BACKGROUNDImproving islet graft revascularization has become a crucial task for prolonging islet graft survival. Endothelial cells (ECs) are the basis of new microvessels in an isolated islet, and EC coating has been demonstrated to improve the vascularization and survival of an islet. However, the traditional method of EC coating of islets has low efficiency in vitro. This study was conducted to evaluate the effect of a polyglycolic acid (PGA) scaffold on the efficiency of islet coating by ECs and the angiogenesis in the coated islet graft.

METHODSA PGA fibrous scaffold was used for EC coating of islet culture and was evaluated for its efficiency of EC coating on islets and islet graft angiogenesis.

RESULTSIn in vitro experiments, we found that apoptosis index of ECs-coating islet in PGA group (27% ± 8%) was significantly lower than that in control group (83% ± 20%, P < 0.05) after 7 days culture. Stimulation index was significantly greater in the PGA group than in the control group at day 7 after ECs-coating (2.07 ± 0.31 vs. 1.80 ± 0.23, P < 0.05). vascular endothelial growth factor (VEGF) level in the PGA group was significantly higher than the coating in the control group after 7 days culture (52.10 ± 13.50 ng/ml vs. 16.30 ± 8.10 ng/ml, P < 0.05). Because of a tight, circumvallated, adhesive and three-dimensional growth microenvironment, islet cultured in a PGA scaffold had higher coating efficiency showing stronger staining intensity of enzyme than those in the control group after 14 days of culture following ECs-coating. For in vivo study, PGA scaffold significantly prolonged the average survival time of EC-coated islet graft after transplantation compared with control group (15.30 ± 5.60 days vs. 8.30 ± 2.45 days, P < 0.05). The angiogenesis and area of survived grafts were more in the PGA group compared with the control group by measuring the mean microvessel density (8.60 ± 1.21/mm2 vs. 5.20 ± 0.87/mm2, P < 0.05). In addition, expression of VEGF and tyrosin-protein kinase receptor (Tie-2) gene increased in PGA scaffold group than that in control group by real-time reverse transcription-polymerase chain reaction analysis.

CONCLUSIONSThese results demonstrate that the efficiency of EC coating of islets was successfully increased by culturing ECs on a PGA scaffold. This method enhances the function, survival, and vascularization of isolated islets in vitro and in vivo.

Animals ; Apoptosis ; drug effects ; Endothelial Cells ; drug effects ; Enzyme-Linked Immunosorbent Assay ; Graft Survival ; drug effects ; Insulin ; metabolism ; Islets of Langerhans ; drug effects ; Islets of Langerhans Transplantation ; methods ; Neovascularization, Physiologic ; drug effects ; Polyglycolic Acid ; chemistry ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Rats, Wistar ; Tissue Scaffolds ; chemistry

Pancreatic islet transplantation is a physiologically advantageous and minimally invasive procedure for the treatment of type 1 diabetes mellitus. Here, we describe the first reported case of successful allogeneic islet transplantation alone, using single-donor, marginal-dose islets in a Korean patient. A 59-yr-old patient with type 1 diabetes mellitus, who suffered from recurrent severe hypoglycemia, received 4,163 islet equivalents/kg from a single brain-death donor. Isolated islets were infused intraportally without any complications. The immunosuppressive regimen was based on the Edmonton protocol, but the maintenance dosage was reduced because of mucositis and leukopenia. Although insulin independence was not achieved, the patient showed stabilized blood glucose concentration, reduced insulin dosage and reversal of hypoglycemic unawareness, even with marginal dose of islets and reduced immunosuppressant. Islet transplantation may successfully improve endogenous insulin production and glycemic stability in subjects with type 1 diabetes mellitus.
Blood Glucose/analysis ; Diabetes Mellitus, Type 1/*surgery ; Female ; Humans ; Hypoglycemia/*surgery ; Immunosuppression/methods ; Immunosuppressive Agents/therapeutic use ; Islets of Langerhans/physiology/*surgery ; Islets of Langerhans Transplantation/*methods ; Middle Aged ; Republic of Korea ; Tissue Donors

OBJECTIVETo review the current status and progress on pig islet xenotransplantation.

DATA SOURCESData used in this review were mainly from English literature of Pubmed database. The search terms were "pig islet" and "xenotransplantation".

STUDY SELECTIONThe original articles and critical reviews selected were relevant to this review's theme.

RESULTSPigs are suggested to be an ideal candidate for obtaining available islet cells for transplantation. However, the potential clinical application of pig islet is still facing challenges including inadequate yield of high-quality functional islets and xenorejection of the transplants. The former can be overcome mainly by selection of a suitable pathogen-free source herd and the development of isolation and purification technology. While the feasibility of successful preclinical pig islet xenotranplantation provides insights in the possible mechanisms of xenogeneic immune recognition and rejection to overwhelm the latter. In addition, the achievement of long-term insulin independence in diabetic models by means of distinct islet products and novel immunotherapeutic strategies is promising.

CONCLUSIONSPig islet xenotransplantation is one of the prospective treatments to bridge the gap between the needs of transplantation in patients with diabetes and available islet cells. Nonetheless, further studies and efforts are needed to translate obtained findings into tangible applications.

Animals ; Graft Rejection ; immunology ; prevention & control ; Islets of Langerhans Transplantation ; immunology ; methods ; Swine ; Transplantation, Heterologous ; methods

Non-human primate studies must be conducted prior to the clinical trial of xenotransplantation. In order to develop clinically applicable immune-modulatory regimen through non-human primate studies, close monitoring of xenogeneic immune responses is required. We adopted multiplex cytokine analysis in assessment of the immune status during the course of pig-to-non-human primate islet transplantation. This study aimed to assess the feasibility of this multiplex cytokine assay in the development of immune-modulatory regimen. Using this assay, we were able to detect different cytokines with a minimal usage of blood samples, and this allowed us to detect various immunological situations in the recipients. Detection of TNF-alpha surge (347.8 pg/mL) guided us to block TNF-alpha in the early phase of transplantation. Supportive information for in vivo efficacy of cytokine neutralizing antibody could be speculated by in vitro neutralization assay (1,250 pg/mL --> 0 pg/mL). In addition, periodic monitoring of cytokines in peripheral blood allowed the detection of the infection episode prior to other routine assays. These benefits of multiplex cytokine assay may be generally applied to other pre-clinical research, which is a prerequisite for clinical trials.
Animals ; Antibodies, Neutralizing/immunology ; Blood Cell Count ; Cytokines/*blood/immunology ; Immunoassay/*methods ; Interleukin-6/blood ; Islets of Langerhans Transplantation/*immunology ; Macaca mulatta ; Swine ; Transplantation, Heterologous ; Tumor Necrosis Factor-alpha/blood/immunology

Transplantation of islet cells into diabetic patients is a promising therapy, provided that the islet cells are able to evade host immune rejection. With improved islet viability, this strategy may effectively reverse diabetes. We applied 2% calcium alginate to generate small and large capsules to encapsulate porcine neonatal pancreatic cell clusters (NPCCs) using an air-driven encapsulator. After encapsulation, the viability was assessed at 1, 4, 7, 14 and 28 days and secretion of functional insulin in response to glucose stimulation were tested at days 14 and 28. Selective permeability of the small alginate capsules was confirmed using various sizes of isothiocyanate-labeled dextran (FITC-dextran). Encapsulation of NPCCs was performed without islet protrusion in the small and large capsules. The viability of NPCCs in all experimental groups was greater than 90% at day 1 and then gradually decreased after day 7. The NPCCs encapsulated in large capsules showed significantly lower viability (79.50 +/- 2.88%) than that of naive NPCCs and NPCCs in small capsule (86.83 +/- 2.32%, 87.67 +/- 2.07%, respectively) at day 7. The viability of naive NPCCs decreased rapidly at day 14 (75.67 +/- 1.75%), whereas the NPCCs encapsulated in small capsules maintained (82.0 +/- 2.19%). After 14 and 28 days NPCCs' function in small capsules (2.67 +/- 0.09 and 2.13 +/- 0.09) was conserved better compared to that of naive NPCCs (2.04 +/- 0.25 and 1.53 +/- 0.32, respectively) and NPCCs in large capsules (2.04 +/- 0.34 and 1.13 +/- 0.10, respectively), as assessed by a stimulation index. The small capsules also demonstrated selective permeability. With this encapsulation technique, small capsules improved the viability and insulin secretion of NPCCs without islet protrusion.
Alginates/chemistry/metabolism ; Animals ; Animals, Newborn ; Capsules/chemistry ; Cell Survival ; Diabetes Mellitus/pathology/*therapy ; Disease Models, Animal ; Glucuronic Acid/chemistry/metabolism ; Graft Rejection/etiology/*prevention & control ; Hexuronic Acids/chemistry/metabolism ; Humans ; Insulin/secretion ; Islets of Langerhans/*metabolism/pathology ; Islets of Langerhans Transplantation/*methods ; Postoperative Complications/etiology/*prevention & control ; *Swine

Up till 2000 when Edmonton group introduced islet transplant procedure in conjunction with a novel glucocorticoid-free immunosuppressive regimen rendering 100% (n=7) of patients with type 1 diabetes insulin-independent for at least 1 year, islet transplant was taken into the clinic. Although significant progress in clinical islet transplant has occurred during recent years, challenges remain, including shortage of available donor organs, technical aspects of islet preparation and transplantation, immunological rejection post-transplant, unclear long-term outcomes of islet transplantation. Special attention is given to current limitation in islet transplantation together with new possible strategies that raise expectations for the widespread use of islet transplantation in the future.
Diabetes Mellitus ; surgery ; Humans ; Immunosuppressive Agents ; therapeutic use ; Islets of Langerhans Transplantation ; immunology ; methods ; trends

BACKGROUNDCostimulatory signals play a vital role in T cell activation. Blockade of costimulatory pathway by CTLA4Ig or CD40LIg have enhanced graft survival in experimental transplantation models yet mechanisms remain undetermined. We investigated the effects of CTLA4Ig and CD40LIg gene transfer on islet xenografts rejection in rats.

METHODSHuman islets were infected with recombinant adenoviruses containing CTLA4Ig and CD40LIg genes and implanted beneath the kidney capsule of diabetic rats. Levels of blood sugar, morphological changes, and survival of grafts were recorded. Expressions of CTLA4Ig, CD40LIg and insulin were detected by immunohistochemical staining and cytokines levels were quantified by enzyme-linked immunosorbent assay (ELISA).

RESULTSBlood glucose levels in transplant rats decreased to normal level on the 2nd day post transplantation. The mean blood glucose in the control group, CTLA4Ig transfected group, CD40LIg transfected group and CTLA4Ig + CD40LIg cotransfected group increased on days 8, 24, 21, 68, post transplantation respectively. The grafts in control group, CTLA4Ig transfected group, CD40LIg transfected group and CTLA4Ig + CD40LIg cotransfected group survived for (8 ± 1), (29 ± 4), (27 ± 3), and (74 ± 10) days, respectively. Survival in CTLA4Ig + CD40LIg cotransfected group was significantly longer. Survivals of CTLA4Ig transfected group and CD40LIg transfected group were significantly longer than control group. In control animals, serum interleukin-2 and tumor necrosis factor α concentration significantly increased within seven days post transplantation. Haematoxylin eosin staining of grafts showed live islets in situ of transplant rats without inflammatory cell infiltration. Immunohistochemical staining confirmed the expression of insulin at islets in all experimental groups.

CONCLUSIONSTransfer of CTLA4Ig and CD40LIg genes, especially the cotransfer of both, inhibits rejection of murine islet xenografts. Downregulated expressions of Th1 cells related cytokines might be related to the beneficial effects.

Abatacept ; Animals ; Enzyme-Linked Immunosorbent Assay ; Graft Rejection ; therapy ; Graft Survival ; genetics ; physiology ; Humans ; Immunoconjugates ; genetics ; metabolism ; Immunohistochemistry ; Insulin ; metabolism ; Islets of Langerhans Transplantation ; immunology ; methods ; Rats ; Recombinant Fusion Proteins ; genetics ; metabolism ; Transplantation, Heterologous ; immunology ; methods

OBJECTIVE: To evaluate transplanted porcine pancreatic islets in the kidney capsules of diabetic mice using a clinically approved superparamagnetic iron oxide (SPIO) and a 1.5T MR scanner. MATERIALS AND METHODS: Various numbers of porcine pancreatic islets labeled with Resovist, a carboxydextran-coated SPIO, were transplanted into the kidney capsules of normal mice and imaged with a 3D FIESTA sequence using a 1.5T clinical MR scanner. Labeled (n = 3) and unlabeled (n = 2) islets were transplanted into the kidney capsules of streptozotocin-induced diabetic mice. Blood glucose levels and MR signal intensities were monitored for 30 days post-transplantation. RESULTS: There were no significant differences in viability or insulin secretion between labeled and unlabeled islets. A strong correlation (r2 > 0.94) was evident between the number of transplanted islets and T2 relaxation times quantified by MRI. Transplantation with labeled or unlabeled islets helped restore normal sustained glucose levels in diabetic mice, and nephrectomies induced the recurrence of diabetes. The MR signal intensity of labeled pancreatic islets decreased by 80% over 30 days. CONCLUSION: The transplantation of SPIO-labeled porcine islets into the kidney capsule of diabetic mice allows to restore normal glucose levels, and these islets can be visualized and quantified using a 1.5T clinical MR scanner.
Animals ; Contrast Media/pharmacology ; Dextrans/pharmacology ; Diabetes Mellitus, Experimental/*therapy ; Glucose Tolerance Test ; *Islets of Langerhans Transplantation ; Magnetic Resonance Imaging/*methods ; Magnetite Nanoparticles ; Mice ; Microscopy, Electron ; Statistics, Nonparametric ; Swine

In the conventional treatments of type I diabetes, there are various problems. As a new adequate treatment of diabetes, cell replacement therapy of diabetes has been applied and given research priority. We have investigated the applications of cell transplantation in the treatment of diabetes and have retrieved the relevant articles on cells transplantation for the treatment of diabetes. In this paper, we review the history, development, merits and demerits of cell transplantation and the recent advances in pancreatic islet transplantation research. The latest progress in the induction of stem cell to differentiate into the insulin-producing cells was also introduced.
Animals ; Diabetes Mellitus, Type 1 ; surgery ; therapy ; Humans ; Insulin-Secreting Cells ; cytology ; Islets of Langerhans Transplantation ; methods ; Stem Cell Transplantation

OBJECTIVE: To compare the changes of portal hemodynamics after microcapsule transplantation by intraportal and transarterial approach with color doppler sonography. METHODS: Thirty male dogs were divided into 2 groups randomly: Group PV (microcapsules implanted into the portal vein) and Group HA (microcapsules implanted into the hepatic artery). Both groups were divided into 3 subgroups(PV1, PV2, and PV3; HA1, HA2, and HA3) according to the number of implanted microcapsules (8,000/kg, 16,000/kg, and 32,000/kg). The internal diameter and flow velocity of the portal vein were measured with color doppler sonography before the transplantation,within 24 hours and 1, 2, and 4 weeks after microcapsule transplantation. RESULTS: The flow velocity of the portal vein in Group PV1 and PV2 within 24 hours increased significantly (P<0.05); The meanwhile the internal diameters did not change significantly (P> 0.05). The flow velocity of the portal vein in Group PV3 within 24 hours decreased significantly (P<0.05), but the internal diameter increased significantly (P<0.05). Portal hemodynamics of different transarterial subgroups did not change significantly (P> 0.05). The level of ALT in Group PV and Group HA all increased significantly (P<0.05). And when the numbers of microcapsule transplantation were same, the level of ALT in subgroup PV were significantly higher than that in subgroup HA (P<0.05). CONCLUSION Microcapsule transplantation by transarterial approach is safer than by intraportal way, and the hepatic artery can contain more microcapsule than the portal vein.
Alginates ; Animals ; Capsules ; Dogs ; Glucuronic Acid ; Hemodynamics ; Hepatic Artery ; Hexuronic Acids ; Infusions, Intra-Arterial ; methods ; Infusions, Intravenous ; methods ; Islets of Langerhans Transplantation ; methods ; Male ; Portal Vein ; diagnostic imaging ; physiopathology ; Random Allocation ; Ultrasonography, Doppler, Color