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- Friberg, Andrew S., et al.
(författare)
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Quantification of the Islet Product : Presentation of a Standardized Current Good Manufacturing Practices Compliant System With Minimal Variability
- 2011
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 91:6, s. 677-683
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Tidskriftsartikel (refereegranskat)abstract
- Background. Accurate islet quantification has proven difficult to standardize in a good manufacturing practices (GMP) approved manner. Methods. The influence of assessment variables from both manual and computer-assisted digital image analysis (DIA) methods were compared using calibrated, standardized microspheres or islets alone. Additionally, a mixture of microspheres and exocrine tissue was used to evaluate the variability of both the current, internationally recognized, manual method and a novel GMP-friendly purity-and volume-based method (PV) evaluated by DIA in a semiclosed, culture bag system. Results. Computer-assisted DIA recorded known microsphere size distribution and quantities accurately. By using DIA to evaluate islets, the interindividual manually evaluated percent coefficients of variation (CV%; n = 14) were reduced by almost half for both islet equivalents (IEs; 31% vs. 17%, P = 0.002) and purity (20% vs. 13%, P = 0.033). The microsphere pool mixed with exocrine tissue did not differ from expected IE with either method. However, manual IE resulted in a total CV% of 44.3% and a range spanning 258 kIE, whereas PV resulted in CV% of 10.7% and range of 60 k IE. Purity CV% for each method were similar approximating 10.5% and differed from expected by +7% for the manual method and +3% for PV. Conclusion. The variability of standard counting methods for islet samples and clinical quantities of microspheres mixed with exocrine tissue were reduced with DIA. They were reduced even further by use of a semiclosed bag system compared with standard manual counting, thereby facilitating the standardization of islet evaluation according to GMP standards.
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- Goto, Masafumi, et al.
(författare)
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Dissecting the instant blood-mediated inflammatory reaction in islet xenotransplantation
- 2008
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Ingår i: Xenotransplantation. - : Wiley. - 0908-665X .- 1399-3089. ; 15:4, s. 225-234
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A massive destruction of transplanted tissue occurs immediately following transplantation of pancreatic islets from pig to non-human primates. The detrimental instant blood-mediated inflammatory reaction (IBMIR), triggered by the porcine islets, is a likely explanation for this tissue loss. This reaction may also be responsible for mediating an adaptive immune response in the recipient that requires a heavy immunosuppressive regimen. MATERIALS AND METHODS: Low molecular weight dextran sulfate (LMW-DS) and the complement inhibitor Compstatin were used in a combination of in vitro and in vivo studies designed to dissect the xenogeneic IBMIR in a non-human primate model of pancreatic islet transplantation. Adult porcine islets (10,000 IEQs/kg) were transplanted intraportally into three pairs of cynomolgus monkeys that had been treated with LMW-DS or heparin (control), and the effects on the IBMIR were characterized. Porcine islets were also incubated in human blood plasma in vitro to assess complement inhibition by LMW-DS and Compstatin. RESULTS: Morphological scoring and immunohistochemical staining revealed that the severe islet destruction and macrophage, neutrophilic granulocyte, and T-cell infiltration observed in the control (heparin-treated) animals were abrogated in the LMW-DS-treated monkeys. Both coagulation and complement activation were significantly reduced in monkeys treated with LMW-DS, but IgM and complement fragments were still found on the islet surface. This residual complement activation could be inhibited by Compstatin in vitro. CONCLUSIONS: The xenogeneic IBMIR in this non-human primate model is characterized by an immediate binding of antibodies that triggers deleterious complement activation and a subsequent clotting reaction that leads to further complement activation. The effectiveness of LMW-DS (in vivo and in vitro) and Compstatin (in vitro) in inhibiting this IBMIR provides the basis for a protocol that can be used to abrogate the IBMIR in pig-human clinical islet transplantation.
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| 7. |
- Goto, Masafumi, et al.
(författare)
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The ADP/ATP ratio : A novel predictive assay for quality assessment of isolated pancreatic islets
- 2006
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Ingår i: American Journal of Transplantation. - : Elsevier BV. - 1600-6135 .- 1600-6143. ; 6:10, s. 2483-2487
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Tidskriftsartikel (refereegranskat)abstract
- The current standard assays for islet product release criteria are unable to predict the outcome after clinical islet transplantation. Therefore, establishment of reliable and rapid assays enabling pre-transplantation prediction of islet potency is warranted. In the present study, we have evaluated the adenosine diphosphate (ADP)/adenosine triphosphate (ATP) test, the glucose-stimulated insulin release, the loss of islets during the first 24 h in culture, and the insulin/deoxyribonucleic acid as predictive assays for the ability of isolated porcine islets to cure athymic mice with streptozotocin-induced diabetes. From the results presented, it is concluded that the measurement of the ADP/ATP ratio was the only test that correlated with transplantation outcome. In summary, we propose that the ADP/ATP assay is worthwhile as applied to human islet transplantation and seek to validate it as a rapid and potent predictor of transplant outcome.
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