Transplantation of macroencapsulated human islets within the bioartificial pancreas βAir to patients with type 1 diabetes mellitus

Macroencapsulation devices provide the dual possibility of immunoprotecting transplanted cells while also being retrievable, the latter bearing importance for safety in future trials with stem cell–derived cells. However, macroencapsulation entails a problem with oxygen supply to the encapsulated cells. The βAir device solves this with an incorporated refillable oxygen tank. This phase 1 study evaluated the safety and efficacy of implanting the βAir device containing allogeneic human pancreatic islets into patients with type 1 diabetes. Four patients were transplanted with 1‐2 βAir devices, each containing 155 000‐180 000 islet equivalents (ie, 1800‐4600 islet equivalents per kg body weight), and monitored for 3‐6 months, followed by the recovery of devices. Implantation of the βAir device was safe and successfully prevented immunization and rejection of the transplanted tissue. However, although beta cells survived in the device, only minute levels of circulating C‐peptide were observed with no impact on metabolic control. Fibrotic tissue with immune cells was formed in capsule surroundings. Recovered devices displayed a blunted glucose‐stimulated insulin response, and amyloid formation in the endocrine tissue. We conclude that the βAir device is safe and can support survival of allogeneic islets for several months, although the function of the transplanted cells was limited (Clinicaltrials.gov: NCT02064309).     

Impact of ischemia time on islet isolation success and posttransplantation outcomes: A retrospective study of 452 pancreas isolations

Many variables impact islet isolation, including pancreas ischemia time. The ischemia time upper limit that should be respected to avoid a negative impact on the isolation outcome is not well defined. We have performed a retrospective analysis of all islet isolations in our center between 2008 and 2018. Total ischemia time, cold ischemia time, and organ removal time were analyzed. Isolation success was defined as an islet yield ≥200 000 IEQ. Of the 452 pancreases included, 288 (64%) were successfully isolated. Probability of isolation success showed a significant decrease after 8 hours of total ischemia time, 7 hours of cold ischemia time, and 80 minutes of organ removal time. Although we observed an impact of ischemia time on islet yield, a probability of isolation success of 50% was still present even when total ischemia time exceeds 12 hours. Posttransplantation clinical outcomes were assessed in 32 recipients and no significant difference was found regardless of ischemia time. These data indicate that although shorter ischemia times are associated with better islet isolation outcomes, total ischemia time >12 hours can provide excellent results in appropriately selected donors.     

Single center results of simultaneous pancreas-kidney transplantation in patients with type 2 diabetes

Studies have found similar outcomes of Simultaneous Pancreas-Kidney transplantation (SPKT) in patients with Type 2 (T2D) and Type 1 diabetes (T1D). However, there are scarce data evaluating the association of recipient factors such as age, BMI, or pretransplant insulin requirements with outcomes, thus the criteria for the optimal recipient selection remains unclear. In this study, 284 T1D and 39 T2D patients, who underwent SPKT between 2006 and 2017 with 1 year of follow-up at minimum, were assessed for potential relationship of pretransplant BMI and insulin requirements with posttransplant diabetes and pancreatic graft failure. Kaplan-Meier analysis showed similar rates of freedom from posttransplant diabetes (94.7% T2D vs. 92.3% T1D at 1 yr, and 88.1% T2D vs. 81.1% T1D at 5 yrs) and graft survival (89.7% T2D vs. 90.4% T1D at 1 yr, and 89.7% T2D vs. 81.2% T1D at 5 yrs). There was no significant association between BMI or pretransplant insulin requirements with posttransplant diabetes occurrence in either T1D (p = .10, .43, respectively) or T2D (p = .12, .63) patients in the cohort; or with graft failure (T1D: p = .40, .09; T2D: p = .71, .28). These observations suggest a less restricted approach to selective use of SPKT in patients with T2D.     

Validation of the BETA‐2 Score: An Improved Tool to Estimate Beta Cell Function After Clinical Islet Transplantation Using a Single Fasting Blood Sample

The beta score, a composite measure of beta cell function after islet transplantation, has limited sensitivity because of its categorical nature and requires a mixed‐meal tolerance test (MMTT). We developed a novel score based on a single fasting blood sample. The BETA‐2 score used stepwise forward linear regression incorporating glucose (in millimoles per liter), C‐peptide (in nanomoles per liter), hemoglobin A1c (as a percentage) and insulin dose (U/kg per day) as continuous variables from the original beta score data set (n = 183 MMTTs). Primary and secondary analyses assessed the score's ability to detect glucose intolerance (90‐min MMTT glucose ≥8 mmol/L) and insulin independence, respectively. A validation cohort of islet transplant recipients (n = 114 MMTTs) examined 12 mo after transplantation was used to compare the score's ability to detect these outcomes. The BETA‐2 score was expressed as follows (range 0–42): A score <20 and ≥15 detected glucose intolerance and insulin independence, respectively, with >82% sensitivity and specificity. The BETA‐2 score demonstrated greater discrimination than the beta score for these outcomes (p < 0.05). Using a fasting blood sample, the BETA‐2 score estimates graft function as a continuous variable and shows greater discrimination of glucose intolerance and insulin independence after transplantation versus the beta score, allowing frequent assessments of graft function. Studies examining its utility to track long‐term graft function are required.     

The impact of islet mass,number of transplants,and time between transplants on graft function in a national islet transplant program

The UK islet allotransplant program is nationally funded to deliver one or two transplants over 12 months to individuals with type 1 diabetes and recurrent severe hypoglycemia. Analyses were undertaken 10 years after program inception to evaluate associations between transplanted mass; single versus two transplants; time between two transplants and graft survival (stimulated C-peptide >50 pmol/L) and function. In total, 84 islet transplant recipients were studied. Uninterrupted graft survival over 12 months was attained in 23 (68%) single and 47 (94%) (p = .002) two transplant recipients (separated by [median (IQR)] 6 (3–8) months). 64% recipients of one or two transplants with uninterrupted function at 12 months sustained graft function at 6 years. Total transplanted mass was associated with Mixed Meal Tolerance Test stimulated C-peptide at 12 months (p < .01). Despite 1.9-fold greater transplanted mass in recipients of two versus one islet infusion (12 218 [9291–15 417] vs. 6442 [5156–7639] IEQ/kg; p < .0001), stimulated C-peptide was not significantly higher. Shorter time between transplants was associated with greater insulin dose reduction at 12 months (beta ?0.35; p = .02). Graft survival over the first 12 months was greater in recipients of two versus one islet transplant in the UK program, although function at 1 and 6 years was comparable. Minimizing the interval between 2 islet infusions may maximize cumulative impact on graft function.     

Fasting parameters for estimation of stimulated β cell function in islet transplant recipients with or without basal insulin treatment

In order to assess β cell secretory capacity after islet transplantation, standardized mixed meal stimulation tests are often used. But these tests are cumbersome and the effect of exogenous insulin on the test results is unclear. The aim of our study was to determine to what extent fasting glycemic indices can estimate stimulated β cell function in islet transplant recipients with and without basal insulin. In total 100 mixed meal stimulation tests, including 31 with concurrent basal insulin treatment, were performed in 36 islet transplant recipients. In a multivariate model, fasting C-peptide and fasting glucose together estimated peak C-peptide with R² = .87 and area under the curve (AUC) C-peptide with a R² = .93. There was a larger increase of glucose during tests in which exogenous insulin was used (+7.9 vs +5.3 mmol/L, P < .001) and exogenous insulin use was associated with a slightly lower estimated peak C-peptide (relative change: −15%, P = .02). In islet transplant recipients the combination of fasting C-peptide and glucose can be used to accurately estimate stimulated β cell function after a mixed meal stimulation test, whether exogenous basal insulin is present or not. These data indicate that graft function can be reliably determined during exogenous insulin treatment and that regular islet graft stimulation tests can be minimized.     

Unmethylated Insulin DNA Is Elevated After Total Pancreatectomy With Islet Autotransplantation: Assessment of a Novel Beta Cell Marker

Beta cell death may occur both after islet isolation and during infusion back into recipients undergoing total pancreatectomy with islet autotransplantation (TPIAT) for chronic pancreatitis. We measured the novel beta cell death marker unmethylated insulin (INS) DNA in TPIAT recipients before and immediately after islet infusion (n = 21) and again 90 days after TPIAT, concurrent with metabolic functional assessments (n = 25). As expected, INS DNA decreased after pancreatectomy (p = 0.0002). All TPIAT recipients had an elevated unmethylated INS DNA ratio in the first hours following islet infusion. In four samples (three patients), INS DNA was also assessed immediately after islet isolation and again before islet infusion to assess the impact of the isolation process: Unmethylated and methylated INS DNA fractions both increased over this interval, suggesting death of beta cells and exocrine tissue before islet infusion. Higher glucose excursion with mixed‐meal tolerance testing was associated with persistently elevated INS DNA at day 90. In conclusion, we observed universal early elevations in the beta cell death marker INS DNA after TPIAT, with pronounced elevations in the islet supernatant before infusion, likely reflecting beta cell death induced by islet isolation. Persistent posttransplant elevation of INS DNA predicted greater hyperglycemia at 90 days.     

Metabolic measures before surgery and long-term diabetes outcomes in recipients of total pancreatectomy and islet autotransplantation

In this single-center, retrospective cohort study, we aimed to elucidate simple metabolic markers or surrogate indices of β-cell function that best predict long-term insulin independence and goal glycemic HbA1c control (HbA1c ≤ 6.5%) after total pancreatectomy with islet autotransplantation (TP-IAT). Patients who underwent TP-IAT (n = 371) were reviewed for metabolic measures before TP-IAT and for insulin independence and glycemic control at 1, 3, and 5 years after TP-IAT. Insulin independence and goal glycemic control were achieved in 33% and 68% at 1 year, respectively. Although the groups who were insulin independent and dependent overlap substantially on baseline measures, an individual who has abnormal glycemia (prediabetes HbA1c or fasting glucose) or estimated IEQs/kg < 2500 has a very high likelihood of remaining insulin dependent after surgery. In multivariate logistic regression modelling, metabolic measures correctly predicted insulin independence in about 70% of patients at 1, 3, and 5 years after TP-IAT. In conclusion, metabolic testing measures before surgery are highly associated with diabetes outcomes after TP-IAT at a population level and correctly predict outcomes in approximately two out of three patients. These findings may aid in prognostic counseling for chronic pancreatitis patients who are likely to eventually need TP-IAT.     

成人胰岛细胞移植治疗1型糖尿病

目的 探讨新型成人胰岛细胞分离、纯化技术分离的成人胰岛细胞移植治疗1型糖尿病的安全性与有效性.方法 采用全氟化碳液(PFC)和UW液双层冷藏胰腺,Liberase酶消化,COBE 2991型专用胰岛细胞分离机分离及连续密度梯度纯化,获取高纯度与高活性的胰岛细胞.通过上腹部小切口,胃右静脉或脐静脉插管,将经短期培养的胰岛细胞经门静脉移植到11例1型糖尿病患者肝脏内.采用达利珠单抗或阿来佐单抗进行诱导,西罗莫司和他克莫司联用的方案预防排斥反应,术后观察胰岛素使用情况,监测血糖、G-肽与糖化血红蛋白水平以及肝功能、肾功能.结果 45个胰腺中,42个成功分离出胰岛细胞,其数量平均为28.5×104胰岛当量(IEQ)/个,纯度为95.7%,活率为93.2%,胰岛素释放试验刺激指数为2.43.11例1型糖尿病患者共行胰岛细胞移植20次,其中移植1次4例,2次5例,3次2例,每次移植胰岛细胞数平均为11 200 IEQ/kg.术后随访6个月至4年,6例完全撤除胰岛素,2例胰岛素用量较术前减少80%,3例减少50%.术后血糖稳定维持在正常水平,C-肽均超过0.166 nmol/L,糖化血红蛋白基本正常,肝、肾功能正常,未发生与胰岛细胞输注相关的并发症.结论 新型成人胰岛细胞分离、纯化方法可靠,采用该技术分离、纯化的成人胰岛细胞移植治疗1型糖尿病临床效果较好.     

BETA‐2 score is an early predictor of graft decline and loss of insulin independence after pancreatic islet allotransplantation

This study aimed to evaluate whether the BETA‐2 score is a reliable early predictor of graft decline and loss of insulin independence after islet allotransplantation. Islet transplant procedures were stratified into 3 groups according to clinical outcome: long‐term insulin independence without islet graft decline (group 1, N = 9), initial insulin independence with subsequent islet graft decline and loss of insulin independence (group 2, N = 13), and no insulin independence (group 3, N = 13). BETA‐2 was calculated on day 75 and multiple times afterwards for up to 145 months posttransplantation. A BETA‐2 score cut‐off of 17.4 on day 75 posttransplantation was discerned between group 1 and groups 2 and 3 (area under the receiver operating characteristic 0.769, P = .005) with a sensitivity and negative predictive value of 100%. Additionally, BETA‐2 ≥ 17.4 at any timepoint during follow‐up reflected islet function required for long‐term insulin independence. While BETA‐2 did not decline below 17.4 for each of the 9 cases from group 1, the score decreased below 17.4 for all transplants from group 2 with subsequent loss of insulin independence. The reduction of BETA‐2 below 17.4 predicted 9 (1.5‐21) months in advance subsequent islet graft decline and loss of insulin independence (P = .03). This finding has important implications for posttransplant monitoring and patient care.     

Polymer scaffolds for pancreatic islet transplantation — Progress and challenges

Pancreatic‐islet transplantation is a safe and noninvasive therapy for type 1 diabetes. However, the currently applied site for transplantation, ie, the liver, is not the optimal site for islet survival. Because the human body has shortcomings in providing an optimal site, artificial transplantation sites have been proposed. Such an artificial site could consist of a polymeric scaffold that mimics the pancreatic microenvironment and supports islet function. Recently, remarkable progress has been made in the technology of engineering scaffolds. The polymer‐islet interactions, the site of implantation, and scaffold prevascularization are critical factors for success or failure of the scaffolds. This article critically reviews these factors while also discussing translation of experimental studies to human application as well as the steps required to create a clinically applicable prevascularized, retrievable scaffold for implantation of insulin‐producing cells for treatment of type 1 diabetes mellitus.     

Posttransplant oxygen inhalation improves the outcome of subcutaneous islet transplantation: A promising clinical alternative to the conventional intrahepatic site

Subcutaneous tissue is a promising site for islet transplantation, due to its large area and accessibility, which allows minimally invasive procedures for transplantation, graft monitoring, and removal of malignancies as needed. However, relative to the conventional intrahepatic transplantation site, the subcutaneous site requires a large number of islets to achieve engraftment success and diabetes reversal, due to hypoxia and low vascularity. We report that the efficiency of subcutaneous islet transplantation in a Lewis rat model is significantly improved by treating recipients with inhaled 50% oxygen, in conjunction with prevascularization of the graft bed by agarose–basic fibroblast growth factor. Administration of 50% oxygen increased oxygen tension in the subcutaneous site to 140 mm Hg, compared to 45 mm Hg under ambient air. In vitro, islets cultured under 140 mm Hg oxygen showed reduced central necrosis and increased insulin release, compared to those maintained in 45 mm Hg oxygen. Six hundred syngeneic islets subcutaneously transplanted into the prevascularized graft bed reversed diabetes when combined with postoperative 50% oxygen inhalation for 3 days, a number comparable to that required for intrahepatic transplantation; in the absence of oxygen treatment, diabetes was not reversed. Thus, we show oxygen inhalation to be a simple and promising approach to successfully establishing subcutaneous islet transplantation.     

First update of the International Xenotransplantation Association consensus statement on conditions for undertaking clinical trials of porcine islet products in type 1 diabetes—Executive summary

The International Xenotransplantation Association has updated its original “Consensus Statement on Conditions for Undertaking Clinical Trials of Porcine Islet Products in Type 1 Diabetes,” which was published in Xenotransplantation in 2009. This update is timely and important in light of scientific progress and changes in the regulatory framework pertinent to islet xenotransplantation. Except for the chapter on “informed consent,” which has remained relevant in its 2009 version, all other chapters included in the initial consensus statement have been revised for inclusion in this update. These chapters will not provide complete revisions of the original chapters; rather, they restate the key points made in 2009, emphasize new and under‐appreciated topics not fully addressed in 2009, suggest relevant revisions, and communicate opinions that complement the consensus opinion. Chapter 1 provides an update on national regulatory frameworks addressing xenotransplantation. Chapter 2 a, previously Chapter 2, suggests several important revisions regarding the generation of suitable source pigs from the perspective of the prevention of xenozoonoses. The newly added Chapter 2b discusses conditions for the use of genetically modified source pigs in clinical islet xenotransplantation. Chapter 3 reviews porcine islet product manufacturing and release testing. Chapter 4 revisits the critically important topic of preclinical efficacy and safety data required to justify a clinical trial. The main achievements in the field of transmission of all porcine microorganisms, the rationale for more proportionate recipient monitoring, and response plans are reviewed in Chapter 5. Patient selection criteria and circumstances where trials of islet xenotransplantation would be both medically and ethically justified are examined in Chapter 6 in the context of recent advances in available and emerging alternative therapies for serious and potentially life‐threatening complications of diabetes. It is hoped that this first update of the International Xenotransplantation Association porcine islet transplant consensus statement will assist the islet xenotransplant scientific community, sponsors, regulators, and other stakeholders actively involved in the clinical translation of islet xenotransplantation.     

Comparative evaluation of simple indices using a single fasting blood sample to estimate beta cell function after islet transplantation

Six single fasting blood sample–based indices—Secretory Unit of Islet Transplant Objects (SUITO), Transplant Estimated Function (TEF), Homeostasis Model Assessment (HOMA)2‐B%, C‐peptide/glucose ratio (CP/G), C‐peptide/glucose creatinine ratio (CP/GCr), and BETA‐2 score—were compared against commonly used 90‐minute mixed meal tolerance test (MMTT) serum glucose and beta score to assess which of them best recognizes the state of acceptable blood glucose control without insulin supplementation after islet allotransplantation (ITx). We also tested whether the indices could identify the success of ITx based on the Igls classification of beta cell graft function. We analyzed values from 47 MMTT tests in 4 patients with up to 140 months follow‐up and from 54 MMTT tests in 13 patients with up to 42 months follow‐up. SUITO, CP/G, HOMA2‐B%, and BETA‐2 correlated well with the 90‐minute glucose of the MMTT and beta‐score (r 0.54‐0.76), whereas CP/GCr showed a modest performance (r 0.41‐0.52) while TEF showed little correlation. BETA‐2 and SUITO were the best identifiers and predictors of the need for insulin support, glucose intolerance, and ITx success (P < .001), while HOMA2‐B% and TEF were unreliable. Single fasting blood sample SUITO and BETA‐2 scores are very practical alternative tools that allow for frequent assessments of graft function.

     

Clinical use of donation after circulatory death pancreas for islet transplantation

Due to a shortage of donation after brain death (DBD) organs, donation after circulatory death (DCD) is increasingly performed. In the field of islet transplantation, there is uncertainty regarding the suitability of DCD pancreas in terms of islet yield and function after islet isolation. The aim of this study was to investigate the potential use of DCD pancreas for islet transplantation. Islet isolation procedures from 126 category 3 DCD and 258 DBD pancreas were performed in a 9-year period. Islet yield after isolation was significantly lower for DCD compared to DBD pancreas (395 515 islet equivalents [IEQ] and 480 017 IEQ, respectively; p = .003). The decrease in IEQ during 2 days of culture was not different between the two groups. Warm ischemia time was not related to DCD islet yield. In vitro insulin secretion after a glucose challenge was similar between DCD and DBD islets. After islet transplantation, DCD islet graft recipients had similar graft function (AUC C-peptide) during mixed meal tolerance tests and Igls score compared to DBD graft recipients. In conclusion, DCD islets can be considered for clinical islet transplantation.     

Improved outcomes of islet autotransplant after total pancreatectomy by combined blockade of IL‐1β and TNFα

The efficacy of islet transplant is compromised by a significant loss of islet mass posttransplant due to an innate inflammatory reaction. We report the use of a combination of etanercept and anakinra (ANA+ETA) to block inflammatory islet damage in 100 patients undergoing total pancreatectomy with islet autotransplant. The patients were divided into 3 groups: no treatment (control [CTL]), etanercept alone (ETA), or a combination of etanercept and anakinra (ANA+ETA). Peritransplant serum samples were analyzed for protein markers of islet damage and for inflammatory cytokines. Graft function was assessed by fasting blood glucose, basal C‐peptide, secretory unit of islet transplant objects (SUITO) index, and hemoglobin A_1c. Administration of both antiinflammatory drugs was well tolerated without any major adverse events. Reductions in interleukin‐6, interleukin‐8, and monocyte chemoattractant protein 1 were observed in patients receiving ANA+ETA compared with the CTL group, while also showing a modest improvement in islet function as assessed by basal C‐peptide, glucose, hemoglobin A_1c, and SUITO index but without differences in insulin dose. These results suggest that double cytokine blockade (ANA+ETA) reduces peritransplant islet damage due to nonspecific inflammation and may represent a promising strategy to improve islet engraftment, leading to better transplant outcomes.