Achievement of insulin independence via pancreatic islet transplantation using a remote isolation center: a first-year review

Improved Baculovirus Vectors for Transduction and Gene Expression in Human Pancreatic Islet Cells

Pancreatic islet transplantation is a promising treatment for type 1 diabetes mellitus offering improved glycaemic control by restoring insulin production. Improved human pancreatic islet isolation has led to higher islet transplantation success. However, as many as 50% of islets are lost after transplantation due to immune responses and cellular injury, gene therapy presents a novel strategy to protect pancreatic islets for improved survival post-transplantation. To date, most of the vectors used in clinical trials and gene therapy studies have been derived from mammalian viruses such as adeno-associated or retrovirus. However, baculovirus BacMam vectors provide an attractive and safe alternative. Here, a novel BacMam was constructed containing a frameshift mutation within fp25, which results in virus stocks with higher infectious titres. This improved in vitro transduction when compared to control BacMams. Additionally, incorporating a truncated vesicular stomatitis virus G protein increased transduction efficacy and production of EGFP and BCL2 in human kidney (HK-2) and pancreatic islet β cells (EndoC βH3). Lastly, we have shown that our optimized BacMam vector can deliver and express egfp in intact pancreatic islet cells from human cadaveric donors. These results confirm that BacMam vectors are a viable choice for providing delivery of transgenes to pancreatic islet cells.

Maintenance of Mouse, Rat, and Pig Pancreatic Islet Functions by Coculture with Human Islet-Derived Fibroblasts

Development of an efficient preculture system of islets is ideal. Toward that goal, we constructed a human pancreatic islet-derived fibroblast cell line MNNK-1 for a source as a coculture system for freshly isolated islets to maintain islet functions. Human pancreatic islet cells were nucleofected with a plasmid vector pYK-1 expressing simian virus 40 large T antigen gene (SV40T) and hygromycin resistance gene (HygroR). One of the transduced cell lines, MNNK-1, was established and served as a feeder cell in the coculture for freshly isolated mouse, rat, and pig islets. Morphology, viability, and glucose-responding insulin secretion were analyzed in the coculture system. MNNK-1 cells were morphologically spindle shaped and were negative for pancreatic endocrine markers. MNNK-1 cells were positive for α-smooth muscle actin and collagen type I and produced fibroblast growth factor. Coculture of the mouse, rat, and pig islets with MNNK-1 cells maintained their viability and insulin secretion with glucose responsiveness. A human pancreatic islet-derived fibroblast cell line MNNK-1 was established. MNNK-1 cells were a useful means for maintaining morphology and insulin secretion of islets in the coculture system.

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 HbA1c 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.

Percutaneous portal vein access and transhepatic tract hemostasis

Percutaneous portal vein interventions require minimally invasive access to the portal venous system. Common approaches to the portal vein include transjugular hepatic vein to portal vein access and direct transhepatic portal vein access. A major concern of the transhepatic route is the risk of postprocedural bleeding, which is increased when patients are anticoagulated or receiving pharmaceutical thrombolytic therapy. Thus percutaneous portal vein access and subsequent closure are important technical parts of percutaneous portal vein procedures. At present, various techniques have been used for either portal access or subsequent transhepatic tract closure and hemostasis. Regardless of the method used, meticulous technique is required to achieve the overall safety and effectiveness of portal venous procedures. This article reviews the various techniques of percutaneous transhepatic portal vein access and the various closure and hemostatic methods used to reduce the risk of postprocedural bleeding.

Dimeric MHC-peptides inserted into an immunoglobulin scaffold as new immunotherapeutic agents

The interactions of the T cell receptor (TCR) with cognate MHC-peptide and co-stimulatory molecules expressed at surface of antigen presenting cells (APC) leads to activation or tolerance of T cells. The development of molecular biological tools allowed for the preparation of soluble MHC-peptide molecules as surrogate for the APC. A decade ago a monomeric class II MHC molecule in which the peptide was covalently linked to β-chain of class II molecule was generated. This type of molecule had a low-binding affinity and did not cause the multimerization of TCR. The requirement of multimerization of TCR led to development of a new class of reagents, chimeric peptides covalently linked to MHC that was dimerized via Fc fragment of an immunoglobulin and linked to 3' end of the β-chain of MHC class II molecule. These soluble dimerized MHC-peptide chimeric molecules display high affinity for the TCR and caused multimerization of TCR without processing by an APC. Because dimeric molecules are devoid of co-stimulatory molecules interacting with CD28, a second signal, they induce anergy rather the activation of T cells. In this review, we compare the human and murine dimerized MHC class II-peptides and their effect on CD4(+) T cells, particularly the generation of T regulatory cells, which make these chimeric molecules an appealing approach for the treatment of autoimmune diseases.

Improved quantification of islet transplants by magnetic resonance imaging with Resovist

OBJECTIVES

We aimed to develop an accurate and reproducible method to quantify transplanted islets and monitor their functional status in vivo. To support this aim, we investigated the cytotoxic effect of Resovist on islet function and survival.

METHODS

The average pixel number for a single Resovist-labeled islet was measured. To determine Resovist cytotoxicity, DNA fragmentation, adenosine diphosphate-adenosine triphosphate ratio, ion channel activity, and in vivo islet function were evaluated. To quantitatively monitor the fate of islet transplant, we transplanted Resovist-labeled islets into syngeneic C57BL/6 mice for magnetic resonance imaging analysis.

RESULTS

The average pixel volume for a medium-sized islet (100-150 μm in diameter) was determined from the contrast signal void of magnetic resonance image. Toxicological analysis showed that Resovist did not affect islet at concentrations up to 40 times the labeling dose. In the quantitative analysis, the number of contrast spots did not correlated with the number of transplanted islets, whereas our newly adopted measure showed a significant correlation.

CONCLUSIONS

Islet transplant survival may be safely and accurately monitored using magnetic resonance imaging with the Resovist. We found in this study that pixel number may correlate more closely than the number of contrast spots with the number of islets transplanted.

A polyethylene oxide-functionalized self-organized alumina nanochannel array for an immunoprotection biofilter

Nanochannel membranes have been fabricated for many biological and engineering applications. However, due to low-throughput process, high cost, unsuitable pore geometries, and low chemical/mechanical stability, we could not have obtained optimized nanochannel membranes for biomedical treatments as well as a novel building block for artificial cell membranes. Here, we report a PEO-functionalized straight nanochannel array based on a self-organized porous alumina for a novel biofilter with antifouling, superior immunoprotection and high permeability of nutrients, which have excellent in vivo mechanical stability. Thus, our strategy may provide great advantages in novel membrane biotechnologies such as biofiltration, artificial cells, and drug delivery.

Improved intraportal islet transplantation outcome by systemic IKK-beta inhibition: NF-κB activity in pancreatic islets depends on oxygen availability

Intraportal islet transplantation suffers from low efficiency caused by substantial islet mass loss after transplantation. How this process is regulated is still unclear. Here, we show that NF-κB activation was detectable in islet grafts shortly after transplantation of porcine islets to diabetic NMRI nu/nu mice, and systemic NF-κB inhibition in transplanted animals significantly prolonged islet graft survival. Proinflammatory cytokines alone did not cause evident cell death in pancreatic islet within 24 h, while the combination of cytokines with hypoxia resulted in a strong induction of cell death that could be blocked dose-dependently by a selective IKK-β inhibitor. Under hypoxia, NF-κB activity impaired expression of antiapoptotic gene BCL-xL, c-FLIP and survivin. NF-κB activation in isolated islets was reduced by hypoxia in a time-dependent manner, accordingly, NF-κB activation in transplanted islets diminished by time. Our data indicate that, while NF-κB has an antiapoptotic role under normoxia, low oxygen conditions decrease its activity and transform it to a proapoptotic transcription factor in pancreatic islets. We conclude that NF-κB inhibition represents a potential strategy to improve islet transplantation efficiency.

MRI as a tool to monitor islet transplantation

The development of new methods for noninvasive imaging is an area of biotechnology that is of great relevance for the diagnosis and characterization of diabetes mellitus. Noninvasive imaging can be used to study the dynamics of beta-cell mass and function; beta-cell death; vascularity, innervation and autoimmune attack of pancreatic islets; and the efficacy of islet transplantation to remedy beta-cell loss in patients with diabetes mellitus. In this Review, we focus on the application of MRI for monitoring islet transplantation and on the potential causes of islet graft failure, which are still poorly understood. Questions that have been addressed by MRI studies encompass graft longevity, and the effects of immune rejection, glucose toxic effects, and the transplanted islets' purity on graft fate. We also highlight novel technologies for simultaneous imaging and delivery of experimental therapies that aim to extend the lifespan and functionality of islet grafts. On the basis of this evidence, MRI represents a valuable platform for a thorough investigation of beta-cell function in the context of islet transplantation. State-of-the-art multimodality approaches, such as PET-MRI, can extend our current capabilities and help answer the critical questions that currently inhibit the prevention and cure of diabetes mellitus.

Anti-inflammatory thalidomide improves islet grafts survival and functions in a xenogenic environment

Thalidomide possesses both anti-inflammatory and anti-angiogenic properties. This study investigates its potential application in islet transplantation with a xenogenic transplantation model. Transplantation was performed using C57Bl/6 mice and NMRI nu/nu mice as recipients of porcine islets. Moreover, islet graft vasculature and inflammation were investigated to identify the mechanisms of thalidomide action. In the immunocompetent environment of C57Bl/6 mice, a fast graft rejection was observed. The group treated with thalidomide 200 mg/kg BW per day achieved and maintained euglycemia in the complete observation period for 42 days. The treated mice had more functional islet graft mass with less leukocyte infiltration. The pro-inflammatory TNF-α and VEGF content in islet grafted kidneys was significantly lowered by the treatment. By comparison, thalidomide was not effective in improving graft survival in immunocompromised nude mice. It strongly inhibited the VEGF and TNF-α-induced endothelial proliferation of isolated pig islets in a dose dependent manner. The magnitude of thalidomide's inhibitory effect was nearly identical to the effect of VEGF- receptor 2 inhibitor SU416 and anti-TNF-receptor 1 neutralizing antibody, and was reversed by sphingosine-1-phosphate. In conclusion, the anti-inflammatory effect of thalidomide improved islet graft survival and function in a transplantation model with a maximum immune barrier.

A peptide-major histocompatibility complex II chimera favors survival of pancreatic beta-islets grafted in type 1 diabetic mice

BACKGROUND

Transplantation of pancreatic islets showed a tremendous progress over the years as a promising, new therapeutic strategy in patients with type 1 diabetes. However, additional immunosuppressive drug therapy is required to prevent rejection of engrafted islets. The current immunosuppressive therapies showed limited success in maintaining long-term islet survival as required to achieve insulin independence in type 1 diabetes, and they induce severe adverse effects. Herein, we analyzed the effects of a soluble peptide-major histocompatibility complex (MHC) class II chimera aimed at devising an antigen-specific therapy for suppression of anti-islet T cell responses and to improve the survival of pancreatic islets transplants.

METHODS

Pancreatic islets from transgenic mice expressing the hemagglutinin antigen in the beta islets under the rat insulin promoter (RIP-HA) were grafted under the kidney capsule of diabetic, double transgenic mice expressing hemagglutinin in the pancreas and T cells specific for hemagglutinin (RIP-HA, TCR-HA). The recipient double transgenic mice were treated or not with the soluble peptide-MHC II chimera, and the progression of diabetes, graft survival, and T cell responses to the grafted islets were analyzed.

RESULTS

The peptide-MHC II chimera protected syngeneic pancreatic islet transplants against the islet-reactive CD4 T cells, and prolonged the survival of transplanted islets. Protection of transplanted islets occurred by polarization of antigen-specific memory CD4 T cells toward a Th2 anti-inflammatory response.

CONCLUSIONS

The peptide-MHC II chimera approach is an efficient and specific therapeutic approach to suppress anti-islet T cell responses and provides a long survival of pancreatic grafted islets.

Resolving the conundrum of islet transplantation by linking metabolic dysregulation, inflammation, and immune regulation

Although type 1 diabetes cannot be prevented or reversed, replacement of insulin production by transplantation of the pancreas or pancreatic islets represents a definitive solution. At present, transplantation can restore euglycemia, but this restoration is short-lived, requires islets from multiple donors, and necessitates lifelong immunosuppression. An emerging paradigm in transplantation and autoimmunity indicates that systemic inflammation contributes to tissue injury while disrupting immune tolerance. We identify multiple barriers to successful islet transplantation, each of which either contributes to the inflammatory state or is augmented by it. To optimize islet transplantation for diabetes reversal, we suggest that targeting these interacting barriers and the accompanying inflammation may represent an improved approach to achieve successful clinical islet transplantation by enhancing islet survival, regeneration or neogenesis potential, and tolerance induction. Overall, we consider the proinflammatory effects of important technical, immunological, and metabolic barriers including: 1) islet isolation and transplantation, including selection of implantation site; 2) recurrent autoimmunity, alloimmune rejection, and unique features of the autoimmune-prone immune system; and 3) the deranged metabolism of the islet transplant recipient. Consideration of these themes reveals that each is interrelated to and exacerbated by the other and that this connection is mediated by a systemic inflammatory state. This inflammatory state may form the central barrier to successful islet transplantation. Overall, there remains substantial promise in islet transplantation with several avenues of ongoing promising research. This review focuses on interactions between the technical, immunological, and metabolic barriers that must be overcome to optimize the success of this important therapeutic approach.

Real-time imaging of the pancreas during development of diabetes

Type 1 diabetes (T1D) is the most common autoimmune disease affecting almost 20 million people worldwide. T1D is thought to be caused by autoaggressive T cells infiltrating pancreatic islets and destroying insulin-producing beta cells. Because insulin therapy, the current treatment for T1D, does not protect against all late complications and because life expectancy is affected, researchers are searching for preventive or curative approaches that block or prevent immune-mediated islet destruction. However, the precise in vivo events that take place in islets during T1D development remain unknown. During the past decade, 2-photon microscopy (2PM) has emerged as a new technique to assess cell-cell interactions in real-time and at high resolution in vivo. This technique has been demonstrated recently to be a promising tool to study the progressive development of T1D pathogenesis at the cellular level. In this review, we propose a new surgical and immunological approach so that 2PM can be utilized to monitor the duration that effector cells reside within an islet, determine the number of effector cells needed for elimination of beta cells, and follow the fate of beta cells when regulatory cells are present. Understanding the cellular dynamics during T1D development is critical for the rational design of immunotherapies.

Estado actual del trasplante de islotes pancreáticos

Due to the numerous advances in islet transplantation in the last few years, clinical outcomes following this procedure are continually improving. Novel immunosuppression protocols, improved donor and recipient selection, and careful attention to the process of organ extraction, preservation and islet isolation have contributed to long-term success. The present article reviews the results of clinical islet transplantation and their relationship with the different advances introduced. The use of new islet sources such as living and non-heart-beating donors, as well as recent advances in our knowledge of the mechanisms of rejection and its prevention, are also reviewed.

In vivo imaging of immune rejection in transplanted pancreatic islets

As islet transplantation becomes an acceptable clinical modality for restoring normoglycemia in type 1 diabetic patients, there is a crucial need for noninvasive assessment of the fate of the grafts. In spite of the success of the Edmonton Protocol, a significant graft loss occurs due to immunological and nonimmunological events immediately after transplantation. Allogeneic rejection in graft recipients is one of the major reasons for islet death and graft failure. Therefore, monitoring the islet rejection using reliable noninvasive methods would significantly aid in clinical assessment of graft success. We have previously developed a method to detect transplanted islets noninvasively using magnetic resonance imaging (MRI). For this procedure, human pancreatic islets are labeled with an MRI contrast agent that enables their visualization on magnetic resonance images. In our present study, we not only detected labeled human islets in a preclinical intrahepatic model of human islet transplantation in mice but also showed that islet rejection can be monitored noninvasively and repeatedly in real time by MRI. In addition, in this study, we have adapted, for islet cell labeling, a Food and Drug Administration-approved commercially available contrast agent, Feridex, that is used clinically for liver imaging. We believe that this agent, in combination with our preclinical model of islet transplantation, will facilitate the transition of imaging immune rejection to clinical trials.

The effect of whole organ pancreas transplantation and PIT on diabetic complications

Diabetes mellitus is a leading cause of morbidity and mortality in the Western world. Currently, the only forms of beta-cell replacement are whole organ pancreas transplantation and pancreatic islet transplantation. Whole organ transplantation has demonstrated benefits in prevention and reversal of diabetic complications with sustainable long-term outcomes. Pancreatic islet transplantation continues to be a field that needs further study to ascertain the true benefit of islet transplantation for diabetic complications. This can only be achieved with improvement in long-term islet allograft survival.

A Newly Developed Bioartificial Pancreas Successfully Controls Blood Glucose in Totally Pancreatectomized Diabetic Pigs

Construction of a safe and functional bioartificial pancreas (BAP) that provides an adequate environment for islet cells may be an important approach to treating diabetic patients. Various types of BAP devices have been developed, but most of them involve extravascular implantation of islets in microcapsules or diffusion chambers. These devices have poor diffusive exchange between the islets and blood, and often rupture. To overcome these problems, we developed a new type of BAP composed of polyethylene-vinyl alcohol (EVAL) hollow fibers that are permeable to glucose and insulin and a poly-amino-urethane-coated, non-woven polytetrafluoroethylene (PTFE) fabric that allows cell adhesion. Porcine islets attached to the surface of the PTFE fabric, but not to the surface of the EVAL hollow fibers, allowing nutrient and oxygen exchange between blood flowing inside the fibers and cells outside. We inoculated this BAP with porcine islets and connected it to the circulation of totally pancreatectomized diabetic pigs. We found that blood glucose levels were reduced to a normal range and general health was improved, resulting in longer survival times. In addition, regulation of insulin secretion from the BAP was properly controlled in response to glucose both in vitro and in vivo. These results indicate that our newly developed BAP may be a potential therapy for the treatment of diabetes in humans.

Assessment of glycemic control after islet transplantation using the continuous glucose monitor in insulin-independent versus insulin-requiring type 1 diabetes subjects

BACKGROUND

The aim of this study was to assess and compare glycemic control using the continuous glucose monitor (CGMS, Medtronic Minimed, Northridge, CA) in type 1 diabetes mellitus (T1DM) subjects who are insulin-independent versus those who require insulin after islet transplantation alone (ITA).

METHODS

Glycemic control was assessed using 72-h CGMS in eight T1DM subjects who were insulin-independent after ITA (ITA-II), eight T1DM subjects who were C-peptide-positive but insulin-requiring after ITA (ITA-IR), and eight non-transplanted (NT) T1DM subjects.

RESULTS

Standard deviation of glucose values was not significantly different between ITA-II and ITA-IR subjects (ITA-II, 1.2 +/- 0.1 mM; ITA-IR, 2.0 +/- 0.3 mM; P = 0.072). Both ITA groups were more stable than NT subjects (NT, 3.3 +/- 0.3 mM; P = 0.001 vs. ITA). Mean high glucose values were significantly lower in ITA subjects compared with NT subjects (ITA-II, 10.5 +/- 0.6 mM; ITA-IR, 13.0 +/- 1.0 mM; NT, 16.1 +/- 1.1 mM; P = 0.002). Mean average glucose values were not significantly different among all groups (ITA-I, 6.7 +/- 0.2 mM; ITA-IR, 7.8 +/- 0.3 mM; NT, 7.7 +/- 0.6 mM; P = 0.198). Mean low glucose values were significantly higher in both ITA groups compared with NT subjects (ITA-II, 4.5 +/- 0.2 mM; ITA-IR, 4.3 +/- 0.3 mM; NT, 3.0 +/- 0.2 mM; P = 0.003). Duration of hypoglycemic excursions (<3.0 mM) was markedly reduced in both ITA groups (ITA-II, 0%; ITA-IR, 2.4 +/- 0.2%; NT, 11.8 +/- 4.2%). Glycated hemoglobin was not significantly different between ITA groups (ITA-II, 6.4 +/- 0.2%; ITA-IR, 6.5 +/- 0.3%) and was significantly higher in NT subjects (8.3 +/- 0.2%; P < 0.001 vs. ITA).

CONCLUSIONS

CGMS monitoring demonstrates that glycemic lability and hypoglycemia are significantly reduced in C-peptide-positive islet transplant recipients, whether or not supplementary, exogenous insulin is used, compared with non-transplanted T1DM subjects.

Immunosuppression and procedure-related complications in 26 patients with type 1 diabetes mellitus receiving allogeneic islet cell transplantation

BACKGROUND

The success of sirolimus and low-dose tacrolimus in islet cell transplantation has influenced many transplant centers to utilize this novel regimen. The long-term safety and tolerability of this steroid-free immunosuppressive protocol for allogeneic islet transplantation has yet to be determined.

METHODS

We transplanted 26 adult patients with long standing type 1 diabetes mellitus between April 2000 and June 2004. Immunosuppression consisted of induction with daclizumab and maintenance therapy with tacrolimus and sirolimus. Adverse events (AEs) in patients were followed and graded using the Common Terminology Criteria for Adverse Events, version 3.0 (National Cancer Institute).

RESULTS

To date, the majority of patients were able to remain on the immunosuppression combination for up to 22+/-11 months. Four patients were successfully converted to Mycophenolate Mofetil due to tacrolimus-related toxicity. Withdrawal from immunosuppression was decided in four patients due to hypereosinophilic syndrome, parvovirus infection, aspiration pneumonia, and severe depression, respectively. Six patients required filgrastim therapy for neutropenia. Transient elevation of liver enzymes was observed in most patients early after islet infusion. Increased LDL in 20 patients required medical treatment.

CONCLUSION

There was a varying range of AEs, most of them mild and self-limiting; however, some required urgent medical attention. The majority of patients were able to tolerate and remain on this effective regimen. To date, no deaths, cytomegalovirus disease, graft-versus-host disease, or posttransplant lymphoproliferative disease has been observed.

Prevention of bleeding after islet transplantation: lessons learned from a multivariate analysis of 132 cases at a single institution

Islet transplantation is being offered increasingly for selected patients with unstable type 1 diabetes. Percutaneous transhepatic portal access avoids a need for surgery, but is associated with potential risk of bleeding. Between 1999 and 2005, we performed 132 percutaneous transhepatic islet transplants in 67 patients. We encountered bleeding in 18/132 cases (13.6%). In univariate analysis, the risk of bleeding in the absence of effective track ablation was associated with an increasing number of procedures (2nd and 3rd procedures with an odds ratio (OR) of 9.5 and 20.9, respectively), platelets count <150,000 (OR 4.4), elevated portal pressure (OR 1.1 per mm Hg rise), heparin dose > or =45 U/kg (OR 9.8) and pre-transplant aspirin (81 mg per day) (OR 2.6, p = 0.05). A multivariate analysis further confirmed the cumulative transplant procedure number (p < 0.001) and heparin dose > or =45 U/kg (p = 0.02) as independent risk factors for bleeding. Effective mechanical sealing of the intrahepatic portal catheter tract with thrombostatic coils and tissue fibrin glue completely prevented bleeding in all subsequent procedures (n = 26, p = 0.02). We conclude that bleeding after percutaneous islet implantation is an avoidable complication provided the intraparenchymal liver tract is sealed effectively.

How good is your glucose control?

BACKGROUND

Glycemic control is fundamental to the management of diabetes and maintenance of health. Popular measures of performance in glycemic control include A1c and self-monitoring of blood glucose (SMBG). As measures of performance, A1c has perspective, but it fails to recognize hypoglycemia, while SMBG lacking overall perspective finds use mainly by patients to simply evaluate their glycemic status and current response to therapy. An additional, preferably visual, measure of performance in diabetes management in general and glycemic control in particular is needed.

METHODS

To form a visual measure of performance, a graphical method of analysis from the statistician's toolbox (known as the lag plot) was adapted. It can utilize SMBG data sets from any source, including memory meters and registry databases in call centers. Data are retrieved, processed, formatted, and then plotted on a PC screen or printer. The resulting lag plots visually characterize the performance of glucose control achieved over periods (selectable by the user) from days to months. Supporting numerical statistics provide rigorous outcome measures that correlate with glycated hemoglobin.

RESULTS

Clinical use of the lag plot is illustrated in seven case studies spanning the range from no diabetes, through glucose intolerance, early-onset type 2 diabetes mellitus, type 1 diabetes, intensified therapy, pump therapy, and finally islet cell transplantation. Visual comparisons before and after action/referral show impacts of interventions, incidences of hypoglycemia, and changes in the polyglycemia of unstable diabetes. Statistical significance of observed changes are quantified.

CONCLUSIONS

The simple lag plot can empower patients and their providers to identify problems in glycemic control, seek proactive action, adopt beneficial strategies, evaluate outcomes, and, most importantly, rule out interventions with no benefit.

The effect of pancreatic islet transplantation on progression of diabetic retinopathy and neuropathy

INTRODUCTION

Pancreatic islet transplantation (PIT) has only become an effective treatment for type 1 diabetes mellitus within the past 4 years. As a result, the long-term effects of PIT on progression of diabetic neuropathy and retinopathy are unknown. The benefit of halting or improving diabetic neuropathy and retinopathy is of particular interest since most PIT recipients have not developed the advanced complications of diabetes. Herein, we describe the improvement and stabilization of diabetic neuropathy and retinopathy in 12 PIT recipients.

PATIENTS AND METHODS

Between January 1, 2002, and June 30, 2004, there have been 12 patients who have received PIT. Currently, there are eight patients who have sufficient follow-up to assess the progression of diabetic retinopathy and neuropathy. To assess for disease progression, patients were examined by a single ophthalmologist and single neurologist throughout the study period. Eye exams were performed using a slit-lamp exam while neurological status was assessed using electromyelograms and clinical exams.

RESULTS

All PIT recipients had decreases in hemoglobin A(1)C and increases in serum C-peptide. All study patients had stabilization of their retinopathic disease. One patient demonstrated improvement of retinopathy at 1 year posttransplant. Fifty percent of patients demonstrated improvement or stabilization of their diabetic neuropathy. One patient had mild reinnervation of the fingers and wrist extensors by clinical exam 1 year posttransplant. Four patients exhibited an average decrease of 19% in sural nerve conduction velocities.

CONCLUSION

Our series has demonstrated that all PIT recipients have had stabilization of their diabetic retinopathy and that 50% of patients exhibited stabilization or even improvement of their diabetic neuropathy.

Islet transplantation in type 1 diabetes mellitus using cultured islets and steroid-free immunosuppression: Miami experience

Following the success obtained with transplantation of fresh human islets under steroid-free immunosuppression, this trial evaluated the transplantation of islets that had undergone a period of in vitro culture and the potential of tumor necrosis factor (TNF-alpha) blockade to improve islet engraftment. Subjects included 16 patients with type 1 diabetes mellitus (T1DM); half were randomly assigned to receive Infliximab immediately preceding initial infusion. Immunosuppression consisted of daclizumab induction and sirolimus/tacrolimus maintenance. Out of 16 subjects 14 achieved insulin independence with one or two islet infusions; adverse events precluded completion in two. Without supplemental infusions, 11/14 (79%) subjects were insulin independent at 1 year, 6/14 (43%) at 18 months; these same subjects remain insulin independent at 33+/-6 months. While on immunosuppression, all patients maintained graft function. Out of 14 patients, 8 suffered chronic partial graft loss, likely immunological in nature, 5 of these received supplemental infusions. Currently, 11 subjects remain on immunosuppression, 8 (73%) are insulin independent, two with supplemental infusions. Insulin independent subjects demonstrated normalization of HbA1c, fructosamine and Mean Amplitude of Glycemic Excursions (MAGE) values. No clinical benefit of infliximab was identified. These results demonstrate that transplantation of cultured human islet allografts results in reproducible insulin independence in all subjects under this immunosuppressive regimen, comparable to that of freshly transplanted islets (Edmonton protocol).

Effect of the immunosuppressive regime of Edmonton protocol on the long-term in vitro insulin secretion from islets of two different species and age categories

The success of the new immunosuppressive regime known as the Edmonton protocol in islet allotransplantation may suggest that it is also possible that this regime may prevent the rejection of xenografts. This protocol applies a combination of Tacrolimus, Sirolimus and Daclizumab at low doses. This combination may have some toxicity that affects the function and viability of the pancreatic islets. The choice of species or age category, whose islets can tolerate the toxicity of this immunosuppressive combination, may become important for the graft survival. It was the aim of this study to investigate the long-term effect of this regime on insulin secretion from pancreatic islets isolated from two species (rats and pigs) and from two age categories (day 7 postnatal [P7] and adult rat). Islets were cultured for three weeks in medium containing Tacrolimus in a concentration of 5 ng/ml, while the concentration of Sirolimus was 15 ng/ml. Daclizumab was added at the beginning of culture and once weekly in a final concentration of 10 ng/ml. In immunosuppressive-treated groups, Glucose was able to stimulate increases of insulin secretion over the basal value after 1 and 3 weeks in adult rat islets, and could not stimulate this secretion in P7 islets, while it stimulated the secretion only after 1 week, but not 3 weeks, in porcine islets. The immunosuppressive regimen caused significant reductions of glucose-stimulated insulin secretion magnitude in adult rat and porcine islets after 3 weeks, while it reduced both basal and stimulated secretions after 1 and 3 weeks in P7 rat islets. There was no difference in DNA contents between control and immunosuppressive-treated groups after 1 or 3 weeks in any of the islet preparations. DNA decreased considerably with the time in culture. The change in DNA content over 3 weeks was higher in the Edmonton group of adult porcine and P7 rat than in adult rat islets. Comparison of the responses of islets from different age categories and species leads to conclude that in vitro cultures of adult rat islets are more tolerant to this immunosuppressive combination toxicity than P7 islets, and there is variable responses of islets from different adult species to this toxicity.

Home blood glucose prediction: clinical feasibility and validation in islet cell transplantation candidates

AIMS/HYPOTHESIS

Diabetic subjects do home monitoring to substantiate their success (or failure) in meeting blood glucose targets set by their providers. To succeed, patients require decision support, which, until now, has not included knowledge of future blood glucose levels or of hypoglycaemia. To remedy this, we devised a glucose prediction engine. This study validates its predictions.

METHODS

The prediction engine is a computer program that accesses a central database in which daily records of self-monitored blood glucose data and life-style parameters are stored. New data are captured by an interactive voice response server on-line 24 h a day, 7 days a week. Study subjects included 24 patients with debilitating hypoglycaemia (unawareness), which qualified them for islet cell transplantation. Comparison of each prediction with the actually observed data was done using a Clarke Error Grid (CEG). Patients and providers were blinded as to the predictions.

RESULTS

Prior to transplantation, a total of 31,878 blood glucose levels were reported by the study subjects. Some 31,353 blood glucose predictions were made by the engine on a total of 8,733 days-used. Of these, 79.4% were in the clinically acceptable Zones of the CEG. Of 728 observed episodes of hypoglycaemia, 384 were predicted. After transplantation, a total of 45,529 glucose measurements were reported on a total of 12,906 days-used. Some 42,316 glucose predictions were made, of which 97.5% were in the acceptable CEG Zones A and B. Successful transplantation eliminated hypoglycaemia, improved glycaemic control, lowered HbA(1)c and freed 10 of 24 patients from daily insulin therapy.

CONCLUSIONS/INTERPRETATION

It is clinically feasible to generate valid predictions of future blood glucose levels. Prediction accuracy is related to glycaemic stability. Risk of hypoglycaemia can be predicted. Such knowledge may be useful in self-management.

Health-Related Quality of Life after Pancreatic Islet Transplantation: A Longitudinal Study

BACKGROUND

Pancreatic islet transplantation (PIT) has proven effective in achieving insulin independence, but to date, the impact of PIT on health-related quality of life (HRQL) has not been studied.

METHODS

Ten patients who have undergone PIT at our institution were administered three HRQL questionnaires: the Hypoglycemia Fear Survey, the 36-Item Short Form Health Survey (SF-36), and a fatigue questionnaire. HRQL was assessed before PIT, then 3, 6, and 12 months after PIT. Responses were compared by analysis of variance and paired Student's t tests.

RESULTS

Hypoglycemia Fear Survey responses demonstrated that hypoglycemia-related anxiety and hypoglycemia-related behavior modification occurred less frequently after PIT (P=0.003 and 0.0001, respectively). The total scores of the hypoglycemia questionnaire were also significantly improved after PIT, from a median score of 156 points before transplantation to 55 points 3 months after PIT (P=0.004), 38 points 6 months after PIT (P=0.001), and 69 points 12 months after PIT (P=0.04). The median scores of all SF-36 components also improved after PIT. No significant changes were seen in the fatigue symptoms as assessed by the fatigue questionnaire.

CONCLUSION

PIT recipients have less anxiety about the symptoms and consequences of hypoglycemia. PIT recipients also indicate that their behavior requires significantly less modification to prevent or treat hypoglycemia after PIT compared with before PIT. Further investigation is needed to determine whether PIT improves generic measures of HRQL.

Closed-loop insulin delivery – what lies between where we are and where we are going?

Closed-loop insulin delivery in individuals with diabetes can potentially lead to near-normal glucose profiles. To this end, existing subcutaneous glucose sensors and external insulin pumps can be linked with an insulin delivery algorithm to create a completely automated closed-loop system. This paper reviews current research into the development of such a system, with particular emphasis on creating a system emulating the physiological properties of the beta-cell. Issues related to using subcutaneous interstitial fluid for glucose sensing and insulin delivery are reviewed. Criteria for optimising the system are discussed using historical data. Existing strategies for open-loop pump therapy are presented with the objective of defining a path to advance from the existing physician/patient determined insulin therapy to a completely automated system.

Logistics and Transplant Coordination Activity in the GRAGIL Swiss-French Multicenter Network of Islet Transplantation

BACKGROUND

Since the Edmonton trial in 2000, increasing numbers of transplant centers have been implementing islet transplantation programs. Some institutions have elected to associate in multicenter networks, such as the Swiss-French GRAGIL (Groupe Rhin-Rhône-Alpes-Genève pour la Transplantation d'Ilots de Langerhans) consortium.

METHODS

All pancreata offers to the University of Geneva Cell Isolation and Transplantation Center from within the network in 2002 and 2003 were reviewed. Islet preparations were attributed to the most suitable recipient on a centrally managed waiting list. All shipments were performed by ambulance in less than 5 hr.

RESULTS

Over the period of study, 260 pancreata were offered, from a total of 1,304 cadaveric donors in the four allocation regions (20%). Fifty-two patients were on the waiting list at any time during this 2-year period. The percentage of organs offered varied in the range of 0.5% to 42%, depending on region of origin, with a correlation with number of patients on the waiting list in each region. Of these, 104 (40%) were accepted for processing. Ninety-two pancreata were actually processed, resulting in 42 islet preparations being transplanted. The number of international equivalents of transplanted preparations was 378,500+/-16,000 versus 165,400+/-15,400 (P<0.0001) for nontransplanted preparations. Total cold ischemia time was 6+/-0.3 hr for transplanted preparations versus 6.7+/-0.4 hr for nontransplanted preparations (not significant). CONCLUSIONS.: A high rate of pancreas offers, successful isolation, and islet transplantation can be achieved in multicenter networks such as GRAGIL. Such an approach can expand both the donor pool and the recipient population.

Transaminitis after pancreatic islet transplantation

BACKGROUND

An asymptomatic, self-limited transaminitis uniformly follows pancreatic islet transplantation (PIT) performed through portal vein (PV) infusion. The underlying cause and significance of this transaminitis is unclear.

STUDY DESIGN

Records of all patients with insulin-dependent diabetes mellitus who had undergone PIT at our institution were reviewed. All PITs were performed in conjunction with a remote pancreatic islet isolation center and done through percutaneous transhepatic PV infusion. Alanine aminotransferase (ALT) levels, serum glucose concentrations, insulin requirements, and color-flow Doppler ultrasonography examinations of the right upper quadrant were assessed before and after PIT.

RESULTS

Eleven patients have undergone a total of 26 PITs. An elevated ALT level occurred in all 11 patients (100%) after the first PIT, with the median post-PIT peak ALT level reaching 187 IU/L. Transaminitis was less frequent and less marked after the second PIT. A negative correlation between viability of the pancreatic islets transplanted (r = -0.44, p = 0.03) and a positive correlation between the ratio of maximum to initial PV pressure (r = 0.41, p = 0.04) were seen with the subsequent ALT peak. Color-flow Doppler ultrasonography examinations showed no occurrences of PV thrombosis or intrahepatic hematoma. Finally, the degree of transaminitis did not correlate with post-PIT insulin requirements, indicating that post-PIT transaminitis cannot be used to measure allograft rejection or function.

CONCLUSIONS

Transaminitis after PIT is common and self-limited. Post-PIT transaminitis does not signal acute rejection or serious procedure-related complications such as PV thrombosis or intrahepatic hematoma.

Inflammation-mediated dysfunction and apoptosis in pancreatic islet transplantation: implications for intrahepatic grafts

Recent advances in clinical protocols have improved the outcomes of pancreatic islet transplantation (PIT), yet PIT recipients typically require pancreatic islet grafts derived from multiple donors to achieve insulin independence. This along with experimental models of syngeneic PIT, showing that up to 60% of pancreatic islet tissue undergoes apoptosis within the first several days post-transplantation, strongly suggest the involvement of nonalloantigen-specific, inflammatory events in partial destruction of the graft following PIT. Interleukin-1beta appears to be among the most important inflammatory mediators, causing pancreatic islet dysfunction and apoptosis through the up-regulation of inducible nitric oxide (NO) synthase and cyclooxygenase-2. Kupffer cells secrete many molecules, including cytokines, NO, and free radicals, which are known to be directly toxic to the pancreatic islets, and depletion or inhibition of Kupffer cells improves outcomes following experimental PIT. Immediately after transplantation, the pancreatic islets are perfused only by portal vein blood until the process of angiogenesis restores arterial blood flow some 7-10 days later. This delayed vascularization may have implications for the expression of leukocyte adhesion molecules, the effects of free radicals, and the role of ischemia-reperfusion injury. Finally, in the immediate post-transplant period, hepatocytes may contribute to pancreatic islet injury through the production of NO. This paper reviews literature regarding the inflammatory events that follow PIT as well as the pathogenesis of diabetes and the pathophysiology of hepatic ischemia-reperfusion and their relation to the survival and function of intrahepatic pancreatic islet grafts.