopic and orthotopic models were differentiated. Important factors concerning a good survival rate are the chosen model (heterotopic has a better outcome compared with orthotopic), a vascular flush of the graft in situ, a careful luminal flush of the graft, adequate fluid resuscitation, and a warm ischemia time of less than 40 min.

CONCLUSIONS

SBTx in rats remains a complex and challenging procedure, which necessitates a standardized technique as well as sufficient training. By choosing the optimal experimental model, applying established strategies, and proven techniques, a standardized and scientifically reliable model can be achieved.

Anorectal transplantation

BACKGROUND

Anorectal transplantation is a valid procedure for the treatment of anorectal dysfunction; however, the lack of a suitable animal model has hampered the development of this method. We describe a simple technique for anorectal transplantation in the rat and compare this procedure with colostomy.

METHODS

The anorectal segment including the skin surrounding the anus were freed by abdominal and perineal dissection. In a heterotopically transplanted group the segment was exteriorized by the formation of an anus through an abdominal incision. In an orthotopically transplanted group the segment was replaced in its original position and reimplanted by suturing. In another group a distal colostomy was performed. A sham-treated control group (simulated surgical procedure) was also included. Changes in behavior, characteristics of the stool, body weight and survival rate were assessed by daily clinical examination. Moribund animals, those with a weight loss of more than 30%, and those surviving at 1 month were killed by an overdose of anesthetic. The results were analyzed using the Mann Whitney, Student's t and chi-squared tests, and p<0.05 was considered significant.

RESULTS

Within 4 days after the operation, animals submitted to orthotopic or heterotopic transplantation had achieved normal defecation, body weight gain and clinical evolution similar to the sham-treated group. The overall mortality in these groups was 4.16%. In contrast, colostomized animals showed a high incidence of diarrhea, intestinal obstruction, stress posture and violent behavior (p</=0.05), and a mortality rate of 58.33%.

CONCLUSION

Autotransplantation in the rat is a simple technique, achieves a high rate of success and better clinical evolution than colostomy. This model may ultimately lead to research into anorectal transplantation.

Cuff-glue sutureless microanastomosis

Hand suture microanastomosis is a difficult procedure. This report describes a simplified microanastomosis using cuff and glue apparatus.

MODEL

Vena cava and intestine of rat were sectioned. The distal margin was introduced into an everted cuff covering the outer wall and fixed to the base of the tube by three stitches. The proximal segment was inserted into the cuff system and an encircling ligature was performed to attach both margins to the cuff. Proximal margin below ligature was pulled up exposing both intimae where glue was deposited. The proximal margin was pulled down, sealing the borders by glue adhesion. Ligatures fixing the system were sectioned and the cuff was removed. Anastomosis acquired a waveform shape, obtaining ideal intima-intima union and improving the healing process. After short training, this anastomosis can be performed within 10 min. This technique avoids cuff foreign body reaction, simplifies microanastomosis research, and may improve glue technology for tissue anastomosis.

Teaching intestinal transplantation in the rat for medical student

Technical difficulties hamper the widespread use of intestinal transplantation in rats. We evaluated the feasibility in training this microsurgical model for medical students. Thirty eight students were assessed. After information about intestinal transplantation in rats, they spontaneously agreed to be trained for this procedure. The course consisted of 4-h weekly lessons during 4-month period. The teaching process includes assessment in four phases: I) conception of intestinal transplantation and rat anatomy; II) basic microsurgery training; III) donor operation; IV) donor/recipient operation. Wistar rats were used as donors and recipients in one-step small bowel transplantation. All students (100%) reached phase II, seven students (18.42%) reached phase III and two students (5.26%) reached phase IV. Decreased interest about the theme, lack of time and patience, frustration and/or inability were all reasons given by the student that may have contributed to the low rate of success. Medical students achieved a low rate of completion for training in rat intestinal transplantation microsurgical procedures.