IsletSwipe, a mobile platform for expert opinion exchange on islet graft images

We previously developed a deep learning-based web service (IsletNet) for an automated counting of isolated pancreatic islets. The neural network training is limited by the absent consensus on the ground truth annotations. Here, we present a platform (IsletSwipe) for an exchange of graphical opinions among experts to facilitate the consensus formation. The platform consists of a web interface and a mobile application. In a small pilot study, we demonstrate the functionalities and the use case scenarios of the platform. Nine experts from three centers validated the drawing tools, tested precision and consistency of the expert contour drawing, and evaluated user experience. Eight experts from two centers proceeded to evaluate additional images to demonstrate the following two use case scenarios. The Validation scenario involves an automated selection of images and islets for the expert scrutiny. It is scalable (more experts, images, and islets may readily be added) and can be applied to independent validation of islet contours from various sources. The Inquiry scenario serves the ground truth generating expert in seeking assistance from peers to achieve consensus on challenging cases during the preparation for IsletNet training. This scenario is limited to a small number of manually selected images and islets. The experts gained an opportunity to influence IsletNet training and to compare other experts' opinions with their own. The ground truth-generating expert obtained feedback for future IsletNet training. IsletSwipe is a suitable tool for the consensus finding. Experts from additional centers are welcome to participate.

Finding Eden - alternative transplantation sites for pancreatic islets

Pancreatic islets transplantation is an established treatment method for type 1 diabetic patients with the hypoglycemia unawareness syndrome in whom a therapy with modern technologies fails. Islet transplantation is most commonly done using an interventional radiology method: a tissue suspension of pancreatic islets is applied into a branch of the portal vein through a percutaneously installed catheter. Although being minimally invasive unlike pancreas organ transplant, this method is associated with many technical difficulties. Possible complications of the procedure include hemorrhage and portal vein thrombosis. Unlike their natural dispersed localization in exocrine pancreas, isolated pancreatic islets are exposed to hypoxia, toxins and immunosuppressive drugs in the liver parenchyma. Direct contact with the recipients blood causes an instant blood mediated inflammatory reaction (IBMIR) resulting in the death of more than half of the pancreatic islets shortly after their application. Therefore the size of the islet graft is often insufficient and a number of transplanted patients require administration of exogenous insulin. All of these are reasons for seeking an alternative transplantation site with more hospitable conditions for long-term islet survival. Various transplantation sites have been tested in experimental and clinical research. The advantages and disadvantages of some of them are summarized in this paper. Currently, transplantation into the greater omentum seems most promising, which has already been used in clinical practice at several institutions.

Incidence and Risk Factors of Diabetic Foot Syndrome in Patients Early After Pancreas or Kidney/Pancreas Transplantation and its Association with Preventive Measures

Diabetic foot (DF) can develop in diabetic patients after organ transplantation (Tx) due to several factors including peripheral arterial disease (PAD), diabetic neuropathy and inappropriate DF prevention. Aim: To assess the occurrence of DF and associated risk factors in transplant patients. Methods: Fifty-seven diabetic patients were enrolled as part of this prospective study. All patients underwent organ Tx (01/2013-12/2015) and were followed up for minimum of 12 months up to a maximum of 50 months. Over the study period we evaluated DF incidence and identified a number of factors likely to influence DF development, including organ function, presence of late complications, PAD, history of DF, levels of physical activity before and after Tx, patient education and standards of DF prevention. Results: Active DF developed in 31.6% (18/57) of patients after organ Tx within 11 months on average (10.7 ± 8 months). The following factors significantly correlated with DF development: diabetes control (p = .0065), PAD (p<0.0001), transcutaneous oxygen pressure (TcPO2;p = .01), history of DF (p = .0031), deformities (p = .0021) and increased leisure-time physical activity (LTPA) before Tx (p = .037). However, based on logistic stepwise regression analysis, the only factors significantly associated with DF during the post-transplant period were: PAD, deformities and increased LTPA. Education was provided to patients periodically (2.6 ± 2.5 times) during the observation period. Although 94.7% of patients regularly inspected their feet (4.5 ± 2.9 times/week), only 26.3% of transplant patients used appropriate footwear. Conclusions: Incidence of DF was relatively high, affecting almost 1/3 of pancreas and kidney/pancreas recipients. The predominant risk factors were: presence of PAD, foot deformities and higher LTPA before Tx. Therefore, we recommend a programme involving more detailed vascular and physical examinations and more intensive education focusing on physical activity and DF prevention in at-risk patients before transplantation.

Bioluminescence Imaging In Vivo Confirms the Viability of Pancreatic Islets Transplanted into the Greater Omentum

PURPOSE

The liver is the most widely used site for pancreatic islet transplantation. However, several site-specific limitations impair functional success, with instant blood-mediated inflammatory reaction being the most important. The aim of this study was to develop a preclinical model for placement of the islet graft into a highly vascularized omental flap using a fibrin gel. For this purpose, we tested islet viability by bioluminescence imaging (BLI).

PROCEDURES

Pancreatic islets were isolated from luciferase-positive and luciferase-negative rats, mixed at a 1:1 ratio, placed into a plasma-thrombin bioscaffold, and transplanted in standard (10 pancreatic islets/g wt; n = 10) and marginal (4 pancreatic islets/g wt; n = 7) numbers into the omentums of syngeneic diabetic animals. For the control, 4 pancreatic islets/g were transplanted into the liver using the standard procedure (n = 7). Graft viability was tested by bioluminescence at days 14, 30, 60, and 90 post transplant. Glucose levels, intravenous glucose tolerance, and serum C-peptide were assessed regularly.

RESULTS

Nonfasting glucose levels < 10 mmol/l were restored in all animals. While islet viability in the omentum was clearly detected by stable luminescence signals throughout the whole study period, no signals were detected from islets transplanted into the liver. The bioluminescence signals were highly correlated with stimulated C-peptide levels detected at 80 days post transplant. Glucose tolerance did not differ among the 3 groups.

CONCLUSIONS

We successfully tested a preclinical model of islet transplantation into the greater omentum using a biocompatible scaffold made from autologous plasma and human thrombin. Both standard and marginal pancreatic islet numbers in a gel-form bioscaffold placed in the omentum restored glucose homeostasis in recipients with diabetes. Bioluminescence was shown promising as a direct proof of islet viability.

A Preliminary Characterization of a Novel Recombinant Clostridial Collagenase Blend

Clostridial collagenases are essential biotechnological tissue dissociation agents owing to their ability to cleave different types of collagen. Standardization of collagenase-based protocols has been hampered by impurities in products manufactured from Clostridium histolyticum. To enhance the purification process, we produced recombinant collagenase classes G and H, taking advantage of the Escherichia coli expression system. The respective gene sequences were derived from C. histolyticum and modified by addition of a C-terminal polyhistidine tag. Harvested bacteria were lysed and the collagenase protein was affinity purified using a His-tag column. The purity, identity, integrity of the eluted collagenases G and H were determined by SDS electrophoresis and Western blot. The proteolytic activity of the collagenase G and H blend (rColGH) was determined by the standard FALGPA assay. The tissue dissociation activity was verified using a standardized method for isolation of rat pancreatic islets. Biocompatibility of the blend was validated by a standardized viability assay on the isolated islets. Two batches of rColGH were produced and compared to a commercially available collagenase. Based on our results, we conclude that rColGH is a functional and non-toxic novel recombinant collagenase worth further characterization and blend optimization in order to make it a competitive commercial product.

Early worsening of diabetic retinopathy after simultaneous pancreas and kidney transplantation-Myth or reality?

Early worsening of diabetic retinopathy due to sudden glucose normalization is a feared complication of pancreas transplantation; however, its rate or severity has not been studied prospectively. We followed up 43 pancreas and kidney recipients for a composite endpoint comprising new need for laser therapy, newly diagnosed proliferation, macular edema, visual acuity worsening, and blindness over 12 months. Although 37% of patients met this primary endpoint, its severity was rather low. Mean central retinal thickness and proportion of patients with subclinical macular edema increased significantly, with spontaneous resolution in half of them. Visual acuity did not change. There was no significant difference in the absolute glycated hemoglobin (HbA1c) drop, age, and diabetes duration between the patients who met and those who did not meet the primary endpoint, but a higher proportion of patients with worsening had a recent history of laser treatment. Retinopathy remained stable in 62.8% of patients. In 26%, the visual acuity significantly improved. Although retinopathy worsening was documented in more than one-third of patients, its evolution was not related to the magnitude of metabolic change; rather, it corresponded to the expected natural course of retinopathy. Nonetheless, comprehensive ophthalmologic care should be a substantial component of the recipient management.

Sirolimus vs mycophenolate mofetil (MMF) in primary combined pancreas and kidney transplantation. Results of a long-term prospective randomized study

The study was intended to compare pancreas graft survival rates in two groups of pancreas and kidney transplant recipients prospectively randomized to treatment either with sirolimus or MMF. From 2002 to 2013, 238 type 1 diabetic recipients with end-stage kidney disease were randomized 1:1 to sirolimus or MMF treatment. Noncensored pancreas survival at 5 years was 76.4 and 71.6% for sirolimus and MMF groups, respectively (P > .05). Death-censored pancreas survival was better in the sirolimus group (P = .037). After removal of early graft losses pancreas survival did not differ between groups (MMF 83.1% vs sirolimus 91.6%, P = .11). Nonsignificantly more grafts were lost due to rejection in the MMF group (10 vs 5; P = .19). Cumulative patient 5-year survival was 96% in the MMF group and 91% in the sirolimus group (P > .05). Five-year cumulative noncensored kidney graft survival rates did not statistically differ (85.6% in the sirolimus group and 88.8% in MMF group). Recipients treated with MMF had significantly more episodes of gastrointestinal bleeding (7 vs 0, P = .007). More recipients in the sirolimus group required corrective surgery due to incisional hernias (21 vs 12, P = .019). ClinicalTrials No.: NCT03582878.

Distant diabetes care: what can the patient, nurse and patient do

Due to the spread of new coronavirus disease, COVID-19, social interactions between people have been significantly reduced. In healthcare, outpatient care is a high-risk frontline of infection transmission in both patients and healthcare professionals. The presence of routine digital communication, remote data management and the availability of glucose monitoring and insulin delivery devices have given diabetology a certain advantage in this situation. However, the potential of these modalities has not been fully utilized so far. We provide an overview of practical methods of distance patient management, which can be used in most diabetes outpatient clinics without any difficult adjustments or additional investments. This approach can be used in different patients according to their treatment strategies and individual abilities.

Retrospective Analysis of Bone Metabolism in Patients on Waiting List for Simultaneous Pancreas-Kidney Transplantation

Posttransplant osteoporosis, which evolves from preexisting bone pathologies, represents a serious complication with deteriorating consequences. The aim of our study was to evaluate epidemiological data on bone mineral density (BMD) in subjects with type 1 diabetes (T1DM) in advanced stages of diabetic nephropathy indicated for simultaneous pancreas-kidney transplantation (SPK). We retrospectively compiled biochemical and densitometrical data from 177 patients with T1DM at CKD (chronic kidney disease) stages G4-G5 (115 men, 62 women, median age 40 yr, diabetes duration 23 yr) enrolled on waiting list for SPK for the first time between the years 2011 and 2016. Median Z-scores were as follows: lumbar spine (LS): -0.8 [interquartile range -1.75 to 0.1]; total hip (TH): -1.2 [-1.75 to -0.6]; femoral neck (FN): -1.2 [-1.9 to -0.7]; and distal radius (DR): -0.8 [-1.4 to -0.1]. We noted a gender difference in LS, with worse results for men (-1.1 vs. -0.3) even after adjusting for BMI (body mass index) and glomerular filtration (p < 0.001). Osteoporotic and osteopenic ranges (based on T-scores) for all major sites were 27.7% and 56.5%, respectively, with similar results across both genders. Women had a significantly higher proportion of normal BMD in LS than men (67.7 vs. 49.4%, p < 0.05). Patients with T1DM at CKD stages G4-G5 exhibited serious BMD impairment despite their young age. Men surprisingly displayed lower Z-scores and higher percentages of pathological BMD values in LS than women did. The introduction of adequate preventive measures during the advanced stages of diabetic nephropathy to prevent bone loss is recommended.

Reprogramming of Human Pancreatic Organoid Cells into Insulin-Producing β-Like Cells by Small Molecules and in Vitro Transcribed Modified mRNA Encoding Neurogenin 3 Transcription Factor

Reprogramming of non-endocrine pancreatic cells into insulin-producing cells represents a promising therapeutic approach for the restoration of endogenous insulin production in diabetic patients. In this paper, we report that human organoid cells derived from the pancreatic tissue can be reprogrammed into the insulin-producing cells (IPCs) by the combination of in vitro transcribed modified mRNA encoding transcription factor neurogenin 3 and small molecules modulating the epigenetic state and signalling pathways. Upon the reprogramming, IPCs formed 4.6 ± 1.2 % of the total cells and expressed typical markers (insulin, glucokinase, ABCC8, KCNJ11, SLC2A2, SLC30A8) and transcription factors (PDX1, NEUROD1, MAFA, NKX2.2, NKX6.1, PAX4, PAX6) needed for the proper function of pancreatic β-cells. Additionally, we have revealed a positive effect of ALK5 inhibitor RepSox on the overall reprogramming efficiency. However, the reprogrammed IPCs possessed only a partial insulin-secretory capacity, as they were not able to respond to the changes in the extracellular glucose concentration by increasing insulin secretion. Based on the achieved results we conclude that due to the incomplete reprogramming, the IPCs have immature character and only partial properties of native human β-cells.

Preserved Expression of Skin Neurotrophic Factors in Advanced Diabetic Neuropathy Does Not Lead to Neural Regeneration despite Pancreas and Kidney Transplantation

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes with potential severe consequences. Its pathogenesis involves hyperglycemia-linked mechanisms, which may include changes in the expression of neurotrophic growth factors. We analyzed the expression of 29 factors potentially related to nerve degeneration and regeneration in skin biopsies from 13 type 1 diabetic pancreas and kidney recipients with severe DPN including severe depletion of intraepidermal nerve fibers (IENF) in lower limb skin biopsies (group Tx1 1st examination). The investigation was repeated after a median 28-month period of normoglycemia achieved by pancreas transplantation (group Tx1 2nd examination). The same tests were performed in 13 stable normoglycemic pancreas and kidney recipients 6-12 years posttransplantation (group Tx2), in 12 matched healthy controls (group HC), and in 12 type 1 diabetic subjects without severe DPN (group DM). Compared to DM and HC groups, we found a significantly higher (p < 0.05-0.001) expression of NGF (nerve growth factor), NGFR (NGF receptor), NTRK1 (neurotrophic receptor tyrosine kinase 1), GDNF (glial cell-derived neurotrophic factor), GFRA1 (GDNF family receptor alpha 1), and GFAP (glial fibrillary acidic protein) in both transplant groups (Tx1 and Tx2). Enhanced expression of these factors was not normalized following the median 28-month period of normoglycemia (Tx1 2nd examination) and negatively correlated with IENF density and with electrophysiological indices of DPN (vibration perception threshold, electromyography, and autonomic tests). In contrast to our expectation, the expression of most of 29 selected factors related to neural regeneration was comparable in subjects with severe peripheral nerve fiber depletion and healthy controls and the expression of six factors was significantly upregulated. These findings may be important for better understanding the pathophysiology of nerve regeneration and for the development of intervention strategies.

Nkx6.1 decline accompanies mitochondrial DNA reduction but subtle nucleoid size decrease in pancreatic islet β-cells of diabetic Goto Kakizaki rats

Hypertrophic pancreatic islets (PI) of Goto Kakizaki (GK) diabetic rats contain a lower number of β-cells vs. non-diabetic Wistar rat PI. Remaining β-cells contain reduced mitochondrial (mt) DNA per nucleus (copy number), probably due to declining mtDNA replication machinery, decreased mt biogenesis or enhanced mitophagy. We confirmed mtDNA copy number decrease down to <30% in PI of one-year-old GK rats. Studying relations to mt nucleoids sizes, we employed 3D superresolution fluorescent photoactivable localization microscopy (FPALM) with lentivirally transduced Eos conjugate of mt single-stranded-DNA-binding protein (mtSSB) or transcription factor TFAM; or by 3D immunocytochemistry. mtSSB (binding transcription or replication nucleoids) contoured "nucleoids" which were smaller by 25% (less diameters >150 nm) in GK β-cells. Eos-TFAM-visualized nucleoids, composed of 72% localized TFAM, were smaller by 10% (immunochemically by 3%). A theoretical ~70% decrease in cell nucleoid number (spatial density) was not observed, rejecting model of single mtDNA per nucleoid. The β-cell maintenance factor Nkx6.1 mRNA and protein were declining with age (>12-fold, 10 months) and decreasing with fasting hyperglycemia in GK rats, probably predetermining the impaired mtDNA replication (copy number decrease), while spatial expansion of mtDNA kept nucleoids with only smaller sizes than those containing much higher mtDNA in non-diabetic β-cells.

Benefits of Islet Transplantation as an Alternative to Pancreas Transplantation: Retrospective Study of More Than 10 Ten Years of Experience in a Single Center

BACKGROUND

Pancreas transplantation (PTx) represents the method of choice in type 1 diabetic patients with conservatively intractable hypoglycemia unawareness syndrome. In 2005, the Institute for Clinical and Experimental Medicine (IKEM) launched a program to investigate the safety potential of islet transplantation (ITx) in comparison to PTx.

AIM

This study aims to compare the results of PTx and ITx regarding severe hypoglycemia elimination, metabolic control, and complication rate.

METHODS

We analyzed the results of 30 patients undergoing ITx and 49 patients treated with PTx. All patients were C-peptide-negative and suffered from hypoglycemia unawareness syndrome. Patients in the ITx group received a mean number of 12,349 (6,387-15,331) IEQ/kg/person administered percutaneously into the portal vein under local anesthesia and radiological control. The islet number was reached by 1-3 applications, as needed. In both groups, we evaluated glycated hemoglobin, insulin dose, fasting and stimulated C-peptide, frequency of severe hypoglycemia, and complications. We used the Mann Whitney test, Wilcoxon signed-rank test, and paired t-test for analysis. We also individually assessed the ITx outcomes for each patient according to recently suggested criteria established at the EPITA meeting in Igls.

RESULTS

Most of the recipients showed a significant improvement in metabolic control one and two years after ITx, with a significant decrease in HbA1c, significant elevation of fasting and stimulated C-peptide, and a markedly significant reduction in insulin dose and the frequency of severe hypoglycemia. Seventeen percent of ITx recipients were temporarily insulin-independent. The results in the PTx group were comparable to those in the ITx group, with 73% graft survival and insulin independence in year 1, 68% 2 years and 55% 5 years after transplantation. There was a higher rate of complications related to the procedure in the PTx group. Severe hypoglycemia was eliminated in the majority of both ITx and PTx recipients.

CONCLUSION

This report proves the successful initiation of pancreatic islet transplantation in a center with a well-established PTx program. ITx has been shown to be the method of choice for hypoglycemia unawareness syndrome, and may be considered for application in clinical practice if conservative options are exhausted.

Lipasin/betatrophin is differentially expressed in liver and white adipose tissue without association with insulin resistance in Wistar and Goto-Kakizaki rats

Lipasin is a recently identified lipokine expressed predominantly in liver and in adipose tissue. It was linked to insulin resistance in mice and to type 1 and type 2 diabetes (T1D, T2D) in humans. No metabolic studies concerning lipasin were performed yet in rats. Therefore, we used rat model of T2D and insulin resistance, Goto-Kakizaki (GK) rats, to determine changes of lipasin expression in liver and in white adipose tissue (WAT) over 52 weeks in the relation to glucose tolerance, peripheral tissue insulin sensitivity and adiposity. GK rats were grossly glucose intolerant since the age of 6 weeks and developed peripheral insulin resistance at the age of 20 weeks. Expression of lipasin in the liver did not differ between GK and Wistar rats, declining with age, and it was not related to hepatic triacylglycerol content. In WAT, the lipasin expression was significantly higher in Wistar rats where it correlated positively with adiposity. No such correlation was found in GK rats. In conclusion, lipasin expression was associated neither with a mild age-related insulin resistance (Wistar), nor with severe genetically-based insulin resistance (GK).

Severe Epidermal Nerve Fiber Loss in Diabetic Neuropathy Is Not Reversed by Long-Term Normoglycemia After Simultaneous Pancreas and Kidney Transplantation

Whether nerve fiber loss, a prominent feature of advanced diabetic neuropathy, can be reversed by reestablishment of normal glucose control remains questionable. We present 8-year follow-up data on epidermal nerve fiber (ENF) density and neurological function in patients with type 1 diabetes after simultaneous pancreas and kidney transplantation (SPK) with long-term normoglycemia. Distal thigh skin biopsies with ENF counts, vibration perception thresholds (VPTs), autonomic function testing (AFT) and electrophysiological examinations were performed at time of SPK and 2.5 and 8 years after SPK in 12 patients with type 1 diabetes. In comparison to controls, baseline ENF density, VPT and AFT results of patients indicated severe neuropathy. At follow-up, all SPK recipients were insulin independent with excellent glycemic control and kidney graft function; however, the severe ENF depletion present at baseline had not improved, with total ENF absence in 11 patients at 8-year follow-up. Similarly, no amelioration occurred in the VPT and AFT results. Numerical improvement was seen in some electrophysiological parameters; however, statistical significance was achieved only in median motor nerve conduction velocity. ENF loss and functional deficits in advanced diabetic peripheral neuropathy are rarely reversible, even by long-term normoglycemia, which underscores the importance of neuropathy prevention by early optimal glycemic control.

Unstable Expression of Commonly Used Reference Genes in Rat Pancreatic Islets Early after Isolation Affects Results of Gene Expression Studies

The use of RT-qPCR provides a powerful tool for gene expression studies; however, the proper interpretation of the obtained data is crucially dependent on accurate normalization based on stable reference genes. Recently, strong evidence has been shown indicating that the expression of many commonly used reference genes may vary significantly due to diverse experimental conditions. The isolation of pancreatic islets is a complicated procedure which creates severe mechanical and metabolic stress leading possibly to cellular damage and alteration of gene expression. Despite of this, freshly isolated islets frequently serve as a control in various gene expression and intervention studies. The aim of our study was to determine expression of 16 candidate reference genes and one gene of interest (F3) in isolated rat pancreatic islets during short-term cultivation in order to find a suitable endogenous control for gene expression studies. We compared the expression stability of the most commonly used reference genes and evaluated the reliability of relative and absolute quantification using RT-qPCR during 0–120 hrs after isolation. In freshly isolated islets, the expression of all tested genes was markedly depressed and it increased several times throughout the first 48 hrs of cultivation. We observed significant variability among samples at 0 and 24 hrs but substantial stabilization from 48 hrs onwards. During the first 48 hrs, relative quantification failed to reflect the real changes in respective mRNA concentrations while in the interval 48–120 hrs, the relative expression generally paralleled the results determined by absolute quantification. Thus, our data call into question the suitability of relative quantification for gene expression analysis in pancreatic islets during the first 48 hrs of cultivation, as the results may be significantly affected by unstable expression of reference genes. However, this method could provide reliable information from 48 hrs onwards.

[Islet transplantation as a treatment for hypoglycemia unawareness syndrome. Evaluation of the pilot program and comparison with pancreas transplantation]

Islet transplantation (ITx) started in 2005 in IKEM as a potentially safer alternative to pancreas transplantation (PTx), which so far had represented the method of choice in type-1 diabetic patients with conservatively intractable hypoglycemia unawareness syndrome. The aim of the study was to compare these two methods with regard to severe hypoglycemia elimination and to frequency of complications.Up to November 2015 a total number of 48 patients underwent ITx. The results from 22 patients with hypoglycemia unawareness were statistically analyzed. The mean number of transplanted islet equivalents was 12,096 (6,93316,705) IEQ/kg administered percutaneously in local anesthesia under radiological control to the portal vein. 44 patients underwent PTx from 1996. We evaluated glycated hemoglobin(HbA1c), insulin dose, fasting and stimulated C-peptide, frequency of severe hypoglycemia and complications. Medians (interquartile range) were analyzed using the Wilcoxon signed-rank test.One and two years after ITx, HbA1c decreased, C-peptide became significantly positive, insulin dose and frequency of severe hypoglycemia decreased and 18 % of ITx recipients were temporarily insulin-independent. Bleeding was present in 41 % of patients. One year after PTx, 73 % of patients were insulin and hypoglycemia-free, after two years 68 % of patients were insulin and hypoglycemia-free; graftectomy occurred in 20 % of recipients.Both methods led to restoration of insulin secretion and severe hypoglycemia elimination. PTx made more recipients insulin-independent at the cost of serious complications.

Formation of Cholangiogenic Cysts Following Intrahepatic Islet Transplantation in Streptozotocin Diabetic Rats

Permanent hyperinsulinemia and the resulting overstimulation of the insulin receptor signaling pathway is suspected as a trigger of cancer genesis in the livers of type 2 diabetic patients. Liver tissue (LT) surrounding transplanted pancreatic islets (PI) can be permanently exposed to insulin in even higher concentrations than in type 2 diabetic patients. Therefore, this study examines the effect of PI transplantation (Tx) on LT in animals with streptozotocin (STZ)-induced diabetes mellitus. The suboptimal mass (400 or 1000) of isogeneic PI was transplanted into either the portal vein or under the kidney capsule of diabetic Brown Norway (BN) rats. Healthy BN rats treated with 400 isogeneic PI transplanted in the portal vein served as a control group. During the first 6 months after PI Tx, small and infrequent cystic lesions developed in animals with STZ diabetes, irrespective of the Tx site. In 10 months, frequent and complex cystic lesions appeared in these animals. In the control group, several small lesions were detected but not until 10 months after the PI Tx. In summary, STZ is the likely main inductor of hepatic cystic lesions, but the contribution of PI was not confirmed.

[Pancreas transplantation: State of the art and future prospects]

During the past 30 years pancreas transplantation evolved into a routine procedure especially suitable for type 1 diabetic recipients undergoing simultaneously kidney transplantation significantly improving quality of life and life expectancy as compared with kidney only recipients. It provides insulin independence with near-normal glucose control without special dietary restriction, freedom from hypoglycemia and chance for halting or regression of microangiopathic diabetes complications. As a separate procedure, pancreas transplantation is carried out mainly in selected subjects suffering from severe hypoglycemic episodes and impaired hypoglycemia awareness or as a subsequent procedure in type 1 diabetic kidney recipients from both cadaveric or living donors. Five-year insulin independence rate following combined pancreas and kidney, pancreas only and pancreas after kidney procedures currently exceed 75, 50 and 62 %, respectively. Though the outcomes still continue to improve, the rate of pancreas transplants has reached a plateau in several European countries or even declines in the United States. Main reasons for that include fewer referrals from diabetes specialist, decreased donor quality, introduction of islet transplantation as a less invasive procedure but probably most of all probably insufficient information on the latest progress and trends achieved in this area. In the area of transplant therapy of diabetes Czech Republic traditionally ranks to the most active countries providing different transplant options according to individual clinical needs including islet transplantation.

Delta Cell Hyperplasia in Adult Goto-Kakizaki (GK/MolTac) Diabetic Rats

Reduced beta cell mass in pancreatic islets (PI) of Goto-Kakizaki (GK) rats is frequently observed in this diabetic model, but knowledge on delta cells is scarce. Aiming to compare delta cell physiology/pathology of GK to Wistar rats, we found that delta cell number increased over time as did somatostatin mRNA and delta cells distribution in PI is different in GK rats. Subtle changes in 6-week-old GK rats were found. With maturation and aging of GK rats, disturbed cytoarchitecture occurred with irregular beta cells accompanied by delta cell hyperplasia and loss of pancreatic polypeptide (PPY) positivity. Unlike the constant glucose-stimulation index for insulin PI release in Wistar rats, this index declined with GK age, whereas for somatostatin it increased with age. A decrease of GK rat PPY serum levels was found. GK rat body weight decreased with increasing hyperglycemia. Somatostatin analog octreotide completely blocked insulin secretion, impaired proliferation at low autocrine insulin, and decreased PPY secretion and mitochondrial DNA in INS-1E cells. In conclusion, in GK rats PI, significant local delta cell hyperplasia and suspected paracrine effect of somatostatin diminish beta cell viability and contribute to the deterioration of beta cell mass. Altered PPY-secreting cells distribution amends another component of GK PI's pathophysiology.

Assessment of mitochondrial DNA as an indicator of islet quality: an example in Goto Kakizaki rats

BACKGROUND

Diabetic Goto Kakizaki (GK) rats represent an established model of type 2 diabetes that exhibit an onset of pancreatic islet (PI) pathology characterized by islet hypertrophy with a decreased number of insulin-secreting β-cells. Among the remaining β-cells, oxidative phosphorylation (OXPHOS) and consequently glucose-stimulated insulin secretion (GSIS) are impaired, perhaps owing to a deficit in mitochondrial DNA (mtDNA). We sought to identify this abnormality.

METHODS

β-Cells were obtained from Accutase-dissolved PI isolated from GK or Wistar rats and sorted based on the positive Zn(2+) signal of Newport Green. The mtDNA copy number per cell was quantified as the amplicon ratio by polymerase chain reaction using specific primers against the rat ND5 mt gene and UCP2 nuclear gene.

RESULTS

The 12-month-old GK rats exhibited drastically reduced copy numbers per remaining β-cell, from 7,400 ± 600 in 12-month old Wistar rats (100%) to 24 ± 4%; mtDNA content in heart and liver was 70 ± 25% and 60 ± 20%, respectively. Versus age-paired Wistar rats, 6- and 4-month-old GK rats showed reductions to 60 ± 15% and 50 ± 20%, respectively.

CONCLUSIONS

OXPHOS of remnant β-cells in diabetic GK was drastically impaired due to the lack of sufficient mtDNA levels. We suggest the use of mtDNA quantification to quickly assess PI quality before transplantation.

Pancreatic islet autotransplantation after completion pancreatectomy for pancreatic fistula after hemipancreatoduodenectomy for carcinoma

OBJECTIVE

Pancreatic islet autotransplantation (IAT) has a potential to prevent brittle diabetes in patients after total pancreatectomy. Because of the fear of tumor spread, IAT has rarely been used in case of malignancy. We report our experience with patients who underwent hemipancreatoduodenectomy for carcinoma and later completion pancreatectomy for pancreatic fistula with islet autotransplantation at our institution.

METHODS

From August 2007 to December 2012, 5 patients underwent IAT after completion pancreatectomy for pancreatic fistula after hemipancreatoduodenectomy for carcinoma. Islets were isolated from the pancreatic tail with the use of digestion with collagenase. Nonpurified islet suspension was infused into the portal vein during surgery.

RESULTS

The median number of islets transplanted was 175,000 islet equivalents (range, 70,000-365,000). One patient died after surgery for reasons unrelated to IAT. Another 3 patients had stable diabetes with partial graft function (fasting C-peptide levels 0.23, 0.41, and 0.61 nmol/L and HbA1c 4.8%, 4.6%, and 6.9% at 24, 24 and 9 months after IAT, respectively). The 1st patient, with pancreatic head carcinoma, was alive 28 months after IAT with lymph node and liver recurrence since 18 months after IAT. The 2nd patient, with gall bladder and distal bile duct carcinoma, died 47 months after IAT with tumor recurrence. The 3rd patient, with ampullary carcinoma, died 12 months after IAT with local recurrence and solitary liver metastasis. The last patient had been off insulin 9 months after IAT without tumor recurrence (fasting C-peptide, 0.89 nmol/L; HbA1c, 4.2%).

CONCLUSIONS

Autotransplantation of pancreatic islets isolated from the residual pancreatic tissue in patients who previously underwent hemipancreatoduodenectomy for cancer may provide stable glucose control and thus improve quality of life. In this small series we did not observe early development of multiple liver metastases caused by islet suspension contamination with malignant cells. Oncologic outcome of the patients was not worse than what would be expected without IAT.

Processing of superparamagnetic iron contrast agent ferucarbotran in transplanted pancreatic islets

Labeling of pancreatic islets with superparamagnetic iron oxide (SPIO) nanoparticles enables their post-transplant monitoring by magnetic resonance imaging (MRI). Although the nanoparticles are incorporated into islet cells in culture, little is known about their fate in vivo. We studied the morphology of labeled islets after transplantation, aiming to identify the MRI contrast particles and their relationship to transplantation outcomes. Rat islets labeled with the ferucarbotran were transplanted into the liver or under the kidney capsule of syngeneic and allogeneic rats. After in vivo MRI, morphology was studied by light, fluorescence and transmission electron microscopy. Morphology of syngeneic islets transplanted beneath the kidney capsule vs into the liver was similar. Iron particles were almost completely eliminated from the endocrine cells and remained located in host-derived macrophages surrounding the vital islets for the entire study period. In the allogeneic model, islets lost their function and were completely rejected within nine days following transplantation in both transplant models. However, intercellular transport of the SPIO particles and subsequent MRI findings was different in the liver and kidney. In the liver, the decreasing number of islet-related MRI spots corresponded with clearance of iron particles in rejected islets; in contrast, with renal transplants extensive iron deposits with a high effect on MRI signal persisted in phagocytic cells beneath the capsule. We conclude that MRI detection of the iron contrast agent correlates with islet survival and function in islet transplantation into the liver, while it does not correlate in the case of transplantation beneath the renal capsule.

The effects of DPP-IV inhibition in NOD mice with overt diabetes

Sitagliptin is a dipeptidyl peptidase IV (DPP-IV) inhibitor that exerts an anti-hyperglycaemic effect by preventing degradation of glucagon-like peptide 1 with subsequent β-cell stimulation and potential regeneration. We tested whether sitagliptin therapy in symptomatic non-obese diabetic (NOD) mice would lead to changes in the immune cell profile, improve β-cell survival and induce diabetes remission. Flow cytometry analysis of immune cells in the spleen and peripheral lymph nodes, immunohistology of the pancreas and DPP-IV activity were investigated in diabetic NOD mice, either treated or non-treated with sitagliptin, at 0, 7, 14 and 28 days after hyperglycaemia onset, and in non-diabetic NOD controls. While compared to diabetic controls sitagliptin prevented increase of the CD8+/CD4+ ratio in pancreatic nodes after four weeks (0.443 ± 0.067 vs. 0.544 ± 0.131; P < 0.05), the population of Tregs in lymph nodes increased from day 0 to 28 in both treated and non-treated diabetic groups (8 ± 1.76 vs. 13.45 ± 5.07 % and 8 ± 1.76 vs. 13.19 ± 5.58 %, respectively). The severity of islet infiltration was similar in both diabetic groups and decreased in parallel with β-cell loss. Surprisingly, sitagliptin blocked the DPP-IV activity only temporarily (on day 7, 277.68 ± 89.2 vs. 547.40 ± 94.04 ng/ml in the diabetic control group) with no apparent effect later on. In conclusion, sitagliptin administered after the onset of overt hyperglycaemia in NOD mice had only a marginal immunological effect and did not lead to diabetes remission. Failure to block DPP-IV over time represents an important finding that requires further explanation.

Activation of the Jak/Stat signalling pathway by leukaemia inhibitory factor stimulates trans-differentiation of human non-endocrine pancreatic cells into insulin-producing cells

Differentiation of pancreatic β-cells is regulated by a wide range of signalling pathways. The aim of our current work was to evaluate the effect of the Jak/Stat signalling pathway on the differentiation of human non-endocrine pancreatic cells into insulin-producing cells. Activation of the Jak/Stat signalling pathway by leukaemia inhibitory factor (LIF) stimulated differentiation of C-peptide-negative human non-endocrine pancreatic cells into insulin-producing cells in 6.3 ± 2.0 % cells (N = 5) and induced expression of pro-endocrine transcription factor neurogenin 3, Notch signalling pathway suppressor HES6 and stimulator of β-cell neogenesis REG3A. The expression of the REG3A gene and increased rate of differentiation into insulin-producing cells (10.2 ± 2.1 %) were further stimulated by a combination of LIF with nicotinamide and dexamethasone. Glucose-stimulated (5 vs. 20 mM) C-peptide secretion confirmed proper insulin secretory function of trans-differentiated insulin-producing cells (0.51 vs. 2.03 pmol C-peptide/μg DNA, P < 0.05). Our results indicate that Jak/Stat signalling critically contributes to trans-differentiation of non-endocrine pancreatic cells into functional insulin-producing cells. The positive effect of the Jak/Stat signalling pathway on trans-differentiation is mediated by the key genes that activate differentiation of pancreatic β-cells.

Detection of pancreatic islet allograft impairment in advance of functional failure using magnetic resonance imaging

This study evaluated the ability of magnetic resonance imaging (MRI) to predict failure of pancreatic islets (PI) transplanted into the hepatic portal vein. Brown-Norway (n = 18) and Lewis (n = 6) rats received islets isolated from Lewis donors. The rejection process in Brown-Norway recipients was mitigated by two different immunosuppressive regimens [tacrolimus + hydrocortisone for 3 months (n = 6) or tacrolimus for 12 days (n = 12)]. Longitudinal MRI monitoring of recipients at post-transplantation weeks 1, 2, 3, 4, 6, 8, 10, and 12 confirmed the ability to detect SPIO labeled PI after transplantation into the liver. The relative number of MRI signals related to PI isografts remained stable up to study completion. Recipients of PI allografts were normoglycemic until the end of study; signals declined gradually to 44 ± 17% in these animals. In animals with islets failure during post-transplant week 12, the number of signals decreased to 25 ± 10% of initial values. The difference between groups (islet function/failed) became significant post-transplant week 3. Our data demonstrate that the MRI changes attributable to rejection become apparent within 3 weeks after transplantation, i.e. at least 8 weeks before functional allograft failure.

The effect of epigenetic factors on differentiation of pancreatic progenitor cells into insulin-producing cells

Differentiation of pancreatic progenitors into insulin-producing β cells is regulated by various transcription factors. To be expressed the genes coding these transcription factors need to be in accessible DNA. Whether a particular gene is present in a form of active euchromatin structure with accessible DNA or in an inactive heterochromatin structure with inaccessible DNA is determined by various epigenetic modifications. We studied the effect of epigenetic modifiers on differentiation of human nonendocrine cells into insulin-producing cells with the aim to evaluate the effect of epigenetic modifications in that process. Within 3 days of cultivation nonendocrine cells form isletlike cell clusters (ILCCs) containing mainly cytokeratin-19-positive cells. After cultivation with epigenetic modifiers and further differentiation, the highest number of C-peptide-positive cells (10.3% ± 2.9%) as well as glucagon-positive cells (7.2% ± 2.8%) was observed in a sample supplemented with a combination of 5-Aza-2'-deoxycytidine modifiers, BIX01294 and MC1568. In response to glucose stimulation (5 vs 20 mmol/L) these ILCCs secreted increased amounts of C-peptide (0.45 vs 1.05 pmol C-peptide/μg DNA). Control samples treated without any epigenetic modifiers showed significantly lower numbers of C-peptide-positive cells (3.5% ± 1.6%). These results showed that a combination of epigenetic modifiers 5-Aza-2'-deoxycytidine (BIX01294 and MC1568) significantly improved reproducible differentiation of nonendocrine pancreatic cells into insulin-producing cells.

[Simultaneous transplantation of the kidney and the islets of Langerhans]

Simultaneous kidney and islet transplantation is recent therapeutic alternative for diabetics with end-stage kidney disease, who are not acceptable for simultaneous pancreas-kidney transplantation. Islet transplantation has less complications but still worse long-term function compared to whole pancreas transplantation.

In vivo differentiation of human umbilical cord blood-derived cells into insulin-producing beta cells

In our study we confirmed the potential of human umbilical cord blood cells to differentiate into insulin-producing cells following transplantation into immunocompromised mice. The average number of C-peptide-positive human cells per animal was 18 +/- 13 as assessed by immunofluorescence staining and fluorescence in situ hybridization specific for human ALU sequence. Differentiation into insulin-producing cells was further confirmed by reverse transcription-polymerase chain reaction specific for human insulin mRNA. Successful differentiation required sublethal irradiation of xenogeneic recipient at least at a dose of 3 Gy. However, transplantation of human umbilical cord blood cells did not improve hyperglycaemia in diabetic animals. The results of our study show that human umbilical cord blood may be considered as a potential source of stem cells for treatment of diabetes mellitus.

Clinical magnetic resonance imaging of pancreatic islet grafts after iron nanoparticle labeling

There is a crucial need for noninvasive assessment tools after cell transplantation. This study investigates whether a magnetic resonance imaging (MRI) strategy could be clinically applied to islet transplantation. The purest fractions of seven human islet preparations were labeled with superparamagnetic iron oxide particles (SPIO, 280 microg/mL) and transplanted into four patients with type 1 diabetes. MRI studies (T2*) were performed prior to and at various time points after transplantation. Viability and in vitro and in vivo functions of labeled islets were similar to those of control islets. All patients could stop insulin after transplantation. The first patient had diffuse hypointense images on her baseline liver MRI, typical for spontaneous high iron content, and transplant-related modifications could not be observed. The other three patients had normal intensity on pretransplant images, and iron-loaded islets could be identified after transplantation as hypointense spots within the liver. In one of them, i.v. iron therapy prevented subsequent visualization of the spots because of diffuse hypointense liver background. Altogether, this study demonstrates the feasibility and safety of MRI-based islet graft monitoring in clinical practice. Iron overload (spontaneous or induced) represents the major obstacle to the technique.

[Transplantation in the treatment of diabetes]

Diabetes mellitus continues to be the most common cause of chronic kidney failure, blindness acquired in adulthood, non-traumatic amputations and severe forms of neuropathy. Therefore it is necessary to look for new forms of therapy capable of achieving long-term normalisation of blood sugar levels. The only standard method so far is pancreas transplantation. Most often, it is performed in combination with kidney transplantation and only exceptionally as an isolated procedure. A new and considerably less invasive option is transplantation of isolated Langerhans islets. While the number of pancreas transplantations in IKEM has exceeded 300, the program of islet transplantation is in its formative phase, with 10 clinical surgeries having been performed since May 2007. However, the number of suitable patients who could benefit from this method of treatment largely exceeds the availability of organs suitable for transplantation. Therefore, new possibilities of acquiring insulin producing cell lines are searched for, both from animal tissue and, primarily, from embryonic or adult stem cells. Also the possibility of in vivo regeneration of endogenous or transplanted beta cells of the pancreas has now became an object of study. Combined transplantation of the kidney and pancreas is still the best available method in the treatment of uremic type 1 diabetes patients and its long-term results have shown to be very good, even though their further improvement has been but of a lesser degree. Isolated transplantation of the pancreas is still reserved for a limited group of patients with very labile diabetes. The transplantation of isolated Langerhans isletes is an alternative option which is far safer for the patient, but the long-term results of which still leave much to be desired. The method currently used in the Institute of Clinical and Experimental Medicine (IKEM) is organ transplantation of the pancreas while a program of transplantation of isolated islets has been launched, and also studied are the possibilities of insulin producing cell lines propagation.

Isolation and characterization of human CXCR4-positive pancreatic cells

The existence of an adult PSC that may be used in the treatment of diabetes is still a matter of scientific debate as conclusive evidence of such a stem cell in the adult pancreas has not yet been presented. The main reason why putative PSC has not yet been identified is the lack of specific markers that may be used to isolate and purify them. In order to increase the list of potential PSC markers we have focused on the human pancreatic cells that express cell surface receptor CXCR4, a marker of stem cells derived from different adult tissues. Here we report that CXCR4-positive pancreatic cells express markers of pancreatic endocrine progenitors (neurogenin-3, nestin) and markers of pluripotent stem cells (Oct-4, Nanog, ABCG2, CD133, CD117). Upon in vitro differentiation, these cells form ILCC and produce key islet hormones including insulin. Based on our results, we assume that CXCR4 marks pancreatic endocrine progenitors and in combination with other cell surface markers may be used in the attempt to identify and isolate PSC.

Vitality of pancreatic islets labeled for magnetic resonance imaging with iron particles

We previously described an in vivo method for pancreatic islet visualization using magnetic resonance imaging with the aid of superparamagnetic nanoparticles of iron oxide (Resovist) or by magnetic beads precoated with antibodies (Dynabeads). The aim of this study was to investigate the in vitro effect of islet labeling on their quality. Isolated rat islets were cultivated for 48 hours with a contrast agent or, in the case of magnetic antibody-coated beads, for only 2 hours. The ability to secrete insulin was tested by a static insulin release assay and the results were expressed as a stimulation index. Staining with propidium iodide and acridine orange was performed to determine the ratio of live to dead cells. Stimulation indices in the Resovist islets (n = 23) vs controls (n = 14) were 15.3 and 15.0, respectively, and in the Dynabeads islets (n = 15) vs controls (n = 12) 21.3 and 19.9, respectively. The vitality of the Resovist islets vs controls determined by live/dead cells ratio was 90.8% and 91.1%, respectively (n = 20), and in the Dynabeads islets vs controls was 89.4% and 91.8%, respectively (n = 11). Islet labeling with the contrast agent as well as with specific antibodies with iron beads did not change the vitality and insulin-secreting capacity assessed in vitro (P > .05). Magnetic resonance using iron nanoparticles represents the only method for in-vivo visualization of transplanted islets so far. Our data represent an important contribution for its clinical use.

Metabolic effect of sirolimus versus mycophenolate mofetil on pancreatic graft function in the early posttransplant period

Metabolic effects of immunosuppressive agents are of great importance in pancreas or islet transplantation. The aim of our study was to compare effects of tacrolimus-based immunosuppression in conjunction with sirolimus (RAPA) versus mycophenolate mofetil (MMF) on glucose metabolism in type 1 diabetic recipients following a simultaneous pancreas and kidney transplantation (SPK). We examined 30 insulin-independent patients after SPK with venous systemic drainage of the pancreatic graft. All recipients had good kidney graft function. Fasting glycemia, insulin levels, glycosylated hemoglobin (HbA(lc)), standard intravenous glucose tolerance test (IVGTT), and trough RAPA levels were assessed in pancreas recipients before elective steroid withdrawal. Insulin sensitivity was evaluated using the homeostasis model assessment (HOMA-IR). The groups did not differ in age, BMI, posttransplant period, steroid daily dose, HbA(lc), and fasting glycemia. We did not find any significant difference in the IVGTT response. Area under the curve of insulin levels during IVGTT and HOMA-IR were significantly lower in the RAPA group. Trough levels of RAPA had no significant impact on any of the examined parameters. Glucose tolerance measured with the use of IVGTT was similar in patients treated with RAPA and MMF. However, recipients on sirolimus treatment had significantly lower insulinemia during the test and consequently more favorable indices of insulin action as assessed by HOMA-IR.

Magnetic resonance imaging of intrahepatically transplanted islets using paramagnetic beads

Superparamagnetic agents can be reliably used for magnetic resonance imaging (MRI) of pancreatic islets located in the liver sinusoids. However, the main disadvantages seemed to be the rather long culture time necessary for islet labeling and the low specificity of these agents. In the present study we investigated a more specific approach with a shorter labeling time using immunomagnetic particles. Isolated rat islets were cultivated with immunomagnetic beads coated with antibody against rat MHC class I antigen. Labeled islets were transplanted into the livers of syngeneic rats. The animals were examined weekly by MRI or livers explanted 10 minutes after islet transplantation for in vitro experiments. In both in vitro and in vivo studies, labeled transplanted islets were imaged as hypointensive spots, diffusely distributed throughout the liver. This experiment represents an alternative way of islet imaging by magnetic resonance, which is as effective as the use of known superparamagnetic contrast agents and more specific owing to targeting to specific donor antigens.

Tacrolimus compared with cyclosporine microemulsion in primary simultaneous pancreas-kidney transplantation: the EURO-SPK 3-year results

This 3-year study compared tacrolimus versus cyclosporine (CsA) microemulsion (ME) in conjunction with rATG induction, mycophenolate mofetil (MMF) and short-term corticosteroids in primary simultaneous pancreas-kidney (SPK) transplantation.

PATIENTS AND METHODS

This large, prospective, multicenter study was conducted in 10 European centers and one center in Israel. Of the 205 SPK transplants performed from 1998 to 2000, 103 patients were randomly assigned to tacrolimus and 102 to CsA ME. All patients received concomitant rATG induction therapy, MMF, and short-term corticosteroids.

RESULTS

In total, 36.9% patients receiving tacrolimus and 57.8% receiving CsA ME discontinued treatment (P = .003). Although 3-year patient and kidney graft survival rates were similar in both groups, pancreas survival was superior with tacrolimus (89.2% versus 72.4%; P = .002). Thrombosis resulted in pancreatic allograft loss in 10 patients receiving CsA ME and in 2 treated with tacrolimus (P = .02). The first episode of biopsy-proven rejection was moderate or severe in 1 of 31 tacrolimus-treated patients and 11 of 39 patients receiving CsA ME (P = .009). Overall adverse event frequency was similar in both groups, but surgical events were lower in the tacrolimus treated group.

CONCLUSION

Tacrolimus was more effective than CsA-ME to prevent moderate or severe kidney or pancreas rejection after SPK transplantation. It also provided superior pancreatic graft survival and reduced the risk of pancreas thrombosis.

In Vitro Assessment of Pancreatic Islet Vitality by Oxymetry

In order to assess the quality of freshly isolated and cultivated pancreatic islets designed for experimental transplantation in rats we combined the vitality staining test, in vitro measurement of insulin secretion capacity, and assessment of islet respiration. Oxygen consumption was measured using the respirometer Oxygraph 2K equipped with polarographic oxygen sensors. The results of oxymetry demonstrated a linear correlation between islet number and oxygen consumption. Respiration per unit of viable islet tissue was constant. Oxygen consumption tests were in good correlation with the results of insulin release assays, with a correlation coefficient of 0.82. We found no significant differences in all three vitality-testing methods performed with fresh and 24-hour cultivated islets (P > .05). We conclude that polarographic oxymetry provides a fast and easy evaluation test of islet quality. After appropriate standardization, the oxymetric technique can be used for routine clinical pretransplant islet quality testing. In addition, cell membrane integrity and mitochondrial function could be assessed after addition of specific respiration inhibitors or stimulators.

Severe Depletion of Intraepidermal Nerve Fibers in Skin Biopsies of Pancreas Transplant Recipients

BACKGROUND

The minimally invasive method of skin biopsy with intraepidermal nerve fiber (IENF) counts may be used to analyze nerve regeneration in pancreas transplant (PTx) recipients. We assessed IENF counts as a database for long-term follow-up of diabetic neuropathy.

METHODS

Skin biopsies were performed using a 3-mm punch from lower thigh and upper calf areas of 16 (13 pancreas/kidney, 3 pancreas alone) PTx patients (mean +/- SD: age, 45+/-8 years; type 1 diabetes duration, 27 +/- 8 years) at 1 month posttransplant. Ten healthy gender- and age-matched controls (C) were also examined. After fixation and freezing, 40-microm sections were stained using rabbit polyclonal antibody to the panaxonal marker PGP 9.5 followed by mouse antirabbit IgG antibody conjugated with rhodamine. Samples were imaged with a digital camera, mounted on a microscope, and equipped for fluorescence. The average number of IENF per millimeter length of epidermis was derived. Clinical neuropathy was assessed by foot vibration perception thresholds (VPT) with a biothesiometer (normal values < mean + 2 SD of C).

RESULTS

Significantly lower IENF densities were found in skin biopsies from PTx (PTx vs C: thigh, 0.74 +/- 0.88 vs 9.74 +/- 2.41 IENF/mm; calf, 0.34 +/- 0.91 vs 7.66 +/- 3.16 IENF/mm; P < .001). IENF were totally absent from the thigh and calf samples of 7 and 12 PTxs, respectively. Clinical neuropathy (VPT > 21 V) was present in all but one PTx.

CONCLUSIONS

Severe intraepidermal nerve fiber depletion is present in the lower limb area of pancreas transplant recipients with neuropathy. Long-term follow-up would probably be necessary to assess the possibility of posttransplant nerve fiber regeneration.

Modulating amylase and lipase secretion in the pancreatic graft by somatostatin administration: preliminary results of a prospective, randomized trial

Pancreas transplantation is a routine method for the treatment of diabetes mellitus. One of the main challenges of a transplant with extraperitoneal placement of the pancreatic graft is impaired wound healing due to massive amylase and lipase secretion by the pancreatic graft, evoking edemtous fluid. From February 2002 through January 2003, we performed pancreatic transplant procedures in 21 patients who were prospectively and randomly assigned to two groups: 8 organ donors and the recipients were administered somatostatin by continuous infusion. Thirteen grafts were harvested and transplanted without somatostatin infusion. The two groups did not show significantly differences in mean donor or recipient ages, weights, of serum amylase and lipase content values or drain output until day 6. There was a significantly lower lipase in the drain output of transplant recipients given somatostatin (12.5 and 54.2 micromol/L, respectively; P <.05). Neither the post-pancreatic transplant wound healing nor the number of rejection episodes were affected by somatostatin administration.

A prospective comparison of bladder versus enteric drainage in vascularized pancreas transplantation

In previous years, the number of pancreas transplants has increased significantly. Debate continues over the optimum technique for exocrine drainage. Enteric drainage (ED) has recently been increasingly popular owing to the long-term complications of bladder drainage (BD). We prospectively evaluated 40 consecutive pancreas transplant recipients undergoing either bladder (n = 20) or enteric (n = 20) drainage. After simultaneous kidney-pancreas transplantation 1-year patient, kidney, and pancreas graft survival rates were 95%, 95%, 85% for the BD group, and 90%, 85%, 85%, for the ED group. Surgical complications were not significantly different between the two groups. The incidence of acute rejection, major infections and cytomegalovirus disease were also similar. The length of the initial hospital stay was likewise comparable. However, the BD group was characterized by a slight increase in the number of urologic complications, metabolic acidosis, and dehydration. Our results suggest excellent patient and graft survival irrespective of the drainage technique.

A prospective comparison of bladder versus enteric drainage in vascularized pancreas transplantation

Although the number of pancreas transplants has increased significantly in previous years, debate continues concerning the optimum technique for exocrine pancreas drainage. Enteric drainage (ED) has recently been increasingly popular due to the long-term complications with bladder drainage (BD). We prospectively assigned 40 consecutive pancreas transplant recipients to either bladder (n = 20) or enteric (n = 20) drainage. Patient, kidney, and pancreas graft survival rates at 1 year after simultaneous kidney-pancreas transplantation were 95%, 95%, 85%, for BD group and 90%, 85%, 85% for ED group, respectively. Surgical complications were not significantly different between the two groups. The incidence of acute rejection, major infections, and CMV disease were similar between groups. The length of the initial hospital stay was likewise comparable. However, the BD group showed a slight increase in the number of urologic complications, metabolic acidosis, and dehydration. Based on the results of our study, patient and graft survivals were excellent irrespective of technique.

Enhancement of rat islet tolerance with bone marrow transplantation using a non-myeloablative procedure II: failure despite the presence of lymphocyte microchimerism in the fully allogeneic Lewis/Brown-Norway model

Transplantation of donor bone marrow cells (BMTx) has been proven to be capable of including allogeneic transplant tolerance. In our previous experiments we reported the positive effect of BMTx together with short-term tacrolimus/hydrocortisone therapy on pancreatic islet survival in recipients haploidentical with donors. In this project we used the same transplant protocol to further investigate this effect in a fully mean histocompatibility system-mismatched model. Lewis male rats and Brown-Norway female rats were used as donors and recipients, respectively. Diabetic animals were treated according to four different protocols. Recipients in group I (n = 12) underwent islet transplantation (ITx) only. Group II (n = 12) and group III (n = 11) included animals treated for 52 days with tacrolimus (0.5 mg/kg) and hydrocortisone (2 mg/kg). Diabetes was induced by intravenously applied streptozocin (50 mg/kg). Seven days later islets were injected intrahepatically through the portal vein. In addition, rats in group III underwent BMTx on day 10. In group IV (n = 6) tacrolimus therapy, ITx and BMTx were used according to the previously published protocol of Ricordi et al. After more than 120 days, cumulative survival rates were 56% and 64% for recipients in groups II and III, respectively (p > 0.05). All animals in group I became hyperglycemic by day 11 following transplantation. Despite positive detection of lymphocyte microchimerism, we did not observe improved survival of allogeneic islets in animals treated with BMTx. Surprisingly, better islet survival was not found in group IV either (survival rate at 100 days: 33%). We conclude that demonstration of lymphocyte microchimerism, as detected by a sensitive polymerase chain reaction method, did not improve allogeneic islet survival in vivo and was not able to block mixed lymphocyte reaction in vitro. Whether a larger amount of transplanted hematopoietic cells could induce tolerance in this model remains to be evaluated.

[Vascular complications after pancreatic transplantation]

Transplantation of pancreas is presently the only way of treating diabetes of the 1st type, capable to secure a long-term normoglycemia. In spite of the fact that the surgical technique and tactics of the whole intervention has been standardized over the last years, surgical complications and more specifically vascular complications still pose a certain risk of the graft loss. The thrombosis of vessels of the transplanted pancreas occurred in our group in 4.1 per cent of cases. The other rare complications included a false aneurysm of the supplying artery and stenosis of the out-coming vein from the pancreatic graft. Both these complications were successfully treated by a radio-invasive approach. A refinement of the surgical technique and the introduction of new immunosuppressive drugs manifests favorably in decreasing occurrence of vascular complications after the transplantation of pancreas.

Spectral analysis of heart rate variation following simultaneous pancreas and kidney transplantation

Only marginally improved results have been observed in standard autonomic function tests (AFT) in follow-up studies after simultaneous pancreas and kidney transplantation (SPK). We therefore used power spectral analysis (PSA) of heart rate variability (HRV) to assess the effect of SPK on autonomic neuropathy in patients with type I diabetes mellitus (DM I). We evaluated 82 patients with DM I who were insulin and dialysis free following SPK. Both pre- and posttransplant (at [mean +/- SD], 25 +/- 15 months post-SPK) examinations were performed in 29 patients. Posttransplant evolution was examined in another 60 patients with two serial examinations at 20 +/- 20 and 43 +/- 27 months after SPK. Comparisons included 32 age-matched healthy controls and 13 patients with kidney transplant alone (KTA) matched for age and duration of DM I at a comparable time point posttransplant. Short-term time (modified Ewing battery) and frequency domain (PSA of HRV: LF-low, HF-high frequency, and TP-total spectral power) analysis was performed with a telemetric, on-line, computer-aided system. Significantly worse results in all standard AFT and PSA indexes were obtained for SPK patients compared with controls at all time points. No significant improvement was seen in SPK patients in the posttransplant period and no differences were found compared with KTA patients. Thus the results of a power spectral analysis of HRV failed to show improvement following SPK. This examination adds little positive information to that obtained from standard autonomic function tests.