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Crutchlow MF, Yu M, Bae YS, Deng S, Stoffers DA. Exendin-4 does not promote Beta-cell proliferation or survival during the early post-islet transplant period in mice. Transplant Proc 2008; 40:1650-7. [PMID: 18589167 DOI: 10.1016/j.transproceed.2008.03.161] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Accepted: 03/11/2008] [Indexed: 10/21/2022]
Abstract
Current pancreatic islet transplantation protocols achieve remarkable short-term success, but long-term insulin independence remains elusive. Hypoxic and inflammatory insults cause substantial early posttransplant graft loss while allo/autoimmunity and immunosuppressive drug toxicity threaten long-term graft mass and function. Exendin-4 (Ex4) is a GLP-1 receptor agonist that promotes beta-cell proliferation, survival, and differentiation. To determine whether Ex-4 displays potential as a graft-supportive agent, we transplanted 500 murine islets under the kidney capsule of syngeneic or allogeneic streptozocin-treated recipient mice and immediately initiated daily treatment with vehicle or Ex4. Graft beta-cell proliferation, death, and vascularity were assessed at 1, 3, and 10 days after syngeneic islet transplantation. For allogeneic recipients, blood glucose and body weight were assessed until glycemic deterioration. Ex-4 did not promote graft beta-cell proliferation, reduce beta-cell death, or enhance graft vascularity over the first 10 days after syngeneic islet transplantation. A trend toward prolongation of posttransplant euglycemia was observed with Ex4 treatment in nonimmune-suppressed allograft recipients, but its use in this setting was associated with frequent, severe hypoglycemia over the first 2 posttransplant days. Our findings do not support a beneficial effect of Ex-4 on islet grafts during the critical early posttransplant period, further, they demonstrate a significant hypoglycemic potential of Ex-4 in the first days after islet transplantation in mice. Optimal application of GLP-1 receptor agonists for long-term proliferative and survival benefits in transplantation may require earlier intervention prior to and/or during islet isolation for peri-transplant cytoprotection and administration beyond the period of engraftment.
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Affiliation(s)
- M F Crutchlow
- Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania, USA
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Merani S, Truong W, Emamaullee JA, Toso C, Knudsen LB, Shapiro AMJ. Liraglutide, a long-acting human glucagon-like peptide 1 analog, improves glucose homeostasis in marginal mass islet transplantation in mice. Endocrinology 2008; 149:4322-8. [PMID: 18511515 DOI: 10.1210/en.2008-0501] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The current scarcity of high-quality deceased pancreas donors prevents widespread application of islet transplantation for treatment of labile type 1 diabetes mellitus. Opportunities for the improvement of current techniques include optimization of islet isolation and purification, use of culture with pharmacological insulinotropic agents, strategies to reduce graft rejection and inflammation, and the search for alternative insulin producing tissue. Here, we report our findings on the efficacy of the long-acting human glucagon-like peptide 1 analog, liraglutide, in a mouse model of marginal mass islet transplantation. Liraglutide was administered (200 microg/kg sc twice daily) after a marginal mass syngeneic islet transplant in streptozotocin-induced diabetic BALB/c mice. Time-to-normoglycemia was significantly shorter in liraglutide-treated animals (median 1 vs. 7 d; P = 0.0003), even in recipients receiving sirolimus (median 1 vs. 72.5 d; P < 0.0001). Liraglutide-treated animals also demonstrated improved glucose tolerance as assessed by an ip glucose tolerance test. Liraglutide discontinuation at postoperative d 90 resulted in diminished glucose tolerance during the ip glucose tolerance test, whereas a late-start liraglutide therapy 90 d after transplant resulted in no improvement. These findings suggest that liraglutide therapy mediates early and late insulinotropic effects. In accord with this hypothesis, insulin/terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick end labeling fluorescence microscopy showed reduced transplanted beta-cell apoptosis in liraglutide-treated recipients 48 h after transplant. In addition, liraglutide resulted in improved glucose-dependent insulin secretion. Overall, our data show that liraglutide has a beneficial impact on the engraftment and function of syngeneic islet transplants in mice, when administered continuously starting on the day of transplant.
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Affiliation(s)
- S Merani
- Surgical Medical Research Institute, University of Alberta, Edmonton, Alberta, Canada
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Papadimitriou A, King AJF, Jones PM, Persaud SJ. Anti-Apoptotic Effects of Arachidonic Acid and Prostaglandin E 2 in Pancreatic β-Cells. Cell Physiol Biochem 2008; 20:607-16. [PMID: 17762187 DOI: 10.1159/000107544] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2007] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND/AIMS The polyunsaturated fatty acid arachidonic acid (AA) has been implicated in beta-cell defence mechanisms and prostaglandin (PG) products of cyclooxygenase (COX) 2 action confer resistance to alloxan-induced apoptosis in insulin-secreting RIN cells. We have now investigated the anti-apoptotic effects of AA and its metabolite, PGE(2), in the MIN6 mouse insulin-secreting beta-cell line and mouse islets. METHODS Apoptosis was determined in MIN6 beta-cell and mouse islet extracts by measurement of capase-3 activity, and COX2 mRNA levels were quantified by real-time RT-PCR. RESULTS Exposure of MIN6 cells to AA (3.1-12.5 microM) caused concentration-dependent reductions in apoptosis, and similar results were obtained when endogenous AA levels were elevated in cytosolic phospholipase A(2)-overexpressing MIN6 cells. 25mM glucose caused both a significant up-regulation of MIN6 cell COX2 mRNA levels and a decrease in apoptosis. Inhibition of MIN6 cell COX2 activity with a selective inhibitor, NS-398 (10-100 microM), increased apoptosis and exogenous PGE(2) (0.2-5 microM) reduced NS-398-induced apoptosis in a concentration-dependent manner. The protective effects of AA and PGE(2) were also observed in primary mouse islets. CONCLUSION These data show that AA and its COX2-generated metabolite, PGE(2), can protect beta-cells from apoptosis.
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Affiliation(s)
- Alexandros Papadimitriou
- Beta Cell Development and Function Group, School of Biomedical and Health Sciences, King's College London, London, UK
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Toyoda K, Okitsu T, Yamane S, Uonaga T, Liu X, Harada N, Uemoto S, Seino Y, Inagaki N. GLP-1 receptor signaling protects pancreatic beta cells in intraportal islet transplant by inhibiting apoptosis. Biochem Biophys Res Commun 2008; 367:793-8. [PMID: 18211828 DOI: 10.1016/j.bbrc.2008.01.046] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2008] [Accepted: 01/08/2008] [Indexed: 01/09/2023]
Abstract
To clarify the cytoprotective effect of glucagon-like peptide-1 receptor (GLP-1R) signaling in conditions of glucose toxicity in vivo, we performed murine isogenic islet transplantation with and without exendin-4 treatment. When a suboptimal number of islets (150) were transplanted into streptozotocin-induced diabetic mice, exendin-4 treatment contributed to the restoration of normoglycemia. When 50 islets expressing enhanced green fluorescent protein (EGFP) were transplanted, exendin-4 treatment reversed loss of both the number and mass of islet grafts one and 3 days after transplantation. TUNEL staining revealed that exendin-4 treatment reduced the number of apoptotic beta cells during the early posttransplant phase, indicating that GLP-1R signaling exerts its cytoprotective effect on pancreatic beta cells by inhibiting their apoptosis. This beneficial effect might be used both to ameliorate type 2 diabetes and to improve engraftment rates in clinical islet transplantation.
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Affiliation(s)
- Kentaro Toyoda
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin Sakyo-ku, Kyoto 606-8507, Japan
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Noguchi H, Yamada Y, Okitsu T, Iwanaga Y, Nagata H, Kobayashi N, Hayashi S, Matsumoto S. Secretory unit of islet in transplantation (SUIT) and engrafted islet rate (EIR) indexes are useful for evaluating single islet transplantation. Cell Transplant 2008; 17:121-8. [PMID: 18468242 DOI: 10.3727/000000008783906991] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The evaluation of engraftment is important to assess the success of islet transplantation, but it is complex because islet transplantation usually requires two or more donors to achieve euglycemia. Islet transplantation from NHBDs was evaluated using new assessment forms for the secretory unit of islet in transplantation (SUIT) and engrafted islet rate (EIR) indexes. Insulin independence was obtained when the SUIT index was more than 28, which might indicate that 28% of the beta-cell mass of a normal subject is required for insulin independence. Because the average EIR for a single transplantation is about 30, the percentage of engrafted islets following one transplantation is about 30%, assuming that a normal subject has 1 million islet equivalents. Although few cultured islet transplants have been performed, the increase of the SUIT and EIR indexes in patients who received cultured islets was significantly lower than in patients who received fresh islets, suggesting that fresh islets may be more effective than cultured islets. The SUIT and EIR indexes are thus considered to be useful values for evaluating islet transplantation, especially for single islet transplantation.
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Affiliation(s)
- Hirofumi Noguchi
- Transplantation Unit, Kyoto University Hospital, Kyoto 606-8507, Japan.
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Medarova Z, Evgenov NV, Dai G, Bonner-Weir S, Moore A. In vivo multimodal imaging of transplanted pancreatic islets. Nat Protoc 2007; 1:429-35. [PMID: 17406265 DOI: 10.1038/nprot.2006.63] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Interest is increasing in the transplantation of pancreatic islets as a means to achieve insulin independence in individuals with type I diabetes. The success of this approach is hampered by the absence of methods to follow the fate of transplanted islets non-invasively. In vivo imaging seems to be the most appropriate technique to achieve this goal in small animals and eventually in humans. Here we describe a protocol for labeling and subsequent imaging of transplanted islets in vivo using magnetic resonance imaging (MRI) and optical imaging. The whole series of experiments can be carried out in roughly 48 h. We believe that our approach can significantly advance the current ability to determine islet distribution, and possibly survival, after transplantation. This information would be essential not only for the long-term monitoring of graft function but also for the design of improved transplantation and immunomodulatory methods.
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Affiliation(s)
- Zdravka Medarova
- MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, USA
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Bohman S, Waern I, Andersson A, King A. Transient beneficial effects of exendin-4 treatment on the function of microencapsulated mouse pancreatic islets. Cell Transplant 2007; 16:15-22. [PMID: 17436851 DOI: 10.3727/000000007783464452] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Transplantation of microencapsulated islets may reduce hyperglycemia in the absence of immunosuppression. However, the efficiency of microencapsulated islet transplantation is low, requiring more islets to achieve normoglycemia than in vascularized islet transplantation. Exendin-4 (a glucagon-like receptor agonist) has been previously shown to improve islet transplantation outcome in rodents. We investigated whether this treatment would enhance the function of microencapsulated islets in vitro and in vivo. Encapsulated or naked islets were cultured with or without exendin-4 for 72 h. To test in vitro function, insulin release and glucose oxidation rates were measured in the absence or presence of exendin-4. In addition, in vivo function of a minimal mass of 350 microencapsulated islets was assessed by syngeneic transplantation into the peritoneal cavity of alloxan-diabetic mice. Glucose oxidation rates of microencapsulated islets were improved by 72-h pretreatment with exendin-4. Insulin release was increased both acutely after glucose stimulation and over a 40-h culture period by the presence of exendin-4. Transplantation outcome of microencapsulated islets cultured with exendin-4 was initially improved, but by day 7 there were no differences compared with control cultured microencapsulated islets. Culture of microencapsulated islets with exendin-4 increases glucose oxidation and insulin release rates, but the increased function seen in vitro was not enough to improve the long term outcome in a transplantation model.
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Affiliation(s)
- Sara Bohman
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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59
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Islet autotransplantation to prevent or minimize diabetes after pancreatectomy. Curr Opin Organ Transplant 2007; 12:82-88. [DOI: 10.1097/mot.0b013e328012dd9e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Bohman S, Andersson A, King A. No differences in efficacy between noncultured and cultured islets in reducing hyperglycemia in a nonvascularized islet graft model. Diabetes Technol Ther 2006; 8:536-45. [PMID: 17037968 DOI: 10.1089/dia.2006.8.536] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Although islet transplantation is a promising method to restore normoglycemia in recipients with diabetes, large numbers of pancreatic islets are still needed. It has been suggested that the use of freshly isolated islets could improve transplantation outcome through better vascular engraftment. Using a technique of microencapsulation, a model where revascularization is not possible, we investigated the importance of revascularization for transplantation outcome. METHODS Either 700 or 350 3-day-cultured or noncultured encapsulated islets were transplanted intraperitoneally into syngeneic mice with alloxan-induced diabetes. In addition, 700 nonencapsulated islets were transplanted to mice with diabetes. Blood glucose concentrations were monitored, and glucose tolerance tests were carried out. After 42 days, the encapsulated islets were retrieved and assayed for glucose oxidation and insulin release rates. RESULTS There were no differences between capsules containing fresh or cultured islets in their capacity to lower the blood glucose concentration of the recipients or in the in vitro function after capsule retrieval. Interestingly, mice that were intraperitoneally transplanted with 700 encapsulated islets had average blood glucose levels well below 11 mM for most of the study, whereas the same number of nonencapsulated islets had no beneficial effects on the blood glucose homeostasis. CONCLUSIONS Encapsulated islets can reverse hyperglycemia after transplantation to the intraperitoneal site. This effect was not seen when nonencapsulated islets were grafted. Since a 3- day culture period did not influence the outcome of transplantation of encapsulated islets there is evidence to suggest that a more appropriate revascularization may explain why freshly isolated islets are more efficient than cultured islets.
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Affiliation(s)
- Sara Bohman
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
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Shapiro AMJ, Ricordi C, Hering BJ, Auchincloss H, Lindblad R, Robertson RP, Secchi A, Brendel MD, Berney T, Brennan DC, Cagliero E, Alejandro R, Ryan EA, DiMercurio B, Morel P, Polonsky KS, Reems JA, Bretzel RG, Bertuzzi F, Froud T, Kandaswamy R, Sutherland DER, Eisenbarth G, Segal M, Preiksaitis J, Korbutt GS, Barton FB, Viviano L, Seyfert-Margolis V, Bluestone J, Lakey JRT. International trial of the Edmonton protocol for islet transplantation. N Engl J Med 2006; 355:1318-30. [PMID: 17005949 DOI: 10.1056/nejmoa061267] [Citation(s) in RCA: 1378] [Impact Index Per Article: 76.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
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].).
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Affiliation(s)
- A M James Shapiro
- Clinical Islet Transplant Program, University of Alberta, Edmonton, AB, Canada.
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Chen J, Couto FM, Minn AH, Shalev A. Exenatide inhibits beta-cell apoptosis by decreasing thioredoxin-interacting protein. Biochem Biophys Res Commun 2006; 346:1067-74. [PMID: 16782054 DOI: 10.1016/j.bbrc.2006.06.027] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Accepted: 06/04/2006] [Indexed: 10/24/2022]
Abstract
Exenatide (Ex-4) is a novel anti-diabetic drug that stimulates insulin secretion and enhances beta-cell mass, but the mechanisms involved are not fully understood. We found that Ex-4 protects INS-1 beta-cells against oxidative stress-induced apoptosis (TUNEL) and also reduces expression (mRNA and protein) of thioredoxin-interacting protein (TXNIP), a pro-apoptotic factor involved in beta-cell glucose toxicity and oxidative stress. This reduction was observed in INS-1 cells, mouse, and human islets as well as in wild-type mice receiving Ex-4 and was accompanied by decreased expression of the apoptotic factors caspase-3 and Bax. To determine whether Ex-4-mediated TXNIP reduction is critical for this inhibition of apoptosis, we stably overexpressed TXNIP in INS-1 cells, which completely blunted the anti-apoptotic Ex-4 effects. Thus, Ex-4 inhibits apoptosis by reducing TXNIP expression and early initiation of Ex-4 treatment may help preserve endogenous beta-cell mass, protect against oxidative stress, and delay type 2 diabetes progression.
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Affiliation(s)
- Junqin Chen
- Department of Medicine, University of Wisconsin, Madison, WI 53792, USA
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Sharma A, Sörenby A, Wernerson A, Efendic S, Kumagai-Braesch M, Tibell A. Exendin-4 treatment improves metabolic control after rat islet transplantation to athymic mice with streptozotocin-induced diabetes. Diabetologia 2006; 49:1247-53. [PMID: 16609877 DOI: 10.1007/s00125-006-0251-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Accepted: 01/27/2006] [Indexed: 10/24/2022]
Abstract
AIMS/HYPOTHESIS Early islet graft survival is crucial in determining the outcome after clinical islet transplantation. Exendin-4 has anti-apoptotic and beta cell proliferative properties, which could improve islet graft survival and function. The aim of these studies was to evaluate the effect of exendin-4 on graft function after islet transplantation. MATERIALS AND METHODS Rat islets were transplanted under the kidney capsule of diabetic athymic mice. First, we performed a dose-finding study and found that 30 islets just failed to cure diabetic mice. In the following two studies, we transplanted 30 islets and treated the mice that had received these islets with exendin-4 i.p. (100 ng/mouse) once daily for 1 week. Blood glucose levels and body weights were used as evaluation criteria. In the short-term study evaluation was done at day 8. This study was followed by a long-term study that was evaluated at 4 weeks. In this study, islets were precultured with exendin-4 (0.1 nmol/l) in addition to the treatment given to mouse-recipients of transplanted islets. The cured mice underwent an intraperitoneal glucose tolerance test (IPGTT). RESULTS In the short-term study, 63% of exendin-4-treated mice achieved graft function compared with 21% of untreated mice (p = 0.033). In the long-term study, 88% of treated mice had functioning grafts compared with 22% of controls (p = 0.015). Cured mice showed a normal response in the IPGTT, comparable to that of healthy mice. Exendin-4-treated mice gained significantly more weight than their untreated counterparts. CONCLUSIONS/INTERPRETATION Islet preculture and a short course of therapy with exendin-4 improves metabolic control after rat islet transplantation in athymic mice. The beneficial effect lasts beyond the treatment period.
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Affiliation(s)
- A Sharma
- CLINTEC, Division of Transplantation Surgery, Karolinska Institutet, Stockholm, Sweden
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Abstract
Gut peptides, exemplified by glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are secreted in a nutrient-dependent manner and stimulate glucose-dependent insulin secretion. Both GIP and GLP-1 also promote beta cell proliferation and inhibit apoptosis, leading to expansion of beta cell mass. GLP-1, but not GIP, controls glycemia via additional actions on glucose sensors, inhibition of gastric emptying, food intake and glucagon secretion. Furthermore, GLP-1, unlike GIP, potently stimulates insulin secretion and reduces blood glucose in human subjects with type 2 diabetes. This article summarizes current concepts of incretin action and highlights the potential therapeutic utility of GLP-1 receptor agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors for the treatment of type 2 diabetes.
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Affiliation(s)
- Daniel J Drucker
- Department of Medicine, The Banting and Best Diabetes Centre, Toronto General Hospital, University of Toronto, Ontario M5G 2C4, Canada.
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