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C Ricordi

Publications and source records attributed to C Ricordi.

At least 19 recordsLinked to original sources
PubMed2006

Simple measures to monitor beta-cell mass and assess islet graft dysfunction.

The aim of this study was to develop a simple test for the assessment of islet graft dysfunction based on measures involving fasting C-peptide. Calculations were made to account for the dependence of C-peptide secretion on glucose concentration (C-peptide/glucose ratio [CP/G]) and adjusted for renal function by calculating the C-peptide/glucose-creatinine ratio (CP/GCr). Values from 22 recipients were analyzed at different times post-last islet infusion. Receiver operating characteristic curves were used to determine which of these measures best predicts high 90-minute glucose (90 min-Glc; >10 mmol/L) after a Mixed Meal Tolerance Test (MMTT). In this initial analysis, CP/G was found to be superior predicting high 90 min-Glc with a larger area under the ROC curve than C-peptide (p = 0.01) and CP/GCr (p = 0.06). We then correlated C-peptide and CP/G with islet equivalents--IEQ/kg infused, 90 min-Glc after MMTT and clinical outcome (beta-score). C-peptide and CP/G in the first 3 months post-last islet infusion correlated with IEQ/kg infused. CP/G correlated with 90 min-Glc and beta-score. C-peptide and CP/G are good indicators of islet mass transplanted. CP/G is more indicative of graft dysfunction and clinical outcome than C-peptide alone. The ease of calculation and the good correlation with other tests makes this ratio a practical tool when monitoring and managing islet transplant recipients.

Adult↗
PubMed2006

Antiangiogenic and immunomodulatory effects of rapamycin on islet endothelium: relevance for islet transplantation.

Donor intra-islet endothelial cells contribute to neovascularization after transplantation. Several factors may interfere with this process and ultimately influence islet engraftment. Rapamycin, a central immunosuppressant in islet transplantation, is an mTOR inhibitor that has been shown to inhibit cancer angiogenesis. The aim of this study was to evaluate the effects of rapamycin on islet endothelium. Rapamycin inhibited the outgrowth of endothelial cells from freshly purified human islets and the formation of capillary-like structures in vitro and in vivo after subcutaneous injection within Matrigel plugs into SCID mice. Rapamycin decreased migration, proliferation and angiogenic properties of human and mouse islet-derived endothelial cell lines with appearance of apoptosis. The expression of angiogenesis-related factors VEGF, alphaVbeta3 integrin and thrombospondin-1 on islet endothelium was altered in the presence of rapamycin. On the other hand, rapamycin decreased the surface expression of molecules involved in immune processes such as ICAM-1 and CD40 and reduced the adhesion of T cells to islet endothelium. Our results suggest that rapamycin exerts dual effects on islet endothelium inducing a simultaneous inhibition of angiogenesis and a down-regulation of receptors involved in lymphocyte adhesion and activation.

Angiogenesis Inhibitors↗
PubMed2006

Improved human islet isolation using nicotinamide.

We investigated the effects of nicotinamide (NA) supplementation of the processing medium during islet isolation. One hundred and two human pancreata were processed for clinical transplantation after preservation either in the University of Wisconsin (UW) or using the two-layer method (TLM). Pancreata were then divided into four groups and retrospectively analyzed. Group I: UW preservation followed by processing without NA, Group II: UW preservation and processing with NA, Group III: TLM preservation without NA, Group IV: TLM preservation with NA. We observed a significant increase in islet yield in Group II (4343+/-348 IEQ/g) [mean+/-SEM], compared to Group I (2789+/-348 IEQ/g) (p=0.005). Similarly, a significant increase in islet yield was observed when NA was used in the processing of organs preserved with TLM (Group IV: 5538+/-413 vs. Group III: 3500+/-629; p=0.02). Furthermore islet yield was higher in Group IV than in Group II (p<0.05). The percentages of preparations that qualified for transplantation were 25, 47, 45, 69% in Groups I, II, III, IV, respectively. Addition of NA to the processing medium significantly improved islet yields in both the UW and TLM preservation protocols, allowing for a higher percentage of islet preparations to qualify for clinical transplantation.

Adenosine↗
PubMed2006

Continuous glucose monitoring system for early detection of graft dysfunction in allogenic islet transplant recipients.

BACKGROUND: There are no effective indicators of graft dysfunction in islet transplantation. This study evaluated the role of the Continuous Glucose Monitoring System (CGMS) as an early indicator of graft dysfunction in islet transplant recipients. METHODS: In 5 islet allograft recipients, we retrospectively determined the date of graft dysfunction: 3 fasting blood glucose levels >7.8 mmol/L (140 mg/dL) and/or 3 postprandial blood glucose levels >10 mmol/L (180 mg/dL) in 1 week. We then determined 2 time points in respect to graft dysfunction, 5 to 9 months before (time point A) and 2 to 3 months before (time point B). For these 2 time points, we assessed the following: HbA1c, C-peptide (CP), C-peptide glucose ratio (CPGR), 90-minute glucose from mixed meal tolerance test, and percentage of capillary blood glucose levels >7.8 mmol/L (%CBG >7.8) in a 15-day interval (1 week before and after CGMS placement). From the CGMS recordings, we calculated the glucose variability and the percentage of time spent in hyperglycemia >7.8 mmol/L (%HGT >7.8) and >10 mmol/L (%HGT >10). RESULTS: No difference was found between time points A and B for the following parameters: HbA1c, CP, CPGR, 90-minute glucose, %CBG >7.8, and %HGT >10. We observed a statistically significant increase from time point A to time point B in glucose variability (1.1 +/- 0.5 mmol/L to 1.6 +/- 0.6 mmol/L; P = .004), and in the %HGT >7.8 (11 +/- 12% to 22 +/- 18%; P = .036). CONCLUSION: Glucose variability and %HGT >7.8 determined using CGMS are useful as early indicators of graft dysfunction in islet transplant recipients. Further studies with larger sample sizes will help validate these observations.

Adult↗
PubMed2006

Quality of life after islet transplantation.

This study analyzed quality of life in patients with type 1 diabetes that received islet transplantation. Twenty-three subjects were followed over 3 years. In addition to an interview, patients self-completed two standardized psychometric questionnaires, HSQ 2.0 and DQOL, before and after transplant, and scores were compared. Analysis was also adjusted for potential "confounders" such as graft dysfunction, insulin therapy and adverse events. DQOL: the Impact score significantly improved at all time points of the follow-up; satisfaction and worry scales also significantly improved at selected time points. Longitudinal analysis demonstrated that reintroduction of insulin had a negative effect on all three scales, but significant improvement in Impact scale persisted even after adjusting for this factor. HSQ 2.0: only the Health Perception scale preliminarily showed significant improvement at most time points. Longitudinal analysis showed loss of significance when insulin therapy was considered. Other scores were improved only at selected time points or not affected. Bodily pain scale showed deterioration at selected times. Interview: glucose control stability, not insulin independence, was reported as the main beneficial factor influencing QOL. In conclusion, islet transplantation has a positive influence on patients' QOL, despite chronic immunosuppression side effects. Re-introduction of insulin modifies QOL outcomes.

Female↗
PubMed2006

Clinical islet transplantation.

Achieving stable metabolic control in patients with type 1 diabetes mellitus (T1DM) is highly desirable and may contribute to delaying and/or preventing the development of secondary complications. Transplantation of pancreatic islets represents a viable option for the treatment of patients with unstable T1DM with frequent severe hypoglycemia and hypoglycemia unawareness. The benefits of the transplant include improvement of glycemic control, prevention of severe hypoglycemia and amelioration of quality of life. The success of future clinical trials will depend on the implementation of an integrated therapeutic approach combining strategies to maximize islet availability and engraftment with those aiming at safely modulating the recipients' immunity to afford long-term function. The steady progress of recent years in islet cell processing and patient management after transplantation justify great optimism for the years to come.

Diabetes Mellitus, Type 1↗
PubMed2005

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

AIMS/HYPOTHESIS: Diabetic subjects do home monitoring to substantiate their success (or failure) in meeting blood glucose targets set by their providers. To succeed, patients require decision support, which, until now, has not included knowledge of future blood glucose levels or of hypoglycaemia. To remedy this, we devised a glucose prediction engine. This study validates its predictions. METHODS: The prediction engine is a computer program that accesses a central database in which daily records of self-monitored blood glucose data and life-style parameters are stored. New data are captured by an interactive voice response server on-line 24 h a day, 7 days a week. Study subjects included 24 patients with debilitating hypoglycaemia (unawareness), which qualified them for islet cell transplantation. Comparison of each prediction with the actually observed data was done using a Clarke Error Grid (CEG). Patients and providers were blinded as to the predictions. RESULTS: Prior to transplantation, a total of 31,878 blood glucose levels were reported by the study subjects. Some 31,353 blood glucose predictions were made by the engine on a total of 8,733 days-used. Of these, 79.4% were in the clinically acceptable Zones of the CEG. Of 728 observed episodes of hypoglycaemia, 384 were predicted. After transplantation, a total of 45,529 glucose measurements were reported on a total of 12,906 days-used. Some 42,316 glucose predictions were made, of which 97.5% were in the acceptable CEG Zones A and B. Successful transplantation eliminated hypoglycaemia, improved glycaemic control, lowered HbA(1)c and freed 10 of 24 patients from daily insulin therapy. CONCLUSIONS/INTERPRETATION: It is clinically feasible to generate valid predictions of future blood glucose levels. Prediction accuracy is related to glycaemic stability. Risk of hypoglycaemia can be predicted. Such knowledge may be useful in self-management.

Blood Glucose Self-Monitoring↗
PubMed2005

A functional CD40 receptor is expressed in pancreatic beta cells.

AIMS/HYPOTHESIS: Despite differences in function and embryonic origin, pancreatic islet cells and neurons express proteins belonging to the tumour necrosis factor receptor superfamily. While neurons express the CD40 receptor, it is unknown whether islet cells also express it. We investigated CD40 expression in human and mouse pancreatic islets as well as in NIT-1 insulinoma cells. METHODS: CD40 expression was studied by reverse transcriptase polymerase chain reaction, flow cytometry, immunohistochemistry and western blot. Responses mediated by CD40 were assessed by a luciferase gene reporter assay following stimulation with a CD40 agonist antibody. RESULTS: We found that CD40 is expressed in mouse and human pancreatic islet cells. CD40 is expressed by beta cells, and its expression is upregulated by proinflammatory cytokines (IL-1beta, IFN-gamma and TNF-alpha). CD40 signalling in NIT-1 insulinoma cells activates nuclear factor kappa-B, demonstrating that CD40 is functional. CONCLUSIONS/INTERPRETATION: We present evidence that, in addition to immune cell types, mouse and human pancreatic beta cells express CD40. Its expression is upregulated by proinflammatory stimuli, and signalling through this receptor activates NF-kappaB. We suggest that the effects of inflammatory stimuli that affect beta cell function and survival may be also mediated by signalling through the CD40 receptor. Thus, CD40 may have a role in processes associated with islet autoimmunity and transplantation.

Animals↗
PubMed2005

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

INTRODUCTION: Pancreatic islet transplantation (PIT) has only become an effective treatment for type 1 diabetes mellitus within the past 4 years. As a result, the long-term effects of PIT on progression of diabetic neuropathy and retinopathy are unknown. The benefit of halting or improving diabetic neuropathy and retinopathy is of particular interest since most PIT recipients have not developed the advanced complications of diabetes. Herein, we describe the improvement and stabilization of diabetic neuropathy and retinopathy in 12 PIT recipients. PATIENTS AND METHODS: Between January 1, 2002, and June 30, 2004, there have been 12 patients who have received PIT. Currently, there are eight patients who have sufficient follow-up to assess the progression of diabetic retinopathy and neuropathy. To assess for disease progression, patients were examined by a single ophthalmologist and single neurologist throughout the study period. Eye exams were performed using a slit-lamp exam while neurological status was assessed using electromyelograms and clinical exams. RESULTS: All PIT recipients had decreases in hemoglobin A(1)C and increases in serum C-peptide. All study patients had stabilization of their retinopathic disease. One patient demonstrated improvement of retinopathy at 1 year posttransplant. Fifty percent of patients demonstrated improvement or stabilization of their diabetic neuropathy. One patient had mild reinnervation of the fingers and wrist extensors by clinical exam 1 year posttransplant. Four patients exhibited an average decrease of 19% in sural nerve conduction velocities. CONCLUSION: Our series has demonstrated that all PIT recipients have had stabilization of their diabetic retinopathy and that 50% of patients exhibited stabilization or even improvement of their diabetic neuropathy.

Adult↗
PubMed2005

C-peptide and glucose values in the peritransplant period after intraportal islet infusions in type 1 diabetes.

BACKGROUND: Successful islet allograft transplantation has been achieved worldwide. This study aimed at evaluating the relationship between peritransplant C-peptide (CP) values and long-term allograft function. METHODS: We measured CP-to-glucose ratio (CPGR) in intraportal samples pre- and postinfusion, and in peripheral circulation at baseline pretransplant and at 1, 3, 6, 12, 72 hours, 1 week, and 15 and 30 days after first and second infusion in 13 islet allograft recipients. Peritransplant treatment included intravenous (IV) 5% dextrose in saline in all patients. We compared portal CPGR to insulin reduction (%) at 30 days after each infusion, and at 1 year after second infusion. RESULTS: CPGR peaked between the immediate postinfusion and 3 hours and decreased at 12 hours. At 1 week, CPGR was 0.76 +/- 0.45 and 1.44 +/- 0.37 after first and second infusion, respectively. CPGR at 30 days after second infusion doubled compared to first infusion (P < .001). There was no correlation between peak CPGR and insulin reduction percent at any time point. One patient experienced hypoglycemia (47 mg/dL) 1 hour after second infusion. CONCLUSIONS: There was no relationship between the CP values in the peritransplant period and long-term graft function or success rate. The early peak in the C-peptide levels is indicative of a significant insulin release after each islet infusion. For this reason, it is important to carefully monitor serum glucose levels in the peritransplant period (hourly for the first 6 hours) and to maintain an IV glucose infusion to avoid hypoglycemia.

Adult↗
PubMed2004

Improved in vitro function of islets using small intestinal submucosa.

Transplantation of human pancreatic islets has been demonstrated to be a viable alternative to exogenous insulin therapy for diabetes mellitus. However, optimum results require transplantation of islets from two to three pancreas donors after a minimum number of days in culture. This implies that a substantial part of the transplanted islet mass may be nonfunctional. This study investigates the ability of an optimized technique to retain islet function using porcine-derived small intestinal submucosa (SIS) during in vitro culture. Groups of purified human islets were cultured for 3 weeks in modified standard islet culture conditions of CMRL = 1066 tissue culture medium supplemented with 25 mmol/L HEPES, penicillin/streptomycin, and a commercial insulin-transferin-selenium (ITS) supplement. Islets (50 to 200 IE/condition; n = 5 preparations) were cultured in plates containing noncoated Biopore membrane inserts alone, or on inserts that had been covered with SIS. Function was assessed by static incubation with low (4 mmol/L), or high (20 mmol/L) glucose at the end of each week. Glucose-stimulated release of human insulin was measured by radioimmunoassay (Linco, St. Charles, Missouri). Remaining islets were stained and evaluated visually. Neither culture condition resulted in significantly different basal secretion until week 3 (P =.05). However, by the end of week 2 and for the duration of the experiment thereafter, SIS-treated islets exhibited a higher SI (P <.05). At the end of the experiment, islets cultured on the SIS exhibited excellent morphology, with greater than 90% staining positive with Dithizone. Islets cultured on the inserts alone lost their initial morphology, becoming "loose" in appearance. The results of this study indicate that SIS enables enhanced function of islets in vitro as compared to non-SIS supported culture conditions.

Cell Culture Techniques↗
PubMed2004

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

BACKGROUND: Owing to advances in both immunosuppressive protocols and pancreatic islet isolation techniques, insulin independence has recently been achieved in type 1 insulin-dependent diabetics (IDDM) via pancreatic islet transplantation (PIT). Although the dissemination of immunosuppressive protocols is relatively easy, transferring the knowledge and expertise required to isolate a large number of quality human islets for transplantation is a far greater challenge. Therefore, in an attempt to centralize the critical islet processing needed for islet transplantation and to avoid the development of another islet processing center, we have established a collaborative islet transplant program between two geographically distant transplant centers. PATIENTS AND METHODS: Eleven consecutive type 1 IDDM patients with a history of severe hypoglycemia and metabolic instability underwent PIT at the Methodist Hospital (TMH) in Houston, Texas, utilizing pancreatic islets isolated at the Diabetes Research Institute (DRI) at the University of Miami in Miami, Florida between January 1, 2002 and June 31, 2003. Forty-one pancreata have been procured in the Houston area and have subsequently been transported for isolation at the DRI following enzymatic ductal perfusion by the automated method (Ricordi chamber). Following purification the islets were immediately transported back to TMH in Houston and transplanted via percutaneous transhepatic portal infusion. Immunosuppression regimen consisted of sirolimus, tacrolimus, and daclizumab. RESULTS: Following harvesting, donor pancreata arrived at the DRI for initiation of the isolation process within 6.5 hours of cross-clamping (median time 5.4 hours; range 4.8 to 6.5 hours). The islets were immediately transported back to TMH for final sterility and viability tests and transplanted via percutaneous transhepatic portal vein infusion. The harvesting of 41 pancreata has yielded a number of pancreatic islets sufficient for transplantation (>5000 IEQ/kg recipient body weight) 26 times (63% of harvested pancreata). Thus far, three patients have received three PITs and eight patients have received two PITs. Six remain insulin independent. All have experienced a decrease in serum hemoglobin A(1c) levels, and both basal and stimulated C-peptide levels have increased. There have been no major complications related to the procedure or the immunosuppressive regimen used. CONCLUSIONS: Our series demonstrates that pancreatic islets isolated at a remote isolation center can successfully and safely be used for PIT and the achievement of insulin independence.

Adult↗
PubMed2004

Enhanced recovery of cryopreserved islets using SIS.

Although cryopreservation of pancreatic islets would add flexibility to transplantation, the recoveries are only 60% to 90% and function is decreased. Islets are multicellular structures approximately 50 to 250 microm in diameter organized into a network of cells and vascular channels. Due to this complexity, islets are more susceptible to damage during cryopreservation than an individual cell. This study investigated porcine small intestinal submucosa (SIS) as a matrix to support islets recovery and function post-thaw. Groups of frozen/thawed human islets (150 IE/condition; n = 4 preparations) were cultured for 5 weeks in plates containing noncoated Biopore membrane inserts alone or inserts covered with SIS. Islets were placed directly on the insert post-thaw (SIS(1)), or cultured overnight in standard plates, washed, and then transferred to the SIS (SIS(2)). Function was assessed by determining glucose-stimulated release of insulin, which was measured by radioimmunoassay. Analysis of basal insulin secretion showed time and treatment to be significantly different (P =.0043 and P =.0123, respectively) but without an interaction (P >.05). The two SIS treatments were not significantly different (P >.05); however, both SIS(1) and SIS(2) were significantly different from controls (P =.0108 and P =.0420, respectively). Similar results were obtained for stimulation indices; time and treatment were significantly different (P =.0161 and P =.0264, respectively) but not an interaction (P >.05). The two SIS treatments were not significantly different (P =.05); however, both SIS(1) and SIS(2) differed from controls (P =.0248 and P =.0407, respectively). The results indicate that SIS enables frozen-thawed islets to exhibit superior post-thaw function compared with a non-SIS-supported condition.

Animals↗
PubMed2003

Targeting recombinant adeno-associated virus vectors to enhance gene transfer to pancreatic islets and liver.

Human pancreatic islet cells and hepatocytes represent the two most likely target cells for genetic therapy of type I diabetes. However, limits to the efficiency of rAAV serotype 2 (rAAV2)-mediated gene transfer have been reported for both of these cell targets. Here we report that nonserotype 2 AAV capsids can mediate more efficient transduction of islet cells, with AAV1 being the most efficient serotype in murine islets, suggesting that receptor abundance could be limiting. In order to test this, we generated rAAV particles that display a ligand (ApoE) that targets the low-density lipoprotein receptor, which is present on both of these cell types. The rAAV/ApoE viruses greatly enhanced the efficiency of transduction of both islet cells ex vivo and murine hepatocytes in vivo when compared to native rAAV2 serotype (220- and four-fold, respectively). The use of receptor-targeted rAAV particles may circumvent the lower abundance of receptors on certain nonpermissive cell types.

Animals↗
PubMed2002

ALEX (artificial liver for extracorporeal xenoassistance): a new bioreactor containing a porcine autologous biomatrix as hepatocyte support. Preliminary results in an ex vivo experimental model.

Long-term maintenance of viability and expression of differentiated hepatocyte function is crucial for bioartificial liver support. We developed a new bioreactor design (ALEX), associated with a new extracellular autologous hepatocyte biomatrix (Porcine Autologous Biomatrix - PBM) support. To test this new bioreactor, we compared it to a standard BAL (BioArtificial Liver) cartridge in a ex vivo model using human plasma added to bilirubin, ammonium and lidocaine. A pathology study was performed on both bioreactors. The results suggest that ALEX allows a maximal contact between the perfusing plasma and the liver cells and a proper hepatocyte support by a cell-to-matrix attachment. ALEX is a suitable cell support bioreactor, guaranteeing long-term maintenance of the metabolic activity of hepatocytes when compared to a standard BAL cartridge.

Ammonia↗