Hyun-Je Kim

Porcine antigen-specific IFN-γ ELISpot as a potentially valuable tool for monitoring cellular immune responses in pig-to-non-human primate islet xenotransplantation.

Recent progress in xenotransplantation of porcine islets to non‐human primates (NHPs) gives hope for human clinical trials in the near future. Thus, implementation of an appropriate monitoring method to detect the development of detrimental porcine antigen‐specific cellular immune responses is necessary. The enzyme‐linked immunospot (ELISpot) assay has been widely used to monitor antigen‐specific alloreactive T‐cell responses in humans; however, the utility of porcine islet‐specific ELISpot assay has not yet been thoroughly evaluated for pig‐to‐NHPs intraportal islet xenotransplantation.

Induction, management, and complications of streptozotocin-induced diabetes mellitus in rhesus monkeys.

Diabetes mellitus (DM) model using streptozotocin (STZ) which induces chemical ablation of β cell in the pancreas has been widely used for various research purposes in non‐human primates. However, STZ has been known to have a variety of adverse effects such as nephrotoxicity, hepatotoxicity, and even mortality. The purpose of this study is to report DM induction by STZ, toxicity associated with STZ and procedure and complication of exogenous insulin treatment for DM management in rhesus monkeys (Macaca mulatta) that are expected to be transplanted with porcine islets within 2 months.

Cross-sensitization between xeno- and allo-antigens on subsequent allogeneic and xenogeneic pancreatic islet transplantation in a murine model.

The number of patients in need of organ transplantation is continuously on the rise. However, because of organ donor shortage, xenotransplantation has been highlighted as an alternative. Among the various porcine organs and tissues, porcine islets are considered to be the best-matching implantable candidates for clinical application based on recent progress in nonhuman primate pre-clinical studies. Nevertheless, before initiation of clinical trials, it should be confirmed whether the requisite xeno-antigen sensitization would have a deleterious effect on subsequent allo-transplantation or vice versa. Therefore, in the present study, the survival rate of islets grafted in naïve recipients was compared with that in cross-sensitized recipients. Enzyme-linked immunosorbent spot, fluorescence-activated cell sorting, and immunohistochemistry were conducted to assess the cellular and humoral immune responses. The survival days of Balb/c mouse islets transplanted into B6 mice that had been previously sensitized with porcine cells (i.e., xeno-sensitized) showed no significant difference from that of naïve B6 mice. Moreover, the survival days of porcine islets transplanted into allo-antigen (Balb/c)-sensitized B6 recipients was not significantly different from that in naïve B6 mice. Furthermore, our data provide the first demonstration that the cellular xenogeneic immune response (against porcine antigen) measured by an enzyme-linked immunosorbent spot assay is not cross-reactive to the allogeneic immune responses in a murine islet transplantation model. These results suggest that clinical application of islet xenotransplantation is not likely to have a deleterious effect on subsequent allogeneic islet transplantation.

A novel method for murine intrahepatic islet transplantation via cecal vein.

Islet transplantation is one of the most beneficial treatment modality to treat type 1 diabetic patients with frequent hypoglycemic unawareness. In clinical setting, human islets are infused via portal vein and are settled in the end-portal venules in the liver. However, mouse islets are transplanted into kidney subcapsule or liver through direct portal vein. These conventional transplantation methods have several drawbacks such as different physiological environments around the transplanted islets in kidney subcapsule from the liver and high mortality rate in direct portal vein approach. In this study, we introduced murine intrahepatic islet transplantation method via cecal vein to have the same surgical operation route in humans as well as guaranteeing low mortality rate after islet transplantation. With this protocol, consistent normoglycemia can be obtained in diabetic mice, while keeping operation-related mortality extremely low. This approach with easier accessibility and low mortality will make murine intrahepatic islet transplantation a useful model for studying immunological mechanisms such as strong innate and adaptive immune responses that occur in human islet transplantation.

Delayed revascularization of islets after transplantation by IL-6 blockade in pig to non-human primate islet xenotransplantation model

Pancreatic islet transplantation is currently proven as a promising treatment for type 1 diabetes patients with labile glycemic control and severe hypoglycemia unawareness. Upon islet transplantation, revascularization is essential for proper functioning of the transplanted islets. As IL‐6 is important for endothelial cell survival and systemic inflammation related to xenograft, the effect of IL‐6 receptor antagonist, tocilizumab, on revascularization of the transplanted islets was examined in pig to non‐human primate islet xenotransplantation model. Also, the endothelial cell origin in a new vessel of the transplanted pig islets was determined.

β-Catenin Accumulation is Associated with Increased Expression of Nanog Protein and Predicts Maintenance of MSC Self-renewal.

Human mesenchymal stem cells (hMSCs) are self-renewing cells with the ability to differentiate into organized, functional network of cells. Recent studies have revealed that activation of the Wnt/β-catenin pathway by a glycogen synthase kinase (GSK)-3-specific pharmacological inhibitor, Bio, results in the maintenance of self-renewal in both mouse and human ES cells. The molecular mechanism behind the maintenance of hMSCs by these factors, however, is not fully understood. We found that rEGF enhances the level of β-catenin, a component of the Wnt/β-catenin signaling pathway. Furthermore, it was found that β-catenin upregulates Nanog. EGF activates the β-catenin pathway via the Ras protein and also increased the Nanog protein and gene expression levels 2 h after rEGF treatment. These results suggest that adding EGF can enhance β-catenin and Nanog expression in MSCs and facilitate EGF-mediated maintenance of MSC self-renewal. EGF was shown to augment MSC proliferation while preserving early progenitors within MSC population and thus did not induce differentiation. Thus, EGF not only can be used to expand MSC in vitro but also be utilized to autologous transplantation of MSCs in vivo.

Corrigendum to “Cross-sensitization between xeno- and allo-antigens on subsequent allogeneic and xenogeneic pancreatic islet transplantation in a murine model” [Biochem. Biophy. Res. Commun. 480 (2016) 474–478]

Corrigendum to “Cross-sensitization between xenoand allo-antigens on subsequent allogeneic and xenogeneic pancreatic islet transplantation in a murine model” [Biochem. Biophy. Res. Commun. 480 (2016) 474e478] Hyun-Je Kim a, b, , Nari Byun a, b, , Ohsang Kwon , Chung-Gyu Park a, b, c, * a Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, 110-799, South Korea b Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, 110-799, South Korea c Xenotransplantation Research Center, Seoul National University College of Medicine, Seoul, 110-799, South Korea

Bullous pemphigoid-like skin blistering disease in a rhesus macaque (Macaca mulatta).

Autoimmune bullous disease is very uncommon in non‐human primates. We observed a bullous skin disease in a male rhesus monkey while conducting porcine islet xenotransplantation. Fifty days after the transplantation, multiple bullous skin lesions were observed. There was no mucosal involvement. Skin biopsy results demonstrated a subepidermal blister with no necrotic keratinocytes. Immunofluorescent staining showed linear IgG deposition at the roof of the blister. These skin lesions spontaneously disappeared. Considering these results, this monkey was diagnosed with bullous pemphigoid (BP). As far as we know, this is the first report of BP in non‐human primates.