Model of mouse pancreaticoduodenal transplantation

A New Mouse Model of Whole Pancreas Transplant With Graft Blood Through the Portal Vein

OBJECTIVES

Pancreas transplant is currently the most effective method for maintaining physiological blood sugar levels and reversing small blood vessel injuries. Our team developed a model of whole pancreas transplant based on microsurgical techniques following the investigation of more than 300 mice.

MATERIALS AND METHODS

A mouse pancreatic transplant model is required to investigate the pathophysiological process of pancreas transplant and pancreatic preservation technologies. Recently, the segment-neck pancreas transplant has been the most utilized mouse pancreatic transplant model. The innovative mouse pancreatic transplant modelthat we developed in this study uses the whole pancreas and returns heart blood flow into the liver via the portal vein.

RESULTS

With our mouse pancreatic transplant model, the survivalrate of mice aftertransplant was >80%, and the success rate of pancreatic transplant was >90%.

CONCLUSIONS

The segment-neck and the whole pancreas model can guarantee that the transplanted pancreas functions effectively, and both have excellent postoperative outcomes, survivalrates and pancreatic active rates.

Mouse Model for Pancreas Transplantation Using a Modified Cuff Technique

Mouse models have several advantages in transplantation research, including easy handling, a variety of genetically well-defined strains, and the availability of the widest range of molecular probes and reagents to perform in vivo as well as in vitro studies. Based on our experience with various murine transplantation models, we developed a heterotopic pancreas transplantation model in mice with the intent to analyze mechanisms underlying severe ischemia reperfusion injury-associated early graft damage. In contrast to previously described techniques using suture techniques, herein we describe a new procedure using a non-suture cuff technique.

In recent years, we have performed more than 300 pancreas transplantations in mice with an overall success rate of >90%, a success rate never described before in mouse pancreas transplantation. The backbone of this non-suture cuff technique for graft revascularization consists of two major steps: (I) pulling the recipient vessel over a polyethylene/polyamide cuff and fixing it with a circumferential ligature, and (II) placing the donor vessel over the everted recipient vessel and fixing it with a second circumferential ligature. The resultant continuity of the endothelial layer results in less thrombogenic lesions with high patency rates and, finally, high success rates.

In this model, arterial anastomosis is achieved by pulling the abdominal aorta of the donor graft over the everted common carotid artery of the recipient animal. Venous drainage of the graft is achieved by pulling the portal vein of the graft over the everted external jugular vein of the recipient. This manuscript provides details and crucial steps of the organ recovery and organ implantation procedures, which will allow researchers with microsurgical skills to perform the transplantation successfully in their laboratories.

Comprehensive and innovative techniques for liver transplantation in rats: A surgical guide

AIM: To investigate our learning curves of orthotopic liver transplantation (OLT) in rats and the most important factor for successful surgery.

METHODS: We describe the surgical procedures for our rat OLT model, and determined the operator learning curves. The various factors that contributed to successful surgery were determined. The most important surgical factors were evaluated between successful and unsuccessful surgeries.

RESULTS: Learning curve data indicated that 50 cases were required for operator training to start a study. Operative time, blood loss, warm ischemic time, anhepatic phase, unstable systemic hemodynamic state, and body temperature after surgery significantly affected surgery success by univariate analysis, while the anhepatic phase was the most critical factor for success by multivariate analysis.

CONCLUSION: OLT in rats is the only liver transplantation model that provides clinically relevant and reliable results. Shortened anhepatic phase is key to success in this model.

Interleukin-10 Gene Transfection of Donor Pancreas Grafts Protects against Rejection after Heterotopic Pancreas Transplantation in a Rat Model

OBJECTIVE

The aim of this study was to assess the effect of immunoregulatory cytokine interleukin-10 (IL-10) gene therapy on pancreas tissue rejection in a heterotopic pancreas transplantation model.

BACKGROUND

Modulation of inflammatory responses by anti-inflammatory cytokines (e.g., IL-10) has been suggested to minimize organ rejection. In this context, modulation of cytokines using gene therapy could be a new therapeutic modality in preventing organ rejection.

METHODS

The study was performed using male inbred Wistar rats as recipients and Sprague-Dawley rats as donors. 24 h before transplantation, groups of rats, named IL-10 (n = 20) and green fluorescent protein (GFP, n = 20), were injected with viral vectors Ad5CMVhIL10 or Ad5CMVGFP. Sham-operated rats (n = 20) underwent saline injection only before transplantation. The pancreatic tissue from each of these donor rats was subsequently transplanted into the corresponding groups of streptozotocin-induced diabetic recipient rats. Recipients were thus transfected with either IL-10 (n = 20), GFP-only carrying viral vectors (n = 20) or no viral vectors (normal saline, n = 20). A selected number of animals from each recipient group (n = 5) was sacrificed at weekly intervals for 3 weeks and some were further followed up to 12 weeks before sacrifice. Histological assessment of the pancreatic tissue was made based on rejection and GFP expression. Blood glucose levels were checked daily in all groups until sacrifice. Upon sacrifice, serum cytokine and insulin levels were measured. Histopathological correlations between blood glucose levels, serum insulin levels and serum IL-10 levels were made.

RESULTS

IL-10 gene therapy significantly attenuated pancreas rejection compared to controls, provided more normal blood glucose levels and elevated plasma insulin levels. Upon assumed natural deactivation of transferred viruses after 4 weeks, differences between groups in terms of rejection, blood glucose and insulin levels disappeared.

CONCLUSION

These findings suggest that IL-10 gene therapy significantly reduced pancreas rejection.

Chimerism and bone marrow based therapies in transplantation

Composite tissue allotransplantation holds a great potential for providing increased knowledge of anatomy and microsurgical experience for life-enhancing reconstructions. Many transplant cases around the world have made this a clinical reality at the present time. Composite tissue allotransplants contain multiple tissue types, including bone, muscle, vessels, nerves, skin, and immune cells and bear a huge antigenic load. Although immunosuppressive drugs are applied successfully to prevent allograft rejection, their side effects pose a barrier to worldwide use. Bone marrow therapy in many tolerance induction protocols, therefore, provides a guide to reaching the target of permanent immunotolerance. Multiple studies suggest that bone marrow is immunomodulatory and may facilitate allograft acceptance. In this review, bone marrow based therapy protocols of clinical and experimental models are presented in two major categories: solid organ and composite tissue transplantation.

A novel technique for heterotopic vascularized pancreas transplantation in mice to assess ischemia reperfusion injury and graft pancreatitis

BACKGROUND

Although various suture techniques for murine pancreas transplantation have been described, severe limitations have limited their widespread use. We therefore designed a surgical model for cervical heterotopic pancreas transplantation using a cuff technique.

METHODS

C57BL6 mice were used as donor and recipient pairs. Recipients were rendered diabetic with streptozotocin and subsequently transplanted. The donor pancreas was isolated using a no-touch technique and then placed in the recipient's cervical region. Vascular anastomoses were completed by pulling the portal vein over the external jugular vein cuff and the donor aortic segment over the carotid cuff and fixed with an 8-0 ligature thereby facilitating a nonsuture technique. To test applicability of this model, graft microcirculation was evaluated by intravital microscopy after prolonged cold ischemia (16 h).

RESULTS

The immediate success rate was >90%. Donor operation lasted 40 +/- 5 min; dissection of recipient vessels lasted 20 +/- 4 min. Revascularization time was 4 to 6 min, resulting in a total pancreas ischemia time of 33 +/- 6 min. No thromboembolic complications on the cuff side were observed. Preoperative glucose levels were 518 +/- 59 mg/dl and returned to normal by postoperative day 1 (88 +/- 13 mg/dl). Histology on postoperative days 10 and 30 showed almost normal islet cell and acinar architecture of all grafts. In groups with prolonged cold ischemia, graft microcirculation was significantly reduced and paralleled by increased inflammation, interstitial edema, hemorrhage, acinar vacuolization, and focal areas of necrosis compared with nonischemic controls.

CONCLUSIONS

This new model may provide an excellent tool to further investigate the pathophysiology as well as novel therapeutic strategies of preservation, ischemia reperfusion injury, and graft pancreatitis.