Effect of venous drainage site on insulin action after pancreas transplantation in the rat--is there insulin resistance and a risk for atherosclerosis?

A Simplified Technique of Pancreas Transplantation in a Porcine Model

Background: The incidence of diabetes has been steadily increasing. The only curative option for diabetes is pancreas transplantation (PTx). Porcine models are valuable because of their anatomical and physiological similarities to human beings. Our aim is to introduce a simplified technique of PTx in a porcine model. Methods: In Landrace pigs (n = 32), after median laparotomy, the pancreas was mobilized, and the portal and splenic veins were divided. The proper hepatic and splenic arteries and the bile duct were also prepared, and the duodenal bulb was prepared and stapled. The third portion of the duodenum was freed up to the ligament of Treitz and stapled, and the renal arteries were ligated. After systemic heparinization, the pancreas was perfused through the abdominal aorta with histidine-tryptophan-ketoglutarate solution. The portal and splenic veins were cut for evaluating the sufficiency of perfusion. Whole pancreaticoduodenal graft was procured along with an aortic jump graft containing mesenteric and celiac trunks. In recipients, after total pancreatectomy, the suprarenal inferior vena cava and infrarenal aorta were prepared for vascular anastomosis in an end-to-side manner. After pancreas reperfusion, duodenoduodenostomy was performed in an end-to-side manner. Results: Median cold and warm ischemia times were 10 h (range, 9-14 h) and 50 min (range, 35-80 min), respectively. The hemodynamic status was stable throughout the operation. The median follow-up period was 7 days (range, 4-10). There were no major intra- and postoperative complications. Conclusion: By using an aortic jump graft, there was no need to perform additional arterial reconstruction resulting in a short warm ischemic and operation time. End-to-side portocaval and duodenoduodenal anastomoses make this model of PTx a very feasible method for experimental evaluations.

[Therapy of diabetes mellitus. Pancreas transplantation, islet transplantation, stem cell and gene therapy]

The long-term normalization of glucose metabolism - a prerequisite for the prevention of secondary complications in patients with diabetes mellitus - is only possible by transplantation of a whole pancreas or a reasonable number of islets. An absolute indication for pancreas grafting is given in type 1 diabetic patients with end-stage renal disease. The 1-year survival after simultaneous kidney/pancreas transplantation is, according to the international registry, 94-100% for patients, 89-92% for kidneys and 85-87% for the pancreas. The high success rate with long lasting normalization of glucose metabolism leads to a stabilization and/or amelioration of secondary complications, to an increase in quality of life and, most importantly, to a significant reduction in mortality when compared to diabetic kidney recipients. The indications for islet transplantation are similar to those for pancreatic grafting. Islet grafting is only a minor surgical procedure, but islet isolation is difficult. The 1-year survival for the recipients is 98%, for the islets 82% and for insulin-independency 42%. There is a significant decline of islet function to 10% 5 years after transplantation. Stem cell therapy would provide a definitive treatment solution not only for patients with type 1 diabetes. So far, this therapeutic option is still at an early stage of development.

Glucose and lipid metabolism after liver transplantation in inbred rats: consequences of hepatic denervation

The liver plays a central role in glucose and lipid homeostasis. Because liver transplantation severs the hepatic nerves which influence this function, we hypothesized that insulin resistance and hyperlipidemia develop after liver transplantation, thus increasing the atherosclerotic risk. Therefore, we studied inbred rats 8 months after orthotopic liver transplantation (Tx, n = 39) or laparotomy (sham, n = 37) by either oral glucose tolerance test (Tx, n = 13; sham, n = 8), meal tolerance test (Tx, n = 9; sham, n = 13), or euglycemic hyperinsulinemic clamp with tritiated glucose infusion (Tx, n = 17; sham, n = 16). We found that liver transplantation significantly increased basal hepatic glucose production (HGP) in the clamp study by 20% (37.3 +/- 2.2 vs 31.0 +/- 2.1 micromol kg -1 .min -1 , P < .05) and fasting plasma low-density lipoprotein (LDL) cholesterol by 36% (0.79 +/- 0.06 vs 0.58 +/- 0.05 mmol/L, P < .05). However, it did not affect HGP, total glucose uptake, metabolic clearance rate of insulin, and suppression of plasma nonesterified fatty acids, which were all normal in response to rising plasma insulin concentrations in the dose-response clamp studies. The oral glucose tolerance test and meal tolerance test also showed normal glucose and nonesterified fatty acids homeostasis with adequate pancreatic insulin secretion and hepatic insulin clearance after liver transplantation. The only consequences of liver transplantation are increased basal HGP and plasma LDL cholesterol, which may be caused by persistent vagal denervation of the liver. Although insulin resistance is absent, elevated plasma LDL cholesterol increases the atherosclerotic risk.

Pancreas transplantation: indications and consequences

Pancreas transplantation continues to evolve as a strategy in the management of diabetes mellitus. The first combined pancreas-kidney transplant was reported in 1967, but pancreas transplant now represents a number of procedures, each with different indications, risks, benefits, and outcomes. This review will summarize these procedures, including their risks and outcomes in comparison to kidney transplantation alone, and how or if they affect the consequences of diabetes: hyperglycemia, hypoglycemia, and microvascular and macrovascular complications. In addition, the new risks introduced by immunosuppression will be reviewed, including infections, cancer, osteoporosis, reproductive function, and the impact of immunosuppression medications on blood pressure, lipids, and glucose tolerance. It is imperative that an endocrinologist remain involved in the care of the pancreas transplant recipient, even when glucose is normal, because of the myriad of issues encountered post transplant, including ongoing management of diabetic complications, prevention of bone loss, and screening for failure of the pancreas graft with reinstitution of treatment when indicated. Although long-term patient and graft survival have improved greatly after pancreas transplant, a multidisciplinary team is needed to maximize long-term quality, as well as quantity, of life for the pancreas transplant recipient.

EFFECT OF VENOUS DRAINAGE SITE ON INSULIN ACTION AFTER SIMULTANEOUS PANCREAS-KIDNEY TRANSPLANTATION

BACKGROUND

The aim of the present study was to determine the influence of the venous drainage site on insulin homeostasis in simultaneous pancreas-kidney (SPK) transplant recipients.

METHODS

The study included 12 SPK patients with portal venous drainage (P) and 11 SPK patients with systemic venous drainage (S) of pancreas allograft. All of the participants presented similar characteristics. The euglycemic hyperinsulinemic clamp was performed using a 0.4-mU/kg/min insulin infusion. An infusion of [6,6-(2)H2] glucose was used to determine glucose turnover at the basal state and during the clamp to determine liver and peripheral tissue sensitivity to insulin.

RESULTS

Minor changes in glycemia and insulinemia were shown: fasting plasma glucose was significantly higher in the SPK-P group and insulinemia was higher in the SPK-S group. Hepatic glucose production was similar in both groups. During the clamp, insulin levels were higher in SPK-S recipients, but hepatic glucose production was suppressed in both groups. Glucose use was lower in SPK-S recipients than in SPK-P recipients, 3.32 +/-1.41 mg/kg/min and 4.70 +/-1.64 mg/kg/min, respectively (P<0.02). Basal and under-clamp free fatty acid levels were similar. In addition, no significant difference in cholesterol and low-density lipoprotein levels was shown, whereas high-density lipoprotein levels were higher in the SPK-S group; triglycerides during fasting and under clamp were significantly higher in the SPK-P group.

CONCLUSIONS

In both groups, neither hepatic nor peripheral insulin resistance was detected. In SPK-S recipients, the authors have showed only a lower insulin clearance and a slight decreased peripheral responsiveness to insulin without modifications of lipid status.