Insulin-induced normoglycemia reduces islet number needed to achieve normoglycemia after allogeneic islet transplantation in diabetic mice

The Edmonton protocol established that insulin independence could be reached with the transplantation of an appropriate number of islet cells. However, to effect a cure, islets from two or three pancreases are needed. The aim of this study was to examine whether normoglycemia, with insulin treatment before and after transplantation, reduces the islet number needed to achieve normoglycemia in allogeneic islet transplantation. Swiss mice were used as donors and recipients. Diabetes was induced by i.p. administration of streptozotocin (180 mg/kg BW). Diabetic mice were transplanted with 300 (n = 16), 400 (n = 16), or 500 (n = 16) islets under the left kidney capsule. For every group, half the animals were kept normoglycemic with insulin treatment from day 4 before transplantation to day 10 after transplantation. At the end of the study, all normoglycemic mice were given an i.p. glucose tolerance test (IPGTT). For statistical analysis, paired or unpaired Student's t-test or ANOVA was used. Only insulin-treated mice achieved normoglycemia by the end of the study (37.5% of animals transplanted with 400 islets and 50% transplanted with 300 or 500 islets). At the end of the study, normoglycemic mice transplanted with 300 allogeneic islets showed better glycosylated hemoglobin (HbA1C) than did normoglycemic mice transplanted with 500 islets (300 islets: 2.7 +/- 0.2%; 500 islets: 3.6 +/- 0.2%; p < 0.05). After the IPGTT, insulin-treated mice transplanted with 500 islets showed abnormal glucose tolerance; however, insulin-treated mice transplanted with 300 or 400 islets showed normal glucose tolerance. Insulin treatment reduced the islet number needed to achieve normoglycemia in allogeneic islet transplantation. The HbA1C and IPGTT results suggest that transplanting smaller numbers of allogeneic islets improves beta-cell function; some studies suggest that this may be due to lower immunogenicity, hypoxia, and inflammation.     

From islet of Langerhans transplantation to the bioartificial pancreas

Type 1 diabetes is a disease resulting from autoimmune destruction of the insulin-producing beta cells in the pancreas. When type 1 diabetes develops into severe secondary complications, in particular end-stage nephropathy, or life-threatening severe hypoglycemia, the best therapeutic approach is pancreas transplantation, or more recently transplantation of the pancreatic islets of Langerhans. Islet transplantation is a cell therapy procedure, that is minimally invasive and has a low morbidity, but does not display the same rate of functional success as the more invasive pancreas transplantation because of suboptimal engraftment and survival. Another issue is that pancreas or islet transplantation (collectively known as beta cell replacement therapy) is limited by the shortage of organ donors and by the need for lifelong immunosuppression to prevent immune rejection and recurrence of autoimmunity.A bioartificial pancreas is a construct made of functional, insulin-producing tissue, embedded in an anti-inflammatory, immunomodulatory microenvironment and encapsulated in a perm-selective membrane allowing glucose sensing and insulin release, but isolating from attacks by cells of the immune system. A successful bioartificial pancreas would address the issues of engraftment, survival and rejection. Inclusion of unlimited sources of insulin-producing cells, such as xenogeneic porcine islets or stem cell-derived beta cells would further solve the problem of organ shortage.This article reviews the current status of clinical islet transplantation, the strategies aiming at developing a bioartificial pancreas, the clinical trials conducted in the field and the perspectives for further progress.     

Human pancreas procurement for pancreas and islet transplantation

Insulin-dependent diabetes mellitus is a disease characterized by a deficiency of insulin secretion by beta islet cells. Integral pancreatic transplantation and islet cell transplantation represent two possibilities of replacing the beta islet cells. The aim of this paper is to analyze the main aspects of selection criteria of the pancreas donor and surgical methods of preservation for integral pancreas or islet cell transplantation. There are described the pancreas procurements realized by the Center of General Surgery and Liver Transplantation team from Fundeni Clinical Institute between December 2005-December 2006 and correlation between the donor's and pancreas features and the quality of islet cell isolation. The selection of pancreas donor and the accomplishment of pancreas procurement represent important factors in the post-transplantation course of the graft. The data from pancreas/islet cell transplantation centers suggest that the factors that influence positively the course of graft are: the donor's age, body mass index, cold ischemia time.     

Islet alloautotransplantation: Allogeneic pancreas transplantation followed by transplant pancreatectomy and islet transplantation

Simultaneous pancreas–kidney (SPK) transplantation is an important treatment option for patients with type 1 diabetes (T1D) and end‐stage renal disease (ESRD). Due to complications, in up to 10% of patients, allograft pancreatectomy is necessary shortly after transplantation. Usually the donor pancreas is discarded. Here, we report on a novel procedure to rescue endocrine tissue after allograft pancreatectomy. A 39‐year‐old woman with T1D and ESRD who had undergone SPK transplantation required emergency allograft pancreatectomy due to bleeding at the vascular anastomosis. Islets were isolated from the removed pancreas allograft, and almost 480 000 islet equivalents were infused into the portal vein. The patient recovered fully. After 3 months, near‐normal mixed meal test (fasting glucose 7.0 mmol/L, 2‐hour glucose 7.5 mmol/L, maximal stimulated C‐peptide 3.25 nmol/L, without insulin use in the preceding 36 hours) was achieved. Glycated hemoglobin while taking a low dose of long‐acting insulin was 32.7 mmol/mol hemoglobin (5.3%). When a donor pancreas is lost after transplantation, rescue β cell therapy by islet alloautotransplantation enables optimal use of scarce donor pancreata to optimize glycemic control without additional HLA alloantigen exposure.     

胰腺移植与胰岛移植比较及展望

近些年,糖尿病在世界范围内受到越来越广泛的关注,其发病率不断增加,给病人及其家庭带来沉重的负担,大约30-50%的糖尿病病人合并各种并发症,进而导致生活质量下降,生存期缩短.糖尿病病人持续的高血糖水平是合并并发症的决定性危险因素.因此,只有建立安全有效的治疗方案,长期维持正常的血糖水平,才能给糖尿病病人带来健康、良好的生活.DCCT指出,即使是严格遵守糖尿病的强化治疗方案,也难以长期维持血糖稳定,且增加发生低血糖无感知等严重并发症的发生率.     

Long-term exocrine function of the pancreas transplant

The long-term exocrine function of fifty-nine pancreaticoduodenal isografts was evaluated in rats for up to one year post transplantation. At one, three, six, nine, and twelve months after transplantation the grafts were cannulated and the exocrine secretion was collected. The volume, protein content, pH, amylase and trypsin concentrations, and electrolyte composition of the secretion were compared with those obtained from the host pancreas in nineteen control rats. Twenty-four hour secretion studies demonstrated normal basal function of the pancreas transplant when compared with that of the host. Pancreozymin stimulation caused an increase in volume, trypsin concentration, and amylase concentration of the graft pancreas secretion that was similar to those seen in the host. These studies indicate that there is normal exocrine secretion of pancreas transplants in the absence of rejection and that denervation of the gland has little direct effect on over-all pancreatic function.     

Preservation of the donor pancreas for whole pancreas and islet transplantation

Ridgway D, Manas D, Shaw J, White S. Preservation of the donor pancreas for whole pancreas and islet transplantation.
Clin Transplant 2010: 24: 1–19. © 2009 John Wiley & Sons A/S.
Abstract:  Whole pancreas and islet cell transplantation are both reliant upon the procurement and preservation of a high quality donor pancreas for a successful outcome. In the climate of a reducing donor pool it is imperative that donor optimization, meticulous surgical retrieval and evidence based methods of preservation are practiced to ensure optimal graft quality. Moreover expanded criteria donors and novel methods of pancreas preservation have the potential to expand the number of usable grafts and increase the availability of these transplant modalities to suitable patients with diabetes. This article provides a review of the current literature surrounding donor management, surgical technique and the various technologies of organ preservation applicable to the donor pancreas.     

Cold storage of the pancreas with a view to preservation of islet cell function following transplantation

Three solutions, hyperosmolar citrate, modified Collins' C2, and Sacks' II solutions were compared as media for cold storage preservation (arterial infusion and subsequent cold storage in the same medium at 0-4 C) of the rat pancreas with a view to preservation of endocrine function. Pancreatic isotransplantation was performed following cold ischemic intervals of 0, 24, 30, and 36 hr, into streptozotocin-induced diabetic recipients. Results were assessed by normoglycemic survival and insulin response, together with K values following i.v. glucose tolerance tests at 3 months postoperatively; 24-hr preservation was achieved with equal success using modified Collins' C2 solution or hyperosmolar citrate-but not with Sacks' II solution. Preservation for 30 hr was consistently successful using modified Collins C2 solution only, but the period could not be extended with success to 36 hr. Hypoglycemia and hyperinsulinemia occurred 24 hr postoperatively in the majority of animals receiving grafts stored in Sacks' II solution, but to a much lesser extent using modified Collins' C2 and hyperosmolar citrate. This was also temporarily seen in grafts stored for 36 hr in modified Collins C2 solution. At 3 months postoperatively after 30 hr cold ischemia, i.v. glucose tolerance tests showed the hyperosmolar citrate cold-stored grafts had lower K values and significantly reduced insulin responses compared with grafts stored in modified Collins' C2 solution. The modified Collins' C2 solution proved to be the most effective of the three solutions tested.     

Insulin and islet autoantibodies after pancreas transplantation

Autoimmune recurrence and subsequent diabetes after pancreas transplantation has been described. In this cross-sectional study 91 type 1 diabetic patients were examined after successful pancreas/kidney transplantation (SPK). We studied the prevalence of autoantibodies to insulin (IAA), glutamate decarboxylase (GAD) and tyrosine phosphatase (IA-2) as well as parameters of pancreas graft function. Graft recipients were grouped according to immunoreactivity: group 1: no immunoreactivity; group 2: immunoreactivity to one antigen; group 3: immunoreactivity to two or three antigens. Twenty-five percent of graft recipients displayed no immunoreactivity, 39% displayed positivity for one antigen and 36% were positive for two or three antigens. There were no significant differences concerning fasting glucose, HbA1(c), glucose tolerance and renal function between the groups. Patients with cyclosporine (n = 42) as first-line immunosuppression displayed more often immunoreactivity to IA-2 and IAA than patients treated with tacrolimus (n = 49) (31% vs. 14%, P = 0.04; 67% vs. 47%, P = 0.04). In addition methylprednisolone therapy was related to less immunoreactivity to IA-2. Immunological markers for type 1 diabetes can be determined in the majority of pancreas graft recipients despite adequate immunosuppression. However, immunoreactivity was not associated with impaired graft function. Patients with cyclosporine for immunosuppression and withdrawal of glucocorticoids therapy were more often immunoreactive to IAA and IA-2.     

Reperfusion injury of pancreas allografts: relation to islet cell function

It is unknown to what extent preservation and/or reperfusion may damage islet cells in pancreas allografts. In this study, the release of insulin after reperfusion was used as a marker of injury to the islet cell and compared with the best insulin secretory response (ISR) after glucagon stimulation over a period of 100 days after pancreas transplantation.     

The role of exocrine tissue in pancreatic islet transplantation

Isolated pancreatic islet transplantation has been proposed as a possible way of treating diabetes, but despite extensive experimental research, successful clinical transplantation remains elusive. A major problem has been the isolation of sufficient viable islet tissue for transplantation, especially from the human pancreas. It is possible to improve the yield of islet tissue by omitting purification steps, and unpurified dispersed pancreas has been successfully transplanted experimentally. However, attempts to apply the same technique clinically have been unsuccessful and have produced unacceptable complications. There is evidence that exocrine contamination may impair the implantation of islet tissue when transplanted to restricted sites, such as the kidney capsule. Yet, complete purification of islet tissue is probably not necessary for safe transplantation with adequate implantation of tissue in sites such as the spleen or liver. Exocrine tissue may be more immunogenic than islet tissue, and complete purification may have advantages for the prevention of rejection.     

Pancreas preservation for pancreas and islet transplantation: a minireview

Pancreas preservation by cold storage using University of Wisconsin solution was the mainstay method used for pancreas transplantation during the past 2 decades. Other solutions, such as HTK, Celsior, and SCOT 15, could not demonstrate any advantage for short preservation periods. But the advent of clinical islet transplantation and the larger use of controlled non-heart-beating donors have prompted the transplantation community to develop methods for increasing pancreas graft quality while preventing ischemic reperfusion damages. Oxygenation by 1- or 2-layer methods during pancreas preservation, as well as the use of perfluorocarbons, might increase the islet yield. Based on the former methods, there is a renewed interest in machine perfusion and oxygenation in pancreas preservation for pancreas transplantation and islet preparation.     

Procurement of the human pancreas for pancreatic islet transplantation

BACKGROUND: The full potential of pancreatic islet transplantation (PIT) has not been realized because of the difficulties associated with islet isolation, particularly when associated with a remote islet isolation center. Herein, we describe the principles of pancreatic procurement for PIT, which have allowed us to achieve a successful pancreatic islet isolation rate 67% of the time when using a remote islet isolation center. METHODS: Between January 16, 2002 and June 30, 2003, 39 pancreata were procured and processed for PIT at a distant islet isolation center. All pancreata were procured by a single surgeon, and special attention was given to careful dissection of the pancreas, maintenance of arterial inflow and the pressure differential between arterial and venous systems during perfusion, rapid organ cooling, and rapid removal of the pancreas from the body. RESULTS: Twenty-six of 39 (67%) procured pancreata yielded more tha 5,000 islet equivalents (IEQ)/kg recipient weight and were transplanted. Median IEQs per isolation was 413,867, whereas median purity and viability were 65% and 100%, respectively. The median time for pancreatic excision was 34 minutes, whereas cold ischemia time was 6 hours and 40 minutes. DISCUSSION: The principles we have adopted for pancreatic procurement for PIT have resulted in a 67% islet isolation success rate despite the maintenance of more than 5,000 IEQ/kg and the use of a remote islet isolation center.