Improved technique of vascular anastomosis for small intestinal transplantation in rats

Importance Rat Liver Morphology and Vasculature in Surgical Research

BACKGROUND The laboratory rat is one of the most popular experimental models for the experimental surgery of the liver. The objective of this study was to investigate the morphometric parameters, physiological data, differences in configuration of liver lobes, biliary system, and vasculature (arteries, veins, and lymphatic vessels) of the liver in laboratory rats. In addition, this study supports the anatomic literature and identified similarities and differences with human and other mammals. MATERIAL AND METHODS Forty laboratory rats were dissected to prepare corrosion casts of vascular system specimens (n=20), determine the lymph vessels and lymph nodes (n=10), and for macroscopic anatomical dissection (n=10) of the rat liver. The results are listed in percentages. The anatomical nomenclature of the liver morphology, its arteries, veins, lymph nodes, and lymphatic vessels are in accordance with Nomina Anatomica Veterinaria. RESULTS We found many variations in origin, direction, and division of the arterial, venous, and lymphatic systems in rat livers, and found differences in morphometric parameters compared to results reported by other authors. The portal vein was formed by 4 tributaries in 23%, by 3 branches in 64%, and by 2 tributaries in 13%. The liver lymph was drained to the 2 different lymph nodes. The nomenclature and morphological characteristics of the rat liver vary among authors. CONCLUSIONS Our results may be useful for the planing of experimental surgery and for cooperation with other investigation methods to help fight liver diseases in human populations.

Formation of microchimerism in rat small bowel transplantation by splenocyte infusion

AIM: To investigate the effect of donor splenocyte infusion combined with cyclosporine A (CsA) on rejection of rat small bowel transplantation (SBT).

METHODS: Male Sprague-Dawley (SD) rats and female Wistar rats weighing 230-270 g were used as donors and recipients respectively in the study. Heterotopic small bowel transplantation was performed. The rats were divided into three groups: group one receiving allotransplantation (SD→Wistar), group two receiving allotransplantation (SD→Wistar) + donor splenocyte infusion, group three receiving allotransplantation (SD→Wistar) + donor splenocyte infusion + CsA followed by CsA 10 mg/kg per day after transplantation, in which recipient Wistar rats were injected with 2 ×10⁸ SD splenocytes 28 d before transplantation, and treated with CsA after transplantation. Finally, the specific DNA fragment of donor Y chromosome was detected in recipient peripheral blood and skin by PCR. The survival time after small bowel transplantation was observed. Gross and histopathological examinations were performed.

RESULTS: The survival time after small bowel trans-plantation was 7.1 ± 1.2 d in group 1, 18.4 ± 3.6 d in group 2 and 31.5 ± 3.1 d in group 3. The survival time was significant longer (P < 0.01) in group 3 than in groups 1 and 2. The gross and histopathological examination showed that the rejection degree in group 3 was lower than that in groups 1 and 2.

CONCLUSION: Donor splenocyte infusion combined with CsA decreases remarkably the rejection and prolongs the survival time after rat small bowel transplantation.

Modifications in combined liver-small bowel transplantation in pigs

AIM: To introduce combined liver-small bowel transplantation in pigs.

METHODS: Eighteen transplantations in 36 large white pigs were performed. Three modifications in combined liver-small bowel transplantation model were applied: Veno-venous bypass was not used. Preservation of the donor duodenum and head of pancreas in continuity with the combined graft to avoid biliary reconstruction. The splenic vein of donor was anastomosed end-to-end with the portal vein of recipients by the formation of a “cuff”.

RESULTS: Without immunosuppressive therapy, 72-hour survival rate of the transplanted animals was 72% (13/18). Five of 18 pigs operated died of respiratory failure (3 cases) and bleeding during hepatectomy (2 cases). The longest survival time of animals was 6 days.

CONCLUSION: Our surgical modifications are feasible and reliable, which have made the transplantation in pigs simpler and less aggressive, and thus these can be used for preclinical study.

Early protective effect of ischemic preconditioning on small intestinal graft in rats

AIM: To investigate the early protective effect of ischemic preconditioning on small intestinal graft in rats.

METHODS: SD rats were randomly divided into the following groups: sham operation group (S group, n = 6), small bowel transplantation group (SBT group, n = 12), ischemic preconditioning plus small bowel transplantation group (ISBT group, n = 12). Heterotopic SBT was performed with a technique modified from that described by Monchik et al When the graft was revascularized successfully and reperfused for 1 h, samples were obtained from the different groups. Laminin was analyzed with immunohistochemical staining. Quantitative analysis of laminin positive signals was performed using image acquiring analysis system. Apoptotic epithelia of small intestinal graft were detected by the TdT-mediated dUTP nick end labeling method. The morphological change of epithelial basement membrane was observed by transmission electron microscopy.

RESULTS: The mean optical density value of laminin positive signals was 39.52 ± 2.60, 13.53 ± 0.44, 25.40 ± 1.79, respectively, in S, SBT and ISBT groups. The average optical density value of laminin positive products in SBT group was sharply lower than that in S group (P < 0.05). However, the mean optical density value of laminin positive products in ISBT group was significantly higher than that in SBT group (P < 0.05). The apoptotic index (AI) in S, SBT and ISBT group was 2.2 ± 0.83,30.8 ± 3.2, 13.2 ± 2.86, respectively. The AI in SBT group was significantly higher than that in S group (P < 0.05), and AI in ISBT group was sharply lower than that in SBT group (P < 0.05). On transmission electron microscopy, the epithelial basement membrane in S group stayed normal, but in SBT group it became disrupted and collapsed, even disappeared. The lesion of epithelial basement membrane in ISBT group was slighter compared with that in SBT group.

CONCLUSION: Ischemic preconditioning has an early protective effect on epithelial cells and extracellur matrix of small intestinal graft. Inhibition of epithelial cell apoptosis may be one of the mechanisms of ischemic preconditioning.

Combined small bowel and reduced auxiliary liver transplantation: Case report

AIM: To present a case of combined small bowel and reduced auxiliary liver transplantation.

METHODS: A 55-year-old patient with short bowel syndrome and TPN-related liver dysfunction received small bowel transplantation combined with a reduced auxiliary liver graft. A liver was added to restore the patient's liver function and to protect the intestinal allograft from rejection. His own liver was not removed.

RESULTS: Without donor pretreatment and by conventional immunosuppresive therapy following transplantation, the patient experienced had only one episode of mild intestinal rejection, which was easily reversed by treatment with Methylprednisolone. No liver rejection occurred. Unfortunately, the patient died of heart and lung failure 30 d after transplantation, despite successful graft replacement. Histopathologic examination of specimens after death demonstrated normal structure in both intestinal and liver grafts.

CONCLUSION: The auxiliary liver graft might play a role in preventing intestinal allograft rejection. However, the observation period in this case is short. Further study is needed to determine the risks, effect on the protecting the small-bowel from rejection, and feasibility of general application of this procedure.

Modified techniques of heterotopic total small intestinal transplantation in rats

AIM

To establish a successful model of heterotopic total small intestinal transplantation (SIT) in rats in order to reduce the complications and increase the survival rate.

METHODS

A total of 196 Wistar rats underwent heterotopic SIT with microsurgical technique. Technical modifications included shortening fasting time and supplying energy before surgery, administering optimal volume of crystalloid fluid to the donor and recipient during surgical procedures, reducing mechanical and ischemic injuries to donor intestine, revascularizing small intestinal graft with a combination of conventional aorta to aorta anastomosis and a cuffed portal vein to left renal vein anastomosis which resulted in an acceptably short warm ischemic time, and also an adequate blood supply and drainage of the graft.

RESULTS

The average time for the donor surgery was 86 min +/- 20 min, the mean operative time for the recipient was 115 min +/-20 min and warm ischemia time was shortened to 40 min +/- 5 min. There was a shorter revascularizing time of the graft, the abdominal aorta (AA) to AA anastomosis being 21 min +/- 10 min, and the cuffed portal vein (PV) to the renal vein anastomosis being 5 min +/- 5 min. The one-week survival rate of 98 rats with SIT was 88.78% (87/98), without thrombosis and stenosis of anastomosis. The longest survival time of recipient rats was more than 389 days after SIT, the rats were maintaining normal weight, with perfect intestinal function and intact intestinal histology.

CONCLUSION

These modified techniques for SIT would remarkably reduce the complications and improve survival rate in rats, which provided a potentially more consistent and practical model for experimental and clinical studies.