[Transplantation of islets of Langerhans: procedure, indications and challenges]. / Transplantatie van eilandjes van Langerhans.

Pancreatic islet isolation and transplantation are complicated procedures, indicated for a carefully selected group of patients. After isolation from the pancreas, the islets are infused into the portal vein. Allogeneic islet transplantation is performed in patients with diabetes mellitus, who suffer from severe hypoglycaemic events and/or progressive complications. One or more donor pancreases are used, which necessitates immunosuppressive treatment. In autologous islet transplantation, which is performed in patients in whom the pancreas has to be removed due to a non-malignant disease, the patients' own islets are isolated and reinfused. No immunosuppressive treatment is required. Reconstitution of endogenous insulin production in allogeneic islet transplantation leads to marked improvements in glycaemic regulation, protection against severe hypoglycaemic episodes and fewer diabetes-related complications. Autologous islet transplantation allows for preservation of endogenous insulin production, which prevents (unstable) diabetes from occurring. This article describes the indications, procedure and pitfalls of islet isolation and transplantation, including three representative cases.

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

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

Distinct activation of primary human BDCA1(+) dendritic cells upon interaction with stressed or infected ß cells.

Derailment of immune responses can lead to autoimmune type 1 diabetes, and this can be accelerated or even induced by local stress caused by inflammation or infection. Dendritic cells (DCs) shape both innate and adaptive immune responses. Here, we report on the responses of naturally occurring human myeloid BDCA1(+) DCs towards differentially stressed pancreatic ß cells. Our data show that BDCA1(+) DCs in human pancreas-draining lymph node (pdLN) suspensions and blood-derived BDCA1(+) DCs both effectively engulf ß cells, thus mimicking physiological conditions. Upon uptake of enterovirus-infected, but not mock-infected cells, BDCA1(+) DCs induced interferon (IFN)-α/ß responses, co-stimulatory molecules and proinflammatory cytokines and chemokines. Notably, induction of stress in ß cells by ultraviolet irradiation, culture in serum-free medium or cytokine-induced stress did not provoke strong DC activation, despite efficient phagocytosis. DC activation correlated with the amount of virus used to infect ß cells and required RNA within virally infected cells. DCs encountering enterovirus-infected ß cells, but not those incubated with mock-infected or stressed ß cells, suppressed T helper type 2 (Th2) cytokines and variably induced IFN-γ in allogeneic mixed lymphocyte reaction (MLR). Thus, stressed ß cells have little effect on human BDCA1(+) DC activation and function, while enterovirus-infected ß cells impact these cells significantly, which could help to explain their role in development of autoimmune diabetes in individuals at risk.

Glycemic Stability Through Islet-After-Kidney Transplantation Using an Alemtuzumab-Based Induction Regimen and Long-Term Triple-Maintenance Immunosuppression.

Pancreatic islet transplantation is performed in a select group of patients with type 1 diabetes mellitus. Immunosuppressive regimens play an important role in long-term islet function. We aimed to investigate the efficacy of islet transplantation in patients with type 1 diabetes and a previous kidney transplantation using an alemtuzumab-based induction regimen and triple maintenance immunosuppression. Patients with type 1 diabetes, who had received a kidney transplant previously, were treated with alemtuzumab as induction therapy for their first islet transplantation and basiliximab induction therapy for subsequent islet transplantations. Maintenance immunosuppression consisted of triple immunosuppression (tacrolimus, mycophenolate mofetil, and prednisolone). Thirteen patients (age 50.9 ± 9.2 years, duration of diabetes 35 ± 9 years) received a total of 22 islet transplantations. One- and 2-year insulin independence was 62% and 42%, respectively; graft function was 100% and 92%, respectively. HbA1c dropped from 57.2 ± 13.1 (7.4 ± 1.2%) to 44.5 ± 11.8 mmol/molHb (6.2 ± 0.9%) (p = 0.003) after 2 years. Six of 13 patients suffered from severe hypoglycemia before islet transplantation. After transplantation, severe hypoglycemia was restricted to the only patient who lost graft function. Creatinine clearance was unchanged. Islet-after-kidney transplantation in patients with type 1 diabetes using an alemtuzumab-based induction regimen leads to considerable islet allograft function and improvement in glycemic control.

Vascular calcification: expression patterns of the osteoblast-specific gene core binding factor alpha-1 and the protective factor matrix gla protein in human atherogenesis.

OBJECTIVE: Increasing evidence suggests that vascular calcification is a regulated process. We studied the vascular expression pattern of a key factor in mineralization and a counteracting, protective factor. Based on the phenotype of null mice, Core binding factor alpha-1 (Cbfa-1) plays a pivotal role in bone formation, whereas Matrix Gla Protein (MGP) is a potent inhibitor of vascular calcification. METHODS: We investigated the expression of MGP and Cbfa-1 in cultured, human monocytic cells, endothelial cells and smooth muscle cells (SMC), as well as in normal and atherosclerotic vessel specimens. RESULTS: In cultured cells MGP is expressed in endothelial cells and SMC, whereas Cbfa-1 mRNA is predominantly present in macrophages and to a lesser extent in SMC. In the normal vessel wall MGP expression is high at the luminal side and declines toward the center of the media, whereas Cbfa-1 is absent. Moderate, diffuse calcification of the aorta media was observed only in those regions where MGP is low or absent. In atherosclerotic lesions MGP is expressed in endothelial cells and SMC that form fibrous caps, but is never present in macrophages. Cbfa-1 is synthesized in regions without MGP, it is associated with calcified areas and Cbfa-1 may be considered a marker for osteoprogenitor-like cells in the vessel wall. CONCLUSIONS: Our observations on MGP expression confirm and extend published data and are consistent with a protective function of MGP. Cbfa-1 expression is absent in normal medial SMC and co-localizes with neointimal macrophages and focal calcifications.

In vivo suppression of restenosis in balloon-injured rat carotid artery by adenovirus-mediated gene transfer of the cell surface-directed plasmin inhibitor ATF.BPTI.

Injury-induced neointimal development results from migration and proliferation of vascular smooth muscle cells (SMC). Cell migration requires controlled proteolytic degradation of extracellular matrix surrounding the cell. Plasmin is a major contributor to this process by degrading various matrix proteins directly, or indirectly by activating matrix metalloproteinases. This makes it an attractive target for inhibition by gene transfer. An adenoviral vector, Ad.ATF.BPTI, was constructed encoding a hybrid protein, which consists of the aminoterminal fragment (ATF) of urokinase-type plasminogen activator (u-PA) linked to bovine pancreas trypsin inhibitor (BPTI), a potent inhibitor of plasmin. This hybrid protein binds to the u-PA receptor, thereby inhibiting plasmin activity at the cell surface, and was found to be a potent inhibitor of cell migration in vitro. Local infection with Ad.ATF.BPTI of balloon-injured rat carotid artery resulted in detectable expression of ATF.BPTI mRNA and protein in the vessel wall. Morphometric analysis of arterial cross-sections revealed that delivery of Ad.ATF.BPTI to the carotid artery wall at the time of balloon injury inhibited neointima formation by 53% (P < 0.01) at 14 days and 19% (P = NS) at 28 days after injury when compared with control vector-infected arteries. Intima/media ratios were decreased by 60% (P < 0.01) and 35% (P < 0.05) at 14 and 28 days, respectively, when compared with control vector-infected arteries. Furthermore, a small but significant increase in medial area was found in the Ad.ATF.BPTI-treated arteries at 28 days (P < 0.05). These results show that local infection of the vessel wall with Ad.ATF.BPTI reduces neointima formation, presumably by inhibiting SMC migration, thereby offering a novel therapeutic approach to inhibiting neointima development.

Cell-specific patterns of Cbfa1 mRNA and protein expression in postnatal murine dental tissues.

Cbfa1 (core binding factor alpha 1) is a transcription factor that is a key determinant of the osteoblastic lineage. Recent data showed that Cbfa1 is also highly expressed in early stages of tooth development and is involved in crown morphogenesis and cytodifferentiation of odontoblasts. Here we report the mRNA expression and protein localization of Cbfa1 in the mouse dentition in (later) stages of crown and root development. In addition to osteoblasts, osteocytes, chondrocytes, odontoblasts, dental follicle cells, cementoblasts and periodontal ligament cells, we report also Cbfa1 expression in dental epithelial cells (secretory and maturation ameloblasts) and several non-mineralizing cell types (hair follicles, ducts of salivary glands, and junctional epithelium of the gingiva).

Human activin-A is expressed in the atherosclerotic lesion and promotes the contractile phenotype of smooth muscle cells.

Activin is a member of the transforming growth factor-beta superfamily, and it modulates the proliferation and differentiation of various target cells. In this study, we investigated the role of activin in the initiation and progression of human atherosclerosis. The expression of activin, its physiological inhibitor follistatin, and activin receptors were assayed in human vascular tissue specimens that represented various stages of atherogenesis. In situ hybridization experiments revealed activin mRNA in endothelial cells and macrophages and a strong induction of activin expression in neointimal smooth muscle cells from the early onset of atherogenesis. We developed an "in situ free-activin binding assay" by using biotinylated follistatin, which allowed us to detect bioactive activin at specific sites in atherosclerotic lesions. The mRNAs encoding the activin receptors are expressed similarly in normal and atherosclerotic tissue, which indicates that activin-A signaling in atherogenesis is most likely dependent on changes in growth factor concentrations rather than on receptor levels. In vitro, activin induces the contractile, nonproliferative phenotype in cultured smooth muscle cells, as is reflected by increased expression of smooth muscle-specific markers (SMalpha-actin and SM22alpha). Our data provide evidence that activin induces redifferentiation of neointimal smooth muscle cells, and we hypothesize that activin is involved in plaque stabilization.