Andrew J. Malcolm

Insulin-heparin infusions peritransplant substantially improve single-donor clinical islet transplant success

Background. Successful islet transplantation can result in insulin independence in many patients with type 1 diabetes mellitus, but it often requires more than one islet infusion. The ability to achieve insulin independence with a single donor is an important goal in clinical islet transplantation due to the limited organ supply. Methods. We examined factors that may be associated with insulin independence after islet transplantation with islets from a single donor, using univariate and multivariate analysis. Results. Thirteen of 85 (15.3%) achieved insulin independence after single-donor islet transplantation. Using multivariate analysis, only the use of insulin and heparin infusions peritransplant was a significant factor associated with insulin independence, with an adjusted odds ratio of 8.6 (95% confidence interval 2.0-37.0). Patients who had received insulin and heparin infusions peritransplant had greater indices of islet engraftment and a greater reduction in insulin use (80.1%±4.3% vs. 54.2%±2.8%, P<0.001) even if insulin independence was not achieved. Conclusions. Peritransplant intensive insulin and heparin enhances islet transplantation outcomes likely related in part to mitigation of the effects of the instant blood-mediated inflammatory reaction, combined with islet rest and avoidance of inflammation. It would be important to further investigate the effects of peritransplant insulin and heparin infusions on islet engraftment.

Preliminary Single-Center Canadian Experience of Human Normothermic Ex Vivo Liver Perfusion: Results of a Clinical Trial.

After extensive experimentation, outcomes of a first clinical normothermic machine perfusion (NMP) liver trial in the United Kingdom demonstrated feasibility and clear safety, with improved liver function compared with standard static cold storage (SCS). We present a preliminary single‐center North American experience using identical NMP technology. Ten donor liver grafts were procured, four (40%) from donation after circulatory death (DCD), of which nine were transplanted. One liver did not proceed because of a technical failure with portal cannulation and was discarded. Transplanted NMP grafts were matched 1:3 with transplanted SCS livers. Median NMP was 11.5 h (range 3.3–22.5 h) with one DCD liver perfused for 22.5 h. All transplanted livers functioned, and serum transaminases, bilirubin, international normalized ratio, and lactate levels corrected in NMP recipients similarly to controls. Graft survival at 30 days (primary outcome) was not statistically different between groups on an intent‐to‐treat basis (p = 0.25). Intensive care and hospital stays were significantly more prolonged in the NMP group. This preliminary experience demonstrates feasibility as well as potential technical risks of NMP in a North American setting and highlights a need for larger, randomized studies.

IgY antiporcine endothelial cell antibodies effectively block human antiporcine xenoantibody binding.

Avian IgY antibodies are structurally different from mammalian IgGs and do not fix mammalian complement components or bind human Fc receptors. As these antibody‐mediated interactions are believed to play significant roles in both hyperacute rejection (HAR) and acute vascular xenograft rejection (AVXR), IgY antibodies to xenoantigen target epitopes may inhibit these rejection processes. In this report, we show that chicken IgY antibodies to α‐Gal antigen epitopes and to other porcine aortic endothelial cell (PAEC) antigens block human xenoreactive natural antibody binding to both porcine and rat cardiac tissues and porcine kidney tissues. Chicken IgY antibodies blocked complement‐mediated lysis of PAECs by human serum, and inhibited antibody‐dependent cell‐mediated lysis of PAECs by heat‐inactivated human serum plus peripheral blood leukocytes. Binding of IgY to porcine endothelial cells did not affect cell morphology nor expression of E‐selectin. These results suggest that avian IgYs could be of potential use in inhibiting pig‐to‐human xenograft rejection.

Supplemental islet infusions restore insulin independence after graft dysfunction in islet transplant recipients.

Background. The ability of supplemental islet infusions (SII) to restore insulin independence in islet transplant recipients with graft dysfunction has been attributed to the coadministration of exenatide. However, improving islet transplant outcomes could explain the success of SII. We aimed to determine the effect on islet graft function and insulin independence of SII using these new protocols, without the use of exenatide. Methods. Seventeen islet transplant recipients underwent SIIs after developing graft dysfunction requiring insulin use. For induction therapy, four subjects received daclizumab induction therapy, whereas 13 subjects received thymoglobulin and etanercept. Maintenance immunosuppression consisted of sirolimus+tacrolimus or tacrolimus+cellcept. Results. SII was performed 49.3±4.8 months (mean±SEM) after the preceding islet transplant. Subjects received significantly lower islet mass with their SII compared with initial transplant(s) (6076±492 vs. 9071±796 IEQ/kg; P=0.003). Fifteen of the 17 subjects (88.2%) became insulin independent 2.4±0.5 months after SII. Insulin-independent duration after SII exceeded that of the initial transplant(s) (24.8±2.2 vs. 14.2±2.6 months by Kaplan-Meier analysis, P=0.009). Subjects show improved glycemic control after SII (HbA1c 7.0%±0.2% pre-SII vs. 6.1%±0.2% post-SII, P=0.005) and did not become immunosensitized. Conclusion. Using current protocols, SII in the absence of exenatide results in impressive insulin-independence rates and the durability of insulin independence seems to be promising. However, a beneficial effect of exenatide should not be discounted until tested in randomized controlled studies.

ALEMTUZUMAB INDUCTION AND TAC/MMF MAINTENANCE SUBSTANTIALLY IMPROVES LONG TERM INSULIN INDEPENDENCE RATES AFTER CLINICAL ISLET TRANSPLANTATION, AND STRONGLY SUPPRESSES BOTH AUTO AND ALLOREACTIVITY: 2026

A.M..J. Shapiro1, C. Toso2, A. Koh3, S.R. Calne4, T. Kin5, D. O’Gorman6, A. Malcolm3, P. Dinyari3, S. Imes3, R. Owen3, N.M. Kneteman7, D. Bigam8, P. Senior9, B. Roep10 1Surgery, University of Alberta, Edmonton/AB/CANADA, 2Visceral And Transplantation Surgery, Geneva University Hospitals, Geneva/ SWITZERLAND, 3Surgery, University of Alberta, Edmonton/ CANADA, 4Surgery, University of Cambridge, CB2 2AS/UNITED KINGDOM, 5Clinical Islet Transplant Program, University of Alberta, Edmonton/CANADA, 6Clincal Islet Labroatory, Alberta Helath Sevices, Edmonton/AB/CANADA, 7Department Of Surgery, University of Alberta, Edmonton/AB/CANADA, 8, University of Alberta, Edmonton/CANADA, 9Clincial Islet Transplant Program, University of Alberta, Edmonton/AB/CANADA, 10Dept Immunohaematology And Blood Transfusion, Leiden University Medical Center, NL-233ZA/ NETHERLANDS

Sitagliptin plus pantoprazole can restore but not maintain insulin independence after clinical islet transplantation: results of a pilot study.

Resuming insulin use due to waning function is common after islet transplantation. Animal studies suggest that gastrointestinal hormones, including gastrin and incretins may increase β–cell mass. We tested the hypothesis that pantoprazole plus sitagliptin, would restore insulin independence in islet transplant recipients with early graft insufficiency and determined whether this would persist after a 3–month washout.

Demonstration of a leukemia-associated antigen (CAMAL) in peripheral blood leucocytes of bone marrow transplant patients prior to relapse

We have previously described a monoclonal antibody (CAMAL-1) that reacts in an indirect immunoperoxidase slide test at high frequency with cells of patients with acute nonlymphoblastic leukemia (ANLL), both at presentation and in remission (1). This article reports on a 12-month blind study carried out on peripheral blood leukocytes (PBL) of patients who had received bone marrow transplants for acute leukemias. PBL of patients attending the Royal Marsden Hospital were sent as cytospins to the University of British Columbia for staining and screening. Results of this study showed the following: of the 15 patients who remained in remission during the period of the study, 13 showed no abnormal increase in reactivity with CAMAL-1 (2 patients did show increased levels of reactivity over time); of the four patients relapsing but surviving within this period with ANLL, all showed elevated numbers of cells reactive with CAMAL-1 as long as 3 months prior to relapse (the two relapsing patients who had acute undifferentiated leukemia and acute lymphoblastic leukemia did not show elevations of CAMAL-1-reactive cells); of the 14 patients dying during this time of causes other than leukemia, none had elevated levels of CAMAL-1-reactive cells--and, of 4 patients dying in relapse, all had extremely elevated levels of CAMAL-1-reactive cells as long as 4 months prior to relapse. The implications of these observations are discussed.

BMX‐001, a novel redox‐active metalloporphyrin, improves islet function and engraftment in a murine transplant model

Islet transplantation has become a well‐established therapy for select patients with type 1 diabetes. Viability and engraftment can be compromised by the generation of oxidative stress encountered during isolation and culture. We evaluated whether the administration of BMX‐001 (MnTnBuOE‐2‐PyP5+ [Mn(III) meso‐tetrakis‐(N‐b‐butoxyethylpyridinium‐2‐yl)porphyrin]) and its earlier derivative, BMX‐010 (MnTE‐2‐PyP [Mn(III) meso‐tetrakis‐(N‐methylpyridinium‐2‐yl)porphyrin]) could improve islet function and engraftment outcomes. Long‐term culture of human islets with BMX‐001, but not BMX‐010, exhibited preserved in vitro viability. Murine islets isolated and cultured for 24 hours with 34 μmol/L BMX‐001 exhibited improved insulin secretion (n = 3 isolations, P < .05) in response to glucose relative to control islets. In addition, 34 μmol/L BMX‐001–supplemented murine islets exhibited significantly reduced apoptosis as indicated by terminal deoxynucleotidyl transferase dUTP nick end labeling, compared with nontreated control islets (P < .05). Murine syngeneic islets transplanted under the kidney capsule at a marginal dose of 150 islets revealed 58% of 34 μmol/L BMX‐001–treated islet recipients became euglycemic (n = 11 of 19) compared with 19% of nontreated control islet recipients (n = 3 of 19, P < .05). Of murine recipients receiving a marginal dose of human islets cultured with 34 μmol/L BMX‐001, 92% (n = 12 of 13) achieved euglycemia compared with 57% of control recipients (n = 8 of 14, P = .11). These results demonstrate that the administration of BMX‐001 enhances in vitro viability and augments murine marginal islet mass engraftment.

Photoacoustic imaging of angiogenesis in a subcutaneous islet transplant site in a murine model

Abstract. Islet transplantation (IT) is an established clinical therapy for select patients with type-1 diabetes. Clinically, the hepatic portal vein serves as the site for IT. Despite numerous advances in clinical IT, limitations remain, including early islet cell loss posttransplant, procedural complications, and the inability to effectively monitor islet grafts. Hence, alternative sites for IT are currently being explored, with the subcutaneous space as one potential option. When left unmodified, the subcutaneous space routinely fails to promote successful islet engraftment. However, when employing the previously developed subcutaneous “deviceless” technique, a favorable microenvironment for islet survival and function is established. In this technique, an angiocatheter was temporarily implanted subcutaneously, which facilitated angiogenesis to promote subsequent islet engraftment. This technique has been employed in preclinical animal models, providing a sufficient means to develop techniques to monitor functional aspects of the graft such as angiogenesis. Here, we utilize photoacoustic imaging to track angiogenesis during the priming of the subcutaneous site by the implanted catheter at 1 to 4 weeks postcatheter. Quantitative analysis on vessel densities shows gradual growth of vasculature in the implant position. These results demonstrate the ability to track angiogenesis, thus facilitating a means to optimize and assess the pretransplant microenvironment.

Comparison of metabolic responses to the mixed meal tolerance test vs the oral glucose tolerance test after successful clinical islet transplantation

Following islet transplantation, mixed meal tolerance tests (MMTs) are routinely utilized to assess graft function, but how the 90‐minute MMTT glucose value relates to a 120‐minute glucose concentration of ≥11.1 mmol/L used to diagnose diabetes following a standardized 75 g‐OGTT, is not known. We examined this relationship further. Thirteen subjects with Type 1 diabetes and stable transplant grafts, not on exogenous insulin with HbA1c < 7% (53 mmol/mol), were studied on 17 occasions with paired OGTTs and MMTTs. Receiver operating characteristic (ROC) curves were constructed to derive the 90‐minute MMTT glucose threshold associated with a 120‐minute glucose concentration following a 75 g‐OGTT (OGTT120) ≥11.1 mmol/L and their diagnostic accuracy. Studies with OGTT120 ≥11.1 mmol/L (n = 5) had diminished C‐peptide: glucose, greater integrated glucose and diminished insulin: glucose area under the curve (AUC) ratios (0‐120 minutes) and disposition indices; all P < .05, contrasting with MMTTs where no difference in the 90‐minute glucose concentrations, C‐peptide:glucose, integrated glucose, C‐peptide and C‐peptide: glucose AUCs (0‐90 minutes) was seen; all P > .05. A 90‐minute MMTT glucose concentration ≥8.0 mmol/L demonstrated a sensitivity and specificity of ≥80% for the diagnosis of OGTT120 ≥11.1 mmol/L; area under ROC curve (mean ± SEM) 73 ± 13%. A 90‐minute MMTT glucose ≥8.0 mmol/L, identifies islet transplant recipients who may require closer monitoring for graft dysfunction.