Pancreatic Cancer-Related Mutational Burden Is Not Increased in a Patient Cohort With Clinically Severe Chronic Pancreatitis

INTRODUCTION

Chronic pancreatitis is associated with an increased risk of developing pancreatic cancer, and patients with inherited forms of pancreatitis are at greatest risk. We investigated whether clinical severity of pancreatitis could also be an indicator of cancer risk independent of etiology by performing targeted DNA sequencing to assess the mutational burden in 55 cancer-associated genes.

METHODS

Using picodroplet digital polymerase chain reaction and next-generation sequencing, we reported the genomic profiles of pancreases from severe clinical cases of chronic pancreatitis that necessitated palliative total pancreatectomy with islet autotransplantation.

RESULTS

We assessed 57 tissue samples from 39 patients with genetic and idiopathic etiologies and found that despite the clinical severity of disease, there was no corresponding increase in mutational burden. The average allele frequency of somatic variants was 1.19% (range 1.00%-5.97%), and distinct regions from the same patient displayed genomic heterogeneity, suggesting that these variants are subclonal. Few oncogenic KRAS mutations were discovered (7% of all samples), although we detected evidence of frequent cancer-related variants in other genes such as TP53, CDKN2A, and SMAD4. Of note, tissue samples with oncogenic KRAS mutations and samples from patients with PRSS1 mutations harbored an increased total number of somatic variants, suggesting that these patients may have increased genomic instability and could be at an increased risk of developing pancreatic cancer.

DISCUSSION

Overall, we showed that even in those patients with chronic pancreatitis severe enough to warrant total pancreatectomy with islet autotransplantation, pancreatic cancer-related mutational burden is not appreciably increased.

Progress in individualizing autologous islet isolation techniques for pediatric islet autotransplantation after total pancreatectomy in children for chronic pancreatitis

Total pancreatectomy with islet autotransplantation is performed to treat chronic pancreatitis in children. Successful islet isolation must address the challenges of severe pancreatic fibrosis and young donor age. We have progressively introduced modifications to optimize enzymatic and mechanical dissociation of the pancreas during islet isolation. We evaluated 2 islet isolation metrics in 138 children-digest islet equivalents per gram pancreas tissue (IEQ/g) and digest IEQ per kilogram body weight (IEQ/kg), using multiple regression to adjust for key disease and patient features. Islet yield at digest had an average 4569 (standard deviation 2949) islet equivalent (IEQ)/g and 4946 (4009) IEQ/kg, with 59.1% embedded in exocrine tissue. Cases with very low yield (<2000 IEQ/g or IEQ/kg) have decreased substantially over time, 6.8% and 9.1%, respectively, in the most recent tertile of time compared to 19.2% and 23.4% in the middle and 34.1% and 36.4% in the oldest tertile. IEQ/g and IEQ/kg adjusted for patient and disease factors improved in consistency and yield in the modern era. Minimal mechanical disruption during digestion, warm enzymatic digestion using enzyme collagenase:NP activity ratio < 10:1, coupled with extended distension and trimming time during islet isolation of younger and fibrotic pediatric pancreases, gave increased islet yield with improved patient outcomes.

Endocrine-Exocrine Signaling Drives Obesity-Associated Pancreatic Ductal Adenocarcinoma

Obesity is a major modifiable risk factor for pancreatic ductal adenocarcinoma (PDAC), yet how and when obesity contributes to PDAC progression is not well understood. Leveraging an autochthonous mouse model, we demonstrate a causal and reversible role for obesity in early PDAC progression, showing that obesity markedly enhances tumorigenesis, while genetic or dietary induction of weight loss intercepts cancer development. Molecular analyses of human and murine samples define microenvironmental consequences of obesity that foster tumorigenesis rather than new driver gene mutations, including significant pancreatic islet cell adaptation in obesity-associated tumors. Specifically, we identify aberrant beta cell expression of the peptide hormone cholecystokinin (Cck) in response to obesity and show that islet Cck promotes oncogenic Kras-driven pancreatic ductal tumorigenesis. Our studies argue that PDAC progression is driven by local obesity-associated changes in the tumor microenvironment and implicate endocrine-exocrine signaling beyond insulin in PDAC development.

Circulating Unmethylated Insulin DNA As a Biomarker of Human Beta Cell Death: A Multi-laboratory Assay Comparison

CONTEXT

There is an unmet need for biomarkers of pancreatic beta-cell death to improve early diagnosis of type 1 diabetes, enroll subjects into clinical trials, and assess treatment response. To address this need, several groups developed assays measuring insulin deoxyribonucleic acid (DNA) with unmethylated CpG sites in cell-free DNA. Unmethylated insulin DNA should be derived predominantly from beta-cells and indicate ongoing beta-cell death.

OBJECTIVE

To assess the performance of three unmethylated insulin DNA assays.

DESIGN AND PARTICIPANTS

Plasma or serum samples from 13 subjects undergoing total pancreatectomy and islet autotransplantation were coded and provided to investigators to measure unmethylated insulin DNA. Samples included a negative control taken post-pancreatectomy but pretransplant, and a positive control taken immediately following islet infusion. We assessed technical reproducibility, linearity, and persistence of detection of unmethylated insulin DNA for each assay.

RESULTS

All assays discriminated between the negative sample and samples taken directly from the islet transplant bag; 2 of 3 discriminated negative samples from those taken immediately after islet infusion. When high levels of unmethylated insulin DNA were present, technical reproducibility was generally good for all assays.

CONCLUSIONS

The measurement of beta cell cell-free DNA, including insulin, is a promising approach, warranting further testing and development in those with or at-risk for type 1 diabetes, as well as in other settings where understanding the frequency or kinetics of beta cell death could be useful.

Mitochondrial Proton Leak Regulated by Cyclophilin D Elevates Insulin Secretion in Islets at Nonstimulatory Glucose Levels

Fasting hyperinsulinemia precedes the development of type 2 diabetes. However, it is unclear whether fasting insulin hypersecretion is a primary driver of insulin resistance or a consequence of the progressive increase in fasting glycemia induced by insulin resistance in the prediabetic state. Herein, we have discovered a mechanism that specifically regulates non-glucose-stimulated insulin secretion (NGSIS) in pancreatic islets that is activated by nonesterified free fatty acids, the major fuel used by β-cells during fasting. We show that the mitochondrial permeability transition pore regulator cyclophilin D (CypD) promotes NGSIS, but not glucose-stimulated insulin secretion, by increasing mitochondrial proton leak. Islets from prediabetic obese mice show significantly higher CypD-dependent proton leak and NGSIS compared with lean mice. Proton leak-mediated NGSIS is conserved in human islets and is stimulated by exposure to nonesterified free fatty acids at concentrations observed in obese subjects. Mechanistically, proton leak activates islet NGSIS independently of mitochondrial ATP synthesis but ultimately requires closure of the KATP channel. In summary, we have described a novel nonesterified free fatty acid-stimulated pathway that selectively drives pancreatic islet NGSIS, which may be therapeutically exploited as an alternative way to halt fasting hyperinsulinemia and the progression of type 2 diabetes.

Regulatory considerations of delayed autologous islet infusion in a 4-year-old child undergoing total pancreatectomy for chronic pancreatitis

In patients undergoing total pancreatectomy for chronic pancreatitis, isolation, and infusion of autologous islets must comply with Good Manufacturing Practices standards established by the Food and Drug Administration (FDA) but does not standardly require an Investigational New Drug (IND) status. We report a case of a 4-year-old child with severe hereditary pancreatitis who developed clinical sepsis during total pancreatectomy (TP) surgery; subsequent pancreas, islet, and blood cultures were positive for Enterococcus. Because of clinical deterioration, planned islet infusion was aborted and islets were kept viable in a culture period while the patient was stabilized. Two days later, 38 000 islet equivalents (IEQ, 2808 IEQ/kg) were infused in a second procedure. Because maintaining the islets in culture met the FDA standard for "more than minimal" tissue manipulation, an emergency IND was obtained from the FDA to permit delayed infusion. The patient tolerated islet infusion well, and subsequently has partial islet graft function with normal glucoses and minimal insulin needs. This case highlights the possibility to delay islet infusion in an emergency, the potential for success with few islets in a young child, and the need to consider regulatory complexities of islet transplant in this situation.

Abstract A35: Microenvironmental adaptations drive obesity-associated pancreatic cancer

Obesity is a major modifiable risk factor for pancreatic ductal adenocarcinoma (PDAC), yet how obesity contributes to pancreatic cancer development is not well understood. Moreover, whether and at what point weight loss or other obesity-related interventions may impact PDAC progression remains largely unexplored, with significant implications for prevention and treatment. Leveraging an autochthonous genetically engineered model of PDAC, we demonstrate that obesity plays a stage-specific causal and reversible role in early PDAC progression. Molecular and histologic analyses reveal prominent microenvironmental alterations in tumors from obese mice, including increased inflammation and fibrosis and evidence for marked pancreatic islet cell adaptation. In particular, we identify aberrant expression of the peptide hormone cholecystokinin (CCK) in pancreatic islets in tumors as an adaptive response to obesity and show that islet CCK expression promotes oncogenic Kras-driven pancreatic ductal tumorigenesis. Together, these studies link obesity, changes in the local microenvironment, and tumorigenesis and implicate islet-derived hormones beyond insulin in PDAC development. Furthermore, the reversible nature of these adaptations supports the potential of antiobesity strategies to intercept PDAC early during progression.

Citation Format: Katherine Minjee Chung, Jaffarguribal Singh, Lauren Lawres, Kimberly Judith Dorans, Rebecca Robbins, Arjun Bhutkar, Ana Babic, Sara A. Vayrynen, Andressa D. Costa, Jonathan A. Nowak, Daniel T. Chang, Richard F. Dunne, Aram F. Hezel, Albert C. Koong, Joshua J. Wilhelm, Melena D. Bellin, Vibe Nylander, Anna L. Gloyn, Mark I. McCarthy, Brian M. Wolpin, Tyler Jacks, Charles S. Fuchs, Mandar Deepak Muzumdar. Microenvironmental adaptations drive obesity-associated pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr A35.

Long-term tolerance of islet allografts in nonhuman primates induced by apoptotic donor leukocytes

Immune tolerance to allografts has been pursued for decades as an important goal in transplantation. Administration of apoptotic donor splenocytes effectively induces antigen-specific tolerance to allografts in murine studies. Here we show that two peritransplant infusions of apoptotic donor leukocytes under short-term immunotherapy with antagonistic anti-CD40 antibody 2C10R4, rapamycin, soluble tumor necrosis factor receptor and anti-interleukin 6 receptor antibody induce long-term (≥1 year) tolerance to islet allografts in 5 of 5 nonsensitized, MHC class I-disparate, and one MHC class II DRB allele-matched rhesus macaques. Tolerance in our preclinical model is associated with a regulatory network, involving antigen-specific Tr1 cells exhibiting a distinct transcriptome and indirect specificity for matched MHC class II and mismatched class I peptides. Apoptotic donor leukocyte infusions warrant continued investigation as a cellular, nonchimeric and translatable method for inducing antigen-specific tolerance in transplantation.

Injection of donor apoptotic cells induces graft tolerance in mice. Here the authors combine this approach with short immunosuppressive therapy to achieve long-term tolerance to allogeneic islets and restoration of normoglycemia in diabetic nonhuman primates, and delineate cellular and molecular correlates of tolerance induction.

Effect of intrapancreatic fat on diabetes outcomes after total pancreatectomy with islet autotransplantation

BACKGROUND

Pancreatic fat may adversely affect β-cell mass and function, possibly via local release of non-esterified fatty acids, and proinflammatory and vasoactive factors released by adipose tissue. However, the effects of intrapancreatic fat in patients with chronic pancreatitis undergoing total pancreatectomy with islet autotransplantation (TPIAT) have not been studied. This study investigated whether pancreatic fatty infiltration has a negative effect on metabolic outcomes following TPIAT.

METHODS

The association between pancreatic fatty infiltration and diabetes outcomes was studied in 79 patients with low or high pancreatic fat content (LPF [n = 53] and HPF [n = 26], respectively) undergoing TPIAT. Pancreatic fatty infiltration was stratified using gross examinations during isolation and validated with histomorphometry of archived histology samples.

RESULTS

Fat area percentage in histology samples differed significantly between the LPF and HPF groups (2.1% ± 4.3% vs 10.6% ± 8.9%, respectively; P = 0.0009). Insulin dependence was more common in the HPF group, whereas more patients in the LPF group were insulin independent or on partial insulin supplementation at 1 year (P = 0.022). Furthermore, 1- and 2-h glucose concentrations during mixed-meal tolerance tests were significantly higher in the HPF group (P = 0.032 and 0.027, respectively) and β-scores (a composite measure of islet function and metabolic control) were significantly greater in the LPF than HPF group (6.1 ± 1.7 vs 4.6 ± 2.0; P = 0.034).

CONCLUSIONS

Patients with HPF were more likely to be insulin dependent, with higher postprandial glucose excursion, suggesting that intrapancreatic fat may lead to β-cell dysfunction with detrimental effects on diabetes outcomes after TPIAT.

Total Pancreatectomy With Intraportal Islet Autotransplantation as a Treatment of Chronic Pancreatitis in Patients With CFTR Mutations

OBJECTIVES

Chronic pancreatitis (CP) is an infrequent but debilitating complication associated with CFTR mutations. Total pancreatectomy with islet autotransplantation (TPIAT) is a treatment option for CP that provides pain relief and preserves β-cell mass, thereby minimizing the complication of diabetes mellitus. We compared outcomes after TPIAT for CP associated with CFTR mutations to CP without CTFR mutations.

METHODS

All TPIATs performed between 2002 and 2014 were retrospectively reviewed: identifying 20 CFTR homozygotes (cystic fibrosis [CF] patients), 19 CFTR heterozygotes, and 20 age-/sex-matched controls without CFTR mutations. Analysis of variance and χ tests were used to compare groups.

RESULTS

Baseline demographics were not different between groups. Postoperative glycosylated hemoglobin and C-peptide levels were similar between groups, as were islet yield and rate of postoperative complications. At 1 year, 40% of CF patients, 22% of CFTR heterozygotes, and 35% of control patients were insulin independent.

CONCLUSION

Total pancreatectomy with islet autotransplantation is a safe, effective treatment option for CF patients with CP, giving similar outcomes for those with other CP etiologies.

The prognostic significance of glutamic acid decarboxylase antibodies in patients with chronic pancreatitis undergoing total pancreatectomy with islet autotransplantation

AIM

Islet autotransplantation (IAT) is considered a 'non-immune' model of islet transplant, with no risk for autoimmune-mediated beta cell loss, but we have previously observed de novo type 1 diabetes in one total pancreatectomy with islet autotransplantation (TPIAT) recipient. We aimed to investigate the clinical significance of glutamic acid decarboxylase antibodies (GADA), as a sensitive marker for autoimmune diabetes mellitus (DM), in patients with chronic pancreatitis undergoing TPIAT.

METHODS

We identified 9 patients undergoing TPIAT with elevated GADA pre-TPIAT (8 non-diabetic and 1 with C-peptide positive DM), otherwise demographically similar to GADA negative TPIAT recipients (n=341). Metabolic and clinical measures related to islet cell function were recorded both before and after TPIAT.

RESULTS

None of the 9 TPIAT patients achieved insulin independence after surgery, vs. 33% of GADA negative patients (n=318 with 1-yr follow-up). The two patients with the highest titters of GADA (>250 IU/mL) both experienced islet graft failure, despite normoglycaemia pre-TPIAT and high islet mass transplanted (5276 and 9378 IEQ per kg), with elevated HbA1c levels post-TPIAT (8.3%, 9.6%). The remaining 7 seven were insulin dependent with partial graft function and HbA1c levels <7%.

CONCLUSION

Insulin dependence was more frequent in 9 patients with elevated GADA prior to TPIAT than in GADA negative TPIAT recipients, with graft failure in 2 cases. We speculate that beta-cell autoimmunity may occur in a small subset of TPIAT recipients and that beta cell antibody testing prior to TPIAT may be warranted to identify individuals at higher risk for insulin dependence.

The impact of using an intraoperative goal directed fluid therapy protocol on clinical outcomes in patients undergoing total pancreatectomy and islet cell autotransplantation

BACKGROUND

Patients undergoing total pancreatectomy and islet cell autotransplant (TPIAT) for treatment of pancreatitis are at risk for complications of over and under resuscitation. We hypothesized that using a goal directed fluid therapy (GDFT) protocol might impact clinical outcomes.

MATERIALS AND METHODS

A consecutive series of adult patients undergoing TPIAT were managed intraoperatively using either standard fluid therapy (SFT, n = 44) or GDFT (n = 23) as part of a pilot study between January 2013 and May 2015. Patient characteristics, intraoperative, and postoperative data were recorded prospectively, then retrospectively analyzed for differences between the groups.

RESULTS

The GDFT group had lower total fluid resuscitation (3,240 cc vs 5,173 cc, p < 0.0001) and transfusion requirements (1.0 cc/kg vs 3.3 cc/kg, p = 0.050) compared to the SFT group. The pre to postop nadir hemoglobin change was significantly less for GDFT (4.2 vs 5.1 gm/dl, p = 0.021) despite less transfusion.

CONCLUSIONS

Compared to SFT, using an intraoperative GDFT protocol in TPIAT patients was associated with significantly decreased intraoperative fluid resuscitation, blood transfusion and less postoperative dilutional anemia, without any difference in complications of underresuscitation. This pilot study suggests that GDFT is likely safe and further investigation is warranted.

National Institutes of Health-Sponsored Clinical Islet Transplantation Consortium Phase 3 Trial: Manufacture of a Complex Cellular Product at Eight Processing Facilities

Eight manufacturing facilities participating in the National Institutes of Health-sponsored Clinical Islet Transplantation (CIT) Consortium jointly developed and implemented a harmonized process for the manufacture of allogeneic purified human pancreatic islet (PHPI) product evaluated in a phase 3 trial in subjects with type 1 diabetes. Manufacturing was controlled by a common master production batch record, standard operating procedures that included acceptance criteria for deceased donor organ pancreata and critical raw materials, PHPI product specifications, certificate of analysis, and test methods. The process was compliant with Current Good Manufacturing Practices and Current Good Tissue Practices. This report describes the manufacturing process for 75 PHPI clinical lots and summarizes the results, including lot release. The results demonstrate the feasibility of implementing a harmonized process at multiple facilities for the manufacture of a complex cellular product. The quality systems and regulatory and operational strategies developed by the CIT Consortium yielded product lots that met the prespecified characteristics of safety, purity, potency, and identity and were successfully transplanted into 48 subjects. No adverse events attributable to the product and no cases of primary nonfunction were observed.

Preoperative Computerized Tomography and Magnetic Resonance Imaging of the Pancreas Predicts Pancreatic Mass and Functional Outcomes After Total Pancreatectomy and Islet Autotransplant

OBJECTIVES

Approximately two thirds of patients will remain on insulin therapy after total pancreatectomy with islet autotransplant (TPIAT) for chronic pancreatitis. We investigated the relationship between measured pancreas volume on computerized tomography or magnetic resonance imaging and features of chronic pancreatitis on imaging, with subsequent islet isolation and diabetes outcomes.

METHODS

Computerized tomography or magnetic resonance imaging was reviewed for pancreas volume (Vitrea software) and presence or absence of calcifications, atrophy, and dilated pancreatic duct in 97 patients undergoing TPIAT. Relationship between these features and (1) islet mass isolated and (2) diabetes status at 1-year post-TPIAT were evaluated.

RESULTS

Pancreas volume correlated with islet mass measured as total islet equivalents (r = 0.50, P < 0.0001). Mean islet equivalents were reduced by more than half if any one of calcifications, atrophy, or ductal dilatation were observed. Pancreatic calcifications increased the odds of insulin dependence 4.0 fold (1.1, 15). Collectively, the pancreas volume and 3 imaging features strongly associated with 1-year insulin use (P = 0.07), islet graft failure (P = 0.003), hemoglobin A1c (P = 0.0004), fasting glucose (P = 0.027), and fasting C-peptide level (P = 0.008).

CONCLUSIONS

Measures of pancreatic parenchymal destruction on imaging, including smaller pancreas volume and calcifications, associate strongly with impaired islet mass and 1-year diabetes outcomes.

Microbial contamination of transplant solutions during pancreatic islet autotransplants is not associated with clinical infection in a pediatric population

BACKGROUND/OBJECTIVES

Total pancreatectomy and islet autotransplant (TP-IAT) is a potential treatment for children with severe refractory chronic pancreatitis. Cultures from the resected pancreas and final islet preparation are frequently positive for microbes. It is unknown whether positive cultures are associated with adverse outcomes in pediatric patients.

METHODS

We reviewed the medical records of children (n = 86) who underwent TP-IAT from May 2006-March 2015 with emphasis on demographics, previous pancreatic interventions, culture results, islet yield, hospital days, posttransplant islet function, and posttransplant infections. We compared outcomes in patients with positive (n = 57) and negative (n = 29) cultures.

RESULTS

Patients with positive cultures had higher rates of previous pancreas surgery (P = 0.007) and endoscopic retrograde cholangiopancreatography (P < 0.0001). Positive cultures were not associated with posttransplant infections (P = 1.00) or prolonged hospital length of stay (P = 0.29). Patients with positive final islet preparation culture showed increased rates of graft failure at 2 years posttransplant (P = 0.041), but not when adjusted for islet mass transplanted (P = 0.39).

CONCLUSIONS

Positive cultures during pediatric TP-IATs do not increase the risk of posttransplant infections or prolong hospital length of stay. Endocrine function depends on islet mass transplanted.

A Multicenter Study: North American Islet Donor Score in Donor Pancreas Selection for Human Islet Isolation for Transplantation

Selection of an optimal donor pancreas is the first key task for successful islet isolation. We conducted a retrospective multicenter study in 11 centers in North America to develop an islet donor scoring system using donor variables. The data set consisting of 1,056 deceased donors was used for development of a scoring system to predict islet isolation success (defined as postpurification islet yield >400,000 islet equivalents). With the aid of univariate logistic regression analyses, we developed the North American Islet Donor Score (NAIDS) ranging from 0 to 100 points. The c index in the development cohort was 0.73 (95% confidence interval 0.70-0.76). The success rate increased proportionally as the NAIDS increased, from 6.8% success in the NAIDS < 50 points to 53.7% success in the NAIDS ≥ 80 points. We further validated the NAIDS using a separate set of data consisting of 179 islet isolations. A comparable outcome of the NAIDS was observed in the validation cohort. The NAIDS may be a useful tool for donor pancreas selection in clinical practice. Apart from its utility in clinical decision making, the NAIDS may also be used in a research setting as a standardized measurement of pancreas quality.

Development of Autoimmune-Mediated β Cell Failure After Total Pancreatectomy With Autologous Islet Transplantation

Total pancreatectomy with islet autotransplantation (TPIAT) is performed for definitive treatment of chronic pancreatitis; patients are not diabetic before surgery, or have C-peptide positive pancreatogenous diabetes. Thus, TPIAT recipients are not traditionally considered at risk for autoimmune loss of the islet graft. We describe a 43-year-old female who underwent TPIAT with high mass islet graft of 6031 IEQ/kg, with no evidence of presurgical β cell autoimmunity who developed type 1 diabetes within the first year after TPIAT, resulting in complete loss of beta cell function. The patient had positive GAD and insulin autoantibodies at 1 year and 18 months after TPIAT, not present prior, and undetectable C-peptide after mixed meal and intravenous glucose tolerance testing at 18 months. Glucagon secretion was preserved, suggesting the transplanted alpha cell mass was intact. HLA typing revealed a DR3/DR4 class II haplotype. This case highlights the need to consider de novo type 1 diabetes in patients with unexpected islet graft failure after TPIAT.

Positive sterility cultures of transplant solutions during pancreatic islet autotransplantation are associated infrequently with clinical infection

BACKGROUND

Chronic pancreatitis is a painful and often debilitating disease. Total pancreatectomy with intra-portal islet autotransplantation (TP-IAT) is a treatment option that allows for pain relief and preservation of beta-cell mass, thereby minimizing the complication of diabetes mellitus. Cultures of harvested islets are often positive for bacteria, possibly due to frequent procedures prior to TP-IAT, such as endoscopic retrograde cholangiopancreatography (ERCP), stenting, or other operative drainage procedures. It is unclear if these positive cultures contribute to post-operative infections.

HYPOTHESIS

We hypothesized that positive cultures of transplant solutions will not be associated with increased infection risk.

METHODS

We reviewed retrospectively the sterility cultures from both the pancreas preservation solution used to transport the pancreas and the final islet preparation for intra-portal infusion of patients who underwent TP-IAT between April 2006 and November 2012. Two hundred fifty-one patients underwent total, near-total, or completion pancreatectomy with IAT and had complete sterility cultures. All patients received prophylactic peri-operative antibiotics. Patients with positive pancreas preservation solution or islet sterility cultures received further antibiotics for 5-7 d. Patients' medical records were reviewed for post-operative infections and causative organisms.

RESULTS

Of the 251 patients included, 151 (61%) had one or more positive bacterial cultures from the pancreas preservation solution or final islet product. Seventy-three of the 251 patients (29%) had an infectious complication. Thirty-four of the 73 (22%) patients with a post-operative infectious complication also had positive cultures. Only seven of 151 patients with positive cultures (4.7%) had an infectious complication caused by the same organism as that isolated from their pancreas or islet cell preparation.

CONCLUSIONS

In autologous islet preparations, isolation solutions frequently have positive cultures, but this finding is associated infrequently with clinical infection.

Proposed thresholds for pancreatic tissue volume for safe intraportal islet autotransplantation after total pancreatectomy

The simple question of how much tissue volume (TV) is really safe to infuse in total pancreatectomy-islet autotransplantation (TP-IAT) for chronic pancreatitis (CP) precipitated this analysis. We examined a large cohort of CP patients (n = 233) to determine major risk factors for elevated portal pressure (PP) during islet infusion, using bivariate and multivariate regression modeling. Rates of bleeding requiring operative intervention and portal venous thrombosis (PVT) were evaluated. The total TV per kilogram body weight infused intraportally was the best independent predictor of change in PP (ΔPP) (p < 0.0001; R(2) = 0.566). Rates of bleeding and PVT were 7.73% and 3.43%, respectively. Both TV/kg and ΔPP are associated with increased complication rates, although ΔPP appears to be more directly relevant. Receiver operating characteristic analysis identified an increased risk of PVT above a suggested cut-point of 26 cmH2O (area under the curve = 0.759), which was also dependent on age. This ΔPP threshold was more likely to be exceeded in cases where the total TV was >0.25 cm(3)/kg. Based on this analysis, we have recommended targeting a TV of <0.25 cm(3)/kg during islet manufacturing and to halt intraportal infusion, at least temporarily, if the ΔPP exceeds 25 cmH2O. These models can be used to guide islet manufacturing and clinical decision making to minimize risks in TP-IAT recipients.

Metabolic assessment prior to total pancreatectomy and islet autotransplant: utility, limitations and potential

Islet autotransplant (IAT) may ameliorate postsurgical diabetes following total pancreatectomy (TP), but outcomes are dependent upon islet mass, which is unknown prior to pancreatectomy. We evaluated whether preoperative metabolic testing could predict islet isolation outcomes and thus improve assessment of TPIAT candidates. We examined the relationship between measures from frequent sample IV glucose tolerance tests (FSIVGTT) and mixed meal tolerance tests (MMTT) and islet mass in 60 adult patients, with multivariate logistic regression modeling to identify predictors of islet mass ≥2500 IEQ/kg. The acute C-peptide response to glucose (ACRglu) and disposition index from FSIVGTT correlated modestly with the islet equivalents per kilogram body weight (IEQ/kg). Fasting and MMTT glucose levels and HbA1c correlated inversely with IEQ/kg (r values -0.33 to -0.40, p ≤ 0.05). In multivariate logistic regression modeling, normal fasting glucose (<100 mg/dL) and stimulated C-peptide on MMTT ≥4 ng/mL were associated with greater odds of receiving an islet mass ≥2500 IEQ/kg (OR 0.93 for fasting glucose, CI 0.87-1.0; OR 7.9 for C-peptide, CI 1.75-35.6). In conclusion, parameters obtained from FSIVGTT correlate modestly with islet isolation outcomes. Stimulated C-peptide ≥4 ng/mL on MMTT conveyed eight times the odds of receiving ≥2500 IEQ/kg, a threshold associated with reasonable metabolic control postoperatively.

Prediction of pancreatic tissue densities by an analytical test gradient system before purification maximizes human islet recovery for islet autotransplantation/allotransplantation

BACKGROUND

Using standard density gradient (SDG) ranges for human islet purification frequently results in islet loss and transplantation of lower islet mass. Measuring the densities of islet and acinar tissue beforehand to customize the gradient range for the actual COBE 2991 cell processor (COBE) purification is likely to maximize the recovery of islets. We developed an analytical test gradient system (ATGS) for predicting pancreatic tissue densities before COBE purification to minimize islet loss during purification.

METHODS

Human islets were isolated from deceased donor (n=30) and chronic pancreatitis pancreata (n=30). Pancreatic tissue densities were measured before purification by the ATGS, and the density gradient range for islet purification in a COBE was customized based on density profiles determined by the ATGS. The efficiency of custom density gradients (CDGs) to recover high islet yield was compared with predefined SDGs.

RESULTS

Pancreatic tissue densities from autografts were significantly higher than in allograft preparations. In allograft purifications, a higher proportion of islets were recovered using ATGS-guided CDGs (85.9%±18.0%) compared with the SDG method (69.2%±27.0%; P=0.048). Acinar contamination at 60%, 70%, and 80% cumulative islet yield for allografts was significantly lower in the CDG group. In autograft purifications, more islets were recovered with CDGs (81.9%±28.0%) than SDGs (55.8%±22.8%; P=0.03). CDGs effectively reduced islet loss by minimizing islet sedimentation in the COBE bag.

CONCLUSIONS

Using ATGS-guided CDGs maximizes the islet recovery for successful transplantations by reducing acinar contamination in allograft preparations and by reducing sedimentation of islets in the COBE bag in autograft preparations.

Hysteresis in human HCN4 channels: a crucial feature potentially affecting sinoatrial node pacemaking

The hyperpolarization-activated cyclic nucleotide-gated (HCN) channels modulate and regulate cardiac rhythm and rate. It has been suggested that, unlike the HCN1 and HCN2 channels, the slower HCN4 channel may not exhibit voltage-dependent hysteresis. We studied the electrophysiological properties of human HCN4 (hHCN4) channels and its modulation by cAMP to determine whether hHCN4 exhibits hysteresis, by using single-cell patch-clamp in HEK293 cells stably transfected with hHCN4. Quantitative real-time RT-PCR was also used to determine levels of expression of HCNs in human cardiac tissue. Voltage-clamp analysis revealed that hHCN4 current (I(h)) activation shifted in the depolarizing direction with more hyperpolarized holding potentials. Triangular ramp and action potential clamp protocols also revealed hHCN4 hysteresis. cAMP enhanced I(h) and shifted activation in the depolarizing direction, thus modifying the intrinsic hHCN4 hysteresis behavior. Quantitative PCR analysis of human sinoatrial node (SAN) tissue showed that HCN4 accounts for 75% of the HCNs in human SAN while HCN1 (21%), HCN2 (3%), and HCN3 (0.7%) constitute the remainder. Our data suggest that HCN4 is the predominant HCN subtype in the human SAN and that I(h) exhibits voltage-dependent hysteresis behavior that can be modified by cAMP. Therefore, hHCN4 hysteresis potentially plays a crucial role in human SAN pacemaking activity.

Pericardial delivery of omega-3 fatty acid: a novel approach to reducing myocardial infarct sizes and arrhythmias

Basic and clinical evidence suggests that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) decrease fatal arrhythmias and infarct sizes. This study investigated if pericardial delivery of n-3 PUFAs would protect the myocardium from ischemic damages and arrhythmias. Acute myocardial infarctions were induced in 23 pigs with either 45 min balloon inflations or clamp occlusions of the left anterior descending coronary arteries and 180 min reperfusion. Docosahexaenoic acid (C22:6n-3, DHA, 45 mg), one of the main n-3 PUFAs in fish oil, was infused within the pericardial space only during the 40-min stabilizing phase, 45 min ischemia and initial 5 min reperfusion. Hemodynamics and cardiac functions were very similar between the DHA-treated and control groups. However, DHA therapy significantly reduced infarct sizes from 56.8 ± 4.9% for controls ( n = 12) to 28.8 ± 7.9% ( P < 0.01) for DHA-treated animals ( n = 11). Compared with controls, DHA-treated animals significantly decreased heart rates and reduced ventricular arrhythmia scores during ischemia. Furthermore, three (25%) control animals experienced eight episodes of ventricular fibrillation (VF), and two died subsequent to unsuccessful defibrillation. In contrast, only 1 (9%) of 11 DHA-treated pigs elicited one episode of VF that was successfully converted via defibrillation to normal rhythm; thus, mortality was reduced from 17% in the controls to 0% in the DHA-treated animals. These data demonstrate that pericardial infusion of n-3 PUFA DHA can significantly reduce both malignant arrhythmias and infarct sizes in a porcine infarct model. Pericardial administration of n-3 PUFAs could represent a novel approach to treating or preventing myocardial infarctions.

Electrophysiological characterization of murine HL-5 atrial cardiomyocytes

HL-5 cells are cultured murine atrial cardiomyocytes and have been used in studies to address important cellular and molecular questions. However, electrophysiological features of HL-5 cells have not been characterized. In this study, we examined such properties using whole cell patch-clamp techniques. Membrane capacitance of the HL-5 cells was from 8 to 62 pF. The resting membrane potential was −57.8 ± 1.4 mV ( n = 51). Intracellular injection of depolarizing currents evoked action potentials (APs) with variable morphologies in 71% of the patched cells. Interestingly, the incidence of successful, current-induced APs positively correlated with the hyperpolarizing degrees of resting membrane potentials ( r = 0.99, P < 0.001). Only a few of the patched cells (4 of 51, 7.8%) exhibited spontaneous APs. The muscarinic agonist carbachol activated the acetylcholine-activated K+ current and significantly shortened the duration of APs. Immunostaining confirmed the presence of the muscarinic receptor type 2 in HL-5 cells. The hyperpolarization-activated cation current ( If) was detected in 39% of the patched cells. The voltage to activate 50% of If channels was −73.4 ± 1.2 mV ( n = 12). Voltage-gated Na+, Ca2+, and K+ currents were observed in the HL-5 cells with variable incidences. Compared with the adult mouse cardiomyocytes, the HL-5 cells had prolonged APs and small outward K+ currents. Our data indicate that HL-5 cells display significant electrophysiological heterogeneity of morphological appearance of APs and expression of functional ion channels. Compared with adult murine cardiomyocytes, HL-5 cells show an immature phenotype of cardiac AP morphology.