Islet transplantation in IDDM patients

Interventional Radiological Management and Prevention of Complications after Pancreatic Surgery: Drainage, Embolization and Islet Auto-Transplantation

Pancreatic surgery still remains burdened by high levels of morbidity and mortality with a relevant incidence of complications, even in high volume centers. This review highlights the interventional radiological management of complications after pancreatic surgery. The current literature regarding the percutaneous drainage of fluid collections due to pancreatic fistulas, percutaneous transhepatic biliary drainage due to biliary leaks and transcatheter embolization (or stent–graft) due to arterial bleeding is analyzed. Moreover, also, percutaneous intra-portal islet auto-transplantation for the prevention of pancreatogenic diabetes in case of extended pancreatic resection is also examined. Moreover, a topic not usually treated in other similar reviewsas percutaneous intra-portal islet auto-transplantation for the prevention of pancreatogenic diabetes in case of extended pancreatic resection is also one of our areas of focus. In islet auto-transplantation, the patient is simultaneously donor and recipient. Differently from islet allo-transplantation, it does not require immunosuppression, has no risk of rejection and is usually efficient with a small number of transplanted islets.

PRISM: A Novel Human Islet Isolation Technique

BACKGROUND

Successful pancreatic islet isolations are a key requirement for islet transplantation in selected patients with type 1 diabetes. However, islet isolation is a technically complex, time-consuming, and manual process. Optimization and simplification of the islet isolation procedure could increase islet yield and quality, require fewer operators, and thus reduce cost.

METHODS

We developed a new, closed system of tissue collection, washing, buffer change, and islet purification termed PancReatic Islet Separation Method (PRISM). In the developmental phase, pump and centrifuge speed was tested using microspheres with a similar size, shape, and density as digested pancreatic tissue. After optimization, PRISM was used to isolate islets from 10 human pancreases.

RESULTS

Islet equivalents viability (fluorescein diacetate/propidium iodide), morphology, and dynamic glucose-stimulated insulin secretion were evaluated. PRISM could be performed by 1 operator in 1 flow cabinet. A similar islet yield was obtained using PRISM compared to the traditional islet isolation method (431 234 ± 292 833 versus 285 276 ± 197 392 islet equivalents, P = 0.105). PRISM islets had similar morphology and functionality.

CONCLUSIONS

PRISM is a novel islet isolation technique that can significantly improve islet isolation efficiency using fewer operators.

Total pancreatectomy sequelae and quality of life: results of islet autotransplantation as a possible mitigation strategy

Total pancreatectomy (TP) is a procedure weighed down not only by postoperative morbidity and mortality but also by long-term effects as a consequence of endocrine and exocrine pancreatic insufficiency. While the latter is now managed quite effectively with pancreatic enzyme replacement therapy, the former remains a challenge. The diabetes resulting after TP, with the complete loss of endogenous insulin and contraregulatory hormones, is characterized by important glycemic variations and is, therefore, frequently referred to as "brittle diabetes". One method to reduce the impact of brittle diabetes in patients undergoing TP is the re-infusion of autologous pancreatic islets isolated from the resected pancreas. Indications to islet autotransplantation (IAT), originally described for patients undergoing TP for chronic pancreatitis, have since been extended to selected patients with other benign and malignant diseases of pancreas. This review recaps on the literature regarding long-term postoperative complications, their impact on quality of life after TP and the role of IAT.

Clinical pancreatic islet transplantation

Clinical pancreatic islet transplantation can be considered one of the safest and least invasive transplant procedures. Remarkable progress has occurred in both the technical aspects of islet cell processing and the outcomes of clinical islet transplantation. With >1,500 patients treated since 2000, this therapeutic strategy has moved from a curiosity to a realistic treatment option for selected patients with type 1 diabetes mellitus (that is, those with hypoglycaemia unawareness, severe hypoglycaemic episodes and glycaemic lability). This Review outlines the techniques required for human islet isolation, in vitro culture before the transplant and clinical islet transplantation, and discusses indications, optimization of recipient immunosuppression and management of adjunctive immunomodulatory and anti-inflammatory strategies. The potential risks, long-term outcomes and advances in treatment after the transplant are also discussed to further move this treatment towards becoming a more widely available option for patients with type 1 diabetes mellitus and eventually a potential cure.

The state of the art of islet transplantation and cell therapy in type 1 diabetes

In patients with type 1 diabetes (T1D), pancreatic β cells are destroyed by a selective autoimmune attack and their replacement with functional insulin-producing cells is the only possible cure for this disease. The field of islet transplantation has evolved significantly from the breakthrough of the Edmonton Protocol in 2000, since significant advances in islet isolation and engraftment, together with improved immunosuppressive strategies, have been reported. The main limitations, however, remain the insufficient supply of human tissue and the need for lifelong immunosuppression therapy. Great effort is then invested in finding innovative sources of insulin-producing β cells. One old alternative with new recent perspectives is the use of non-human donor cells, in particular porcine β cells. Also the field of preexisting β cell expansion has advanced, with the development of new human β cell lines. Yet, large-scale production of human insulin-producing cells from stem cells is the most recent and promising alternative. In particular, the optimization of in vitro strategies to differentiate human embryonic stem cells into mature insulin-secreting β cells has made considerable progress and recently led to the first clinical trial of stem cell treatment for T1D. Finally, the discovery that it is possible to derive human induced pluripotent stem cells from somatic cells has raised the possibility that a sufficient amount of patient-specific β cells can be derived from patients through cell reprogramming and differentiation, suggesting that in the future there might be a cell therapy without immunosuppression.

Single-centre experience of extending indications for percutaneous intraportal islet autotransplantation (PIPIAT) after pancreatic surgery to prevent diabetes: feasibility, radiological aspects, complications and clinical outcome

OBJECTIVE

Islet allotransplantation is a less invasive alternative to surgical pancreas transplantation for Type 1 diabetes, while percutaneous intraportal islet autotransplantation (PIPIAT) is usually performed after pancreatic surgery to prevent diabetes. Our aim was to assess the feasibility, radiological aspects, complications and clinical outcome of PIPIAT following pancreatic surgery for not only chronic pancreatitis but also benign and malignant nodules.

METHODS

From 2008 to 2012, 41 patients were enrolled for PIPIAT 12-48 h after pancreatic surgery (extended pancreatic surgery for chronic pancreatitis and benign/malignant neoplasms). PIPIAT was performed using a combined ultrasonography and fluoroscopy-guided technique (4-F catheter). PIPIAT feasibility, median follow-up and metabolic (insulin independence rate, graft function based on C-peptide levels) and oncologic outcomes were recorded.

RESULTS

PIPIAT was not performed in 7/41 patients (4 cases for an inadequate islet mass, 2 cases for haemodynamic instability and 1 case for islet culture contamination), while it was successfully performed in 34/34 patients. Procedure-related major complications occurred in four patients: two bleedings requiring transfusions, one patient with left portal vein thrombosis and one patient with sepsis. Median follow-up duration was 546 days. Insulin independence was achieved in 15/34 (44%) patients, partial graft function in 16/34 (47%) patients and no function in 3/34 (9%) patients. None of the 17 patients with malignant nodules developed liver metastases during follow-up.

CONCLUSION

PIPIAT, performed under ultrasound and fluoroscopy combined guidance and not requiring immunosuppression, is feasible, with a relatively low complication rate and a better metabolic outcome than allotransplantation.

ADVANCES IN KNOWLEDGE

PIPIAT can prevent pancreatogenic diabetes. Ultrasound is a useful tool for the guidance and monitoring of PIPIAT.

Islet transplantation for type 1 diabetes, 2015: what have we learned from alloislet and autoislet successes?

The therapeutic potential of pancreatic islet allotransplantation, in which human donor islets are used, as a treatment for type 1 diabetes (T1D) has fascinated diabetes researchers and clinicians for decades. At the same time, the therapeutic potential of total pancreatectomy and islet autotransplantation (TPIAT) (in which one's own islets are used) as a preventive treatment for diabetes in patients who undergo total pancreatectomy for chronic, painful pancreatitis has received relatively less attention. This is ironic, since the latter has been much more effective than the former in terms of successful glucose management and duration of efficacy. The reasons for this disparity can be partially identified. TPIAT receives very little attention in textbooks of internal medicine and general surgery and surprisingly little print in textbooks of endocrinology and transplantation. T1D is much more predominant than TPIAT as a clinical entity. Provision of insulin or replacement of islets is mandatory and a primary goal in T1D. Provision of pain relief from chronic pancreatitis is the primary goal of total pancreatectomy in TPIAT, whereas treatment of diabetes, and certainly prevention of diabetes, has been more of a secondary consideration. Nonetheless, research developments in both fields have contributed to success in one another. In this Perspective, I will provide a brief history of islet transplantation and contrast and compare the procedures of allo- and autoislet transplantation from three major points of view 1) the procedures of islet procurement, isolation, and transplantation; 2) the role and complications of immunosuppressive drugs; and 3) the posttransplant consequences on β- as well as α-cell function.

Enhancement of in vitro and in vivo function of agarose-encapsulated porcine islets by changes in the islet microenvironment

The transplantation of porcine islets of Langerhans to treat type 1 diabetes may provide a solution to the demand for insulin-producing cells. Porcine islets encapsulated in agarose-agarose macrobeads have been shown to function in nonimmunosuppressed xenogeneic models of both streptozotocin-induced and autoimmune type 1 diabetes. One advantage of agarose encapsulation is the ability to culture macrobeads for extended periods, permitting microbiological and functional assessment. Herein we describe optimization of the agarose matrix that results in improved islet function. Porcine islets (500 IEQs) from retired breeding sows were encapsulated in 1.5% SeaKem Gold (SG), 0.8% SG, or 0.8% Litex (Li) agarose, followed by an outer capsule of 5% SG agarose. Insulin production by the encapsulated islets exhibited an agarose-specific effect with 20% (0.8% SG) to 50% (0.8% Li) higher initial insulin production relative to 1.5% SG macrobeads. Insulin production was further increased by 40-50% from week 2 to week 12 in both agarose types at the 0.8% concentration, whereas islets encapsulated in 1.5% SG agarose increased insulin production by approximately 20%. Correspondingly, fewer macrobeads were required to restore normoglycemia in streptozotocin-induced diabetic female CD(SD) rats that received 0.8% Li (15 macrobeads) or 0.8% SG (17 macrobeads) as compared to 1.5% SG (19 macrobeads). Islet cell proliferation was also observed during the first 2 months postencapsulation, peaking at 4 weeks, where approximately 50% of islets contained proliferative cells, including β-cells, regardless of agarose type. These results illustrate the importance of optimizing the microenvironment of encapsulated islets to improve islet performance and advance the potential of islet xenotransplantation for the treatment of type 1 diabetes.

Evolution of β-Cell Replacement Therapy in Diabetes Mellitus: Islet Cell Transplantation

Diabetes mellitus remains one of the leading causes of morbidity and mortality worldwide. According to the Centers for Disease Control and Prevention, approximately 23.6 million people in the United States are affected. Of these individuals, 5 to 10% have been diagnosed with Type 1 diabetes mellitus (T1DM), an autoimmune disease. Although it often appears in childhood, T1DM may manifest at any age, leading to significant morbidity and decreased quality of life. Since the 1960s, the surgical treatment for diabetes mellitus has evolved to become a viable alternative to insulin administration, beginning with pancreatic transplantation. While islet cell transplantation has emerged as another potential alternative, its role in the treatment of T1DM remains to be solidified as research continues to establish it as a truly viable alternative for achieving insulin independence. In this paper, the historical evolution, procurement, current status, benefits, risks, and ongoing research of islet cell transplantation are explored.

Impact of islet transplantation on diabetes complications and quality of life

Insulin represents a life-saving therapy for patients with type 1 diabetes but, despite appropriate treatment, it prevents only partially long-term diabetic complications, while generating fatal hypoglycemic episodes. Islet transplantation gained attention because of its safety, effectiveness, and minimal invasiveness; however it remains a procedure reserved for a selected group of patients. The introduction of the Edmonton Protocol in 2000, based on a newly designed steroid-free immunosuppressive protocol, revamped the course of islet transplantation. The main goal of islet transplantation remains insulin independence, although the effect of islet transplantation can be more comprehensively evaluated in terms of frequency of hypoglycemic episodes and impact on diabetic complications and quality of life. Islet transplantation was shown to have positive consequences on cardiovascular, renal, neurologic, and ocular diabetic complications. The proof of concept for cellular replacement therapy in diabetes has been established with islet transplantation, it only needs to be improved and rendered widely available.

Immune and cell therapy in type 1 diabetes: too little too late?

INTRODUCTION

Type 1 diabetes is caused by autoimmune destruction of insulin-producing β-cells. Intensive insulin therapy protects most patients against chronic complications of diabetes, but exposes patients to acute complications like hypoglycaemia and impacts on quality of life. Therapies that aim at protecting or restoring endogenous insulin secretion might help in decreasing the risk of severe hypoglycemia and long-term complications.

AREAS COVERED

This article reviews the literature of clinical immunotherapy and β-cell transplantation in treatment of type 1 diabetes with specific focus on the effect on preserving and restoring β-cell mass.

EXPERT OPINION

Several studies in recent-onset type 1 diabetic patients have provided proof of principle that immunotherapy can preserve residual functional β-cell mass. The observation that this strategy is most effective early in the disease process opens possibilities of arresting and even preventing type 1 diabetes. In patients with too few or no surviving β-cells, current protocols of β-cell transplantation can restore functional β-cell mass up to 25% of levels in healthy controls. Unfortunately, both strategies to date are followed by progressive decline of endogenous insulin secretion later on. Strategies to restore functional β-cell mass to a higher level and to restore immune tolerance are thus needed.

Islet transplantation a decade later and strategies for filling a half-full glass

Alloislet transplantation for the treatment of type 1 diabetes enjoyed highly favorable status in the first half of the last decade but declined in favor during the second half. In this Perspective, I will briefly review the literature published in this area from 2000 to 2010 for the purposes of extracting lessons we have learned, considering whether the procedure should be deemed a partial success or a partial failure, and offering several strategies to improve alloislet transplantation outcomes in the future. In the end, I hope to strike a positive note about where this procedure is going, and how it will be applied to establish insulin independence in patients with type 1 diabetes.

Successes and disappointments with clinical islet transplantation

Transplantation of pancreatic islets is considered a therapeutic option for patients with type 1 diabetes mellitus who have life-threatening hypoglycaemic episodes. After the procedure, a decrease in the frequency and severity of hypoglycaemic episodes and sustained graft function as indicated by detectable levels of C-peptide can be seen in the majority of patients. However, true insulin independence, if achieved, usually lasts for at most a few years. Apart from the low insulin independence rates, reasons for concern regarding this procedure are the side effects of the immunosuppressive therapy, allo-immunization, and the high costs. Moreover, whether islet transplantation prevents the progression of diabetic micro- and macrovascular complications is largely unknown. Areas of current research include the development of less toxic immunosuppressive regimens, the control of the inflammatory reaction immediately after transplantation, the identification of the optimal anatomical site for islet infusion, and the possibility to encapsulate transplanted islets to protect them from the allo-immune response. At present, pancreatic islet transplantation is still an experimental procedure, which is only indicated for a highly selected group of type 1 diabetic patients with life-threatening hypoglycaemic episodes.

Histologic graft assessment after clinical islet transplantation

BACKGROUND

An accurate monitoring would help understanding the fate of islet grafts after transplantation.

METHODS

This work assessed the feasibility of needle biopsy monitoring after intraportal islet transplantation (n=16), and islet graft morphology was studied with the addition of autopsy samples (n=2). Pancreas autopsy samples from two nondiabetic individuals were used as control.

RESULTS

Islet tissue was found in five needle samples (31%). Sampling success was related to size (100% sampling for the four biopsies of 1.8 cm in length or higher, P<or=0.01). Mild liver abnormalities included localized steatosis (n=8), mild nodular regenerative hyperplasia and mild portal venopathy (n=3), and hepatocyte swelling (n=2). Endocrine cell composition and distribution were similar between islet grafts and normal islets within the native pancreas. There was no or minimal immune cell infiltrate in patients on and off exogenous insulin, including two patients with ongoing negative metabolic events (increasing HbA1c or insulin requirement). The infiltrate was mainly composed of CD4- and CD8-positive cells.

CONCLUSION

This study demonstrates that needle biopsy is feasible after clinical islet transplantation but with a limited practical value because of its low islet sampling rate using current sampling and analysis methods. Both biopsy and autopsy samples demonstrated the well-preserved islet endocrine composition after transplantation and the presence of focal areas of steatosis. Islet grafts showed no or minimal immune cell infiltration, even in the case of ongoing islet loss. On the basis of the findings, possible reasons for allograft islet loss are discussed.

Minimization and withdrawal of steroids in pancreas and islet transplantation

For reducing the corticosteroid (CS)-related side-effects, especially cardiovascular events, CS-sparing protocols have become increasingly common in pancreas transplantation (PT). Lympho-depleting induction antibodies, such as rabbit anti-thymocyte globulin (rATG) or alemtuzumab, have been widely used in successful trials. The results of various CS-sparing protocols combining calcineurin inhibitors (CNI) and mycophenolate or sirolimus, have been mixed for rejection and survival rates. Most of the studies were uncontrolled trials of low-risk patients, therefore the grade of evidence is limited. Large-scale prospective studies with long-term follow up are necessary to assess risks and benefits of CS-sparing regimens in PT before recommending such strategies as standard practice. Islet allo-transplantation for patients with brittle type 1 diabetes mellitus, less invasive and safer procedure than PT, has been attempted since late 1980s, but diabetogenic immunosuppressants at maintenance, mainly CS and high-dose CNI, prevented satisfactory results (10% insulin-independence at 1-year post-transplant). Since 2000, CS-free and CNI-reducing protocols, including more potent induction [daclizumab, OKT3gamma1(ala-ala) anti-CD3 antibody, rATG] and maintenance (sirolimus, mycophenolate) agents, have significantly improved short-term outcomes whereas long-term are still inadequate (from 80% to 20% insulin-independence from 1- to 5-year post-transplant). Main limitations are allo- and autoimmunity, immunosuppression-related islet and systemic toxicity and transplant site unsuitability, which tolerogenic protocols and biotechnological solutions may solve.

Beta-cell replacement in immunosuppressed recipients: old and new clinical indications

Islet transplantation is an appealing procedure able to improve glycemic control in type 1 diabetic patients. However, the possible side effects that may be induced by immunosuppressive therapy limit its application to a select number of patients for whom the risk of immunosuppressants' side effects can be justified. For patients with type 1 diabetes mellitus-who will take immunosuppressants regardless, as they require a solid organ transplant-islet infusion can be an interesting therapeutic option for improving metabolic compensation, whenever pancreas transplant is not possible. Hence, islet infusion can be an important therapeutic option for patients with secondary diabetes mellitus even when a minor pancreatic endocrine function remains. For these patients, results may be better than those obtained with islet infusion for patients with type 1 diabetes mellitus thanks to the lack of autoimmune reaction to the infused islets. The final result is the improvement of the glycemic compensation and most likely also an extension of the graft survival.

Allogeneic islet transplantation

Significant progress has been made in the field of beta-cell replacement therapies by islet transplantation in patients with unstable Type 1 diabetes mellitus (T1DM). Recent clinical trials have shown that islet transplantation can reproducibly lead to insulin independence when adequate islet numbers are implanted. Benefits include improvement of glycemic control, prevention of severe hypoglycemia and amelioration of quality of life. Numerous challenges still limit this therapeutic option from becoming the treatment of choice for T1DM. The limitations are primarily associated with the low islet yield of human pancreas isolations and the need for chronic immunosuppressive therapies. Herein the authors present an overview of the historical progress of islet transplantation and outline the recent advances of the field. Cellular therapies offer the potential for a cure for patients with T1DM. The progress in beta-cell replacement treatment by islet transplantation as well as those of emerging immune interventions for the restoration of self tolerance justify great optimism for years to come.

Kidney function after islet transplant alone in type 1 diabetes: impact of immunosuppressive therapy on progression of diabetic nephropathy

OBJECTIVE

Islet transplantation alone is an alternative for the replacement of pancreatic endocrine function in patients with type 1 diabetes. The aim of our study was to assess the impact of the Edmonton immunosuppressive protocol (tacrolimus-sirolimus association) on kidney function.

RESEARCH DESIGN AND METHODS

Nineteen patients with type 1 diabetes and metabolic instability received islet transplantation alone and immunosuppressive therapy according to the Edmonton protocol. Serum creatinine (sCr), creatinine clearance (CrCl), and 24-h urinary protein excretion (UPE) were assessed at baseline and during a follow-up of 339 patient-months.

RESULTS

After islet transplantation we observed 1) sCr within the normal range in all but two patients in whom sCr increased immediately after islet transplantation, and despite withdrawal of immunosuppression, patients progressed to end-stage renal disease (ESRD); 2) CrCl remained within the normal range for those patients who had normal baseline values and decreased, progressing to ESRD in two patients with a decreased baseline CrCl; and 3) 24-h UPE worsened (>300 mg/24 h) in four patients. In the two patients who progressed to ESRD, the worsening of 24-h UPE occurred immediately after islet transplantation. In one patient 24-h UPE worsening occurred at 18 months, and, after withdrawal of immunosuppression, it returned to the normal range. In another patient 24-h UPE increased at 24 months and remained stable while immunosuppression was continued.

CONCLUSIONS

In type 1 diabetic patients receiving islet transplantation alone, the association of tacrolimus and sirolimus should be used only in patients with normal kidney function. Alternative options for immunosuppressive treatment should be considered for patients with even a mild decrease of kidney function.

Alloreactivity Against Repeated HLA Mismatches of Sequential Islet Grafts Transplanted in Non-Uremic Type 1 Diabetes Patients

BACKGROUND

Islet transplantation can restore insulin production in type 1 diabetes patients. However, survival of the islet allografts will face rejection or recurrence of autoimmunity or a combination of both. In a study on islet-after-kidney transplants, we previously reported that islet cell recipients presented low T-cell alloresponses for HLA mismatches that were shared by the islet cell graft and the prior kidney graft, that is, repeated mismatch, while vigorous responses were measured against novel HLA mismatches.

METHODS

We now investigated T-cell alloreactivity to repeated HLA-mismatches in three non-uremic type 1 diabetic patients each receiving three sequential islet cell implants.

RESULTS

These islet-after-islet recipients patients exhibited low or absent responses to repeated mismatches to the first graft which was accompanied by sustained graft function, and reduced responsiveness towards subsequent grafts. In one patient, T-cell responses towards these mismatches were noticed following new mismatches in subsequent grafts, with loss of graft function.

CONCLUSION

These case reports further support the view that subsequent islet implantations can reduce alloreactivity for repeated HLA mismatches. They demonstrate the usefulness of monitoring T-cell reactivity against islet allografts to correlate immune function with graft survival and to identify conditions for preservation of beta-cell function.

Natural history of kidney graft survival, hypertrophy, and vascular function in end-stage renal disease type 1 diabetic kidney-transplanted patients: beneficial impact of pancreas and successful islet cotransplantation

OBJECTIVE

Diabetes, hypertension, infections, and nephrotoxicity of certain immunosuppressive drugs (i.e., calcineurin inhibitors) can reduce functional survival of the kidney graft. Our aim was to evaluate survival, hypertrophy, and vascular function of the kidney graft in end-stage renal disease (ESRD) type 1 diabetic patients after transplant.

RESEARCH DESIGN AND METHODS

The study population consisted of 234 ESRD type 1 diabetic patients who underwent kidney-pancreas (KP; 166 patients), successful kidney-islet (KI-s; 24 patients), and kidney (KD; 44 patients) transplant. Kidney size, graft survival, vascular function, and microalbuminuria were evaluated prospectively yearly for 6 years. Sixty-eight protocol kidney biopsies were performed routinely between 1993 and 1998 cross-sectionally (3.2 +/- 0.3 years from kidney transplant).

RESULTS

The KP and KI-s groups had better cumulative kidney graft survival at 6 years than did the KD group (KP: 73%; KI-s: 86%; KD: 42%, P < 0.01). The KP group but not the KI-s/KD groups showed a persistent kidney graft hypertrophy up to 6 years of follow-up. A significant increase in creatinine levels from baseline to year 6 was evident in the KD group (1.58 +/- 0.08 to 2.78 +/- 0.44 mg/dl, P < 0.05) but not in the KP/KI-s groups. The KP/KI-s groups only showed a reduction of renal resistance index from baseline to year 6 (KP at baseline: 0.74 +/- 0.01 to 0.68 +/- 0.01%, P < 0.01; KI-s at baseline: 0.72 +/- 0.02 to 0.69 +/- 0.02%, P < 0.05). At year 6, an increase from baseline in urinary albumin excretion was observed only in the KD group (31.4 +/- 9.0 to 82.9 +/- 33.6 mg/l, P < 0.05). Preliminary data suggested that graft nitric oxide (NO) expression was higher in the KP/KI-s groups than in the KD group (data not shown).

CONCLUSIONS

In ESRD type 1 diabetic patients, KP and KI-s compared with KD resulted in enhanced kidney graft survival, hypertrophy, and vascular function.

Islet transplantation is associated with an improvement of cardiovascular function in type 1 diabetic kidney transplant patients

OBJECTIVE

Cardiovascular mortality and morbidity are major problems in type 1 diabetic patients with end-stage renal disease (ESRD). The aim of this study was to determine whether islet transplantation can improve cardiovascular function in these patients.

RESEARCH DESIGN AND METHODS

We assessed various markers of cardiac function at baseline and 3 years later in a population of 42 type 1 diabetic patients with ESRD who received a kidney transplant. Seventeen patients then received an islet transplant that had persistent function as defined by long-term C-peptide secretion (kidney-islet group). Twenty-five patients did not receive a functioning islet transplant (kidney-only group).

RESULTS

GHb levels were similar in the two groups, whereas the exogenous insulin requirement was lower in the kidney-islet group with persistent C-peptide secretion. Overall, cardiovascular parameters improved in the kidney-islet group, but not in the kidney-only group, with an improvement of ejection fraction (from 68.2 +/- 3.5% at baseline to 74.9 +/- 2.1% at 3 years posttransplantation, P < 0.05) and peak filling rate in end-diastolic volume (EDV) per second (from 3.87 +/- 0.25 to 4.20 +/- 0.37 EDV/s, P < 0.05). Time to peak filling rate remained stable in the kidney-islet group but worsened in the kidney-only group (P < 0.05). The kidney-islet group also showed a reduction of both QT dispersion (53.5 +/- 4.9 to 44.6 +/- 2.9 ms, P < 0.05) and corrected QT (QTc) dispersion (67.3 +/- 8.3 to 57.2 +/- 4.6 ms, P < 0.05) with higher erythrocytes Na(+)-K(+)-ATPase activity. In the kidney-islet group only, both atrial natriuretic peptide and brain natriuretic peptide levels decreased during the follow-up, with a stabilization of intima-media thickness.

CONCLUSIONS

Our study showed that type 1 diabetic ESRD patients receiving a kidney transplant and a functioning islet transplant showed an improvement of cardiovascular function for up to 3 years of follow-up compared with the kidney-only group, who experienced an early failure of the islet graft or did not receive an islet graft.

The therapeutic potential of islet cell transplant in the treatment of diabetes

Diabetic patients requiring insulin treatment are at an increased risk of developing chronic complications affecting the eye, kidney and heart as well as other disabilities, such as neurological and vascular disease. The Diabetes Control and Complications Trial (DCCT) showed that the development of these complications can be profoundly reduced or even prevented by strict glycaemic control through intensive insulin therapy. The DCCT study, which was concluded in 1993, administered intensive insulin treatment either by multiple (three or four per day) insulin injections or by an external insulin pump. However, it is both stressful and difficult to achieve effective glycaemic control by these methods. Furthermore, intensive insulin administration imposes a significant danger of hypoglycaemia to patients receiving this treatment. Biological replacement of the destroyed insulin-producing B-cells of pancreatic islets, with normal functioning islet transplants, remains the best option with which to achieve strict glycaemic control in diabetic patients requiring insulin treatment. The ultimate goal in transplantation is the unlimited availability of organs/tissues to be transplanted in a simple procedure that requires little or no immunosuppression. Other obstacles have also contributed to the delay in islet transplantation becoming a clinical reality. There are now good methods for isolating long-term functional islets, and it has been proposed that these islets can be immunoisolated by microencapsulation to prevent transplant rejection, an approach that could easily lead to the use of islet xenografts in human diabetic patients. Therefore, the development of microencapsulated islets promises to solve the two major obstacles to clinical islet transplantation, transplant rejection and shortage of human islets. This technique has enormous potential as a viable treatment for diabetic patients requiring insulin therapy to achieve glycaemic control.

Technique, complications, and therapeutic efficacy of percutaneous transplantation of human pancreatic islet cells in type 1 diabetes: the role of US

PURPOSE

To retrospectively evaluate the role of ultrasonography (US) with regard to the technique, complications, and therapeutic efficacy of percutaneous intrahepatic transplantation of human pancreatic islet cells with combined US and fluoroscopic guidance.

MATERIALS AND METHODS

The institutional review board approved the study, and informed consent was obtained from all patients. After kidney transplantation, 34 uremic diabetic patients (20 men, 14 women; mean age, 40.9 years; age range, 29-61 years) underwent percutaneous intrahepatic transplantation of islet cells. Portal vein patency and liver echotexture were preliminarily assessed with color Doppler US. US also was used to identify early complications and presence (group A patients) or absence (group B patients) of hepatic parenchymal changes. Differences between the two groups in C peptide serum level and range were analyzed (Mann-Whitney test). Therapeutic efficacy of transplantation was assessed with regard to insulin independence period (rate and duration), exogenous insulin requirement, glycated hemoglobin, and C peptide level. A C peptide level of more than 0.5 ng/mL was considered to indicate well-functioning islet cells.

RESULTS

Fifty-eight procedures were technically successful, with a single puncture used in 51 of 58 patients. Complications occurred in three of 58 patients (hemoperitoneum, hemothorax, and thrombosis in one patient each) and were conservatively treated and resolved. Duration of insulin independence in 12 patients was more than 3 months (mean, 21 months). Well-functioning islet cells at 6 years were found in 19 of 34 patients. Hyperechoic parenchymal changes were evident at US in 12 of 34. No statistically significant difference in C peptide level was found between groups (P > .05), but a wider range of values was recorded in group B.

CONCLUSION

Complication rate of transplantation with US and fluoroscopic guidance was low. Well-functioning islet cells were found in about 50% of patients at 6 years of follow-up. Hepatic implantation of islet cells was evident on US images in more than one-third of patients.

Tissue factor and CCL2/monocyte chemoattractant protein-1 released by human islets affect islet engraftment in type 1 diabetic recipients

Islet survival in the early posttransplantation period is likely to be influenced by inflammatory events in and around islets. Twenty-seven human islet preparations were transplanted by 24 infusions into 14 patients with brittle type 1 diabetes under the Edmonton protocol. Patients were monitored for their coagulation [cross-linked fibrin degradation products (XDPs)] and liver function test [aspartate and alanine aminotransferase (AST and ALT)] as markers of early posttransplant complications, and these were correlated with in vitro islet number, purification, volume, monocyte-chemoattractant protein-1 (CCL2/MCP-1) and tissue factor (TF) islet release. Consistent with activation of coagulation pathways and hepatic damage, serum XDP values increased early after 11 infusions and transaminase after 13 of 24 infusions. TF and CCL2/MCP-1 were detected in supernatants of 21 and 22 islet preparations, respectively. Serum XDP peak values were correlated with TF/equivalent islets (EI) (r(2)=0.26, P = 0.001) and CCL2/MCP-1/EI (r(2) = 0.42; P < 0.001); serum transaminase areas under the curve in the first week posttransplantation were correlated with CCL2/MCP-1/EI (r(2) = 0.55; P < 0.001 for ALT and r(2) = 0.51; P = 0.001 for AST) and TF/EI (r(2) = 0.31; P = 0.002 for ALT, and r(2) = 0.36; P = 0.002 for AST). These data suggest that reducing the islet proinflammatory state may be a means to reduce the early posttransplant complications and perhaps improve islet engraftment.

Immunosuppression for pancreatic islet transplantation

Protocols for islet transplantation have to take into account the diabetogenicity/islet toxicity of the immunosuppressive agents, namely corticosteroids and calcineurin inhibitors, most notably tacrolimus. The development by the Edmonton group of a sirolimus-based, steroid-free, low-tacrolimus regimen was a significant breakthrough that allowed the rate of insulin independence after islet transplantation to increase from 13% to 80% at 1 year. Drawbacks include the side effects of sirolimus and the reduction in insulin independence to 50% at 3 years, the latter being attributed to prolonged tacrolimus exposure. Currently explored alternatives to tacrolimus include cyclosporine, mycophenolate mofetil, and the novel agent FTY 720. Perspectives for the near future involve the achievement of "prope tolerance" by strategies using lymphocyte-depleting antibodies (anti-thymocyte globulin, campath-1H, hOKT3gamma1 [ala,ala]), or costimulatory blockade (anti-CD154 mAbs, CTLA4-Ig).

A wild-type porcine encephalomyocarditis virus containing a short poly(C) tract is pathogenic to mice, pigs, and cynomolgus macaques

Previous studies using wild-type Encephalomyocarditis virus (EMCV) and Mengo virus, which have long poly(C) tracts (61 to 146 C's) at the 5' nontranslated region of the genome, and variants of these viruses genetically engineered to truncate or substitute the poly(C) tracts have produced conflicting data on the role of the poly(C) tract in the virulence of these viruses. Analysis of the nucleotide sequence of an EMCV strain isolated from an aborted swine fetus (EMCV 30/87) revealed that the virus had a poly(C) tract that was 7- to 10-fold shorter than the poly(C) tracts of other EMCV strains and 4-fold shorter than that of Mengo virus. Subsequently, we investigated the virulence and pathogenesis of this naturally occurring short-poly(C)-tract-containing virus in rodents, pigs, and nonhuman primates. Infection of C57BL/6 mice, pigs, and cynomolgus macaques resulted in similar EMCV 30/87 pathogenesis, with the heart and brain as the primary sites of infections in all three animals, but with different disease phenotypes. Sixteen percent of EMCV 30/87-infected pigs developed acute fatal cardiac failure, whereas the rest of the pigs were overtly asymptomatic for as long as 90 days postinfection (p.i.), despite extensive myocardial and central nervous system (CNS) pathological changes. In contrast, mice infected with >/==" BORDER="0">4 PFU of EMCV 30/87 developed acute encephalitis that resulted in the death of all animals (n = 25) between days 2 and 7 p.i. EMCV 30/87-infected macaques remained overtly asymptomatic for 45 days, despite extensive myocardial and CNS pathological changes and viral persistence in more than 50% of the animals. The short poly(C) tract in EMCV 30/87 (CUC(5)UC(8)) was comparable to that of strain 2887A/91 (C(10)UCUC(3)UC(10)), another recent porcine isolate.

Islet transplantation is associated with improvement of renal function among uremic patients with type I diabetes mellitus and kidney transplants

The potential effects of islet transplantation on the renal function of 36 patients with type I diabetes mellitus and kidney transplants were studied with 4 yr of follow-up monitoring. Kidney-islet recipients were divided into two groups, i.e., patients with successful islet transplants (SI-K group) (n = 24, fasting C-peptide levels of >0.5 ng/ml for >1 yr) and patients with unsuccessful islet transplants (UI-K group) (n = 12, fasting C-peptide levels of <0.5 ng/ml). Kidney graft survival rates and function, urinary albumin excretion rates, and sodium handling were compared. Na(+)/K(+)-ATPase activity in protocol kidney biopsies and in red blood cells was cross-sectionally analyzed. The SI-K group demonstrated better kidney graft survival rates (100, 83, and 83% at 1, 4, and 7 yr, respectively) than did the UI-K group (83, 72, and 51% at 1, 4, and 7 yr, respectively; P = 0.02). The SI-K group demonstrated reductions in exogenous insulin requirements and higher C-peptide levels, compared with the UI-K group, whereas GFR values were similar. Microalbuminuria (urinary albumin index) increased significantly in the UI-K group only (UI-K, from 92.0 +/- 64.9 to 183.8 +/- 83.8, P = 0.05; SI-K, from 108.5 +/- 53.6 to 85.0 +/- 39.0, NS). In the SI-K group, but not in the UI-K group, natriuresis decreased at 2 and 4 yr (P < 0.01). The SI-K group demonstrated greater Na(+)/K(+)-ATPase immunoreactivity in renal tubular cells (P = 0.05) and higher activity in red blood cells (P = 0.03), compared with the UI-K group. The Na(+)/K(+)-ATPase activity in red blood cells was positively correlated with circulating C-peptide levels but not with glycated hemoglobin levels. Successful islet transplantation was associated with improvements in kidney graft survival rates and function among uremic patients with type I diabetes mellitus and kidney grafts.

Islet transplantation improves vascular diabetic complications in patients with diabetes who underwent kidney transplantation: a comparison between kidney-pancreas and kidney-alone transplantation

BACKGROUND

The aim of this study was to evaluate the effects of islet transplantation on patient survival and diabetic vascular complications.

METHODS

Thirty-seven type 1 uremic diabetic kidney transplant patients underwent islet transplantation (KI group). Uremic type 1 diabetic kidney-pancreas (KP group, n=162), kidney-alone (KD group, n=42) transplant patients, and uremic type 1 diabetic patients still on hemodialysis (HD+DM group, n=196) constituted the control groups for survival and endothelial morphology.

RESULTS

Patient survival was similar in the KI and KP groups and higher than in the HD+DM group (P<0.05). Patients experiencing long-term islet function (KI-successful [KI-s], n=24) showed a better survival (100%, 100%, and 90%) than those in the KI group who lost islet function (KI-unsuccessful [KI-u], n=13) (84%, 75%, and 45%) at 1, 4 and 7 years, respectively (P=0.02). The cardiovascular death rate for the KI group (18%) was similar to the KD group (19%) but lower when the KI-s group is considered alone (5%), and showed a cardiovascular death rate similar to the KP group (8%). The KI-s group showed a good metabolic profile, with reduction of exogenous insulin requirement and persistent C-peptide secretion, as compared with the KI-u group. The endothelial morphology was evaluated with a skin biopsy obtained in all groups. The KI-s and the KP groups demonstrated decreased signs of endothelial injury compared with the KI-u and HD+DM groups. The KI group showed a better atherothrombotic profile than the HD+DM group, with higher levels of natural anticoagulant protein.

CONCLUSIONS

Successful islet transplantation improves survival, atherothrombotic profile, and endothelial morphology in uremic type 1 diabetic kidney transplant patients.

Long-term beneficial effect of islet transplantation on diabetic macro-/microangiopathy in type 1 diabetic kidney-transplanted patients

OBJECTIVE

Our aim was to evaluate the long-term effects of transplanted islets on diabetic macro-/microangiopathy in type 1 diabetic kidney-transplanted patients.

RESEARCH DESIGN AND METHODS

A total of 34 type 1 diabetic kidney-transplanted patients underwent islet transplantation and were divided into two groups: successful islet-kidney transplantation (SI-K; 21 patients, fasting C-peptide serum concentration >0.5 ng/ml for >1 year) and unsuccessful islet-kidney transplantation (UI-K; 13 patients, fasting C-peptide serum concentration <0.5 ng/ml). Patients cumulative survival, cardiovascular death rate, and atherosclerosis progression were compared in the two groups. Skin biopsies, endothelial dependent dilation (EDD), nitric oxide (NO) levels, and atherothrombotic risk factors [von Willebrand factor (vWF) and D-dimer fragment (DDF)] were studied cross-sectionally.

RESULTS

The SI-K group showed a significant better patient survival rate (SI-K 100, 100, and 90% vs. UI-K 84, 74, and 51% at 1, 4, and 7 years, respectively, P = 0.04), lower cardiovascular death rate (SI-K 1/21 vs. UI-K 4/13, chi(2) = 3.9, P = 0.04), and lower intima-media thickness progression than the UI-K group (SI-K group: delta1-3 years -13 +/- 30 micro m vs. UI-K group: delta1-3 years 245 +/- 20 micro m, P = 0.03) with decreased signs of endothelial injuring at skin biopsy. Furthermore, the SI-K group showed a higher EDD than the UI-K group (EDD: SI-K 7.8 +/- 4.5% vs. UI-K 0.5 +/- 2.7%, P = 0.02), higher basal NO (SI-K 42.9 +/- 6.5 vs. UI-K 20.2 +/- 6.8 micro mol/l, P = 0.02), and lower levels of vWF (SI-K 138.6 +/- 15.3 vs. UI-K 180.6 +/- 7.0%, P = 0.02) and DDF (SI-K 0.61 +/- 0.22 vs. UI-K 3.07 +/- 0.68 micro g/ml, P < 0.01). C-peptide-to-creatinine ratio correlated positively with EDD and NO and negatively with vWF and DDF.

CONCLUSIONS

Successful islet transplantation improves survival, cardiovascular, and endothelial function in type 1 diabetic kidney-transplanted patients.

Pancreatic Islet Cell Transplantation

Pancreatic islet cell transplantation as a treatment for diabetes has hitherto been confined to small patient cohorts with limited success. This article summarizes the results of islet cell transplantation before and after the advent of the new 'Edmonton protocol' of immunosuppression and management of the donor pancreas. Adopting this regimen has achieved unprecedented success and renewed interest in this potential cure for diabetes. Central to recent improvements in the technique has been the transplantation of an adequate islet mass. Improved methods to procure, isolate, and purify islets for clinical use are now being adopted as a new 'gold standard'. The use of new immunosuppressive drugs has further improved clinical results. Corticosteroid sparing-based regimens, and agents such as humanized monoclonal antibodies, are likely to form the mainstay of immunosuppressive protocols with the aim of achieving donor-specific tolerance. Alternative sources of islet cells are also required to expand the technique in an era of reduced numbers of donor pancreata. Manipulation of stem cells and xenotransplantation may yet yield sufficient islets to overcome the problem of donor shortage. Islet cell transplantation now forms the basis of a prospective multicenter trial under the aegis of the Immune Tolerance Network. The results of this are awaited, but it appears that islet cell transplantation may yet emerge as an effective treatment option for some members of the diabetic population.

Reduction of blood glucose variability in type 1 diabetic patients treated by pancreatic islet transplantation: interest of continuous glucose monitoring

OBJECTIVE

To compare the glycemic profiles of patients with type 1 diabetes treated with either an implantable insulin pump or pancreas or islet transplantation by the means of the continuous glucose monitoring system (CGMS; Minimed, Sylmar, CA).

RESEARCH DESIGN AND METHODS

The CGMS enabled recording of subcutaneous glucose concentrations (range 2.2-22 mmol/l) over 72 h (288 measurements per day). Over 3 days, 26 patients with type 1 diabetes were connected to a CGMS: 10 patients were treated with intraperitoneal insulin infusion through an implantable pump (IPII), 9 patients were treated with simultaneous pancreas-kidney transplantation (SPK), and 7 patients were treated with pancreatic islet transplantation after kidney grafting (IAK). All SPK patients and four IAK patients were insulin independent, whereas three IAK patients had partial graft function and reduced exogenous insulin needs. Glucose control was evaluated by the mean glucose concentration, glucose variability, and the number and duration of hypoglycemic events (<3.3 mmol/l) over 3 days.

RESULTS

The mean glucose concentration and the glucose variability in SPK and IAK patients were significantly lower than those observed in patients treated with IPII: 5.38 +/- 1.12 and 5.83 +/- 0.81 vs. 7.81 +/- 1.55 mmol/l (P < 0.001) and 1.40 +/- 0.42 and 1.32 +/- 0.53 vs. 3.47 +/- 1.66 mmol/l (P < 0.001), respectively. Furthermore, the mean glucose concentration and the glucose variability were comparable between SPK and IAK patients. Over 3 days, no hypoglycemic events were observed in SPK patients and insulin-independent IAK patients. A total of 4.12 +/- 1.66 hypoglycemic events were detected in the IPII patient group, whereas only 0.66 +/- 0.57 events were observed in IAK patients with partial graft function (P < 0.001). The duration of the hypoglycemic events was significantly longer in IPII patients as compared with IAK patients: 64 +/- 33 vs. 30 +/- 15 min for the day period and 130 +/- 62 vs. 30 +/- 27 min for the night period (P < 0.001).

CONCLUSIONS

Use of subcutaneous CGMS confirms that islet transplantation can be as efficient as pancreas transplantation in restoring good metabolic control and reducing blood glucose variability. Metabolic improvement due to use of an implantable insulin pump requires insulin delivery by a closed loop.

Human insulin production and amelioration of diabetes in mice by electrotransfer-enhanced plasmid DNA gene transfer to the skeletal muscle

A first-line gene therapy for type 1 diabetes should be based on a safe procedure to engineer an accessible tissue for insulin release. We evaluated the ability of the skeletal muscle to release human insulin after electrotransfer (ET)-enhanced plasmid DNA injection in mice. A furin-cleavable proinsulin cDNA under the CMV or the MFG promoter was electrotransferred to immune-incompetent mice with STZ-induced severe diabetes. At 1 week, mature human insulin was detected in the serum of 17/20 mice. After an initial peak of 68.5 +/- 34.9 microU/ml, insulin was consistently detected at significant levels up to 6 weeks after gene transfer. Importantly, untreated diabetic animals died within 3 weeks after STZ, whereas treated mice survived up to 10 weeks. Fed blood glucose (BG) was reduced in correspondence with the insulin peak. Fasting BG was near-normalized when insulin levels were 12.9 +/- 5.3 (CMV group, 2 weeks) and 7.7 +/- 2.6 microU/ml (MFG group, 4 weeks), without frank hypoglycemia. These data indicate that ET-enhanced DNA injection in muscle leads to the release of biologically active insulin, with restoration of basal insulin levels, and lowering of fasting BG with increased survival in severe diabetes. Therefore the skeletal muscle can be considered as a platform for basal insulin secretion.

Human pancreatic islets produce and secrete MCP-1/CCL2: relevance in human islet transplantation

We investigated the capacity of human islets to produce monocyte chemoattractant protein-1 (MCP-1). Primary cultures of pancreatic islets expressed and secreted MCP-1, as determined by Northern blot, immunohistochemistry, in situ hybridization, and enzyme-linked immunosorbent assay. The produced MCP-1 was biologically active as it attracted monocytes in chemotaxis assay, and chemotactic activity was almost abrogated by a neutralizing anti-MCP-1 monoclonal antibody. Expression of MCP-1 was increased by primary inflammatory cytokines (interleukin-1 beta, tumor necrosis factor-alpha) and lipopolysaccharide at both the mRNA and protein levels but not by glucose. However, MCP-1 did not modulate insulin secretion. MCP-1 secreted by pancreatic islets plays a relevant role in the clinical outcome of islet transplant in patients with type 1 diabetes. In fact, low MCP-1 secretion resulted as the most relevant factor for long-lasting insulin independence. This finding opens new approaches in the management of human islet transplantation. Finally, the finding that MCP-1 appears constitutively present in normal human islet beta-cells (immunohistochemistry and in situ hybridization), in the absence of an inflammatory infiltrate, suggests that this chemokine could have functions other than monocyte recruitment and opens a new link between the endocrine and immune systems.

Porcine encephalomyocarditis virus persists in pig myocardium and infects human myocardial cells

Recent advances toward using pig tissues in human transplantation have made it necessary to determine the risk of transmitting zoonotic viruses from pigs to humans or vice versa. We investigated the suitability of the porcine encephalomyocarditis virus (EMCV) model for such studies by determining its ability to persist in pigs, escape detection by routine serological methods, and infect human cells. Intraperitoneal inoculation of 5-week-old pigs with EMCV-30, a strain isolated from commercial pigs, resulted in acute cellular degeneration, infiltration of lymphocytes, and apoptosis in myocardium in 13 of 15 (86.7%) pigs during the acute phase of disease (3 to 21 days postinfection), followed by less-severe lymphocytic infiltration and apoptosis in 5 of 10 (50%) pigs during the chronic phase of the disease (day 45 to 90 postinfection). In the brain, lymphocytic infiltration, neuronal degeneration, and gliosis were observed in 26 to 33% of pigs in the acute phase of disease whereas perivascular cuffing was the predominant feature during chronic disease. EMCV antigens and RNA were demonstrated in the myocardium and brain during the chronic phase of disease. Analysis of 100 commercial pigs that were negative for EMCV antibodies identified two pig hearts positive for EMCV RNA. Porcine EMCV productively infected primary human cardiomyocytes as demonstrated by immunostaining using a monoclonal antibody specific for EMCV RNA polymerase, which is expressed only in productively infected cells, and by a one-step growth curve that showed production of 100 to 1,000 PFU of virus per cell within 6 h. The findings that porcine EMCV can persist in pig myocardium and can infect human myocardial cells make it an important infectious agent to screen for in pig-to-human cardiac transplants and a good model for xenozoonosis.

Autoantibody response to islet transplantation in type 1 diabetes

Islet allotransplantation into patients with autoimmune type 1 diabetes represents a reexposure to autoantigen. Here, measurement of antibodies to GAD and IA-2 autoantigens before and after islet transplantation in 36 patients (33 receiving islet plus kidney grafts with cyclosporin and steroid-based immunosuppression, and 3 receiving solitary islet transplants with mycophenolate but cyclosporin-free immunosuppression) demonstrated marked rises in GAD antibodies within 7 days posttransplantation in 5 patients (3 receiving islet after kidney transplants, and 2 receiving solitary islet transplants) and within 30 days in the third patient receiving solitary islet transplantation. GAD antibodies were of the IgG1 subclass, against major autoantigenic epitopes, and in cases of islet after kidney transplants, the responses were short-lived and not accompanied by HLA antibodies. Two of these patients had subsequent marked rises of IA-2 antibodies, and an additional patient had a marked rise in IgM-GAD antibodies 3 years after transplantation. Insulin independence was not achieved in patients with autoantibody elevations and was significantly less frequent in these patients. These data are consistent with a reactivation of autoimmunity that may be dependent on immunosuppression therapy and is associated with impaired graft function.

Beta cell replacement for the treatment of diabetes

The replacement of insulin-producing beta cells by islet transplantation can efficiently reverse diabetes. The recent improvements in clinical results were made possible by transplanting higher islet masses and through the introduction of new immunosuppressive protocols that avoid diabetogenicity. The need for alternatives to continuous immunosuppression, and an unlimited source of glucose-sensitive, insulin-secreting tissue, is emerging. In this review we discuss the various key steps in islet transplantation and offer perspectives for future developments in the replacement of insulin-producing beta cells for the treatment of type I diabetes.

Adenoviral vector-mediated insulin gene transfer in the mouse pancreas corrects streptozotocin-induced hyperglycemia

Therapy for type 1 diabetes consists of tight blood glucose (BG) control to minimize complications. Current treatment relies on multiple insulin injections or an insulin pump placement, beta-cell or whole pancreas transplantation. All approaches have significant limitations and have led to the realization that novel treatment strategies are needed. Pancreatic acinar cells have features that make them a good target for insulin gene transfer. They are not subject to autoimmune attack, a problem with pancreas or islets transplantation, they are avidly transduced by recombinant adenoviral vectors, and capable of exporting a variety of peptides into the portal circulation. Recombinant adenoviral vectors were engineered to express either wild-type or furin-modified human insulin cDNA (AdCMVhInsM). Immunodeficient mice were made diabetic with streptozotocin and injected intrapancreatically with the vectors. BG and blood insulin levels have normalized after administration of AdCMVhInsM. Immunohistochemistry and electron microscopy showed the presence of insulin in acinar cells throughout the pancreas and localization of insulin molecules to acinar cell vesicles. The data clearly establish a relationship between intrapancreatic vector administration, decreased BG and elevated blood insulin levels. The findings support the use of pancreatic acinar cells to express and secrete insulin into the blood stream.

Factors influencing Islet of Langerhans graft function and monitoring

Transplantation of islet of Langerhans represents a viable therapeutic option for insulin-dependent diabetes mellitus. Dramatic progress has been recently reported with the introduction of a glucocorticoid-free immunosuppressive regimen that improved success rate, namely, insulin independence for 1 year or more, from 8% to 100%. The fate of islet grafts is determined by many concurrent phenomena, some of which are common to organ grafts (i.e. rejection), while others are unique to nonvascularized cell transplants, including transplant cell mass and viability, as well as nonspecific inflammation at the site of implant. Moreover, islet grafts lack clinical markers of early rejection, making it difficult to recognize imminent rejection and to implement intervention with graft-saving immunosuppressive regimens. In the present review, we will address the problems influencing islet graft success and the monitoring of islet cell graft function.

Metabolic effects of restoring partial beta-cell function after islet allotransplantation in type 1 diabetic patients

Successful intraportal islet transplantation normalizes glucose metabolism in diabetic humans. To date, full function is not routinely achieved after islet transplantation in humans, with most grafts being characterized by only partial function. Moreover, the duration of full function is variable and cannot be sufficiently predicted with available methods. In contrast, most grafts retain partial function for a long time. We hypothesized that partial function can restore normal protein and lipid metabolism in diabetic individuals. We studied 45 diabetic patients after islet transplantation. Labeled glucose and leucine were infused to assess whole-body glucose and protein turnover in 1) 6 type 1 diabetic patients with full function after intraportal islet transplantation (FF group; C-peptide > 0.6 nmol/l; daily insulin dosage 0.03 +/- 0.02 U x kg(-1) body wt x day(-1); fasting plasma glucose < 7.7 mmol/l; HbA1c < or = 6.5%), 2) 17 patients with partial function (PF group; C-peptide > 0.16 nmol/l; insulin dosage < 0.4 U x kg(-1) body wt x day(-1)), 3) 9 patients with no function (NF group; C-peptide < 0.16 nmol/l; insulin dosage > 0.4 U x kg(-1) body wt x day(-1)), and 4) 6 patients with chronic uveitis as control subjects (CU group). Hepatic albumin synthesis was assessed in an additional five PF and five healthy volunteers by means of a primed-continuous infusion of [3,3,3-2H3]leucine. The insulin requirement was 97% lower than pretransplant levels for the FF group and 57% lower than pretransplant levels for the PF group. In the basal state, the PF group had a plasma glucose concentration slightly higher than that of the FF (P = 0.249) and CU groups (P = 0.08), but was improved with respect to the NF group (P < 0.01). Plasma leucine (101.1 +/- 5.9 micromol/l) and branched-chain amino acids (337.6 +/- 16.6 micromol/l) were similar in the PF, FF, and CU groups, and significantly lower than in the NF group (P < 0.01). During insulin infusion, the metabolic clearance rate of glucose was defective in the NF group versus in the other groups (P < 0.01). Both the basal and insulin-stimulated proteolytic and proteosynthetic rates were comparable in the PF, FF, and CU groups, but significantly higher in the NF group (P = 0.05). In addition, the PF group had a normal hepatic albumin synthesis. Plasma free fatty acid concentrations in the PF and FF groups were similar to those of the CU group, but the NF group showed a reduced insulin-dependent suppression during the clamp. We concluded that the restoration of approximately 60% of endogenous insulin secretion is capable of normalizing the alterations of protein and lipid metabolism in type 1 diabetic kidney recipients, notwithstanding chronic immunosuppressive therapy. The results of the present study indicate that "success" of islet transplantation may be best defined by a number of metabolic criteria, not just glucose concentration/metabolism alone.

Human islet cell transplantation--future prospects

BACKGROUND

Islet transplantation has the potential to cure diabetes mellitus. Nevertheless despite successful reversal of diabetes in many small animal models, the clinical situation has been far more challenging. The aim of this review is to discuss why insulin-independence after islet allotransplantation has been so difficult to achieve.

METHODS

A literature review was undertaken using Medline from 1975 to July 2000. Results reported to the International Islet Transplant Registry (ITR) up to December 1998 were also analysed.

RESULTS

Up to December 1998, 405 islet allotransplants have been reported the ITR. Of those accurately documented between 1990 and 1998 (n = 267) only 12% have achieved insulin-independence (greater than 7 days). However with refined peri-transplant protocols insulin independence at 1 year can reach 20%.

CONCLUSIONS

There are many factors which can explain the failure of achieving insulin-independence after islet allotransplantation. These include the use of diabetogenic immunosuppressive agents to abrogate both islet allo-immunity and auto-immunity, the critical islet mass to achieve insulin-independence and the detrimental effects of transplanting islets in an ectopic site. However recent evidence most notably from the Edmonton group demonstrates that islet allotransplantation still has great potential to become an established treatment option for diabetic patients.

Bovine islets are less susceptible than human islets to damage by human cytokines

BACKGROUND

The potential benefits of islet xenografting in type 1 diabetes include the intriguing, but still unanswered, possibility that the grafted xenoislets may be less subjected to human autoimmune attack. Cytokines may play a major role in the pathogenesis of autoimmune diabetes by causing impairment of insulin release and pancreatic islet cell toxicity.

METHODS

We compared insulin secretion, islet cell death and survival, inducible nitric oxide synthase (iNOS) mRNA expression, nitrite production, and Bcl-2 and Bax mRNA expression in isolated human and large mammal (bovine) islets exposed to 50 U/ml recombinant human interleukin-1, 1,000 U/ml recombinant human tumor necrosis factor-alpha and 1,000 U/ml recombinant human interferon-gamma.

RESULTS

After 24-hr exposure, a marked decrease of glucose-stimulated insulin secretion was observed with human, but not with bovine islets. After 48-hr exposure, human, but not bovine, pancreatic islets showed a significantly higher percentage of apoptotic cells compared to controls. Treatment of human islets with human cytokines induced up-regulation of iNOS mRNA, increased levels of nitrites, and down-regulation of Bcl-2 mRNA, with unchanged levels of Bax mRNA. These parameters were not affected by cytokines in bovine islets.

CONCLUSIONS

Bovine islets are less susceptible than human islets to the effects of human cytokines, which may be a potential advantage of xenotransplantation.

Insights from a successful case of intrahepatic islet transplantation into a type 1 diabetic patient

We report a case of long-term (>4 yr) successful intrahepatic islet transplantation into a type 1 diabetic patient chronically immunosuppressed for a prior kidney graft. The exogenous insulin requirement decreased progressively after transplantation, and insulin treatment was withdrawn at 6 months. Glycosylated hemoglobin levels were in the normal range at 1 and 2 yr (5.3%) and increased slightly above the upper normal limit at 3 and 4 yr (6.3% and 6.4%). Fasting C peptide levels remained stable during the entire follow-up, but the proinsulin to insulin ratios increased dramatically at yr 3. Glycemic levels after an oral glucose tolerance test showed a diabetic profile at 1 yr, a normal profile at 2 yr, and an impaired glucose tolerance profile at 3 yr. Intravenous glucose tolerance test-induced first phase insulin release, present at 1 and 2 yr, disappeared at 3 yr. Diabetes-related autoantibodies (islet cell antibodies, glutamic acid decarboxylase antibodies, and tyrosine phosphatase-like protein antibodies) were undetectable before transplantation and remained so during the entire follow-up. The patient died of myocardial infarction 50 months after transplantation while she was still in good metabolic control (glycosylated hemoglobin, <6.8%) in the absence of exogenous insulin administration. The autoptic liver showed well granulated islets, richly vascularized and without evidence of lympho-mononuclear cell infiltration. The morphometrically extrapolated intrahepatic beta-cell mass was 99.9 mg. In conclusion, this successful islet graft showed a bell-shaped clinical effect, maximal at 2 yr after transplantation, followed by a slow progressive decline. The absence of allo- and autoreactivities against the transplanted islets points to a nonimmune-mediated beta-cell loss as the cause of graft functional deterioration.

Cell transplantation for endocrine disorders

Current hormonal replacement therapy for endocrine disorders cannot, unfortunately, reproduce the complex metabolic interactions of hormones. The organ or cell transplantation would be a more physiological approach to the treatment of endocrine disorders. For decades, remarkable progress in organ or cell transplantation in endocrine disorders has been made, especially in recent years. But there are many limitations in the widespread application of allotransplantation because of rejection. Various methods of immunomanipulations designed to overcome rejection have been proposed, which include immunosuppression, immunomodulation and immunoisolation. The transplantation of immunoisolated cells and some clinical results of the transplants were reviewed. Also a perspective for future directions on endocrine cell transplantation was provided in this review. Human islet cell transplantation for the cure of diabetes was emphasized in this chapter and other cell transplantation for endocrine disorders was also discussed briefly, including parathyroid tissue transplantation, bioartificial thyroid transplantation and adrenal cell transplantation.