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Publications (3)11.41 Total impact

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    ABSTRACT: In clinical trials using adult porcine islet products, islets should be isolated from the designated pathogen-free (DPF) pigs under the current good manufacturing practice (GMP) regulations. Our previous studies suggested that male DPF pigs are better donors than retired breeder pigs and histomorphometrical parameters of donor pancreas predict the porcine islet quality. We aimed to investigate whether the use of the newer bovine nervous tissue-free enzymes and a revised donor selection strategy could improve the islet graft function in the context of islet isolation with DPF pigs. Using 30 DPF pigs within a closed herd, we compared the islet yield of porcine islets isolated with Liberase PI (n = 11, as a historical control group), Liberase MTF C/T, which is a GMP-grade enzyme (n = 12), and CIzyme collagenase MA/BP protease (n = 7). We analyzed the relationship between the diabetes reversal rate of recipient NOD/SCID mice (n = 75) and histomorphometric parameters of each donor pancreas as well as donor characteristics. Proportion of islets larger than 200 μm from the biopsied donor pancreas (P = 0.006) better predicted islet yield than age (P = 0.760) or body weight (P = 0.371) of donor. The proportion of islets larger than 200 μm from the biopsied donor pancreas was not related to the sex of the donor miniature pig (P = 0.358). The islet yield obtained with the three enzymes did not differ, even after stratification of the donor with the histomorphometric parameters of the biopsied donor pancreas and the sex of donor. The use of the newer bovine nervous tissue-free enzymes (P < 0.001), a higher proportion of large islets in donor pancreas (P = 0.006), and a male sex of the donor (P = 0.025) were independent predictors of earlier diabetes reversal. Use of the newer bovine nervous tissue-free enzymes including a GMP-grade enzyme resulted in better islet quality than that of islet isolated using Liberase PI. To obtain high-quality islet from DPF pigs, the donor should be male pig and histomorphometrical parameters from donor pancreas should be considered.
    Xenotransplantation 11/2011; 18(6):369-79. · 2.57 Impact Factor
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    ABSTRACT: Intraductal administration of a c-Jun NH(2)-terminal kinase (JNK) inhibitor enhances islet viability. However, its role in reducing the inflammatory response in islets is unknown. It is also unknown whether a JNK inhibitor could act in synergy with statins. We examined if the sequential combination of a JNK inhibitor and simvastatin would reduce islet inflammation and improve islet viability. We performed porcine islet isolation with or without intraductal administration of SP600125, a JNK inhibitor. This was followed by culture medium supplementation with either nicotinamide alone or nicotinamide plus simvastatin. We assessed the viability of islets by flow cytometry, islet loss during overnight culture, graft function in NOD/SCID mice, and expression of inflammation-related genes in islets. The sequential combination of a JNK inhibitor and simvastatin increased the β-cell viability index of porcine islets cultured overnight (p = 0.015) as well as islet viability as assessed by a DNA binding dye staining (p = 0.011). The combination of a JNK inhibitor and simvastatin significantly increased the islet survival rate (p = 0.027) when the histomorphometry of donor pancreas indicated a large islet proportion of greater than 50.55%. When we transplanted the same islet mass per recipient for each group, there was no difference in overall islet graft function. Intraductal administration of JNK inhibitor significantly suppressed mRNA expression levels of interleukin-1β (IL-1β), interferon-γ, tumor necrosis factor-α, IL-6, IL-8, and macrophage chemoattractant protein-1. It also decreased the concentration of IL-1β (p = 0.040) and IL-8 (p = 0.023) in the culture supernatant. In conclusion, the sequential combination of a JNK inhibitor and simvastatin protected porcine islets from peritransplant apoptosis. Inhibition of JNK reduced the inflammatory response and could be considered an alternative target for suppression of porcine islet inflammation.
    Cell Transplantation 12/2010; 20(7):1139-51. · 4.42 Impact Factor
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    ABSTRACT: Prediction of islet yield and posttransplant outcome is essential for clinical porcine islet xenotransplantation. Although several histomorphometric parameters of biopsied porcine pancreases are predictive of islet yield, their role in the prediction of in vivo islet potency is unknown. We investigated which histomorphometrical parameter best predicts islet yield and function, and determined whether it enhanced the predictive value of in vitro islet function tests for the prediction of posttransplant outcome. We analyzed the histomorphometry of pancreases from which 60 adult pig islet isolations were obtained. Islet function was assessed using the beta-cell viability index based on flow cytometry analysis, oxygen consumption rate, ADP/ATP ratio, and/or concurrent transplantation into NOD/SCID mice. Receiver operating characteristic (ROC) analysis revealed that only islet equivalent (IEQ)/cm(2) and the number of islets >200 microm in diameter significantly predicted an islet yield of >2000 IEQ/g (p < 0.001 for both) and in vivo islet potency (p = 0.024 and p = 0.019, respectively). Although not predictive of islet yield, a high proportion of large islets (>100 microm in diameter) best predicted diabetes reversal (p = 0.001). Multiple regression analysis revealed that the beta-cell viability index (p = 0.003) and the proportion of islets >100 microm in diameter (p = 0.048) independently predicted mean posttransplant blood glucose level (BGL). When BGL was estimated using both these parameters [area under the ROC curve (AUC), 0.868; 95% confidence interval (CI), 0.730-1.006], it predicted posttransplant outcome more accurately than the beta-cell viability index alone (AUC, 0.742; 95% CI, 0.544-0.939). In conclusion, we identified the best histomorphometric predictors of islet yield and posttransplant outcome. This further enhanced the predictive value of the flow cytometry analysis. These parameters should be useful for predicting islet yield and in vivo potency before clinical adult porcine islet xenotransplantation.
    Cell Transplantation 12/2009; 19(3):299-311. · 4.42 Impact Factor