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

Long-Term Review of Penetrating Keratoplasty: A 20-Year Review in Asian Eyes

PURPOSE

To review the long-term outcomes of optical, therapeutic and tectonic forms of penetrating keratoplasty over a 20-year period in Asian eyes.

DESIGN

Prospective cohort study involving the Singapore Corneal Transplant Study (SCTS).

METHODS

All penetrating keratoplasties (PK) performed at the Singapore National Eye Centre (SNEC) from January 1991 to December 2010 were analyzed using records from the computerized database of the SCTS. This database includes preoperative, intraoperative, and postoperative patient data and donor cornea data. Only primary grafts were included. Patient demographics, donor cornea source, indications for grafting, complications, graft survival rate, and causes of graft failure were analyzed.

RESULTS

A total of 1,206 primary PKs were performed. The mean age of the patients was 55 years (range: <1-101 years). The overall corneal graft survival rates at 1, 5, 10, 15, and 20 years were 91%, 66.8%, 55.4%, 52%, and 44%, respectively. For optical grafts, pseudophakic bullous keratopathy, postinfectious corneal scarring and thinning and keratoconus were the most common diagnoses. Graft survival for optical grafts was significantly better than therapeutic and tectonic grafts at all time points. Multivariate analysis suggested that a younger donor cornea age and higher donor endothelial cell count are associated with better long-term graft survival for optical grafts. Irreversible allograft rejection and late endothelial failure accounted for more than 60% of graft failures.

CONCLUSIONS

Graft survival decreased over time from 91% at 1 year to 44% at 20 years' follow-up. Allograft rejection and late endothelial failure accounted for more than 60% of graft failures.

Single-donor islet transplantation in type 1 diabetes: patient selection and special considerations

Type 1 diabetes mellitus is an autoimmune disorder of the endocrine pancreas that currently affects millions of people in the United States. Although the disease can be managed with exogenous insulin administration, the ultimate cure for the condition lies in restoring a patient's ability to produce their own insulin. Islet cell allotransplantation provides a means of endogenous insulin production. Though far from perfected, islet transplants are now a proven treatment for type 1 diabetics. However, proper patient selection is critical for achieving optimal outcomes. Given the shortage of transplantable organs, selecting appropriate candidates for whom the procedure will be of greatest benefit is essential. Although many of those who receive islets do not retain insulin independence, grafts do play a significant role in preventing hypoglycemic episodes that can be quite detrimental to quality of life and potentially fatal. Additionally, islet transplant requires lifelong immunosuppression. Antibodies, both preformed and following islet infusion, may play important roles in graft outcomes. Finally, no procedure is without inherent risk and islet transfusions can have serious consequences for recipients' livers in the form of both vascular and metabolic complications. Therefore, patient-specific factors that should be taken into account before islet transplantation include aims of therapy, sensitization, and potential increased risk for hepatic and portal-venous sequelae.

Historical Background of Pancreatic Islet Isolation

Until the discovery of insulin in the twentieth century, diabetes mellitus was a mortal disease with an unclear origin and physiology. Despite the appearance of the concept in an Egyptian papyrus dated c.1550 BC, and the documentation of its study by ancient Chinese, the term "diabetes" was only coined by the Greek Aretaeus in the second century AD. In Europe, the study of diabetes was largely ignored until the seventeenth century, when the characteristic sweet flavor of diabetic urine was first described. However, the link between diabetes and the pancreas was not discovered until 1889 by Minkowski and von Mering, long after the first description of the pancreatic islets by Paul Langerhans in 1869. One of the most significant milestones in the field was the discovery of insulin by Banting and collaborators in 1922, which led to the therapeutic development of insulin administration as a life-saving intervention for type 1 diabetic patients. On the other hand, the isolation of islets was first reported by Bensley in 1911, a critical technical achievement that paved the way for clinical islet transplantation. Here we discuss the history of islet isolation, since the firsts studies of diabetes by ancient civilizations to the birth and parallel evolution of islet isolation and transplantation.

Bioengineered stem cells as an alternative for islet cell transplantation

Type 1 diabetes is an autoimmune and increasingly prevalent condition caused by immunological destruction of beta cells. Insulin remains the mainstay of therapy. Endeavours in islet transplantation have clearly demonstrated that type 1 diabetes is treatable by cellular replacement. Many challenges remain with this approach. The opportunity to use bioengineered embryonic or adult pluripotential stem cells, or islets derived from porcine xenograft sources could address future demands, but are still associated with considerable challenges. This detailed review outlines current progress in clinical islet transplantation, and places this in perspective for the remarkable scientific advances now occurring in stem cell and regenerative medicine approaches in the treatment of future curative treatment of diabetes.

What's new in clinical solid organ transplantation by 2013

Innovative and exciting advances in the clinical science in solid organ transplantation continuously realize as the results of studies, clinical trials, international conferences, consensus conferences, new technologies and discoveries. This review will address to the full spectrum of news in transplantation, that verified by 2013. The key areas covered are the transplantation activity, with particular regards to the donors, the news for solid organs such as kidney, pancreas, liver, heart and lung, the news in immunosuppressive therapies, the news in the field of tolerance and some of the main complications following transplantation as infections and cancers. The period of time covered by the study starts from the international meetings held in 2012, whose results were published in 2013, up to the 2013 meetings, conferences and consensus published in the first months of 2014. In particular for every organ, the trends in numbers and survival have been reviewed as well as the most relevant problems such as organ preservation, ischemia reperfusion injuries, and rejections with particular regards to the antibody mediated rejection that involves all solid organs. The new drugs and strategies applied in organ transplantation have been divided into new way of using old drugs or strategies and drugs new not yet on the market, but on phase Ito III of clinical studies and trials.

Current status of clinical islet transplantation

Islet transplantation (IT) is today a well-established treatment modality for selected patients with type 1 diabetes mellitus (T1DM). After the success of the University of Alberta group with a modified approach to the immune protection of islets, the international experience grew along with the numbers of transplants in highly specialized centers. Yet, long-term analysis of those initial results from the Edmonton group indicated that insulin-independence was not durable and most patients return to modest amounts of insulin around the fifth year, without recurrent hypoglycemia events. Many phenomena have been identified as limiting factor for the islet engraftment and survival, and today all efforts are aimed to improve the quality of islets and their engrafting process, as well as more optimized immunosuppression to facilitate tolerance and ultimately, better long term survival. This brief overview presents recent progress in IT. A concise historical perspective is provided, along with the latest efforts to improve islet engraftment, immune protection and ultimately, prolonged graft survival. It is apparent that as the community continues to work together further optimizing IT, it is hopeful a cure for T1DM will soon be achievable.

Biologic agents in islet transplantation

Islet transplantation is today an accepted modality for treating selected patients with frequent hypoglycemic events or severe glycemic lability. Despite tremendous progress in islet isolation, culture, and preservation, clinical use is still restricted to a limited subset, and lifelong immunosuppression is required. Issues surrounding limited islet revascularization and immune destruction remain. One of the major challenges is to prevent alloreactivity and recurrence of autoimmunity against β-cells. These two hurdles can be effectively reduced by immunosuppressive therapy combining induction and maintenance treatments. The introduction of highly potent and selective biologic agents has significantly reduced the frequency of acute rejection and has prolonged graft survival, while minimizing the complications of this therapeutic scheme. This review will address the most important biological agents used in islet transplantation. We provide a historical perspective of their introduction into clinical practice and their role in current clinical protocols, aiming at improved engraftment efficiency, increased long-term survival, and better overall results of clinical islet transplantation.

Plasma and urine metabolic fingerprinting of type 1 diabetic children

Type 1 diabetes mellitus is one of the most common chronic disorders of childhood. The metabolic control is lost due to the lack of insulin, which is the main treatment for the disease. Nevertheless, long-term complications appear even under good glycemic control. Metabolomics, an emerging strategy, can help in diagnosis, prognosis, and monitoring of metabolic disorders. The objective of the present study was to investigate the alterations in plasma (by LC-MS) and urine (CE-MS) of type 1 diabetic children that were under insulin treatment and good glycemic control. Even without remarkable biochemical differences between the two groups (diabetic and control) except for glucose level and glycosilated hemoglobin, metabolomic tools were able to capture subtle metabolic differences. The main changes in plasma were associated to lipidic metabolism (nonesterified fatty acids, lysophospholipids, and other derivatives of fatty acids), and some markers of the differential activity of the gut microflora were also found (bile acids, p-cresol sulfate). In urine, changes associated to protein and amino acid metabolism were found (amino acids, their metabolites and derivatives), and among them one advanced glycation end product (carboxyethylarginine) and one early glycation end product (fructosamine) were excreted in higher proportion in the diabetic group.

Naturally occurring immunoglobulin M (nIgM) autoantibodies prevent autoimmune diabetes and mitigate inflammation after transplantation

OBJECTIVE

To investigate whether polyclonal serum naturally occurring immunoglobulin M (nIgM) therapy prevents the onset and progression of autoimmune diabetes and promotes islet allograft survival.

BACKGROUND

nIgM deficiency is associated with an increased tendency toward autoimmune disease development. Elevated levels of nIgM anti-leukocyte autoantibodies are associated with fewer graft rejections.

METHODS

Four- to five-week-old female nonobese diabetic (NOD) littermates received intraperitoneal nIgM or phosphate-buffered saline/bovine serum albumin/immunoglobulin G (100 μg followed by 50-75 μg biweekly) until 18 weeks of age. C57BL/6 recipients of 300 BALB/c or 50 C57BL/6 islet grafts received saline or nIgM.

RESULTS

Eighty percent control mice (n = 30) receiving saline became diabetic by 18 to 20 weeks of age. In contrast, none of 33 of nIgM-treated mice became diabetic (P < 0.0001). Discontinuing therapy resulted in hyperglycemia in only 9 of 33 mice at 22 weeks postdiscontinuation, indicating development of β-cell unresponsiveness. nIgM therapy initiated at 11 weeks of age resulted in hyperglycemia in only 20% of treated animals (n = 20) compared with 80% of controls (P < 0.0001). Treatment of mildly diabetic mice with nIgM (75 μg 3× per week) restored normoglycemia (n = 5), whereas severely diabetic mice required minimal dose islet transplant with nIgM to restore normoglycemia (n = 4). The mean survival time of BALB/c islet allografts transplanted in streptozotocin-induced diabetic C57BL/6 mice was 41.2 ± 3.3 days for nIgM-treated recipients (n = 4, fifth recipient remains normoglycemic) versus 10.2 ± 2.6 days for controls (n = 5) (P < 0.001). Also, after syngeneic transplantation, time taken to return to normoglycemia was 15.4 ± 3.6 days for nIgM-treated recipients (n = 5) and more than 35 days for controls (n = 4).

CONCLUSIONS

nIgM therapy demonstrates potential in preventing the onset and progression of autoimmune diabetes and in promoting islet graft survival.

Construction of Plasmid Insulin Gene Vector Containing Metallothionein IIA (pcDNAMTChIns) and Carbohydrate Response Element (ChoRE), and Its Expression in NIH3T3 Cell Line

BACKGROUND

Type 1 diabetes mellitus is one of the metabolic diseases that cause insulin-producing pancreatic ß cells be destroyed by immune system self-reactive T cells. Recent-ly, new treatment methods have been developed including use of the stem cells, ß islet cells transplantation and gene therapy by viral and non-viral gene constructs.

OBJECTIVES

The aim of this project was preparing the non-viral vector containing the glucose inducible insulin gene and using it in the NIH3T3 cell line.

MATERIALS AND METHODS

Cloning was carried out by standard methods. Total RNA was extracted from pancreatic tissue, RNA was converted to cDNA using RT-PCR reaction and preproinsulin gene was amplified using specific primers. PNMTCH plasmid was extract-ed and digested by NotI, HindIII, and MTIIA and ChoRE genes were purified and cloned into pcDNA3.1 (-) plasmid and named pcDNAMTCh. Finally, the preproinsulin genes were cloned into pcDNA3.1 (-) plasmid and pcDNAMTChIns was built.

RESULTS

The cloned gene constructs were evaluated by restriction enzyme digestion and RT-PCR. The NIH3T3 cells were transfected by plasmid naked DNA containing preproinsu-lin gene and expression was confirmed by Reverse Transcriptase PCR and Western Blot-ting Techniques.

CONCLUSIONS

Gel electrophoresis of PCR products confirmed that cloning was per-formed correctly. The expression of preproinsulin gene in recombinant plasmid in NI-H3T3 cell line was observed for the first time. The findings in this study can be the basis of further research on diabetes mellitus type 1 gene therapy on animals.