Collagenase isoforms for pancreas digestion

The available information concerning the characteristics and composition of collagenase batches, which are effective in the digestion of human pancreas for islet transplants, is scarce and incomplete. A large inter- and intrabatched variability in activity and efficiency of blend enzymes available for isolation has been observed. The aim of this study was to characterize enzyme blend components. Liberase batches were characterized by SDS-PAGE analyses, microelectrophoresis, and then by MALDI-TOF MS analysis. Three main bands were detected by SDS-PAGE analysis and submitted to MALDI-TOF MS analysis. Two bands were found to correspond to class I (isoform beta and another of 106 kDa) and one to class II (isoform delta) collagenase. These results represent an important step towards a complete characterization of enzymes, with the final aim of identifying key components for a standardized product.

Disproportionate hyperproinsulinemia, beta-cell restricted prohormone convertase 2 deficiency, and cell cycle inhibitors expression by human islets transplanted into athymic nude mice: insights into nonimmune-mediated mechanisms of delayed islet graft failure

To learn more about nonimmune-mediated islet graft failure, we transplanted different preparations (preps) of isolated human islets under the kidney capsule of streptozotocin (STZ)-diabetic nude mice. One month after the implantation of 1,000 or 2,000 islets, grafts were harvested for morphological, immunohistochemical, and ultrastructural analysis. Only a single islet prep cured the diabetes out of all the recipients, while the remaining preps showed only partial function after the implantation of 2,000 islets. Transplanted mice showed high circulating proinsulin levels but, with the exclusion of those bearing curative grafts, relatively low mature insulin levels. Engrafted beta-cells showed positive carboxypeptidase E (CPE) and prohormone convertase 1 (PC1) staining, while prohormone convertase 2 (PC2) was undetectable. In contrast, PC2 was abundantly expressed by engrafted alpha-cells. Moreover, engrafted beta-cells did not show evidence of replication, and preapoptotic beta-cells, with intra- and extracellular amyloid deposition, were detected with electron microscopy. Cell cycle inhibitors p16(INK4), p21(WAF1), and p27(Kip1) were abundantly expressed in the islet grafts and showed a predominant nuclear localization. In conclusion, diabetic nude mice transplanted with human islets showed disproportionate hyperproinsulinemia and graft evidence of beta-cell restricted PC2 depletion, amyloid deposition and beta-cell death, and lack of beta-cell replication with nuclear translocation of p27(Kip1) and p21(WAF1) that together may contribute to delayed graft failure.

Diabetes mellitus: an opportunity for therapy with stem cells?

In both Type 1 and 2 diabetes, insufficient numbers of insulin-producing beta-cells are a major cause of defective control of blood glucose and its complications. Restoration of damaged beta-cells by endocrine pancreas regeneration would be an ideal therapeutic option. The possibility of generating insulin-secreting cells with adult pancreatic stem or progenitor cells has been investigated extensively. The conversion of differentiated cells such as hepatocytes into beta-cells is being attempted using molecular insights into the transcriptional make-up of beta-cells. Additionally, the enhanced proliferation of beta-cells in vivo or in vitro is being pursued as a strategy for regenerative medicine for diabetes. Advances have also been made in directing the differentiation of embryonic stem cells into beta-cells. Although progress is encouraging, major gaps in our understanding of developmental biology of the pancreas and adult beta-cell dynamics remain to be bridged before a therapeutic application is made possible.

Islet transplantation in patients with autoimmune diabetes induces homeostatic cytokines that expand autoreactive memory T cells

Successful transplantation requires the prevention of allograft rejection and, in the case of transplantation to treat autoimmune disease, the suppression of autoimmune responses. The standard immunosuppressive treatment regimen given to patients with autoimmune type 1 diabetes who have received an islet transplant results in the loss of T cells. In many other situations, the immune system responds to T cell loss through cytokine-dependant homeostatic proliferation of any remaining T cells. Here we show that T cell loss after islet transplantation in patients with autoimmune type 1 diabetes was associated with both increased serum concentrations of IL-7 and IL-15 and in vivo proliferation of memory CD45RO(+) T cells, highly enriched in autoreactive glutamic acid decarboxylase 65-specific T cell clones. Immunosuppression with FK506 and rapamycin after transplantation resulted in a chronic homeostatic expansion of T cells, which acquired effector function after immunosuppression was removed. In contrast, the cytostatic drug mycophenolate mofetil efficiently blocked homeostatic T cell expansion. We propose that the increased production of cytokines that induce homeostatic expansion could contribute to recurrent autoimmunity in transplanted patients with autoimmune disease and that therapy that prevents the expansion of autoreactive T cells will improve the outcome of islet transplantation.

Transplant estimated function: a simple index to evaluate beta-cell secretion after islet transplantation

OBJECTIVE

The beta-score is a highly regarded approach to the assessment of transplant functionality. Our aim was to develop an index of beta-cell function that hinges on the pillars of the beta-score (daily insulin requirement and A1C), has a straightforward physiological interpretation, and does not require the execution of an insulin stimulation test.

RESEARCH DESIGN AND METHODS

The new index is denoted transplant estimated function (TEF) and is obtained from the daily insulin requirement and A1C. TEF estimates the amount of insulin secreted daily and can be normalized to the number of transplanted islets, thus permitting evaluation of the cost-effectiveness of the transplant. TEF was compared with the area under the curve of C-peptide [AUC(C-pep)] concentration over 24 h, as well as the acute insulin response to intravenous glucose (AIR(glu)) and to arginine (AIR(arg)). The association between TEF and beta-score was also investigated.

RESULTS

The correlation of TEF with 24-h AUC(C-pep) was r = 0.73 (P < 0.005), whereas that for beta-score versus 24-h AUC(C-pep) was r = 0.33 (NS). The correlation of TEF with AIR(glu) was r = 0.59 (P < 0.001) and close to that for beta-score versus AIR(glu) (r = 0.65, P < 0.001). The correlation of TEF with AIR(arg) was r = 0.33 (P < 0.005) and was similar to that for beta-score versus AIR(arg) (r = 0.34, P < 0.005). TEF and beta-score were correlated well (r = 0.69, P < 0.0001) and showed similar time profiles.

CONCLUSIONS

TEF estimates daily insulin secretion, it is simpler than the beta-score, and its performance against reference indexes of beta-cell secretion is in line with that exhibited by beta-score. TEF can be normalized to the number of transplanted islets and thereby provides a benchmarking tool to evaluate the cost-effectiveness of the transplant.

Beta-cell replacement in immunosuppressed recipients: old and new clinical indications

Islet transplantation is an appealing procedure able to improve glycemic control in type 1 diabetic patients. However, the possible side effects that may be induced by immunosuppressive therapy limit its application to a select number of patients for whom the risk of immunosuppressants' side effects can be justified. For patients with type 1 diabetes mellitus-who will take immunosuppressants regardless, as they require a solid organ transplant-islet infusion can be an interesting therapeutic option for improving metabolic compensation, whenever pancreas transplant is not possible. Hence, islet infusion can be an important therapeutic option for patients with secondary diabetes mellitus even when a minor pancreatic endocrine function remains. For these patients, results may be better than those obtained with islet infusion for patients with type 1 diabetes mellitus thanks to the lack of autoimmune reaction to the infused islets. The final result is the improvement of the glycemic compensation and most likely also an extension of the graft survival.

Missense mutations in the TGM2 gene encoding transglutaminase 2 are found in patients with early-onset type 2 diabetes. Mutation in brief no. 982. Online

Transglutaminase 2 (TG2 or TGM2) is a multi-functional enzyme which catalyzes transamidation reactions or acts as a G-protein in intracellular signalling. Tgm2-/- Mice lacking TG2 activity are glucose intolerant and show impairment of insulin secretion, suggesting an important physiological role for TG2 in the pancreatic beta cell. We have previously described a TGM2 heterozygous missense mutation ((c.998A>G, p.N333S) in a 14 year-old patient with insulin-treated diabetes and in his diabetic father. The aim of this study was to further investigate the role of TG2 in early-onset type 2 diabetes. We analysed the TGM2 gene in 205 patients with clinically defined Maturity Onset Diabetes of the Young (MODY) or early-onset type 2 diabetes. We found two novel heterozygous mutations (c.989T>G, p.M330R; c.992T>A, p.I331N), which were not detected in 300 normoglycemic controls. All mutations were in residues which are located close to the catalytic site and impaired transamidating activity in vitro. Gene expression of TGM family genes and localization of TG2 in normal human pancreas indicated that TG2 is the only transglutaminase significantly expressed in human pancreatic islet cells. We conclude that reduced TG2 activity can contribute to disorders of glucose metabolism possibly via an impairment of insulin secretion.

Brittle Type 1 Diabetes Mellitus

A small group of patients affected by type 1 diabetes mellitus is characterized by a severe instability of glycemic values with frequent and unpredictable hypoglycemic and/or ketoacidosis episodes which cannot be explained by errors of patients or diabetologists. The quality of life of these patients is dramatically compromised in particular because of the frequency of acute events, hospital recoveries and precocious appearance of chronic complications. This clinical condition has been defined as "brittle diabetes". A precise quantification of these patients is difficult because diagnostic criteria are still not well defined and it is often difficult to verify errors of patients in terms of inappropriate conduct with the pathology. Even more than the other kinds of diabetes, therapy is based on education, glycemic control, intensive therapy and strict interaction between physicians and patients. The introduction of insulin analogous, with either ultra-fast and ultra-slow action and the use of subcutaneous insulin pumps have significantly increased the possibility of treating the most of these cases. However, there is a minority of patients resistant to the therapy. In similar cases, pancreas or islet transplantation represents an effective therapeutic option entailing good expected outcomes. The main limiting factor of beta cell function replacement by transplantation is so far represented by the potentially severe side effects of the immunosuppression therapy necessary to avoid graft rejection and recurrence of autoimmunity.

Kidney function after islet transplant alone in type 1 diabetes: impact of immunosuppressive therapy on progression of diabetic nephropathy

OBJECTIVE

Islet transplantation alone is an alternative for the replacement of pancreatic endocrine function in patients with type 1 diabetes. The aim of our study was to assess the impact of the Edmonton immunosuppressive protocol (tacrolimus-sirolimus association) on kidney function.

RESEARCH DESIGN AND METHODS

Nineteen patients with type 1 diabetes and metabolic instability received islet transplantation alone and immunosuppressive therapy according to the Edmonton protocol. Serum creatinine (sCr), creatinine clearance (CrCl), and 24-h urinary protein excretion (UPE) were assessed at baseline and during a follow-up of 339 patient-months.

RESULTS

After islet transplantation we observed 1) sCr within the normal range in all but two patients in whom sCr increased immediately after islet transplantation, and despite withdrawal of immunosuppression, patients progressed to end-stage renal disease (ESRD); 2) CrCl remained within the normal range for those patients who had normal baseline values and decreased, progressing to ESRD in two patients with a decreased baseline CrCl; and 3) 24-h UPE worsened (>300 mg/24 h) in four patients. In the two patients who progressed to ESRD, the worsening of 24-h UPE occurred immediately after islet transplantation. In one patient 24-h UPE worsening occurred at 18 months, and, after withdrawal of immunosuppression, it returned to the normal range. In another patient 24-h UPE increased at 24 months and remained stable while immunosuppression was continued.

CONCLUSIONS

In type 1 diabetic patients receiving islet transplantation alone, the association of tacrolimus and sirolimus should be used only in patients with normal kidney function. Alternative options for immunosuppressive treatment should be considered for patients with even a mild decrease of kidney function.

Acylated and unacylated ghrelin promote proliferation and inhibit apoptosis of pancreatic beta-cells and human islets: involvement of 3',5'-cyclic adenosine monophosphate/protein kinase A, extracellular signal-regulated kinase 1/2, and phosphatidyl inositol 3-Kinase/Akt signaling

Among its pleiotropic actions, ghrelin modulates insulin secretion and glucose metabolism. Herein we investigated the role of ghrelin in pancreatic beta-cell proliferation and apoptosis induced by serum starvation or interferon (IFN)-gamma/TNF-alpha, whose synergism is a major cause for beta-cell destruction in type I diabetes. HIT-T15 beta-cells expressed ghrelin but not ghrelin receptor (GRLN-R), which binds acylated ghrelin (AG) only. However, both unacylated ghrelin (UAG) and AG recognized common high-affinity binding sites on these cells. Either AG or UAG stimulated cell proliferation through Galpha(s) protein and prevented serum starvation- and IFN-gamma/TNF-alpha-induced apoptosis. Antighrelin antibody enhanced apoptosis in either the presence or absence of serum but not cytokines. AG and UAG even up-regulated intracellular cAMP. Blockade of adenylyl cyclase/cAMP/protein kinase A signaling prevented the ghrelin cytoprotective effect. AG and UAG also activated phosphatidyl inositol 3-kinase (PI3K)/Akt and ERK1/2, whereas PI3K and MAPK inhibitors counteracted the ghrelin antiapoptotic effect. Furthermore, AG and UAG stimulated insulin secretion from HIT-T15 cells. In INS-1E beta-cells, which express GRLN-R, AG and UAG caused proliferation and protection against apoptosis through identical signaling pathways. Noteworthy, both peptides inhibited cytokine-induced NO increase in either HIT-T15 or INS-1E cells. Finally, they induced cell survival and protection against apoptosis in human islets of Langerhans. These expressed GRLN-R but showed also UAG and AG binding sites. Our data demonstrate that AG and UAG promote survival of both beta-cells and human islets. These effects are independent of GRLN-R, are likely mediated by AG/UAG binding sites, and involve cAMP/PKA, ERK1/2, and PI3K/Akt.

Culture medium modulates proinflammatory conditions of human pancreatic islets before transplantation

A portion of transplanted islets is lost during engraftment as a result of stressful events, involving hypoxia and production of proinflammatory molecules by islets. Two of these molecules (monocyte chemoattractant protein-1, CCL2/MCP-1 and tissue factor, TF) are directly correlated with reduced graft function. We evaluated which factors reduce islet proinflammatory conditions. In particular the effects of different culture media supplemented with proteins or antioxidant agents on CCL2/MCP-1 and TF human islet release were evaluated. We observed that human islets after culture in final wash culture medium (FW) significantly decreased CCL2/MCP-1 release and TF production compared with CMRL and M199. These effects were independent from the type of protein added to the media (human serum, human albumin, fetal calf serum). Glutathione in FW further decreased CCL2/MCP-1 in a dose-dependent manner. Culture conditions can modulate the proinflammatory state of islets, and could be used in clinical islet transplantation to reduce inflammation during engraftment.

International trial of the Edmonton protocol for islet transplantation

BACKGROUND

Islet transplantation offers the potential to improve glycemic control in a subgroup of patients with type 1 diabetes mellitus who are disabled by refractory hypoglycemia. We conducted an international, multicenter trial to explore the feasibility and reproducibility of islet transplantation with the use of a single common protocol (the Edmonton protocol).

METHODS

We enrolled 36 subjects with type 1 diabetes mellitus, who underwent islet transplantation at nine international sites. Islets were prepared from pancreases of deceased donors and were transplanted within 2 hours after purification, without culture. The primary end point was defined as insulin independence with adequate glycemic control 1 year after the final transplantation.

RESULTS

Of the 36 subjects, 16 (44%) met the primary end point, 10 (28%) had partial function, and 10 (28%) had complete graft loss 1 year after the final transplantation. A total of 21 subjects (58%) attained insulin independence with good glycemic control at any point throughout the trial. Of these subjects, 16 (76%) required insulin again at 2 years; 5 of the 16 subjects who reached the primary end point (31%) remained insulin-independent at 2 years.

CONCLUSIONS

Islet transplantation with the use of the Edmonton protocol can successfully restore long-term endogenous insulin production and glycemic stability in subjects with type 1 diabetes mellitus and unstable control, but insulin independence is usually not sustainable. Persistent islet function even without insulin independence provides both protection from severe hypoglycemia and improved levels of glycated hemoglobin. (ClinicalTrials.gov number, NCT00014911 [ClinicalTrials.gov].).

Rapamycin induces a caspase-independent cell death in human monocytes

The immunosuppressive activity of rapamycin (RAPA) and its efficacy as an anti-rejection agent in organ transplantation have been ascribed principally to its anti-proliferative effects on T cells, while the activity on monocytes is partially unknown. In vitro, RAPA reduced monocyte survival by inducing a caspase-independent cell death. RAPA-induced monocyte cell death (RAPA-CD) was impeded by activation of granulocyte macrophage-colony stimulating factor family receptors or toll-like receptor 4, and by exposure to inflammatory cytokines. In vivo, in patients who received RAPA monotherapy as part of pre-conditioning for islet transplantation, RAPA affected survival of myeloid lineage cells. In the peripheral blood, CD33(+) and CD14(+) cells decreased, whereas lymphocytes appeared unaffected. In the bone marrow, myeloid precursors such as CD15(+) and CD15(+)/CD16(+) were selectively and significantly decreased, but no major cytotoxic effects were observed. The RAPA-CD suggests a dependence of monocytes on mammalian target of RAPA pathways for nutrient usage, and this feature implies that RAPA could be selectively useful as a treatment to reduce monocytes or myeloid cells in conditions where these cells negatively affect patient, suggesting a potential anti-inflammatory action of this drug.

Islet Cell Transplantation

Islet cell transplantation is an attractive alternative therapy to conventional insulin treatment or vascularized whole pancreas transplantation for type 1 diabetic patients. It represents a successful example of somatic cell therapy in humans based on complex procedures for islet isolation from whole pancreas. The islets, that are only 1% of the total pancreas tissue, are isolated by two steps method starting with collagenase digestion that operates a rapid dissociation of the stromal component of the gland, while preserving islet anatomical integrity. After digestion, islets are then separated from exocrine tissue by centrifugation in density gradients. Transplantation consists of a simple injection of few milliliter-purified tissue in the portal vein through a percutaneous trans-hepatic approach performed in local anesthesia. Several studies have now demonstrated that islet transplant can replace pancreatic endocrine function without major side effects and with liver viability preservation in selected patients affected by long-term type 1 diabetes. It can restore endogenous insulin secretion, achieve insulin independence in more than 80% of patients, and recover the metabolism of glucose, protein and lipids. Improved control of glycated HbA1c, reduced risk of recurrent hypoglycemia and of diabetic complications are also seen as important benefits of islet cell transplantation, irrespective of the status of insulin independence. Many protocols are now on going for reduction of immunosuppression therapy in recipients, induction of tolerance, and prolongation of graft function.

Minimal focal steatosis of liver after islet transplantation in humans: a long-term study

Several reports have been published on islet transplantation in humans, but few data are available on the effect of islet infusion on the hepatic structure. Our aim was to evaluate in a longitudinal study the impact on the liver of intrahepatic islet transplantation. Clinical outcome and liver imaging were evaluated in 31 cases of islet-kidney transplantation (follow-up 38 +/- 4 months, range 12-96 months). Patients were divided into three groups: full function (FF, 9 cases: established insulin independence); partial function (PF, 16 cases: transient insulin independence, prolonged C-peptide secretion): no function (NF, 6 cases: exhaustion of C-peptide secretion within the first year). Upper abdomen sonogram was regularly performed during the whole follow-up period. Percutaneous liver biopsy was performed in case of echographic abnormalities. Multiple small areas of focal hyperechogenicity were observed in nine cases after 6-12 months. These findings were observed only in FF (two) and in PF (seven) patients. Fasting C-peptide levels at the time of echography were higher in negative than in positive patients (2.42 +/- 0.16 vs. 1.51 +/- 0.10 ng/ml, p = 0,0001). Liver biopsies showed focal macrovesicular steatosis, surrounded by normal liver parenchyma. Normal liver function was maintained. In conclusion, our results indicate that islet transplantation can lead to structural changes of the liver parenchyma (focal steatosis). It is more often observed in patients with partial function. Sonogram can be considered a specific method to reveal liver changes after islet transplantation.

Requirements for success in clinical islet transplantation

A few groups have endured the challenges of time, anecdotal success stories, logistic and funding impediments, to bring the field of clinical islet transplantation where it stands today. The recent improvement in clinical results has paralleled a renewed interest in islet transplantation and an increasing number of centers have entered the field. Selected institutions have now clearly demonstrated that insulin independence can be a reproducible and achievable goal. Other centers struggle with mixed results, while occasional early failures of islet transplants are still observed. This center effect underlines not just a learning curve, but also the complexity of the approach, which requires multidisciplinary expertise and attention to critical variables that need to be closely monitored to assure adequate clinical outcomes. The future success and large scale applicability of islet transplantation will rely on the synergistic research progress in critical areas that contribute to the sequential and integrated approach required for success in clinical islet transplantation.

Islet isolation for allotransplantation: variables associated with successful islet yield and graft function

AIMS/HYPOTHESIS

Efficient islet isolation is an important prerequisite for successful clinical islet transplantation. Although progressively improved, islet yield and quality are, however, unpredictable and variable and require standardisation.

METHODS

Since 1989 we have processed 437 pancreases using the automated method. The donor characteristics, pancreas procurement, and digestion and purification procedures including a wide enzyme characterisation of these pancreases were analysed and correlated with islet yield and transplant outcome.

RESULTS

By univariate analysis, islet yield was significantly associated with donor age (r=0.16; p=0.0009), BMI (r=0.19; p=0.0004), good pancreas condition (p=0.0031) and weight (r=0.15; p=0.0056), total collagenase activity (r=0.22; p=0.0001), adjusted collagenase activity/mg (r=0.18; p=0.0002), collagenase activity/solution volume (r=0.18; p=0.0002) and neutral protease activity/solution volume (r=0.14; p=0.0029). A statistically significant contribution to the variability of islet yield in a multivariate analysis performed on donor variables was found for donor BMI (p=0.0008). In a multivariate analysis performed on pancreas variables a contribution was found for pancreas weight (p=0.0064), and for a multivariate analysis performed on digestion variables we found a contribution for digestion time (p=0.0048) and total collagenase activity (p=0.0001). Twenty-four patients with type 1 diabetes received single islet preparations from single donors. In these patients, multivariate analyses showed that the reduction in insulin requirement was significantly associated with morphological aspects of islets (p=0.0010) and that 1-month C-peptide values were associated with islet purity (p=0.0071).

CONCLUSIONS/INTERPRETATION

These data provide baseline donor, digestion and purification selection criteria for islet isolation using the automated method and indicate that the morphological aspect may be a clinically relevant measure of islets on which the decision for transplant can be based.

Bone marrow mesenchymal stem cells express a restricted set of functionally active chemokine receptors capable of promoting migration to pancreatic islets

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are stromal cells with the ability to proliferate and differentiate into many tissues. Although they represent powerful tools for several therapeutic settings, mechanisms regulating their migration to peripheral tissues are still unknown. Here, we report chemokine receptor expression on human BM-MSCs and their role in mediating migration to tissues. A minority of BM-MSCs (2% to 25%) expressed a restricted set of chemokine receptors (CXC receptor 4 [CXCR4], CX3C receptor 1 [CX3CR1], CXCR6, CC chemokine receptor 1 [CCR1], CCR7) and, accordingly, showed appreciable chemotactic migration in response to the chemokines CXC ligand 12 (CXCL12), CX3CL1, CXCL16, CC chemokine ligand 3 (CCL3), and CCL19. Using human pancreatic islets as an in vitro model of peripheral tissue, we showed that islet supernatants released factors able to attract BM-MSCs in vitro, and this attraction was principally mediated by CX3CL1 and CXCL12. Moreover, cells with features of BM-MSCs were detected within the pancreatic islets of mice injected with green fluorescent protein (GFP)-positive BM. A population of bona fide MSCs that also expressed CXCR4, CXCR6, CCR1, and CCR7 could be isolated from normal adult human pancreas. This study defines the chemokine receptor repertoire of human BM-MSCs that determines their migratory activity. Modulation of homing capacity may be instrumental for harnessing the therapeutic potential of BM-MSCs.

Uric acid may inhibit glucose-induced insulin secretion via binding to an essential arginine residue in rat pancreatic β-cells

Uric acid (1a) suppresses basal insulin release in isolated rat pancreatic islets and inhibition of glucose-stimulated insulin secretion (GSIS) occurs right at hyperuricaemic levels (0.4 mM). Conversely, 1 mM guanidinium urate (2a) was completely ineffective, strongly suggesting that binding to an essential arginine residue triggers the inhibitory effect. A specific recognition of 1a molecule at the crucial beta-cell receptor is probably involved in the blocking glucose signal transduction.

Technique, complications, and therapeutic efficacy of percutaneous transplantation of human pancreatic islet cells in type 1 diabetes: the role of US

PURPOSE

To retrospectively evaluate the role of ultrasonography (US) with regard to the technique, complications, and therapeutic efficacy of percutaneous intrahepatic transplantation of human pancreatic islet cells with combined US and fluoroscopic guidance.

MATERIALS AND METHODS

The institutional review board approved the study, and informed consent was obtained from all patients. After kidney transplantation, 34 uremic diabetic patients (20 men, 14 women; mean age, 40.9 years; age range, 29-61 years) underwent percutaneous intrahepatic transplantation of islet cells. Portal vein patency and liver echotexture were preliminarily assessed with color Doppler US. US also was used to identify early complications and presence (group A patients) or absence (group B patients) of hepatic parenchymal changes. Differences between the two groups in C peptide serum level and range were analyzed (Mann-Whitney test). Therapeutic efficacy of transplantation was assessed with regard to insulin independence period (rate and duration), exogenous insulin requirement, glycated hemoglobin, and C peptide level. A C peptide level of more than 0.5 ng/mL was considered to indicate well-functioning islet cells.

RESULTS

Fifty-eight procedures were technically successful, with a single puncture used in 51 of 58 patients. Complications occurred in three of 58 patients (hemoperitoneum, hemothorax, and thrombosis in one patient each) and were conservatively treated and resolved. Duration of insulin independence in 12 patients was more than 3 months (mean, 21 months). Well-functioning islet cells at 6 years were found in 19 of 34 patients. Hyperechoic parenchymal changes were evident at US in 12 of 34. No statistically significant difference in C peptide level was found between groups (P > .05), but a wider range of values was recorded in group B.

CONCLUSION

Complication rate of transplantation with US and fluoroscopic guidance was low. Well-functioning islet cells were found in about 50% of patients at 6 years of follow-up. Hepatic implantation of islet cells was evident on US images in more than one-third of patients.

Donor and Isolation Variables Associated with Human Islet Monocyte Chemoattractant Protein-1 Release

Human islets have chemotactic activity toward macrophages mediated by the secretion of monocyte chemoattractant protein-1 (CCL2/MCP-1) that negatively affect clinical outcome in islet after kidney recipients. The aim of the present work was to identify the donor features and the variables involved in the procedures of islet isolation associated with islet CCL2/MCP-1 release in vitro. We used a retrospective approach studying the outcome in 170 islet isolations. The univariate analysis demonstrated that CCL2/MCP-1 release was significantly associated with the surgical team in charge for organ harvesting, the proteins for dilution solution, the type of gradient, the type of enzyme, and the donor noradrenalin treatment. The multivariate analysis confirmed that the surgical team (P = 0.001) and the enzyme (P = 0.001) were independently associated with in vitro CCL2/MCP-1 islet release (r(2) = 17%). Strategies aimed to optimize the procedures of organ harvesting and islet isolation may reduce the pro-inflammatory properties of the preparation and therefore may improve islet engraftment.

In vitro modulation of monocyte chemoattractant protein-1 release in human pancreatic islets

Islet transplantation is a new approach to treat type 1 diabetic patients. Despite its great potential and progressively increasing success rate, islet engraftment still represents an unsolved problem. Only part of the transplanted beta-cell mass survives after infusion due to hypoxia and inflammatory reactions, principally mediated by macrophages. We have demonstrated that human islets release monocyte chemoattractant protein-1 (MCP-1), one of the most powerful macrophage chemokines, which may impair the fate of a transplant. In this study we have attempted to modulate in vitro MCP-1 release by human islets. Human islets isolated using the automated method were cultured in CMRL or M199 standard culture media alone or supplemented with (1) two intracellular kinase inhibitors (10 micromol/L RO8220, a protein kinase C inhibitor, and rcAMP 20 micromol/L, a protein kinase A inhibitor) or (2) two antioxidant and cell-protective agents (vitamin E, vitamin B); or (3) immunosuppressive drugs (0.001 to 10 ng/mL cyclosporine, 0.1 to 100 ng/mL rapamycin, 0.1 to 10 ng/mL tacrolimus, 0.001 to 10 ng/mL mycophenolate acid). We observed that the only culture condition that significantly decreased MCP-1 in human islets were CMRL (31 +/- 12 in CMRL vs 539 +/- 184 pg/mL, in M199, P <.05) or cyclosporine (514 +/- 83 pg/mL in control islet vs 307 +/- 13, 231 +/- 44, 192 +/- 4, 242 +/- 113, 169 +/- 15 pg/mL in islet plus cyclosporine ranging from 0.001 to 10 ng/mL, respectively, P >.05). The capacity of in vitro factors to decrease human islet MCP-1 release suggests strategies to increase the success of islet transplantation.

Islet transplantation in type 1 diabetic patients

Islet transplantation has been shown to improve overall glucose homeostasis and retard the progression of complications in type I diabetic patients. Also the percentage of recipients achieving complete insulin independence has progressively increased over recent years. An unsolved problem is whether the short-term graft function is secondary to progressive islet exhaustion or to recurrent autoimmunity despite the immunosuppressive therapy. The indications for this procedure remain limited to selected type I diabetic patients. The risks of the immunosuppressive therapy are only proposed to type I diabetic recipients with uncontrolled disease, despite all efforts of the diabetologist and the patient (brittle diabetes), or with a poor quality of life due to unawareness hypoglycemia or severe chronic and progressive complications.