A wireless, battery-free device enables oxygen generation and immune protection of therapeutic xenotransplants in vivo.

The immune isolation of cells within devices has the potential to enable long-term protein replacement and functional cures for a range of diseases, without requiring immune suppressive therapy. However, a lack of vasculature and the formation of fibrotic capsules around cell immune-isolating devices limits oxygen availability, leading to hypoxia and cell death in vivo. This is particularly problematic for pancreatic islet cells that have high O2 requirements. Here, we combine bioelectronics with encapsulated cell therapies to develop the first wireless, battery-free oxygen-generating immune-isolating device (O2-Macrodevice) for the oxygenation and immune isolation of cells in vivo. The system relies on electrochemical water splitting based on a water-vapor reactant feed, sustained by wireless power harvesting based on a flexible resonant inductive coupling circuit. As such, the device does not require pumping, refilling, or ports for recharging and does not generate potentially toxic side products. Through systematic in vitro studies with primary cell lines and cell lines engineered to secrete protein, we demonstrate device performance in preventing hypoxia in ambient oxygen concentrations as low as 0.5%. Importantly, this device has shown the potential to enable subcutaneous (SC) survival of encapsulated islet cells, in vivo in awake, freely moving, immune-competent animals. Islet transplantation in Type I Diabetes represents an important application space, and 1-mo studies in immune-competent animals with SC implants show that the O2-Macrodevice allows for survival and function of islets at high densities (~1,000 islets/cm2) in vivo without immune suppression and induces normoglycemia in diabetic animals.

α- or ß-Adrenergic blockade does not affect transplanted islet cell responses to hypoglycemia in type 1 diabetes.

Type 1 diabetes recipients of intrahepatic islet transplantation exhibit glucose-dependent suppression of insulin and activation of glucagon secretion in response to insulin-induced hypoglycemia associated with clinical protection from hypoglycemia. Whether sympathetic activation of adrenergic receptors on transplanted islets is required for these responses in defense against hypoglycemia is not known. To evaluate the adrenergic contribution to post-transplant glucose counterregulation, we performed a randomized, double-blind crossover study of responses during a hyperinsulinemic euglycemic-hypoglycemic clamp under phentolamine (α-adrenergic blockage), propranolol (ß-adrenergic blockage), or placebo infusion. Participants (5 female/4 male) were median (range) age 53 (34-63) years, diabetes duration 29 (18-56) years, post-transplant 7.0 (1.9-8.4) years, HbA1c 5.8 (4.5-6.8)%, insulin in-/dependent 5/4, all on tacrolimus-based immunosuppression. During the clamp, blood pressure was lower with phentolamine and heart rate lower with propranolol vs. placebo (P <0.05). There was no difference in suppression of endogenous insulin secretion (derived from C-peptide measurements) during the euglycemic or hypoglycemic phases, and while levels of glucagon were similar with phentolamine or propranolol vs. placebo, the increase in glucagon from eu- to hypoglycemia was greater with propranolol vs. placebo (P < 0.05). Pancreatic polypeptide was greater with phentolamine vs. placebo during the euglycemic phase (P < 0.05), and free fatty acids were lower and the glucose infusion rate higher with propranolol vs. placebo during the hypoglycemic phase (P < 0.05). These results indicate that neither physiologic α- nor ß-adrenergic blockade attenuates transplanted islet responses to hypoglycemia, suggesting sympathetic re-innervation of the islet graft is not necessary for post-transplant glucose counterregulation.

Functional maturation and longitudinal imaging of intraportal neonatal porcine islet grafts in genetically diabetic pigs.

Allogeneic intraportal islet transplantation (ITx) has become an established treatment for patients with poorly controlled type 1 diabetes. However, the loss of viable beta-cell mass after transplantation remains a major challenge. Therefore, noninvasive imaging methods for long-term monitoring of the transplant fate are required. In this study, [68Ga]Ga-DOTA-exendin-4 positron emission tomography/computed tomography (PET/CT) was used for repeated monitoring of allogeneic neonatal porcine islets (NPI) after intraportal transplantation into immunosuppressed genetically diabetic pigs. NPI transplantation (3320-15,000 islet equivalents per kg body weight) led to a reduced need for exogenous insulin therapy and finally normalization of blood glucose levels in 3 out of 4 animals after 5 to 10 weeks. Longitudinal PET/CT measurements revealed a significant increase in standard uptake values in graft-bearing livers. Histologic analysis confirmed the presence of well-engrafted, mature islet clusters in the transplanted livers. Our study presents a novel large animal model for allogeneic intraportal ITx. A relatively small dose of NPIs was sufficient to normalize blood glucose levels in a clinically relevant diabetic pig model. [68Ga]Ga-DOTA-exendin-4 PET/CT proved to be efficacious for longitudinal monitoring of islet transplants. Thus, it could play a crucial role in optimizing ITx as a curative therapy for type 1 diabetes.

Bone Marrow Mesenchymal Stem Cells-Derived miR-21-5p Protects Grafted Islets Against Apoptosis by Targeting PDCD4.

The apoptosis of grafted islets is an urgent problem due to the high rate of islet loss soon after transplantation. MicroRNA-21-5p (miR-21-5p) is an essential mediator of bone marrow mesenchymal stem cells-derived exosomes (BMSCs-Exo) during anti-apoptosis, but its effect and the underlying molecular mechanism in islet transplantation remain partially understood. Here, we found that miR-21-5p could be delivered to islet cells via BMSCs-Exo. Subsequently, we demonstrated that miR-21-5p overexpression reduced apoptosis in islets and INS-1 cells, whereas miR-21-5p inhibition enhanced apoptosis. A mechanistic analysis involving RNA sequencing and bioinformatic analysis was performed to determine the interaction between miR-21-5p and its target gene programmed cell death 4 (PDCD4), which was further verified by a dual luciferase assay. In vivo, the grafted islets overexpressing miR-21-5p showed a higher survival rate, better insulin secretion function, and a lower apoptosis rate. In conclusion, these results demonstrated that miR­21­5p from BMSCs-Exo protects against the apoptosis of grafted islets by inhibiting PDCD4 expression. Hence, miR-21-5p can be used as a cell-free therapeutic agent to minimize ß-cell apoptosis at the early stage of islet transplantation.

Noninvasive quantitative evaluation of viable islet grafts using 111 In-exendin-4 SPECT/CT.

Islet transplantation (IT) is an effective ß-cell replacement therapy for patients with type 1 diabetes; however, the lack of methods to detect islet grafts and evaluate their ß-cell mass (BCM) has limited the further optimization of IT protocols. Therefore, the development of noninvasive ß-cell imaging is required. In this study, we investigated the utility of the 111 Indium-labeled exendin-4 probe {[Lys12(111In-BnDTPA-Ahx)] exendin-4} (111 In exendin-4) to evaluate islet graft BCM after intraportal IT. The probe was cultured with various numbers of isolated islets. Streptozotocin-induced diabetic mice were intraportally transplanted with 150 or 400 syngeneic islets. After a 6-week observation following IT, the ex-vivo liver graft uptake of 111 In-exendin-4 was compared with the liver insulin content. In addition, the in-vivo liver graft uptake of 111 In exendin-4 using SPECT/CT was compared with that of liver graft BCM measured by a histological method. As a result, probe accumulation was significantly correlated with islet numbers. The ex-vivo liver graft uptake in the 400-islet-transplanted group was significantly higher than that in the control and the 150-islet-transplanted groups, consistent with glycemic control and liver insulin content. In conclusion, in-vivo SPECT/CT displayed liver islet grafts, and uptakes were corroborated by histological liver BCM. 111 In-exendin-4 SPECT/CT can be used to visualize and evaluate liver islet grafts noninvasively after intraportal IT.

Insulin independence following islet transplantation improves long-term metabolic outcomes.

AIMS: Pancreatic islet allotransplantation is an effective therapy for type 1 diabetes mellitus, restoring glycaemic control and hypoglycaemic awareness in patients with recurrent severe hypoglycaemia. Insulin independence following transplant is being increasingly reported; however, this is not a primary endpoint in the UK. Having surpassed 10 years of islet transplantation in Scotland, we aimed to evaluate the impact of insulin independence following transplant on metabolic outcomes and graft survival. METHODS: We conducted a retrospective analysis on data collected prospectively between 2011 and 2022. Patients who underwent islet transplantation in Scotland up to the 31st January 2020 were included. Primary endpoint was graft survival (stimulated C-peptide >50 pmol/L). Secondary endpoints included GOLD score, HbA1c, C-peptide and insulin requirement. Outcomes were compared between patients who achieved insulin independence at any point following transplant versus those who did not. RESULTS: 60 patients were included. 74.5% experienced >50 severe hypoglycaemic episodes in the year preceding transplant. There was a 55.0% decrease in insulin requirement following transplant and 30.0% achieved insulin independence. Mean graft survival time was 9.0 years (95% CI 7.2-10.9) in patients who achieved insulin independence versus 4.4 years (95% CI 3.4-5.3) in patients who did not. Insulin independence was associated with significantly improved graft function, glycaemic control and hypoglycaemic awareness at 1 year. CONCLUSIONS: This is the largest UK single-centre study on islet transplant to date. Our findings demonstrate significantly improved outcomes in patients who achieved insulin independence following islet transplantation.

Long-term control of diabetes by tofacitinib-based immunosuppressive regimen after allo islet transplantation in diabetic rhesus monkeys that rejected previously transplanted porcine islets.

Porcine islet xenotransplantation has been highlighted as an alternative to allo islet transplantation. Despite the remarkable progress that has been made in porcine-islet pre-clinical studies in nonhuman primates, immunological tolerance to porcine islets has not been achieved to date. Therefore, allo islet transplantation could be required after the failure of porcine islet xenotransplantation. Here, we report the long-term control of diabetes by allogeneic pancreatic islet transplantation in diabetic rhesus monkeys that rejected previously transplanted porcine islets. Four diabetic male rhesus monkeys received the porcine islets and then allo islets (5700-19 000 IEQ/kg) were re-transplanted for a short or long period after the first xeno islet rejection. The recipient monkeys were treated with an immunosuppressive regimen consisting of ATG, humira, and anakinra for induction, and sirolimus and tofacitinib for maintenance therapy. The graft survival days of allo islets in these monkeys were >440, 395, >273, and 127, respectively, similar to that in allo islet transplanted cynomolgus monkeys that received the same immunosuppressive regimen without xeno sensitization. Taken together, it is likely that prior islet xenotransplantation does not affect the survival of subsequent allo islets under clinically applicable immunosuppressants.

Peri-Transplant Inflammation and Long-Term Diabetes Outcomes Were Not Impacted by Either Etanercept or Alpha-1-Antitrypsin Treatment in Islet Autotransplant Recipients.

The instant blood-mediated inflammatory response (IBMIR) causes islet loss and compromises diabetes outcomes after total pancreatectomy with islet autotransplant (TPIAT). We previously reported a possible benefit of etanercept in maintaining insulin secretion 3 months post-TPIAT. Here, we report 2-year diabetes outcomes and peri-operative inflammatory profiles from a randomized trial of etanercept and alpha-1 antitrypsin (A1AT) in TPIAT. We randomized 43 TPIAT recipients to A1AT (90 mg/kg IV x6 doses, n = 13), etanercept (50 mg then 25 mg SQ x 5 doses, n = 14), or standard care (n = 16). Inflammatory cytokines, serum A1AT and unmethylated insulin DNA were drawn multiple times in the perioperative period. Islet function was assessed 2 years after TPIAT with mixed meal tolerance test, intravenous glucose tolerance test and glucose-potentiated arginine induced insulin secretion. Cytokines, especially IL-6, IL-8, IL-10, and MCP-1, were elevated during and after TPIAT. However, only TNFα differed significantly between groups, with highest levels in the etanercept group (p = 0.027). A1AT increased after IAT in all groups (p < 0.001), suggesting endogenous upregulation. Unmethylated insulin DNA ratios (a marker of islet loss) and 2 years islet function testing were similar in the three groups. To conclude, we found no sustained benefit from administering etanercept or A1AT in the perioperative period.

Impact of a Public Health Emergency on Behavior, Stress, Anxiety and Glycemic Control in Patients With Pancreas or Islet Transplantation for Type 1 Diabetes.

A public health emergency such as the COVID-19 pandemic has behavioral, mental and physical implications in patients with type 1 diabetes (T1D). To what extent the presence of a transplant further increases this burden is not known. Therefore, we compared T1D patients with an islet or pancreas transplant (ß-cell Tx; n = 51) to control T1D patients (n = 272). Fear of coronavirus infection was higher in those with ß-cell Tx than without (Visual Analogue Scale 5.0 (3.0-7.0) vs. 3.0 (2.0-5.0), p = 0.004) and social isolation behavior was more stringent (45.8% vs. 14.0% reported not leaving the house, p < 0.001). A previous ß-cell Tx was the most important predictor of at-home isolation. Glycemic control worsened in patients with ß-cell Tx, but improved in control patients (ΔHbA1c +1.67 ± 8.74 vs. -1.72 ± 6.15 mmol/mol, p = 0.006; ΔTime-In-Range during continuous glucose monitoring -4.5% (-6.0%-1.5%) vs. +3.0% (-2.0%-6.0%), p = 0.038). Fewer patients with ß-cell Tx reported easier glycemic control during lockdown (10.4% vs. 22.6%, p = 0.015). All T1D patients, regardless of transplantation status, experienced stress (33.4%), anxiety (27.9%), decreased physical activity (42.0%), weight gain (40.5%), and increased insulin requirements (29.7%). In conclusion, T1D patients with ß-cell Tx are increasingly affected by a viral pandemic lockdown with higher fear of infection, more stringent social isolation behavior and deterioration of glycemic control. This trial has been registered in the clinicaltrials.gov registry under identifying number NCT05977205 (URL: https://clinicaltrials.gov/study/NCT05977205).

Longitudinal Quality of Life and Glycemic Outcomes of Total Pancreatectomy With Islet Autotransplantation in Children With Chronic Pancreatitis Followed in a Pediatric Multidisciplinary Pancreas Clinic.

BACKGROUND: Total pancreatectomy with islet autotransplantation (TPIAT) is a potentially curative treatment for patients with chronic pancreatitis (CP) refractory to medical and endoscopic therapies. Patients often receive the initial follow-up medical care at the surgery-performing center, but then may follow up closer to where they live. We sought to describe the characteristics and outcomes of pediatric patients who underwent TPIAT at a national surgical referral center and were subsequently followed at our regional subspecialty center, the Children's Hospital Colorado. METHODS: We performed a retrospective analysis of baseline and outcomes data for the 10 pediatric patients who underwent TPIAT from 2007 to 2020 and received follow-up care at our institution. RESULTS: All patients had a diagnosis of CP, and nine of 10 patients had an identified underlying genetic risk factor. Insulin usage was common immediately following TPIAT, but at 1 year of follow-up, five of nine patients (55.6%) were insulin-independent and nine of nine had an HbA1c below 6.5%. For the four patients on insulin 1 year after TPIAT, total daily insulin dose ranged from 0.06 to 0.71 units/kg/day. All patients who underwent mixed meal tolerance testing had a robust peak C-peptide response at 1 year. There were significant improvements in nausea, school/work absences, narcotic dependence, and pancreas-related hospital admissions 1 year after TPIAT. CONCLUSIONS: Patients followed at our center had long-term improvements with low-insulin usage, detectable C-peptide, and improved pancreatitis-related outcomes after TPIAT. Pediatric patients who undergo TPIAT can be successfully co-managed in conjunction with the original surgery-performing center.

Minimally invasive total pancreatectomy with islet autotransplantation for chronic pancreatitis: the robotic approach.

INTRODUCTION: Total pancreatectomy with islet autotransplantation (TPIAT) treats refractory pain in chronic pancreatitis, prevents episodes of acute exacerbation, and mitigates postoperative brittle diabetes. The minimally invasive (MIS) approach offers a decreased surgical access trauma and enhanced recovery. Having established a laparoscopic TPIAT program, we adopted a robotic approach (R-TPIAT) and studied patient outcomes compared to open TPIAT. METHODS: Between 2013 and 2021, 61 adult patients underwent TPIAT after a comprehensive evaluation (97% chronic pancreatitis). Pancreatic islets were isolated on-site during the procedure. We analyzed and compared intraoperative surgical and islet characteristics, postoperative morbidity and mortality, and 1-year glycemic outcomes. RESULTS: MIS-TPIAT was performed in 41 patients (67%, 15 robotic and 26 laparoscopic), and was associated with a shorter mean length of intensive care unit stay compared to open TPIAT (2.9 vs 4.5 days, p = 0.002). R-TPIAT replaced laparoscopic TPIAT in 2017 as the MIS approach of choice and demonstrated decreased blood loss compared to open TPIAT (324 vs 843 mL, p = 0.004), similar operative time (609 vs 562 min), 30-day readmission rate (7% vs 15%), and 90-day complication rate (13% vs 20%). The glycemic outcomes including C-peptide detection at 1-year (73% vs 88%) and insulin dependence at 1-year (75% vs 92%) did not differ. The mean length of hospital stay after R-TPIAT was 8.6 days, shorter than for laparoscopic (11.5 days, p = 0.031) and open TPIAT (12.6 days, p = 0.017). Both MIS approaches had a 1-year mortality rate of 0%. CONCLUSIONS: R-TPIAT was associated with a 33% reduction in length of hospital stay (4-day benefit) compared to open TPIAT. R-TPIAT was similar to open TPIAT on measures of feasibility, safety, pain control, and 1-year glycemic outcomes. Our data suggest that robotic technology, a new component in the multidisciplinary therapy of TPIAT, is poised to develop into the primary surgical approach for experienced pancreatic surgeons.

Preoperative and Postoperative Predictors of Insulin Independence From Total Pancreatectomy and Islet Autotransplantation.

OBJECTIVE: This study examined the preoperative and postoperative variables associated with 1 year and long-term insulin independence following total pancreatectomy and islet autotransplantation (TPIAT). METHODS: 46 TPIAT patients from 2010 to 2022 in a single hospital system were retrospectively analyzed. Pre- and postoperative variables were compared between short-term (1 year) and long-term (last follow-up after year 1) insulin-independent versus -dependent patients. RESULTS: Nine (20%) and seven (15%) patients achieved short- and long-term insulin independence, respectively. The patients were followed up for a median of 2.8 years (interquartile range [IQR] 1.0, 4.7). Short-term insulin independence was associated with higher median transplanted islet equivalents (IEQ) per kg (6981 vs 4493, P = .02), lower units of basal insulin on discharge (7 vs 12, P = .009), and lower rates of discharge with an insulin regimen (67% vs 100%, P = .006). Odds of short-term insulin independence increased by 80% for every 1000 increase in IEQ per kg (OR 1.80, CI 1.18-3.12, P = .005) and decreased by 32% for every additional basal unit of insulin on discharge (OR 0.68, CI 0.42-0.91, P = .003) on average. Long-term insulin independence was also associated with transplanted IEQ per kg. No patient on antihyperglycemic medication before surgery achieved insulin independence. CONCLUSION: Short- and long-term insulin independence after TPIAT is associated with higher transplanted IEQ per kg and immediate postoperative variables that can be used to inform the discussions clinicians have with their patients regarding glycemic prognosis following TPIAT.

Improvement effects of transplanting pancreatic islet that previously incubated with biomaterials on the diabetic nephropathy in STZ- diabetic rats.

BACKGROUND: Islet transplantation is an effective treatment for diabetes or even its complications. Aim of this study is to investigate efficacy of biomaterial treated islet transplantation on treating diabetic nephropathy. METHODS: Male rats were randomly divided into 6 groups; Control, diabetic control, diabetic transplanted with untreated islets, with platelet rich plasma treated islets, with pancreatic islets homogenate treated islets, or with these biomaterials combination treated islets. Islets cultured with biomaterials and transplanted to diabetic rats. After 60 days, biochemical, oxidative stress, and stereological parameters were assessed. RESULTS: Serum albumin and BUN concentration, decreased and increased respectively, Oxidative stress of kidney impaired, kidney weight, volume of kidney, cortex, medulla, glomerulus, proximal and distal tubules, collecting ducts, vessels, inflammatory, necrotic and fibrotic tissue in diabetic group increased compared to control group (p < 0.001). In treated groups, especially pancreatic islets homogenate treated islets transplanting animals, there was significant changes in kidney weight, and volume of kidney, proximal and distal tubules, Henle's loop and collecting ducts compared with diabetic group (p = 0.013 to p < 0.001). Combination treated islets animals showed significant increase in vessel volume compared to diabetic group (p < 0.001). Necrotic and fibrotic tissue significantly decreased in islets treated than untreated islet animals, it was higher in pancreatic islets homogenate, and combination treated islets groups (p = 0.001). CONCLUSIONS: Biomaterials treated islets transplanting could improve diabetic nephropathy. Improvement of oxidative stress followed by controlling glucose level, and effects of growth factors presenting in biomaterials can be considered as capable underlying mechanism of ameliorating inflammatory, necrotic and fibrotic tissue volume.

Adipose Tissue-Derived Mesenchymal Stromal Cells Modulate Inflammatory Response and Improve Allograft Islet Transplant in Mice Model of Type 1 Diabetes.

OBJECTIVE: Type 1 diabetes mellitus (T1DM) is an autoimmune disease where immune cells attack insulin-producing beta cells. Islet transplantation is a promising treatment for T1DM. This study aims to evaluate the effects of adipose tissue-derived mesenchymal stem cells (AT-MSCs) in combination with pancreatic islet transplantation using hydrogel. METHODS: T1DM mouse model was established using streptozotocin (STZ). Islets and AT-MSCs were co-embedded in a hydrogel and transplanted into diabetic mice. Five groups with six animals in each (control, hydrogel alone, AT-MSCs embedded hydrogel, islet embedded in hydrogel, and islet + AT-MSCs co-imbedded into a hydrogel) were evaluated in terms of blood glucose, insulin levels and serum and lavage cytokine production. RESULTS: During 32 days, blood glucose levels decreased from over 400 mg/dl to less than 150 mg/dl in the transplanted mice. Analysis showed increased transformation growth factor beta (TGF-ß1) and IL-4 levels, while IL-17 and IFN-γ levels significantly decreased in the MSC-treated groups. CONCLUSION: These findings suggest that using AT-MSCs with hydrogel could be a beneficial alternative for enhancing pancreatic islet engraftment and function.

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.

AIMS/HYPOTHESIS: 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). METHODS: 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). RESULTS: 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. CONCLUSIONS/INTERPRETATION: 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.

Delayed graft rejection in autoimmune islet transplantation via biomaterial immunotherapy.

The induction of operational immune tolerance is a major goal in beta-cell replacement strategies for the treatment of type 1 diabetes. Our group previously reported long-term efficacy via biomaterial-mediated programmed death ligand 1 (PD-L1) immunotherapy in islet allografts in nonautoimmune models. In this study, we evaluated autoimmune recurrence and allograft rejection during islet transplantation in spontaneous nonobese diabetic (NOD) mice. Graft survival and metabolic function were significantly prolonged over 60 days in recipients of syngeneic islets receiving the biomaterial-delivered immunotherapy, but not in control animals. The biomaterial-mediated PD-L1 immunotherapy resulted in delayed allograft rejection in diabetic NOD mice compared with controls. Discrimination between responders and nonresponders was attributed to the enriched presence of CD206+ program death 1+ macrophages and exhausted signatures in the cytotoxic T cell compartment in the local graft microenvironment. Notably, draining lymph nodes had similar remodeling in innate and adaptive immune cell populations. This work establishes that our biomaterial platform for PD-L1 delivery can modulate immune responses to transplanted islets in diabetic NOD mice and, thus, can provide a platform for the development of immunologic strategies to curb the allo- and autoimmune processes in beta-cell transplant recipients.

Diffuse calcification of pancreas impairs endocrine function and predicts poor outcome in total pancreatectomy with islet autotransplantation.

In patients with chronic pancreatitis, pancreatic calcification is a risk factor for diabetes development, poor islet yield, and metabolic outcomes after total pancreatectomy with islet autotransplantation (TPIAT). We investigated whether calcification pattern based on computed tomography is associated with outcomes using our database of 200 consecutive TPIAT procedures. Three groups were compared: noncalcification (NC); focal calcification, limited to the pancreas head, body, or tail; and diffuse calcification (DC), with calcification in >2 sections. Maximum changes in outcomes were seen in the DC vs focal calcification group. In the DC group, preoperative hemoglobin A1c levels were higher (P < .01), and stimulated C-peptide levels were lower (P < .01) than in the NC group. Islet isolation from the DC pancreas resulted in the lowest islet equivalent (IEQ) yield and IEQ/kg among the 3 groups (P < .0001), with no insulin independence 12 months posttransplant (P < .05 vs NC group). Notably, at 12 months, the DC group was 91.7% narcotic-free, significantly higher than the NC group (P < .05). Although DC is a sign of diabetes risk after TPIAT, the DC group showed exceptional pain relief. These findings suggest that TPIAT can be beneficial for patients with chronic pancreatitis with severe calcification.

Localized cytotoxic T cell-associated antigen 4 and antioxidant islet encapsulation alters macrophage signaling and induces regulatory and anergic T cells to enhance allograft survival.

The loss of functional ß-cell mass is a hallmark of type 1 diabetes. Islet transplantation represents a promising alternative approach, but immune-mediated graft destruction remains a major challenge. We sought to use islet encapsulation technologies to improve graft survival and function without systemic immunosuppression. We hypothesized islet encapsulation with nanothin coatings consisting of tannic acid (TA), an antioxidant; poly(N-vinylpyrrolidone) (PVPON), a biocompatible polymer; and cytotoxic T cell-associated antigen 4 immunoglobulin (CTLA-4-Ig), an inhibitory immune receptor, will elicit localized immunosuppression to prolong islet allograft function and suppress effector T cell responses. In the absence of systemic immunosuppression, we demonstrated (PVPON/TA/CTLA-4-Ig)-encapsulated NOD.Rag islet grafts maintain function significantly longer than control IgG-containing (PVPON/TA/IgG) and nonencapsulated controls after transplantation into diabetic C57BL/6 mice. This protection coincided with diminished proinflammatory macrophage responses mediated by signal transducer and activator of transcription 1 signaling, decreased proinflammatory T cell effector responses, and CTLA-4-Ig-specific concomitant increases in anergic CD4+ T cells and regulatory T cells. Our results provide evidence that conjugation of CTLA-4-Ig to (PVPON/TA) coatings can suppress T cell activation, enhance regulatory T cell populations, prolong islet allograft survival, and induce localized immunosuppression after transplantation.

Engineering pancreatic islets with a novel form of thrombomodulin protein to overcome early graft loss triggered by instant blood-mediated inflammatory reaction.

The instant blood-mediated inflammatory reaction (IBMIR) is initiated by innate immune responses that cause substantial islet loss after intraportal transplantation. Thrombomodulin (TM) is a multifaceted innate immune modulator. In this study, we report the generation of a chimeric form of thrombomodulin with streptavidin (SA-TM) for transient display on the surface of islets modified with biotin to mitigate IBMIR. SA-TM protein expressed in insect cells showed the expected structural and functional features. SA-TM converted protein C into activated protein C, blocked phagocytosis of xenogeneic cells by mouse macrophages and inhibited neutrophil activation. SA-TM was effectively displayed on the surface of biotinylated islets without a negative effect on their viability or function. Islets engineered with SA-TM showed improved engraftment and established euglycemia in 83% of diabetic recipients when compared with 29% of recipients transplanted with SA-engineered islets as control in a syngeneic minimal mass intraportal transplantation model. Enhanced engraftment and function of SA-TM-engineered islets were associated with the inhibition of intragraft proinflammatory innate cellular and soluble mediators of IBMIR, such as macrophages, neutrophils, high-mobility group box 1, tissue factor, macrophage chemoattractant protein-1, interleukin-1ß, interleukin-6, tumor necrosis factor-α, interferon-γ. Transient display of SA-TM protein on the islet surface to modulate innate immune responses causing islet graft destruction has clinical potential for autologous and allogeneic islet transplantation.

Diagnosis and treatment of allograft rejection in islet transplantation.

Islet transplantation stabilizes glycemic control in patients with complicated diabetes mellitus. Rapid functional decline could be due to islet allograft rejection. However, there is no reliable method to assess rejection, and treatment protocols are absent. We aimed to characterize diagnostic features of islet allograft rejection and assess effectiveness of high-dose methylprednisolone treatment. Over a median follow-up of 61.8 months, 22% (9 of 41) of islet transplant recipients experienced 10 suspected rejection episodes (SREs). All first SREs occurred within 18 months after transplantation. Important features were unexplained hyperglycemia (all cases), unexplained C-peptide decrease (ΔC-peptide, 77.1% [-59.1% to -91.6%]; ΔC-peptide:glucose, -76.3% [-49.2% to -90.4%]), predisposing event (5 of 10 cases), and increased immunologic risk (5 of 10 cases). At 6 months post-SRE, patients who received protocolized methylprednisolone (n = 4) had significantly better islet function than untreated patients (n = 4), according to C-peptide (1.39 ± 0.59 vs 0.14 ± 0.19 nmol/L; P = .007), Igls score (good [4 of 4 cases] vs failure [3 of 4 cases] or marginal [1 of 4 cases]; P = .018) and ß score (6.0 [6.0-6.0] vs 1.0 [0.0-3.5]; P = .013). SREs are prevalent among islet transplant recipients and are associated with loss of islet graft function. Timely treatment with high-dose methylprednisolone mitigates this loss. Unexplained hyperglycemia, unexpected C-peptide decrease, a predisposing event, and elevated immunologic risk are diagnostic indicators for SRE.