Evolution of pancreas transplant surgery

Culture of Transplant Perfusate Using BACTEC Technology and Antibiotic Prophylaxis Influences Wound Complications Within a Kidney Transplant and SPK Transplant Cohort

PURPOSE

Routine screening for microbial contamination in organ recovery perfusion transport solution (ORPTS) is by microbiological culture without broth enrichment. Our aim was to examine the clinical utility of broth enrichment of perfusion solution, through use of BACTEC (Becton Dickinson) blood culture media, in preventing wound complications for transplant recipients in comparison with culture without enrichment.

METHODS

We prospectively collected samples of ORPTS of 395 kidney (n = 250) or simultaneous pancreas-kidney (SPK, n = 145) donors over a 7-year period. Results of culture with and without broth enrichment (n = 285) using BACTEC blood culture media were examined to compare the sensitivity of BACTEC with non-BACTEC methods. We then conducted a paired analysis of 110 recipients with both BACTEC and non-BACTEC culture organ perfusion media. We examined the rates of wound infection and whether the use of targeted antimicrobials reduced infections in the BACTEC group and recipients with both types of cultures.

RESULTS

Of 395 patients with cultures of ORPTS, first, the results of 79 cultures performed using BACTEC media only were compared with 206 non-BACTEC cultures (n = 285). Second, 110 cultures were performed using both methods. For the first part of the study, BACTEC media detected significantly greater microbial growth than non-BACTEC methods (n = 79, 64.6% vs n = 206, 14.6%; P < .001). In the 110 patients with both BACTEC (52.3%) and non-BACTEC cultures (9.9%), there was significantly higher sensitivity of the BACTEC method (P < .001); 68.2% of these patients had antimicrobial cover in the days immediately following transplant sufficient to cover the cultured organism. In the patients with appropriate antimicrobial cover, the rate of recipient wound infection was significantly reduced (P = .003).

CONCLUSIONS

Routine screening of ORPTS with BACTEC broth enrichment should always be employed. When paired with antimicrobial prophylaxis, it has the potential to significantly reduce the risk of recipient wound infection.

Donor cardiac arrest and cardiopulmonary resuscitation: impact on outcomes after simultaneous pancreas-kidney transplantation - a retrospective study

Donor cardiac arrest and cardiopulmonary resuscitation (CACPR) has been considered critically because of concerns over hypoperfusion and mechanical trauma to the donor organs. We retrospectively analyzed 371 first simultaneous pancreas–kidney transplants performed at the Medical University of Innsbruck between 1997 and 2017. We evaluated short‐ and long‐term outcomes from recipients of organs from donors with and without a history of CACPR. A total of 63 recipients received a pancreas and kidney graft from a CACPR donor. At 1, and 5‐years, patient survival was similar with 98.3%, and 96.5% in the CACPR and 97.0%, and 90.2% in the non‐CACPR group (log rank P = 0.652). Death‐censored pancreas graft survival was superior in the CACPR group with 98.3%, and 91.4% compared to 86.3%, and 77.4% (log rank P = 0.028) in the non‐CACPR group, which remained statistically significant even after adjustment [aHR 0.49 (95% CI 0.24–0.98), P = 0.044]. Similar relative risks for postoperative complications Clavien Dindo > 3a, pancreatitis, abscess, immunologic complications, delayed pancreas graft function, and relative length of stay were observed for both groups. Donors with a history of CACPR are, in the current practice, safe for transplantation. Stringent donor selection and short CPR durations may allow for outcomes surpassing those of donors without CACPR.

Genetic predictors of long-term graft function in kidney and pancreas transplant patients

Kidney and pancreas transplantation have helped transform the lives of people with end-stage renal failure and individuals with type 1 diabetes who have poor glycaemic control/severe secondary complications, respectively. Despite an improvement in immunosuppressive regimes, operative techniques and decreased initial rejection rates, there has been little improvement in long-term graft survival rates over the past decade. Whilst limited progress has been made in establishing clinical markers of graft function, several genetic markers of long-term graft function have been identified. These genetic markers have the potential to (i) assist in selecting marginal donor organs for transplantation, (ii) provide better understanding of the mechanisms behind graft loss enabling identification of new, or repurposing, current treatments to extend graft function and (iii) provide a window of opportunity to identify and treat individuals before graft failure has occurred. This review will discuss the different genetic variants screened for a role in predicting transplant longevity, examine their findings and limitations and introduce where the future of genetic research within the transplantation field lies.

Implanting 1.1B4 human β-cell pseudoislets improves glycaemic control in diabetic severe combined immune deficient mice

AIM

To investigate the potential of implanting pseudoislets formed from human insulin-releasing β-cell lines as an alternative to islet transplantation.

METHODS

In this study, the anti-diabetic potential of novel human insulin releasing 1.1B4 β-cells was evaluated by implanting the cells, either as free cell suspensions, or as three-dimensional pseudoislets, into the subscapular region of severe combined immune deficient mice rendered diabetic by single high-dose administration of streptozotocin. Metabolic parameters including food and fluid intake, bodyweight and blood glucose were monitored throughout the study. At the end of the study animals were given an intraperitoneal glucose tolerance test. Animals were then culled and blood and tissues were collected for analysis. Insulin and glucagon contents of plasma and tissues were measured by insulin radioimmunoassay and chemiluminescent enzyme-linked immunosorbance assay respectively. Histological analyses of pancreatic islets were carried out by quantitative fluorescence immunohistochemistry staining.

RESULTS

Both pseudoislet and cell suspension implants yielded well vascularised β-cell masses of similar insulin content. This was associated with progressive amelioration of hyperphagia (P < 0.05), polydipsia (P < 0.05), body weight loss (P < 0.05), hypoinsulinaemia (P < 0.05), hyperglycaemia (P < 0.05 - P < 0.001) and glucose tolerance (P < 0.01). Islet morphology was also significantly improved in both groups of transplanted mice, with increased β-cell (P < 0.05 - P < 0.001) and decreased alpha cell (P < 0.05 - P < 0.001) areas. Whereas mice receiving 1.1B4 cell suspensions eventually exhibited hypoglycaemic complications, pseudoislet recipients displayed a more gradual amelioration of diabetes, and achieved stable blood glucose control similar to non-diabetic mice at the end of the study.

CONCLUSION

Although further work is needed to address safety issues, these results provide proof of concept for possible therapeutic applicability of human β-cell line pseudoislets in diabetes.

Genetic variation in caveolin-1 correlates with long-term pancreas transplant function

Pancreas transplantation is a successful treatment for a selected group of people with type 1 diabetes. Continued insulin production can decrease over time and identifying predictors of long-term graft function is key to improving survival. The aim of this study was to screen subjects for variation in the Caveolin-1 gene (Cav1), previously shown to correlate with long-term kidney transplant function. We genotyped 435 pancreas transplant donors and 431 recipients who had undergone pancreas transplantation at the Oxford Transplant Centre, UK, for all known common variation in Cav1. Death-censored cumulative events were analyzed using Kaplan-Meier and Cox regression. Unlike kidney transplantation, the rs4730751 variant in our pancreas donors or transplant recipients did not correlate with long-term graft function (p = 0.331-0.905). Presence of rs3801995 TT genotype (p = 0.009) and rs9920 CC/CT genotype (p = 0.010) in our donors did however correlate with reduced long-term graft survival. Multivariate Cox regression (adjusted for donor and recipient transplant factors) confirmed the association of rs3801995 (p = 0.009, HR = 1.83;[95% CI = 1.16-2.89]) and rs9920 (p = 0.037, HR = 1.63; [95% CI = 1.03-2.73]) with long-term graft function. This is the first study to provide evidence that donor Cav1 genotype correlates with long-term pancreas graft function. Screening Cav1 in other datasets is required to confirm these pilot results.

A population pharmacokinetic study of tacrolimus in healthy Chinese volunteers and liver transplant patients

AIM

To develop a population pharmacokinetic (PopPK) model of tacrolimus in healthy Chinese volunteers and liver transplant recipients for investigating the difference between the populations, and for potential individualized medication.

METHODS

A set of 1100 sparse trough concentration data points from 112 orthotopic liver transplant recipients, as well as 851 dense data points from 40 healthy volunteers receiving a single dose of tacrolimus (2 mg, p.o.) were collected. PopPK model of tacrolimus was constructed using the program NONMEM. Related covariates such as age, hepatic and renal functions that were potentially associated with tacrolimus disposition were evaluated. The final model was validated using bootstrapping and a visual predictive check.

RESULTS

A two-compartment model of tacrolimus could best describe the data from the two populations. The final model including two covariates, population (liver transplant recipients or volunteers) and serum ALT (alanine aminotransferase) level, was verified and adequately described the pharmacokinetic characteristics of tacrolimus. The estimates of V2/F, Q/F and V3/F were 22.7 L, 76.3 L/h and 916 L, respectively. The estimated CL/F in the volunteers and liver transplant recipients was 32.8 and 18.4 L/h, respectively. Serum ALT level was inversely related to CL/F, whereas age did not influence CL/F. Thus, the elderly (≥65 years) and adult (<65 years) groups in the liver transplant recipients showed no significant difference in the clearance of tacrolimus.

CONCLUSION

Compared with using the sparse data only, the integrating modeling technique combining sparse data from the patients and dense data from the healthy volunteers improved the PopPK analysis of tacrolimus.

Neurologic complications of pancreas and small bowel transplantation

In the past decade, substantial improvements in patient and graft survival for pancreas and small bowel transplants have been achieved. Despite this progress, many patients still develop neurologic complications in the course of their illness. Small bowel transplants produce more neurologic complications because of the complex metabolic environment in which the procedure is performed and because of the intense immune suppression necessitated by the greater immunogenicity of the intestinal mucosa. Pancreas transplants stabilize and/or improve the signs and symptoms of diabetic neuropathy over time. Because transplantation of the pancreas is often coupled with a kidney transplant and small intestine with liver, neurologic complications in these patients sometimes reflect problems involving the organ partner or both organs. The spectrum of neurologic complications for pancreas and small bowel transplant recipients is similar to other organ transplants but their frequency varies depending on the type of transplant performed.

Surgical Morbidity of Simultaneous Kidney and Pancreas Transplantation: A Single-Centre Experience in the Tacrolimus Era

Introduction. Simultaneous pancreas and kidney (SPK) transplantation is performed to restore normoglycaemia and renal function in patients with Type I diabetes mellitus and end-stage renal failure. We aimed to evaluate the impact of major postoperative complications to patient and graft survival outcomes. Method. Using a prospectively collected database over a 10-year period, major postoperative complications requiring return to operating theatre as well as patient and graft survival outcomes were analysed retrospectively. Results. Between January 2001 and May 2010, 165 patients underwent first-time SPK transplantation. Median age of recipients was 39.8 years (range, 16.9–53.2). Enteric drainage was used in 149 patients, and bladder drainage was used in 16. Median follow-up time was 5.2 years (range 1.1–10.3). Fifty-six patients (34%) returned to operating theatre at least once. Pancreatic allograft loss secondary to vascular thrombosis occurred in 12 patients (7%), and 2 patients (1.2%) required transplant pancreatectomy due to debilitating pancreatic enzyme leaks. At 1 and 5 years, patient survival was 98% and 94%; pancreas graft survival, 86% and 77%; kidney graft survival 96% and 89%, respectively. Conclusion. SPK is a safe and effective treatment for Type I diabetes mellitus and end-stage renal failure although surgical reintervention is required in approximately one-third of patients. Preventing vascular thrombosis remains a major challenge.

Excellent outcomes of simultaneous pancreas kidney transplantation in patients from rural and urban Australia: a national service experience

BACKGROUND

Simultaneous pancreas and kidney (SPK) transplantation is performed to restore normoglycemia and renal function in patients with type 1 diabetes mellitus and end-stage renal failure. The National Pancreas Transplant Unit (NPTU) in Sydney provides a service to a population spread across 7.4 million km. We aimed to see if SPK transplantation outcomes differed between recipients from metropolitan (M) centers and those from nonmetropolitan (NM) regions.

METHODS

Using a prospectively collected database, patient and graft survival were analyzed. Patients were categorized according to region of residence and by distance from the NPTU.

RESULTS

Between January 2001 and May 2010, 165 patients underwent first-time SPK transplantation at the NPTU. There were 126 M and 39 NM recipients. Median distance from the NPTU was 732 km for donors (range, 0-3930 km) and 887 km for recipients (range, 1-4114 km). Median follow-up was 5.2 years (range, 1.1-10.3 years). Actuarial 5-year patient survival was 94% in M and 95% in NM groups. At 5 years, non-death-censored pancreas graft survival was 75% and 82% among M and NM patients, respectively, while kidney allograft survival was 88% in M and 92% in NM groups. There was no significant difference in patient and graft survival between groups. Distance of donor and recipient from the NPTU did not influence graft or patient survival.

CONCLUSIONS

SPK transplantation can be performed with excellent outcomes at a national center with a vast catchment area, irrespective of donor or recipient location.

Pancreatic islet cell transplantation: an update for interventional radiologists

Pancreatic islet cell transplantation is a promising cellular-based therapy for type 1 diabetes mellitus. This procedure involves portal venous injection of islet cells and affords 1-year insulin independence in as many as 80% of recipients. Although transplant surgeons represent historical drivers of islet therapy, requirement for image guidance and transcatheter techniques has fostered collaboration with interventional radiologists, who are positioned to play a significant role in clinical performance of islet transplantation and in basic science research in this field. This review article aims to familiarize interventional radiologists with islet cell transplantation patient selection, procedure technique, clinical outcomes, and future clinical and research avenues.