Islet Infusion Research Articles

Alpha-1 Antitrypsin Augmentation Therapy in Chronic Pancreatitis Patients Undergoing Total Pancreatectomy and Islet Autotransplantation: A Randomized, Controlled Study.

Stress-induced islet graft loss during the peri-transplantation period reduces the efficacy of islet transplantation. In this prospective, randomized, double-blind clinical trial, we evaluated the safety and efficacy of 60 mg/kg human alpha-1 antitrypsin (AAT) or placebo infusion weekly for four doses beginning before surgery in chronic pancreatitis (CP) patients undergoing total pancreatectomy and islet autotransplantation (TP-IAT). Subjects were followed for 12 months post-TP-IAT. The dose of AAT was safe, as there was no difference in the types and severity of adverse events in participants from both groups. There were some biochemical signals of treatment effect with a higher oxygen consumption rate in AAT islets before transplantation and a lower serum C-peptide (an indicator of islet death) in the AAT group at 15 min after islet infusion. Findings per the statistical analysis plan using a modified intention to treat analysis showed no difference in the C-peptide area under the curve (AUC) following a mixed meal tolerance test at 12 months post-TP-IAT. There was no difference in the secondary and exploratory outcomes. Although AAT therapy did not show improvement in C-peptide AUC in this study, AAT therapy is safe in CP patients and there are experiences gained on optimal clinical trial design in this challenging disease.

Impact of GAD65 and IA2 autoantibodies on islet allograft survival.

Islet transplantation (ITx) shows promise in treating T1D, but the role of islet autoantibodies on graft survival has not been clearly elucidated. We aimed to analyze the effect of GAD65 and IA2 autoantibody status on graft survival and attainment of insulin independence in subjects with T1D who underwent ITx. We conducted a retrospective cohort study on 47 ITx recipients from 2000 to 2018. Islet infusion was performed via intrahepatic portal (n=44) or onto the omentum via laparoscopic approach (n=3). Immunosuppression involved anti-IL2 receptor antibody, anti-TNF, and dual combinations of sirolimus, tacrolimus, or mycophenolate mofetil (Edmonton-like) in 38 subjects (80.9%). T-cell depletion induction with Edmonton-like maintenance was used in 9 subjects (19%). GAD65 and IA2 autoantibodies were assessed pre-transplant and post-transplant (monthly) until graft failure, and categorized as persistently negative, persistently positive, or seroconverters. Graft survival was analyzed using U-Mann-Whitney test, and Quade's nonparametric ANCOVA adjusted for confounders. Kaplan-Meier and Log-Rank tests were employed to analyze attainment of insulin independence. P value <0.05 indicated statistical significance. ITx recipients with persistent autoantibody negativity (n = 21) showed longer graft function (98 [61 - 182] months) than those with persistent autoantibody positivity (n = 18; 38 [13 - 163] months), even after adjusting for immunosuppressive induction protocol (P = 0.027). Seroconverters (n=8) had a median graft survival time of 73 (7.7 - 167) months, which did not significantly differ from the other 2 groups. Subjects with persistently single antibody positivity to GAD65 (n = 8) had shorter graft survival compared to negative islet autoantibody (GAD65/IA2) subjects (n = 21; P = 0.016). Time of graft survival did not differ in subjects with single antibody positivity to IA2. The proportion of insulin independence attainment was similar irrespective of autoantibody status. The persistence of islet autoantibodies, as markers of islet autoimmunity, may represent an underappreciated contributing factor to the failure of transplanted β cells. Whether induction with T-cell depletion may lead to improved graft survival, independent of islet autoantibody status, could not be evaluated in our cohort. Larger prospective studies are needed to further address the role of islet autoantibody status on islet graft survival.

Clinical and biological significance of circulating miRNAs in chronic pancreatitis patients undergoing total pancreatectomy with islet autotransplantation.

Specific microRNAs (miRNAs) were elevated in chronic pancreatitis (CP) patients during islet infusion after total pancreatectomy (TPIAT). We aimed to identify circulating miRNA signatures of pancreatic damage, predict miRNA-mRNA networks to identify potential links to CP pathogenesis and identify islet isolation and transplantation functional outcomes. Small RNA sequencing was performed to identify distinct circulating miRNA signatures in CP. Plasma miRNAs were measured using miRCURY LNA SYBR green quantitative real-time polymerase chain reaction assays. Correlation analyses were performed using R software. The miRNA target and disease interactions were determined using miRNet and the miRNA enrichment and annotation tool. Alterations were found in circulating miRNAs in CP patients compared to healthy controls. Further studies were conducted on 12 circulating miRNAs enriched in the pancreas, other tissues and other diseases including cancer and fibrosis. Approximately 2888 mRNAs in the pancreas were their targets, demonstrating interactions with 76 small molecules. Three miRNAs exhibited interactions with morphine and five exhibited interactions with glucose. The miRNA panel targeted 22 genes associated with pancreatitis. The islet-specific, acinar cell-specific and liver-specific miRNAs were elevated at 6h after islet infusion and returned to baseline levels 3 months after TPIAT. Circulating levels of miRNAs returned to pre-transplant levels 1-year post-transplant. Circulating miRNAs measured before and 6h after islet infusion were directly or inversely associated with metabolic outcomes at 3 and 6 months post-transplant. miRNAs may contribute to CP pathogenesis, and elevated circulating levels may be specific to pancreatic inflammation and fibrosis, warranting further investigation.

203.2: Changes in portal pressure, blood glucose, and blood pressure levels during islet infusion in pediatric patients: Close monitoring for every five minutes during islet auto-transplantation

203.2: Changes in portal pressure, blood glucose, and blood pressure levels during islet infusion in pediatric patients: Close monitoring for every five minutes during islet auto-transplantation

Pancreatic Islet Viability Assessment Using Hyperspectral Imaging of Autofluorescence.

Islets prepared for transplantation into type 1 diabetes patients are exposed to compromising intrinsic and extrinsic factors that contribute to early graft failure, necessitating repeated islet infusions for clinical insulin independence. A lack of reliable pre-transplant measures to determine islet viability severely limits the success of islet transplantation and will limit future beta cell replacement strategies. We applied hyperspectral fluorescent microscopy to determine whether we could non-invasively detect islet damage induced by oxidative stress, hypoxia, cytokine injury, and warm ischaemia, and so predict transplant outcomes in a mouse model. In assessing islet spectral signals for NAD(P)H, flavins, collagen-I, and cytochrome-C in intact islets, we distinguished islets compromised by oxidative stress (ROS) (AUC = 1.00), hypoxia (AUC = 0.69), cytokine exposure (AUC = 0.94), and warm ischaemia (AUC = 0.94) compared to islets harvested from pristine anaesthetised heart-beating mouse donors. Significantly, with unsupervised assessment we defined an autofluorescent score for ischaemic islets that accurately predicted the restoration of glucose control in diabetic recipients following transplantation. Similar results were obtained for islet single cell suspensions, suggesting translational utility in the context of emerging beta cell replacement strategies. These data show that the pre-transplant hyperspectral imaging of islet autofluorescence has promise for predicting islet viability and transplant success.

Unlocking the post-transplant microenvironment for successful islet function and survival.

Islet transplantation (IT) offers the potential to restore euglycemia for patients with type 1 diabetes mellitus (T1DM). Despite improvements in islet isolation techniques and immunosuppressive regimes, outcomes remain suboptimal with UK five-year graft survivals (5YGS) of 55% and most patients still requiring exogenous insulin after multiple islet infusions. Native islets have a significant non-endocrine component with dense extra-cellular matrix (ECM), important for islet development, cell survival and function. Collagenase isolation necessarily disrupts this complex islet microenvironment, leaving islets devoid of a supporting framework and increasing vulnerability of transplanted islets. Following portal venous transplantation, a liver injury response is potentially induced, which typically results in inflammation and ECM deposition from liver specific myofibroblasts. The impact of this response may have important impact on islet survival and function. A fibroblast response and ECM deposition at the kidney capsule and eye chamber alongside other implantation sites have been shown to be beneficial for survival and function. Investigating the implantation site microenvironment and the interactions of transplanted islets with ECM proteins may reveal therapeutic interventions to improve IT and stem-cell derived beta-cell therapy.

137-LB: Modified Personal Glycemic State Model Predicts the Need for Islet Transplantation in Human

Continuous glucose monitoring (CGM) has become a valuable tool for assessing glycemic control. The personal glycemic state (PGS)1 is a mathematical model that considers 5 CGM data elements (mean blood glucose, percent time in range, glucose variability percentage, and frequency of moderate and severe hypoglycemia) equally to generate a score representing the degree of metabolic control. Our adapted personal glycemic state for islet transplant (PGSFIT) targets normoglycemia in islet transplantation by limiting the percent time in range to 70-140mg/dl instead of commonly used 70-180mg/dl, and uses weighted components without limiting the influence of any individual component on the total score. This allowed us to account for T1D patients keeping blood glucose high to avoid hypoglycemia or low to avoid long term complications despite increased hypoglycemia. Using PGS and PGSFIT to analyze glycemic control in 16 subjects with T1D post allogenic islet transplantations showed concordance in classifying the glycemic control as acceptable (PGS/PGSFIT &amp;lt;15) or unacceptable (≥15) in 88% of the cases when variability was low (standard deviation of PGS components ≤ 0.1), and both PGSFIT and PGS models had excellent correlation with fasting c-peptide results. In contrast, when variability was high (standard deviation of PGS components &amp;gt; 0.1), 71% of patients deemed clinically suitable for repeat transplant had PGSFIT score ≥15 but only 14% had PGS score ≥15. In patients who had not yet received their final islet infusion, high parameter variability and PGSFIT ≥15 was associated with lower fasting C-peptide compared to patients with high parameter variability and PGSFIT ≤15 who received the maximum therapeutic dose. PGSFIT significantly improved after repeat transplant in patients with high PGSFIT and high component variability. These results suggest PGSFIT may also be used to identify subjects suitable for first islet transplant. Disclosure C. Orr: None. J. Hacker-stratton: None. M. El-shahawy: None. E. Forouhar: None. K. Omori: None. M. Qi: None. F. R. Kandeel: None. Funding National Institutes of Health (U24DK098085)

A Multi-Modal Approach to Islet and Pancreas Transplantation With Calcineurin-Sparing Immunosuppression Maintains Long-Term Insulin Independence in Patients With Type I Diabetes.

Long-term success in beta-cell replacement remains limited by the toxic effects of calcineurin inhibitors (CNI) on beta-cells and renal function. We report a multi-modal approach including islet and pancreas-after-islet (PAI) transplant utilizing calcineurin-sparing immunosuppression. Ten consecutive non-uremic patients with Type 1 diabetes underwent islet transplant with immunosuppression based on belatacept (BELA; n = 5) or efalizumab (EFA; n = 5). Following islet failure, patients were considered for repeat islet infusion and/or PAI transplant. 70% of patients (four EFA, three BELA) maintained insulin independence at 10years post-islet transplant, including four patients receiving a single islet infusion and three patients undergoing PAI transplant. 60% remain insulin independent at mean follow-up of 13.3 ± 1.1years, including one patient 9years after discontinuing all immunosuppression for adverse events, suggesting operational tolerance. All patients who underwent repeat islet transplant experienced graft failure. Overall, patients demonstrated preserved renal function, with a mild decrease in GFR from 76.5 ± 23.1mL/min to 50.2 ± 27.1mL/min (p = 0.192). Patients undergoing PAI showed the greatest degree of renal impairment following initiation of CNI (56% ± 18.7% decrease in GFR). In our series, repeat islet transplant is ineffective at maintaining long-term insulin independence. PAI results in durable insulin independence but is associated with impaired renal function secondary to CNI dependence.

Ultrasound-Guided Human Islet Transplantation: Safety, Feasibility, and Efficacy Analysis

We aimed to analyze the safety, feasibility, and efficacy of human islet transplantation (IT) using ultrasound (US) throughout the entire procedure. A total of 22 recipients (18 males; mean age 42.6±17.5years) with 35 procedures were retrospective included. Under US guidance, percutaneous transhepatic portal catheterization was successfully performed through a right-sided transhepatic approach, and islets were infused into the main portal vein. Color Doppler and contrast-enhanced ultrasound were used to guide the procedure and monitor the complications. After infusion of the islet mass, the access track wasembolized by embolic material. If hemorrhage persisted, US-guided radiofrequency ablation (RFA) was performed to stop bleeding. Factors that could affect the complication were analyzed. After transplantation, primary graft function was evaluated with a β-score 1month after the last islet infusion. The technical success rates were 100% with a single puncture attempt. Six (17.1%) abdominal bleeding episodes were immediately stopped by US-guided RFA. No portal vein thrombosis were encountered. Dialysis (OR (Odd Ratio): 32.0; 95% CI: 1.561-656.054; and P=.025) was identified as a significant factor associated with bleeding. Primary graft function was optimal in eight patients (36.4%), suboptimal in 13 patients (59.1%), and poor in one patient (4.5%). In conclusion, whole-procedure US-guided IT is a safe, feasible, and effective method for diabetes. Complications are either self-limiting or manageable with noninvasive treatment.

Engineering islet surface with a novel form of thrombomodulin protein to mitigate instant blood-mediated inflammatory reaction following intraportal transplantation

Abstract Intraportal infusion of islets initiates an innate immune response termed instant blood-mediated inflammatory reaction (IBMIR) that is responsible for significant islet mass peritransplant. We herein used thrombomodulin (TM) as a multifaceted innate immune regulator to mitigate IBMIR to prevent the destruction of islets in a minimal mass syngeneic intraportal transplantation model. A novel form of TM molecule chimeric with streptavidin (SA-TM) was produced in insect cells and characterized for structure and attachment to biotinylated cell surface taking advantage of the high affinity interaction of biotin with streptavidin (SA). Islets were engineered with SA-TM and assessed for the ability to mitigate IBMIR in an in vitro blood loop assay and survival following intraportal transplantation (200 IEQ/mouse) in STZ diabetic mice (n=7). SA-engineered islets served as control (n=6). Animals were monitored for islet engraftment and subjected to various mechanistic studies. SA-TM prevented phagocytosis of xenogeneic cells by macrophages and inhibited neutrophil NETs formation. Engineering islets with SA-TM did not impact the viability and function of islets and prevented damage in a blood loop assay. SA-TM-engineered islets showed enhanced engraftment compared to SA-engineered islets (83% vs 29%) following transplantation. Enhanced engraftment was associated with decreased frequency of intragraft myeloid cells and expression of various inflammatory mediators, such as HMGB-1, tissue factor, and IL-1β. Engineering islets with the SA-TM protein provides a facile and clinically applicable approach to modulate innate immune responses for prevention of IBMIR with potential applications to allo/auto islet transplantation. Funded in parts by NIH U01AI132817 and R01AI121281 grants.

Association between primary graft function and 5-year outcomes of islet allogeneic transplantation in type 1 diabetes: a retrospective, multicentre, observational cohort study in 1210 patients from the Collaborative Islet Transplant Registry

Allogeneic islet transplantation is a validated therapy in type 1 diabetes; however, there is decline of transplanted islet graft function over time and the mechanisms underlying this decline are unclear. We evaluated the distinct association between primary graft function (PGF) and 5-year islet transplantation outcomes. In this retrospective, multicentre, observational cohort study, we enrolled all patients from the Collaborative Islet Transplant Registry who received islet transplantation alone (ITA recipients) or islet-after-kidney transplantation (IAK recipients) between Jan 19, 1999, and July 17, 2020, with a calculable PGF (exposure of interest), measured 28 days after last islet infusion with a validated composite index of islet graft function (BETA-2 score). The primary outcome was cumulative incidence of unsuccessful islet transplantation, defined as an HbA1c of 7·0% (53 mmol/mol) or higher, or severe hypoglycaemia (ie, requiring third-party intervention to correct), or a fasting C-peptide concentration of less than 0·2 ng/mL. Secondary outcomes were graft exhaustion (fasting C-peptide <0·3 ng/mL); inadequate glucose control (HbA1c ≥7·0% [53 mmol/mol] or severe hypoglycaemia); and requirement for exogenous insulin therapy (≥14 consecutive days). Associations between PGF and islet transplantation outcomes were explored with a competing risk analysis adjusted for all covariates suspected or known to affect outcomes. A predictive model based on PGF was built and internally validated by using bootstraps resampling method. In 39 centres worldwide, we enrolled 1210 patients with a calculable PGF (of those without missing data, mean age 47 years [SD 10], 712 [59·5%] were female, and 865 (97·9%) were White), who received a median of 10·8 thousand islet-equivalents per kg of bodyweight (IQR 7·4-13·5). 986 (82·4%) were ITA recipients and 211 (17·6%) were IAK recipients. Of 1210 patients, 452 (37·4%) received a single islet infusion and 758 (62·6%) received multiple islet infusions. Mean PGF was 14·3 (SD 8·8). The 5-year cumulative incidence of unsuccessful islet transplantation was 70·7% (95% CI 67·2-73·9), and was inversely and linearly related to PGF, with an adjusted subhazard ratio (sHR) of 0·77 (95% CI 0·72-0·82) per 5-unit increase of BETA-2 score (p<0·0001). Secondary endpoints were similarly related to PGF. The model-adjusted median C-statistic values of PGF for predicting 5-year cumulative incidences of unsuccessful islet transplantation, graft exhaustion, inadequate glucose control, and exogenous insulin therapy were 0·70 (range 0·69-0·71), 0·76 (0·74-0·77), 0·65 (0·64-0·66), and 0·72 (0·71-0·73), respectively. This global multicentre study reports a linear and independent association between PGF and 5-year clinical outcomes of islet transplantation. The main study limitations are its retrospective design and the absence of analysis of complications. Public Health Service Research, National Institutes of Health, Juvenile Diabetes Research Foundation International, Agence National de la Recherche, Fondation de l'Avenir, and Fonds de Dotation Line Renaud-Loulou Gasté.

Matching for HLA-DR excluding diabetogenic HLA-DR3 and HLA-DR4 predicts insulin independence after pancreatic islet transplantation.

In pancreatic islet transplantation, the exact contribution of human leukocyte antigen (HLA) matching to graft survival remains unclear. Islets may be exposed to allogenic rejection but also the recurrence of type 1 diabetes (T1D). We evaluated the HLA-DR matching, including the impact of diabetogenic HLA-DR3 or HLA-DR4 matches. We retrospectively examined the HLA profile in 965 transplant recipients and 2327 islet donors. The study population was obtained from patients enrolled in the Collaborative Islet Transplant Registry. We then identified 87 recipients who received a single-islet infusion. Islet-kidney recipients, 2nd islet infusion, and patients with missing data were excluded from the analysis (n=878). HLA-DR3 and HLA-DR4 were present in 29.7% and 32.6% of T1D recipients and 11.6% and 15.8% of the donors, respectively. We identified 52 T1D islet recipients mismatched for HLA-DR (group A), 11 with 1 or 2 HLA-DR-matches but excluding HLA-DR3 and HLA- DR4 (group B), and 24 matched for HLA-DR3 or HLA-DR4 (group C). Insulin-independence was maintained in a significantly higher percentage of group B recipients from year one through five post-transplantation (p<0.01). At five-year post-transplantation, 78% of group B was insulin-independent compared to 24% (group A) and 35% (group C). Insulin-independence correlated with significantly better glycemic control (HbA1c <7%), fasting blood glucose, and reduced severe hypoglycemic events. Matching HLA-A-B-DR (≥3) independently of HLA- DR3 or HLA-DR4 matching did not improve graft survival. This study suggests that matching HLA-DR but excluding the diabetogenic HLA-DR3 and/or 4 is a significant predictor for long-term islet survival.

Implantation underneath the abdominal anterior rectus sheath enables effective and functional engraftment of stem-cell-derived islets

Human pluripotent stem cell-derived islets (hPSC islets) are a promising alternative to primary human islets for the treatment of insulin-deficient diabetes. We previously demonstrated the feasibility of this approach in nonhuman primates; however, the therapeutic effects of hPSC islets can be limited by the maladaptive processes at the transplantation site. Here, we demonstrate successful implantation of hPSC-derived islets in a new transplantation site in the abdomen, the subanterior rectus sheath, in eight nonhuman primates (five male and three female). In this proof-of-principle study, we find that hPSC islets survive and gradually mature after transplantation, leading to improved glycemic control in diabetic primates. Notably, C-peptide secretion responds to meal challenge from 6 weeks post-transplantation (wpt), with stimulation indices comparable to those of native islets. The average post-prandial C-peptide level reaches approximately 2.0 ng ml-1 from 8 wpt, which is five times higher than the peak value we previously obtained after portal vein infusion of hPSC islets and was associated with a decrease of glycated hemoglobin levels by 44% at 12 wpt. Although additional studies in larger cohorts involving long-term follow-up of transplants are needed, our results indicate that the subanterior rectus sheath supports functional maturation and maintenance of hPSC islets, suggesting that it warrants further exploration as a transplantation target site in the context of for hPSC-based cell-replacement therapies.

Factors associated with favourable 5 year outcomes in islet transplant alone recipients with type 1 diabetes complicated by severe hypoglycaemia in the Collaborative Islet Transplant Registry.

Islet transplantation has been studied in small cohorts of recipients with type 1 diabetes complicated by severe hypoglycaemic events (SHEs). We determined factors associated with favourable outcomes in a large cohort of recipients reported to the Collaborative Islet Transplant Registry (CITR). In 398 non-uraemic islet transplant alone (ITA) recipients with type 1 diabetes and SHEs, transplanted between 1999 and 2015 and with at least 1 year follow-up, we analysed specified favourable outcomes against each of all available characteristics of pancreas donors, islet grafts, recipients and immunosuppressive regimens, as well as immunosuppression and procedure-related serious adverse events (SAEs). Four factors were associated with the highest rates of favourable outcomes: recipient age ≥35 years; total infused islets ≥325,000 islet equivalents; induction immunosuppression with T cell depletion and/or TNF-α inhibition; and maintenance with both mechanistic target of rapamycin (mTOR) and calcineurin inhibitors. At 5 years after the last islet infusion, of the recipients meeting these four common favourable factors (4CFF; N=126), 95% were free of SHEs, 76% had HbA1c <53 mmol/mol (7.0%), 73% had HbA1c <53 mmol/mol (7.0%) and absence of SHEs, and 53% were insulin independent, significantly higher rates than in the remaining recipients (<4CFF; N=272). The incidence of procedural and immunosuppression-related SAEs per recipient that resulted in sequelae, disability or death was low in both the 4CFF (0.056 per person) and <4CFF (0.074 per person) groups. In recipients with type 1 diabetes complicated by SHEs, islet transplantation meeting 4CFF protected 95% from SHEs at 5 years after the last islet infusion and exerted a large and significant benefit on glycaemic control, with an acceptable safety profile for this subgroup of type 1 diabetes.

214.1: Strategies to Achieve Long-term Insulin Independence Using a Multimodal Approach to Beta-cell Replacement in Patients With Type I Diabetes

Purpose: Beta cell replacement, via islet or solid organ pancreas transplant, remains the best strategy to restore insulin independence in patients with Type 1 diabetes mellitus (T1DM). Insulin independence beyond ten years is limited, with calcineurin inhibitors (CNI) contributing to beta cell toxicity and impairing renal function. Here, we report long-term results for multimodal beta cell replacement including islet and pancreas after islet (PAI) transplant with CNI-free immunosuppression (IS) regimens based on Belatacept (BELA) and Efalizumab (EFA). Methods: Ten non-uremic patients with severe T1DM received their first islet cell transplant between 2007 and 2009 with CNI-sparing IS based on BELA (n=5) or EFA (n=5). Patients were monitored for a mean of 12.9 ± 1.1 years from islet transplant for beta cell function and renal function. Following islet failure, patients were considered for repeat islet infusion and/or PAI transplant. Circulating immunologic phenotype was characterized in the first year. Results: Seven of 10 patients (70%) maintained insulin independence with normalization of HbA1c (3 BELA, 4 EFA) at 10 years post-islet transplant; four patients (2 EFA, 2 BELA) achieved long-term insulin independence after one islet infusion and three additional patients (2 EFA, 1 BELA) following PAI transplantation (Figure 1, Figure 2). Six of 10 (60%) remain insulin independent currently, at a mean follow-up of 13.3 ± 1.1 years from islet transplant. Eight of 10 patients (80%) maintained renal function with less than 30% decrease in GFR and without progression to stage 4 or stage 5 CKD (Figure 2). One patient progressed to stage 4 CKD following initiation of tacrolimus for PAI, and another progressed to stage 5 CKD after islet failure and return to full insulin dependence. Patients receiving EFA demonstrated profound expansion of circulating CD4+Foxp3+ regulatory T cells (Tregs). One patient (EFA-4) demonstrated Tregs comprising 68% of all circulating CD4+ T cells, and remains insulin independent despite discontinuing all immunosuppression, thus demonstrating the first reported case of operational tolerance in islet transplantation. Conclusions: Our results describe a multi-modal, personalized approach to beta-cell replacement. In our series, repeat islet transplant is ineffective at maintaining long-term insulin independence. PAI results in durable insulin independence but is associated with deterioration of renal function secondary to CNI dependence. EFA-based immunosuppression resulted in significant expansion of Tregs following transplantation, with one islet recipient establishing operational tolerance.Juvenile Diabetes Research Foundation (4-2004-372). NIH P30 (DK63720). NIH UO1 (AIO65193). CRC UL1 (RR024131). NIH T32 (AI125222).

Immune-Protective Formulations and Process Strategies for Improved Survival and Function of Transplanted Islets.

Type 1 diabetes (T1D) is an autoimmune disease caused by the immune system attacking and destroying insulin-producing β cells in the pancreas. Islet transplantation is becoming one of the most promising therapies for T1D patients. However, its clinical use is limited by substantial cell loss after islet infusion, closely related to immune reactions, including instant blood-mediated inflammatory responses, oxidative stress, and direct autoimmune attack. Especially the grafted islets are not only exposed to allogeneic immune rejection after transplantation but are also subjected to an autoimmune process that caused the original disease. Due to the development and convergence of expertise in biomaterials, nanotechnology, and immunology, protective strategies are being investigated to address this issue, including exploring novel immune protective agents, encapsulating islets with biomaterials, and searching for alternative implantation sites, or co-transplantation with functional cells. These methods have significantly increased the survival rate and function of the transplanted islets. However, most studies are still limited to animal experiments and need further studies. In this review, we introduced the immunological challenges for islet graft and summarized the recent developments in immune-protective strategies to improve the outcomes of islet transplantation.

Perioperative Coagulation Changes in Total Pancreatectomy and Islet Autotransplantation.

Thrombotic complications after total pancreatectomy with islet autotransplantation (TPIAT) are common. However, the systemic changes to coagulation in the perioperative period have not been well studied. Our objective was to evaluate the derangements in coagulation in the perioperative period for this procedure. This was a prospective observational study of patients undergoing elective TPIAT for chronic pancreatitis. Multiple methods of evaluating coagulation, including 2 viscoelastic assays and standard laboratory assays were obtained at defined intraoperative and postoperative intervals. Fifteen patients were enrolled. Laboratory values demonstrated initial intraoperative hypercoagulability before significant systemic anticoagulation after islet infusion with heparin. Hypercoagulability is again seen at postoperative days 3 and 7. Subgroup analysis did not identify any major coagulation parameters associated with portal vein thrombosis formation. Apart from the immediate period after islet cell and heparin infusion, patients undergoing TPIAT are generally hypercoagulable leading to a high rate of thrombotic complications. Portal vein thrombosis development had minimal association with systemic derangements in coagulation as it is likely driven by localized inflammation at the time of islet cell infusion. This study may provide the groundwork for future studies to identify improvements in thrombotic complications.

304-OR: Proteomic Profile and Inflammatory Response of Islet Stressomes Released during Isolation

Purpose: Islets undergo enormous stress during isolation and peri-transplant periods which causes a significant release of stressomes (exosomes released during stress) . Uncovering the biological role of such vesicles is vital for long-term graft function and survival. Here, we sought to identify the global protein content and significance of stressomes isolated during isolation in autologous islet transplantation (AIT) . Methods: Post-transplant stress was mimicked in vitro by exposing human islets to hypoxia and cytokines (Cyt+Hyp) . Stressome protein contents were characterized by mass spectrometry and immunoblotting. Similar stressomes were also isolated from the islet infusion bag samples of AIT recipients (N=20) . The stressome protein levels were correlated with 1-year AIT outcomes. Finally, these islet stressomes were treated to another set of purified islets and macrophages to find their uptake and immune response. Results: The mass spectrometry analysis has revealed the islet stressomes contain DAMP proteins like histones (H2B, H3, and H4) . The canonical ER stress signal plays a crucial role in the biogenesis of islet stressomes induced by (Cyt+Hyp) . Exosomes isolated from the infusion bags showed an elevated histone level in the insulin-dependent (ID) group. Moreover, high levels of DAMP proteins were positively correlated with increased post-transplant recipients insulin requirements (p=0.029) . The fluorescent confocal microscopy analysis has revealed these stressomes were easily uptaken by the macrophages and also conferred an inflammatory phenotype. Instead, the stressome treated islets showed elevated expression of innate immune receptors like TLR2 and AGTR1. Conclusion: The study has identified the islet stressome global protein content and briefs its prospective to induce islet inflammation and graft loss in AIT. Disclosure P.Saravanan: None. J.Kalivarathan: None. M.F.Levy: Research Support; Vertex Pharmaceuticals Incorporated, Speaker's Bureau; AbbVie Inc., Sanofi Genzyme. M.A.Kanak: None.

Outcomes Following Extrahepatic and Intraportal Pancreatic Islet Transplantation: A Comparative Cohort Study.

Preliminary studies show promise for extrahepatic islet transplantation (ITx). However, clinical comparisons with intraportal ITx outcomes remain limited. This single-center cohort study evaluates patients receiving extrahepatic or intraportal ITx between 1999 and 2018. Primary outcome was stimulated C-peptide level. Secondary outcomes were fasting plasma glucose, BETA-2 scores, and fasting C-peptide level. Multivariable logistic modeling evaluated factors independently associated with a composite variable of early graft failure and primary nonfunction within 60 d of ITx. Of 264 patients, 9 (3.5%) received extrahepatic ITx (gastric submucosal = 2, subcutaneous = 3, omental = 4). Group demographics were similar at baseline (age, body mass index, diabetes duration, and glycemic control). At 1-3 mo post-first infusion, patients receiving extrahepatic ITx had significantly lower stimulated C-peptide (0.05 nmol/L versus 1.2 nmol/L, P < 0.001), higher fasting plasma glucose (9.3 mmol/L versus 7.3 mmol/L, P < 0.001), and lower BETA-2 scores (0 versus 11.6, P < 0.001) and SUITO indices (1.5 versus 39.6, P < 0.001) compared with those receiving intraportal ITx. Subjects receiving extrahepatic grafts failed to produce median C-peptide ≥0.2 nmol/L within the first 60 d after transplant. Subsequent intraportal infusion following extrahepatic transplants achieved equivalent outcomes compared with patients receiving intraportal transplant alone. Extrahepatic ITx was independently associated with early graft failure/primary non-function (odds ratio 1.709, confidence interval 73.8-39 616.0, P < 0.001), whereas no other factors were independently predictive. Using current techniques, intraportal islet infusion remains the gold standard for clinical ITx, with superior engraftment, graft function, and glycemic outcomes compared with extrahepatic transplantation of human islets.

Transplantation of Pancreatic Islets Into the Omentum Using a Biocompatible Plasma-Thrombin Gel: First Experience at the Institute for Clinical and Experimental Medicine in Prague

Islet transplantation represents an established therapeutic option for people with type 1 diabetes who have hypoglycemia unawareness syndrome and frequent problematic hypoglycemic episodes when other methods comprising diabetes education and use of technological support fail. Because the current standard method of islet infusion into the liver has some limitations, novel approaches are under investigation. We report our first results with 2 cases of islet transplantation into an omental pouch using a biocompatible plasma-fibrin gel. The recipients received 12,350 and 5,350 islet equivalents per kilogram that were mixed with autologous plasma, seeded during a laparoscopic procedure on the omentum, overlaid with human thrombin solution, and fixed by flapping the omentum over. During a 9-month follow-up, neither patient experienced any moderate or severe hypoglycemia. Their glucose control significantly improved, insulin dose decreased by approximately 50%, and C-peptide at 1 year was 0.22 and 0.14 pmol/mL, respectively. The postoperative course was uneventful, but C-peptide production in the first patient progressively declined at 1 year and hypoglycemic episodes recurred. Though the results for these first 2 cases are not fully satisfactory, we have demonstrated the feasibility, safety, and ability of this novel method to restore insulin production. Further refinements to improve immediate islet survival seem necessary.