Expectations and strategies regarding islet transplantation: metabolic data from the GRAGIL 2 trial

BACKGROUND: Whether islet transplantation should be aimed at restoring insulin independence or providing adequate metabolic control is still debated. The GRAGIL2 trial was designed as a phase 1-2 study where primary outcome was the rate of insulin independence, and secondary outcome was the success rate defined by a composite score based upon basal C-peptide, HbA1c, hypoglycemic events, and exogenous insulin needs. METHODS: C-peptide negative type 1 brittle diabetic patients experiencing severe hypoglycemia were eligible to receive a maximum of two islet preparations totalizing 10,000 IE/kg or more, with a threshold of 5,000 IE/kg for the first infusion, according to the Edmonton protocol, within the Swiss-French GRAGIL multicentric network. A sequential analysis with a triangular test was performed in every five patients after 6- and 12-month follow-up. Maximal inefficiency was set at 40% and minimal efficiency at 66%. RESULTS: From September 2003 to October 2005, 10 patients were included. Median waiting time was 6.7 months (first injection) and 9 weeks (second injection). All but one patient received 11,089+/-505 IE/kg: one received a single graft of 5398 IE/kg. At 6 months, insulin independence and composite success rates were 6 of 10 and 6 of 10, respectively. At 12 months, insulin independence was observed in 3 of 10 patients and success in 5 of 10 patients. CONCLUSION: Based upon our sequential analysis settings, islet transplantation failed to achieve the primary goal, insulin independence, but tended to succeed in reaching the secondary goal, successful metabolic control. Currently it appears to be a successful biological closed-loop glucose control method for brittle diabetes.     

Clinical outcomes and insulin secretion after islet transplantation with the Edmonton protocol

Islet transplantation offers the prospect of good glycemic control without major surgical risks. After our initial report of successful islet transplantation, we now provide further data on 12 type 1 diabetic patients with brittle diabetes or problems with hypoglycemia previous to 1 November 2000. Details of metabolic control, acute complications associated with islet transplantation, and long-term complications related to immunosuppression therapy and diabetes were noted. Insulin secretion, both acute and over 30 min, was determined after intravenous glucose tolerance tests (IVGTTs). The median follow-up was 10.2 months (CI 6.5-17.4), and the longest was 20 months. Glucose control was stable, with pretransplant fasting and meal tolerance-stimulated glucose levels of 12.5+/-1.9 and 20.0+/-2.7 mmol/l, respectively, but decreased significantly, with posttransplant levels of 6.3+/-0.3 and 7.5+/-0.6 mmol/l, respectively (P < 0.006). All patients have sustained insulin production, as evidenced by the most current baseline C-peptide levels 0.66+/-0.06 nmol/l, increasing to 1.29+/-0.25 nmol/l 90 min after the meal-tolerance test. The mean HbA1c level decreased from 8.3+/-0.5% to the current level of 5.8+/-0.1% (P < 0.001). Presently, four patients have normal glucose tolerance, five have impaired glucose tolerance, and three have post-islet transplant diabetes (two of whom need oral hypoglycemic agents and low-dose insulin (<10 U/day). Three patients had a temporary increase in their liver-function tests. One patient had a thrombosis of a peripheral branch of the right portal vein, and two of the early patients had bleeding from the hepatic needle puncture site; but these technical problems were resolved. Two patients had transient vitreous hemorrhages. The two patients with elevated creatinine levels pretransplant had a significant increase in serum creatinine in the long term, although the mean serum creatinine of the group was unchanged. The cholesterol increased in five patients, and lipid-lowering therapy was required for three patients. No patient has developed cytomegalovirus infection or disease, posttransplant lymphoproliferative disorder, malignancies, or serious infection to date. None of the patients have been sensitized to donor antigen. In 11 of the 12 patients, insulin independence was achieved after 9,000 islet equivalents (IEs) per kilogram were transplanted. The acute insulin response and the insulin area under the curve (AUC) after IVGTT were consistently maintained over time. The insulin AUC from the IVGTT correlated to the number of islets transplanted, but more closely correlated when the cold ischemia time was taken into consideration (r = 0.83, P < 0.001). Islet transplantation has successfully corrected labile type 1 diabetes and problems with hypoglycemia, and our results show persistent insulin secretion. After a minimum of 9,000 IEs per kilogram are provided, insulin independence is usually attained. An elevation of creatinine appears to be a contraindication to this immunosuppressive regimen. For the subjects who had labile type 1 diabetes that was difficult to control, the risk-to-benefit ratio is in favor of islet transplantation.     

Results of our first nine intraportal islet allografts in type 1, insulin-dependent diabetic patients

With the first demonstration of insulin independence following intraportal islet transplantation into a patient with type 1 diabetes, a new era of clinical islet transplantation will begin. This report provides our initial experience of clinical islet transplantation with a total of nine consecutive portal vein islet transplants in seven diabetic recipients. The first three transplants were done in nonrenal failure diabetics (NRFI) using 6319 +/- 2173 islets/kg body weight with islets processed from single pancreas and cultured for 7 days at 24 degrees C. Prednisone, azathioprine, and cyclosporine were initiated prior to transplant. While all three recipients demonstrated C-peptide function posttransplant, all three rejected their grafts at 2 weeks. Five days of OKT3 treatment failed to recover more than 10% of their rejecting islet grafts. The studies were then shifted to established kidney transplant recipients (EKI) maintaining their basal immunosuppression while adding 7 days of Minnesota antilymphoblast globulin (MALG) to the recipient using islets from single donor pancreas that had been cultured for 7 days at 24 degrees C. There were an average of 6161 +/- 911 islets transplanted intraportally into three EKI recipients. All three had C-peptide response from the transplant, but none achieved insulin independence. While the first patient rejected his graft at 2 weeks, two recipients demonstrated long-term islet function up to 10 months posttransplant. Sustacal challenge testing demonstrated C-peptide responsiveness, but in a delayed pattern suggesting insufficient islet mass had been transplanted. The next three kidney transplant recipients received islets from more than one donor pancreas averaging 13,916 +/- 556 islets/kg body weight. The first of these was the first to achieve insulin independence from 10 to day 25 posttransplant when she appeared to have a rejection episode. The second and third recipients were retransplanted with islets from multiple donors having achieved partial islet function from single pancreas donor. The first patient on triple immunosuppression is demonstrating long-term partial function at 184 days but is not insulin independent. The third patient on prednisone and azathioprine received one half his islets after 7-day culture and the other half after 7-day culture combined with cryopreservation. He is continuing to demonstrate insulin independence for 154 days post-transplant with a glycated hemoglobin value of 5.6%. Sustacal challenge data demonstrate a total stimulated C-peptide response of 155 rhomol/ml at 4 months post-transplant compared with 148 +/- 12 rhomol/ml for normal controls (NC) and 425 rhomol/ml for nondiabetic, established kidney transplant recipients on triple immunosuppression.(ABSTRACT TRUNCATED AT 400 WORDS)     

Intrahepatic islet transplantation in type 1 diabetic patients does not restore hypoglycemic hormonal counterregulation or symptom recognition after insulin independence

Islet allotransplantation can provide prolonged insulin independence in selected individuals with type 1 diabetes. Whether islet transplantation also restores hypoglycemic counterregulation is unclear. To determine if hypoglycemic counterregulation is restored by islet transplantation, we studied hormone responses and hypoglycemic symptom recognition in seven insulin-independent islet transplant recipients using a 3-h stepped hypoglycemic clamp, and compared their responses to those of nontransplanted type 1 diabetic subjects and nondiabetic control subjects. Glucagon responses of islet transplant recipients to hypoglycemia were significantly less than that observed in control subjects (incremental glucagon [mean +/- SE]: -12 +/- 12 vs. 64 +/- 22 pg/ml, respectively; P < 0.05), and not significantly different from that of nontransplanted type 1 diabetic subjects (-17 +/- 10 pg/ml). Epinephrine responses and symptom recognition were also not restored by islet transplantation (incremental epinephrine [mean +/- SE]: 195 +/- 128 [islet transplant recipients] vs. 238 +/- 73 [type 1 diabetic subjects] vs. 633 +/- 139 pg/ml [nondiabetic control subjects], P < 0.05 vs. control; peak symptom scores: 3.3 +/- 0.9 [islet transplant recipients] vs. 3.1 +/- 1.1 [type 1 diabetic subjects] vs. 6.7 +/- 0.8 [nondiabetic control subjects]). Thus the results indicate that despite providing prolonged insulin independence and near-normal glycemic control in these patients with long-standing type 1 diabetes, hypoglycemic hormonal counterregulation and symptom recognition were not restored by intrahepatic islet transplantation.     

Pancreas islet transplantation in patients with type 1 diabetes mellitus after kidney transplantation

Diabetic patients with end-stage renal disease have a high mortality rate. A combined kidney-pancreas transplant is associated with greater life expectancy. Pancreas islet transplantation is an alternative involving a lower degree of morbidity. We present two patients, of 41 and 37 years of age, with a long history of diabetes mellitus (C-peptide negative), both with a previous kidney transplant, who had been treated with 22 and 28 U of insulin/d, respectively. Both patients had frequent episodes of unawareness hypoglycemia. Pancreatic islets were infused to a total of 7809 and 19,180 IE/kg, respectively. Basal posttransplant C peptide levels were 2.9 and 1.3 ng/mL. After the implant, one patient required occasional doses of insulin, and the other patient more than 50% reduced dose. After the first implant neither patient had any episodes of unawareness hypoglycemia. HbA1c at 4 months were 6.2% and 6.9%. There were no transplant-related complications.     

Simple evaluation of engraftment by secretory unit of islet transplant objects for living donor and cadaveric donor fresh or cultured islet transplantation

BACKGROUND: Evaluation of engraftment is important to assess the success of islet transplantation. Recently we developed secretory unit of islet transplant objects (SUITO) index for simple evaluation of engraftment. Assuming that normal subjects aged <40 years have 100% pancreatic beta-cell function, SUITO index was calculated by the formula: 1500 x fasting C-peptide immunoreactivity [ng/dL]/(fasting blood glucose [mg/dL] - 63). In this study, we compared the efficacy of islet transplantation from cadaveric and living donors using the SUITO index. METHODS: We performed eight islet transplantations with non-heart-beating donors (NHBDs) into five patients. Two patients received fresh islets once, one patient received fresh islets twice, one patient received cultured islets once, and one patient received cultured islets twice plus fresh islets once. In addition, one patient received fresh islets from a living donor. We calculated the SUITO index from postoperative days 3 to 30 for each case. RESULTS: Mean SUITO index after one fresh islet transplant was 11.7 +/- 1.0, after two fresh islet transplants was 28.5 +/- 3.4, after one cultured islet transplant was 2.1 +/- 0.4, after two cultured islet transplant was 12.1 +/- 1.9, and after two cultured islet transplant plus one fresh islet transplant was 26.7 +/- 1.7. The mean SUITO index after single living donor islet transplant was 40.7 +/- 2.6, which was significantly higher compared with all other groups. Insulin independence was obtained when the SUITO index was >26, which might reflect that 26% beta-cell mass was required for insulin independence. CONCLUSION: SUITO index is useful to evaluate islet engraftment and to predict the possibility of insulin independence.     

Successful islet transplantation: continued insulin reserve provides long-term glycemic control

Clinical islet transplantation is gaining acceptance as a potential therapy, particularly for subjects who have labile diabetes or problems with hypoglycemic awareness. The risks of the procedure and long-term outcomes are still not fully known. We have performed 54 islet transplantation procedures on 30 subjects and have detailed follow-up in 17 consecutive Edmonton protocol-treated subjects who attained insulin independence after transplantation of adequate numbers of islets. Subjects were assessed pretransplant and followed prospectively posttransplant for immediate and long-term complications related to the procedure or immunosuppressive therapy. The 17 patients all became insulin independent after a minimum of 9,000 islets/kg were transplanted. Of 15 consecutive patients with at least 1 year of follow-up after the initial transplant, 12 (80%) were insulin independent at 1 year. In 14 subjects who have maintained demonstrable C-peptide secretion, glucose control has been stable and glycemic lability and problems with hypoglycemic reactions have been corrected. After 2 of the 54 procedures, some thrombosis was detected in the portal vein circulation. Five subjects had bleeding related to the percutaneous portal vein access procedures: three required transfusion alone, and in one subject, who had a partial thrombosis of the portal vein, an expanding intrahepatic and subscapular hemorrhage occurred while on anticoagulation, requiring transfusion and surgery. Elevated liver function test results were found in 46% of subjects but resolved in all. Complications related to the therapy have been hypercholesterolemia requiring statin therapy in 65%; a rise in creatinine in two patients, both of whom had preexisting renal disease; a rise in protein in four, all of whom had preexisting proteinuria; and antihypertensive therapy increased or started in 53%. Three of the 17 patients have required retinal laser photocoagulation. There have been no cases of posttransplant lymphoproliferative disorder or cytomegalovirus infection, and no deaths. The acute insulin response to arginine correlated better with transplanted islet mass than acute insulin response to glucose (AIR(g)) and area under the curve for insulin (AUC(i)), but the AIR(g) and AUC(i) were more closely related to glycemic control. The AUC(i) directly posttransplant was lower in those who eventually became C-peptide deficient. Our results, with a maximum follow-up of 34 months, indicate that prolonged insulin independence can be achieved after islet transplantation. There are some risks associated acutely with the procedure, and hypercholesterolemia and hypertension are treatable concerns on longer-term follow-up. All patients with persisting C-peptide secretion have had a resolution of both glycemic lability and problems with hypoglycemic reactions. Apart from the rise in serum creatinine in two subjects, no serious consequences of immunosuppressive therapy have been encountered. Islet transplantation is a reasonable option in those with severe problems with glycemic lability or hypoglycemia.     

Human islet graft function in NOD-SCID mice predicts clinical response in islet transplant recipients

The purpose of this study was to evaluate the utility of nondiabetic immune-deficient NOD-SCID mouse model in assessing the functional capacity of isolated human islets. We transplanted 2000 islet equivalents obtained from six preparations used for human islet transplantation in three patients under the kidney capsule of groups of 10 mice. Human (Hu) C-peptide and insulin levels were determined following intraperitoneal (i.p.) glucose challenge at days 0, 7, 14, 21, 30, 60, 90, and 120. The Hu C-peptide level >1.5 ng/mL was the threshold for islet function in this model. The first patient did not achieve insulin independence and had minimal (0.5 ng/mL) fasting C-peptide levels that mirrored the low C-peptide levels observed in the mice. After the first infusion, the insulin requirements were reduced by 50% in the second patient. She became insulin free 10 days after her second infusion with a C-peptide level of 3.0 ng/mL, which corresponded to the peak C-peptide level (3.9 ng/mL) observed in the mice. By 150 days' posttransplant, the decline in C-peptide level paralleled the decline observed in mice. Within 2 weeks after the first transplant, insulin dose was reduced by 75% in the third patient, which corresponded to the robust C-peptide production in mice (7.3 ng/mL). Both patient and mice had a delay in islet function following the second infusion. She remained with a C-peptide level of 1.8 ng/mL and insulin free until suffering a rejection episode 3 months later. We observed that human islet graft function in NOD-SCID mice correlated with clinical response in islet transplant recipients.     

Pretransplant islet culture: a comparison of four serum-free media using a murine model of islet transplantation

INTRODUCTION: Human islet transplant protocols frequently incorporate a brief period of islet culture before transplantation. The optimal medium for pretransplant islet culture is unknown. METHODS: We compared four serum-free media formulated for human islets: Miami (MM1), Memphis (M-SFM), Edmonton (EDM), and hCell OCZEM-SF/AF (hCell). Islets isolated from a single human pancreas with purity >80% were cultured in 2500-islet-equivalent (IE) fractions using the media listed. After 7 days, each 2500-IE fraction was grafted under the kidney capsule of a streptozocin-diabetic rag1 mouse (n = 4 per group). Mice were evaluated with serum glucose monitoring, stimulated C-peptide release, and glucose tolerance tests. Islet fractions transplanted immediately after isolation (n = 4 mice) served as controls. In vitro islet function was assessed on days 0 and 3 and included insulin release (after static glucose stimulation), total cellular C-peptide content, cell count, and viability. RESULTS: Glucose control was improved in all cohorts of mice after transplant, but only islet grafts cultured in MM1 were statistically indistinguishable from fresh islets. MM1- and hCell-cultured islet grafts showed improved glucose tolerance compared with fresh islets; C-peptide release was similar among the four cohorts. In vitro, only islets cultured in MM1 had similar stimulation index to fresh islets, whereas only hCell- and MM1-cultured islets demonstrated recovery of C-peptide content and insulin release. CONCLUSIONS: Media choice before transplant can influence islet quality, even when culture periods are short. Miami MM1 and hCell media may provide better islet protection than alternative media.     

Islet cell hormonal responses to hypoglycemia after human islet transplantation for type 1 diabetes

Islet transplantation can eliminate severe hypoglycemic episodes in patients with type 1 diabetes; however, whether intrahepatic islets respond appropriately to hypoglycemia after transplantation has not been fully studied. We evaluated six islet transplant recipients, six type 1 diabetic subjects, and seven nondiabetic control subjects using a stepped hyperinsulinemic-hypoglycemic clamp. Also, three islet transplant recipients and the seven control subjects underwent a paired hyperinsulinemic-euglycemic clamp. In response to hypoglycemia, C-peptide was similarly suppressed in islet transplant recipients and control subjects and was not detectable in type 1 diabetic subjects. Glucagon was significantly more suppressed in type 1 diabetic subjects than in islet transplant recipients (P < 0.01), although the glucagon in islet transplant recipients failed to activate as in the control subjects (P < 0.01). Pancreatic polypeptide failed to activate in both type 1 diabetic subjects and islet transplant recipients compared with control subjects (P < 0.01). In islet transplant recipients, glucagon was suppressed normally by hyperinsulinemia during the euglycemic clamp and was significantly greater during the paired hypoglycemic clamp (P < 0.01). These results suggest that after islet transplantation and in response to insulin-induced hypoglycemia, endogenous insulin secretion is appropriately suppressed and glucagon secretion may be partially restored.     

Reduced progression of diabetic retinopathy after islet cell transplantation compared with intensive medical therapy

BACKGROUND: Diabetic retinopathy is a major complication of type 1 diabetes and remains a leading cause of visual loss. There have been no comparisons of the effectiveness of intensive medical therapy and islet cell transplantation on preventing progression of diabetic retinopathy. METHODS: The British Columbia islet transplant program is conducting a prospective, crossover study comparing medical therapy and islet cell transplantation on the progression of diabetic retinopathy. Progression was defined as the need for laser treatment or a one step worsening along the international disease severity scale. An interim data analysis was performed after a mean 36-month follow-up postislet transplantation and these results are presented. RESULTS: The medical and postislet transplant groups were similar at baseline. Subjects after islet transplantation had better glucose control than the medically treated subjects (mean HbA1c 6.7%+/-0.9% vs. 7.5+/-1.2, P<0.01) and were C-peptide positive. Progression occurred significantly more often in all subjects in the medical group (10/82 eyes, 12.2%) than after islet transplantation (0/51 eyes, 0%) (P<0.01). Considering only subjects who have received transplants, progression occurred in 6/51 eyes while on medical treatment and 0/51 posttransplant (P<0.02). CONCLUSIONS: Progression of diabetic retinopathy was more likely to occur during medical therapy than after islet cell transplantation.     

Effect of exenatide on beta cell function after islet transplantation in type 1 diabetes

BACKGROUND: Islet transplantation can reduce or eliminate the need for insulin in patients with type 1 diabetes. Exenatide is a long acting analogue of Glucagon-like peptide-1 (GLP-1) that augments glucose induced insulin secretion, and may increase beta cell mass. We evaluated the effect of exenatide on insulin secretion after islet transplantation. METHODS: Eleven C-peptide positive islet cell recipients with elevated glucose levels were treated with exenatide for three months. Response was assessed by insulin requirements, meal tolerance tests, and hyperglycemic glucose clamps. RESULTS: Ten patients responded to exenatide. Two patients who had not restarted insulin achieved good glycemic control and one patient who had received 5500 IE/kg in first islet infusion was able to stop insulin. Seven other patients decreased their insulin dose by 39% on exenatide. Hyperglycemic clamp studies showed a rise in second phase insulin release (before exenatide: 246+/-88 pM; during exenatide: 644+/-294 pM, P<0.01). Meal tolerance studies before and one month after stopping exenatide did not show a difference in glucose or C-peptide values. Nausea and vomiting were the major side effects. CONCLUSIONS: Exenatide stimulates insulin secretion in islet transplant recipients. It reduces insulin dose in some patients and may delay the need to resume insulin in others. We did not find any evidence of a trophic effect on islets.     

Successful islet transplantation from a single pancreas harvested from a young, low-BMI, non-heart-beating cadaver

BACKGROUND: Young donors, donors with low body mass index (BMI), and non-heart-beating (NHB) donors are considered nonideal for islet transplantation. In this report, we successfully used a pancreas from a young, low-BMI, NHB donor for islet transplantation. METHODS: The donor was a 15-year-old adolescent boy whose cause of death was rupture of a primary brain tumor. According to Japanese regulations, his pancreas was procured after cardiac arrest. Warm ischemic time was 3 minutes and cold ischemic time was 300 minutes. The pancreas was digested by the automated method of Ricordi, followed by purification using continuous Euro-Ficoll gradients on a Cobe 2991 device. The recipient was a 35-year-old woman with unstable type 1 diabetes mellitus. Her pretransplant C-peptide level was null. She suffered frequent hypoglycemic unawareness. Her pretransplant M value, which is a good marker for glucose instability, was 125. Islet yield was 252,816 IEQ. There were no signs of contamination. Viability of islets assessed by FDA/PI staining was 83%. Stimulation index was 2.7. RESULTS: The patient received 5160 IEQ/kg of islets via the portal vein under local anesthesia. There were no transplant-related complications. Although she required minimal exogenous insulin, her C-peptide level increased to 0.7 ng/mL at postoperative day (POD) 14. Her M value at POD 15 to 19 decreased dramatically to 23.6, indicating good glycemic control. At 3 months posttransplant, episodes of hypoglycemia disappeared. CONCLUSIONS: Although an additional transplant is mandatory to wean patients from insulin, this case shows the possibility of using marginal donors, such as a young, low-BMI, NHB donor, for pancreas islet transplantation.     

Evaluation of Islet Transplantation from Non-Heart Beating Donors

We evaluated islet transplantation from non-heart beating donors (NHBDs) with our Kyoto Islet Isolation Method. All patients had positive C-peptide after transplantation. The average HbA(1C) levels of the five recipients significantly improved from 7.8 +/- 0.4% at transplant to 5.2 +/- 0.2% currently (p < 0.01). Three patients with no or a single autoantibody became insulin independent while the other two patients with double autoantibodies reduced their insulin requirement but did not become insulin independent. C-peptide in patients who became insulin-independent gradually increased after each transplantation whereas C-peptide in patients who did not become insulin-independent from 3 months after the first transplantation to the next transplantation dramatically decreased. The beta-score of the three patients who became insulin independent was the best of eight. In conclusion, our method makes it feasible to use NHBDs for islet transplant into type 1 diabetic patients efficiently.     

High Risk of Sensitization After Failed Islet Transplantation

Human Leukocyte Antigen (HLA) antibodies posttransplant have been associated with an increased risk of early graft failure in kidney transplants. Whether this also applies to islet transplantation is not clear. To achieve insulin independence after islet transplants multiple donor infusions may be required. Hence, islet transplant recipients are at risk of sensitization after transplantation. Islet transplant recipients were screened for HLA antibodies posttransplant by flow-based methods. A total of 98 patients were studied. Twenty-nine patients (31%) developed de novo donor specific antibodies (DSA) posttransplant. Twenty-three patients developed DSA while on immunosuppression (IS). Among recipients who have discontinued IS, 10/14 (71%) are broadly sensitized with panel reactive antibody (PRA) >or=50%. The risk of becoming broadly sensitized after transplant was 11/69 (16%) if the recipient was unsensitized prior to transplant. The majority of these antibodies have persisted over time. Appearance of HLA antibodies posttransplant is concerning, and the incidence rises abruptly in subjects weaned completely from IS. This may negatively impact the ability of these individuals to undergo further islet, pancreas or kidney transplantation and should be discussed upfront during evaluation of candidates for islet transplantation.     

Assessment of the severity of hypoglycemia and glycemic lability in type 1 diabetic subjects undergoing islet transplantation

Currently, the major indications for solitary islet transplantation are recurrent severe hypoglycemia and labile glucose control. Quantifying these problems remains subjective. We have developed a scoring system for both hypoglycemia and glycemic lability, established normative data, and used them in patients who have undergone islet transplantation. A composite hypoglycemic score (HYPO score) was devised based on the frequency, severity, and degree of unawareness of the hypoglycemia. In addition, using 4 weeks of glucose records, a lability index (LI) was calculated based on the change in glucose levels over time and compared with a clinical assessment of glycemic lability. A mean amplitude of glycemic excursions (MAGE) was also calculated based on 2 consecutive days of seven readings each day. These scores were determined in 100 randomly selected subjects with type 1 diabetes from our general clinic to serve as a control group and in patients before and after islet transplantation. The mean age of the control diabetic subjects was 38.4 +/- 1.3 years (+/-SE), with a duration of diabetes of 21.5 +/- 1.1 years. The median HYPO score in the control subjects was 143 (25th to 75th interquartile range: 46-423). The LI in the diabetic control subjects was 223 (25th to 75th interquartile range: 130-329 mmol/l(2)/h.week(-1)). The LI correlated much more closely than the MAGE with the clinical assessment of lability. A HYPO score of > or = 1,047 (90th percentile) or an LI > or = 433 mmol/l(2)/h.week(-1) (90th percentile) indicated serious problems with hypoglycemia or glycemic lability, respectively. The islet transplant patients (n = 51) were 42.1 +/- 1.4 years old, with a duration of diabetes of 25.7 +/- 1.4 years. Islet transplant patients had a mean HYPO score of 1,234 +/- 184 pretransplant, which was significantly higher than that of the control subjects (P < 0.001), which became negligible posttransplantation with the elimination of hypoglycemia. The median LI pretransplant was 497 mmol/l(2)/h.week(-1) (25th to 75th interquartile range: 330-692), significantly higher than that of control subjects (P < 0.001), and fell to 40 (25th to 75th interquartile range: 14-83) within a month after the final transplant. In those who had lost graft function, the LI rose again. The HYPO score and LI provide measures of the extent of problems with hypoglycemia and glycemic lability, respectively, complement the clinical assessment of the problems with glucose control before islet transplantation, and will allow comparison of selection of subjects for transplants between centers.     

Autoreactive T cell profiles are altered following allogeneic islet transplantation with alemtuzumab induction and re-emerging phenotype is associated with graft function

Islet transplantation is an effective therapy for life-threatening hypoglycemia, but graft function gradually declines over time in many recipients. We characterized islet-specific T cells in recipients within an islet transplant program favoring alemtuzumab (ATZ) lymphodepleting induction and examined associations with graft function. Fifty-eight recipients were studied: 23 pretransplant and 40 posttransplant (including 5 with pretransplant phenotyping). The proportion with islet-specific T cell responses was not significantly different over time (pre-Tx: 59%; 1–6 m posttransplant: 38%; 7–12 m: 44%; 13–24 m: 47%; and >24 m: 45%). However, phenotype shifted significantly, with IFN-γ–dominated response in the pretransplant group replaced by IL-10–dominated response in the 1–6 m posttransplant group, reverting to predominantly IFN-γ–oriented response in the >24 m group. Clustering analysis of posttransplant responses revealed two main agglomerations, characterized by IFN-γ and IL-10 phenotypes, respectively. IL-10–oriented posttransplant response was associated with relatively low graft function. Recipients within the IL-10⁺ cluster had a significant decline in C-peptide levels in the period preceding the IL-10 response, but stable graft function following the response. In contrast, an IFN-γ response was associated with subsequently decreased C-peptide. Islet transplantation favoring ATZ induction is associated with an initial altered islet-specific T cell phenotype but reversion toward pretransplant profiles over time. Posttransplant autoreactive T cell phenotype may be a predictor of subsequent graft function.     

C-peptide and glucose values in the peritransplant period after intraportal islet infusions in type 1 diabetes

BACKGROUND: Successful islet allograft transplantation has been achieved worldwide. This study aimed at evaluating the relationship between peritransplant C-peptide (CP) values and long-term allograft function. METHODS: We measured CP-to-glucose ratio (CPGR) in intraportal samples pre- and postinfusion, and in peripheral circulation at baseline pretransplant and at 1, 3, 6, 12, 72 hours, 1 week, and 15 and 30 days after first and second infusion in 13 islet allograft recipients. Peritransplant treatment included intravenous (IV) 5% dextrose in saline in all patients. We compared portal CPGR to insulin reduction (%) at 30 days after each infusion, and at 1 year after second infusion. RESULTS: CPGR peaked between the immediate postinfusion and 3 hours and decreased at 12 hours. At 1 week, CPGR was 0.76 +/- 0.45 and 1.44 +/- 0.37 after first and second infusion, respectively. CPGR at 30 days after second infusion doubled compared to first infusion (P < .001). There was no correlation between peak CPGR and insulin reduction percent at any time point. One patient experienced hypoglycemia (47 mg/dL) 1 hour after second infusion. CONCLUSIONS: There was no relationship between the CP values in the peritransplant period and long-term graft function or success rate. The early peak in the C-peptide levels is indicative of a significant insulin release after each islet infusion. For this reason, it is important to carefully monitor serum glucose levels in the peritransplant period (hourly for the first 6 hours) and to maintain an IV glucose infusion to avoid hypoglycemia.     

Attainment of Metabolic Goals in the Integrated UK Islet Transplant Program With Locally Isolated and Transported Preparations

The objective was to determine whether metabolic goals have been achieved with locally isolated and transported preparations over the first 3 years of the UK's nationally funded integrated islet transplant program. Twenty islet recipients with C‐peptide negative type 1 diabetes and recurrent severe hypoglycemia consented to the study, including standardized meal tolerance tests. Participants received a total of 35 infusions (seven recipients: single graft; 11 recipients: two grafts: two recipients: three grafts). Graft function was maintained in 80% at [median (interquartile range)] 24 (13.5–36) months postfirst transplant. Severe hypoglycemia was reduced from 20 (7–50) episodes/patient‐year pretransplant to 0.3 (0–1.6) episodes/patient‐year posttransplant (p < 0.001). Resolution of impaired hypoglycemia awareness was confirmed [pretransplant: Gold score 6 (5–7); 24 (13.5–36) months: 3 (1.5–4.5); p < 0.03]. Target HbA_1c of <7.0% was attained/maintained in 70% of recipients [pretransplant: 8.0 (7.0–9.6)%; 24 (13.5–36) months: 6.2 (5.7–8.4)%; p < 0.001], with 60% reduction in insulin dose [pretransplant: 0.51 (0.41–0.62) units/kg; 24 (13.5–36) months: 0.20 (0–0.37) units/kg; p < 0.001]. Metabolic outcomes were comparable 12 months posttransplant in those receiving transported versus only locally isolated islets [12 month stimulated C‐peptide: transported 788 (114–1764) pmol/L (n = 9); locally isolated 407 (126–830) pmol/L (n = 11); p = 0.32]. Metabolic goals have been attained within the equitably available, fully integrated UK islet transplant program with both transported and locally isolated preparations.     

The role of current product release criteria for identification of human islet preparations suitable for clinical transplantation

BACKGROUND: Alloimmunity, autoimmunity, and nonspecific inflammation are known to be potential determinants for long-term islet survival and insulin independence. Sufficient islet mass is a key determinant. But islet engraftment and posttransplant survival may also depend on functional characteristics of the graft. This study investigated the significance of current product release criteria for the transplantation outcome. METHODS: Fourty five consecutive transplanted human islet preparations and their functional outcomes were analyzed. Islet mass was determined according to standard criteria: purity by light microscopy, viability by dye exclusion and Insulin secretory response to static glucose incubation. Islet graft function was monitored for > or = 1 year. Islet function was defined as full (FF), partial (PF), or nonfunction (NF) based on serum C-peptide levels and insulin independence. RESULTS: All islet grafts displayed primary function. Islet mass [IEQ/kg BW]: 7331.3 +/- 679.7 (FF), 5821.3 +/- 546.7 (PF), 6468.6 +/- 658.5 (NF), (FF vs PF p = .032) Purity [%] 86.9 +/- 3.1 (FF), 76.0 +/- 2.87 (PF), 88.2 +/- 2.3 (NF) (FF vs PF P =.045, PF vs NF, P = 0.01). (4) Viability [%]:89.2 +/- 2 (FF), 86.2 +/- 1.7 (PF), 87.3 +/- 1.8 (NF) (ns). Stimulation index (SI): 20 +/- 6.3 (FF), 80.2 +/- 28.2 (PF), 21.6 +/- 3.5 (NF) (ns) No correlation was observed between SI and any other parameter nor between SI and C-peptide levels. Islet mass significantly correlated with C-peptide levels at 6 and 12 months after transplantation for functioning grafts. CONCLUSIONS: Stringent product release criteria allow identification of islet preparations suitable for clinical transplantation. However, currently used parameters are not predictive of long-term graft function, indicating that further refined quality assessments including apoptosis and resistance to early inflammation, are required to assess the primary engrafted islet mass.