Clinical Trial Protocol for Porcine Islet Xenotransplantation in South Korea.

Background: Islet transplantation holds promise for treating selected type 1 diabetes mellitus patients, yet the scarcity of human donor organs impedes widespread adoption. Porcine islets, deemed a viable alternative, recently demonstrated successful longterm survival without zoonotic risks in a clinically relevant pig-to-non-human primate islet transplantation model. This success prompted the development of a clinical trial protocol for porcine islet xenotransplantation in humans. Methods: A single-center, open-label clinical trial initiated by the sponsor will assess the safety and efficacy of porcine islet transplantation for diabetes patients at Gachon Hospital. The protocol received approval from the Gachon Hospital Institutional Review Board (IRB) and the Korean Ministry of Food and Drug Safety (MFDS) under the Investigational New Drug (IND) process. Two diabetic patients, experiencing inadequate glycemic control despite intensive insulin treatment and frequent hypoglycemic unawareness, will be enrolled. Participants and their family members will engage in deliberation before xenotransplantation during the screening period. Each patient will receive islets isolated from designated pathogen-free pigs. Immunosuppressants and systemic infection prophylaxis will follow the program schedule. The primary endpoint is to confirm the safety of porcine islets in patients, and the secondary endpoint is to assess whether porcine islets can reduce insulin dose and the frequency of hypoglycemic unawareness. Conclusion: A clinical trial protocol adhering to global consensus guidelines for porcine islet xenotransplantation is presented, facilitating streamlined implementation of comparable human trials worldwide.

Long-term control of diabetes by tofacitinib-based immunosuppressive regimen after allo islet transplantation in diabetic rhesus monkeys that rejected previously transplanted porcine islets.

Porcine islet xenotransplantation has been highlighted as an alternative to allo islet transplantation. Despite the remarkable progress that has been made in porcine-islet pre-clinical studies in nonhuman primates, immunological tolerance to porcine islets has not been achieved to date. Therefore, allo islet transplantation could be required after the failure of porcine islet xenotransplantation. Here, we report the long-term control of diabetes by allogeneic pancreatic islet transplantation in diabetic rhesus monkeys that rejected previously transplanted porcine islets. Four diabetic male rhesus monkeys received the porcine islets and then allo islets (5700-19 000 IEQ/kg) were re-transplanted for a short or long period after the first xeno islet rejection. The recipient monkeys were treated with an immunosuppressive regimen consisting of ATG, humira, and anakinra for induction, and sirolimus and tofacitinib for maintenance therapy. The graft survival days of allo islets in these monkeys were >440, 395, >273, and 127, respectively, similar to that in allo islet transplanted cynomolgus monkeys that received the same immunosuppressive regimen without xeno sensitization. Taken together, it is likely that prior islet xenotransplantation does not affect the survival of subsequent allo islets under clinically applicable immunosuppressants.

Gold Nanopyramid Arrays for Non-Invasive Surface-Enhanced Raman Spectroscopy-Based Gastric Cancer Detection via sEVs.

Gastric cancer (GC) is one of the most common and lethal types of cancer affecting over one million people, leading to 768,793 deaths globally in 2020 alone. The key for improving the survival rate lies in reliable screening and early diagnosis. Existing techniques including barium-meal gastric photofluorography and upper endoscopy can be costly and time-consuming and are thus impractical for population screening. We look instead for small extracellular vesicles (sEVs, currently also referred as exosomes) sized ⌀ 30-150 nm as a candidate. sEVs have attracted a significantly higher level of attention during the past decade or two because of their potentials in disease diagnoses and therapeutics. Here, we report that the composition information of the collective Raman-active bonds inside sEVs of human donors obtained by surface-enhanced Raman spectroscopy (SERS) holds the potential for non-invasive GC detection. SERS was triggered by the substrate of gold nanopyramid arrays we developed previously. A machine learning-based spectral feature analysis algorithm was developed for objectively distinguishing the cancer-derived sEVs from those of the non-cancer sub-population. sEVs from the tissue, blood, and saliva of GC patients and non-GC participants were collected (n = 15 each) and analyzed. The algorithm prediction accuracies were reportedly 90, 85, and 72%. "Leave-a-pair-of-samples out" validation was further performed to test the clinical potential. The area under the curve of each receiver operating characteristic curve was 0.96, 0.91, and 0.65 in tissue, blood, and saliva, respectively. In addition, by comparing the SERS fingerprints of individual vesicles, we provided a possible way of tracing the biogenesis pathways of patient-specific sEVs from tissue to blood to saliva. The methodology involved in this study is expected to be amenable for non-invasive detection of diseases other than GC.

Long-term control of diabetes in a nonhuman primate by two separate transplantations of porcine adult islets under immunosuppression.

Porcine islet transplantation is an alternative to allo-islet transplantation. Retransplantation of islets is a routine clinical practice in islet allotransplantation in immunosuppressed recipients and will most likely be required in islet xenotransplantation in immunosuppressed recipients. We examined whether a second infusion of porcine islets could restore normoglycemia and further evaluated the efficacy of a clinically available immunosuppression regimen including anti-thymocyte globulin for induction; belimumab, sirolimus, and tofacitinib for maintenance and adalimumab, anakinra, IVIg, and tocilizumab for inflammation control in a pig to nonhuman primate transplantation setting. Of note, all nonhuman primates were normoglycemic after the retransplantation of porcine islets without induction therapy. Graft survival was >100 days for all 3 recipients, and 1 of the 3 monkeys showed insulin independence for >237 days. Serious lymphodepletion was not observed, and rhesus cytomegalovirus reactivation was controlled without any serious adverse effects throughout the observation period in all recipients. These results support the clinical applicability of additional infusions of porcine islets. The maintenance immunosuppression regimen we used could protect the reinfused islets from acute rejection.

Enhancement of anti-inflammatory and immunomodulatory effects of adipose-derived human mesenchymal stem cells by making uniform spheroid on the new nano-patterned plates.

Human mesenchymal stem cells (MSCs) are known to have anti-inflammatory and immunomodulatory functions; thus, several MSC products have been applied as cell therapy in clinical trials worldwide. Recent studies have demonstrated that MSC spheroids have superior anti-inflammatory and immunomodulatory functions to a single cell suspension. Current methods to prepare MSC spheroids include hanging drop, concave microwell aggregation, spinner flask, and gravity circulation. However, all these methods have limitations such as low scalability, easy cell clumping, low viability, and irregular size distribution. Here, we present a nano-patterned culture plasticware named PAMcell™ 3D plate to overcome these limitations. Nano-sized silica particles (700 nm) coated with RGD peptide were arrayed into fusiform onto the PLGA film. This uniform array enabled the seeded MSCs to grow only on the silica particles, forming uniform-sized semi-spheroids within 48 h. These MSC spheroids have been shown to have enhanced stemness, anti-inflammatory, and immunomodulatory functions, as revealed by the increased expression of stem cell markers (Oct4, Sox2, and Nanog), anti-inflammatory (IL-10, TSG6, and IDO), and immunomodulatory molecules (HGF, VEGF, CXCR4) both at mRNA and protein expression levels. Furthermore, these MSC spheroids demonstrated an increased palliative effect on glycemic control in a multiple low-dose streptozotocin-induced diabetes model compared with the same number of MSC single cell suspensions. Taken together, this study presents a new method to produce uniform-sized MSC spheroids with enhanced anti-inflammatory and immunomodulatory functions in vitro and in vivo.

Long-term porcine islet graft survival in diabetic non-human primates treated with clinically available immunosuppressants.

BACKGROUND: Although pancreatic islet transplantation is becoming an effective therapeutic option for patients with type 1 diabetes (T1D) who suffer from a substantially impaired awareness of hypoglycemia, its application is limited due to the lack of donors. Thus, pig-to-human islet xenotransplantation has been regarded as a promising alternative due to the unlimited number of "donor organs." Long-term xenogeneic islet graft survival in pig-to-non-human primate (NHP) models has mainly been achieved by administering the anti-CD154 mAb-based immunosuppressant regimen. Since the anti-CD154 mAb treatment has been associated with unexpected fatal thromboembolic complications in clinical trials, the establishment of a new immunosuppressant regimen that is able to be directly applied in clinical trials is an urgent need. METHODS: We assessed an immunosuppressant regimen composed of clinically available agents at porcine islet transplantation in consecutive diabetic NHPs. RESULTS: Porcine islet graft survival in consecutive diabetic NHPs (n = 7; >222, >200, 181, 89, 62, 55, and 34 days) without severe adverse events. CONCLUSION: We believe that our study could contribute greatly to the initiation of islet xenotransplantation clinical trials.

CD4+ /CD8+ T-cell ratio correlates with the graft fate in pig-to-non-human primate islet xenotransplantation.

BACKGROUND: Xenogeneic islet transplantation using porcine pancreata has been a promising option for substituting human islet transplantation. Moreover, recent advances in pre-clinical results have put islet xenotransplantation closer to the possibility of clinical application. While preparing for the era of clinical xenotransplantation, developing non-invasive immune monitoring method which could predict the graft fate could benefit the patient. However, there are few reports showing predictive immune parameters associated with the fate of the graft in islet xenotransplantation. METHODS: The absolute number and ratio of T-cell subsets have been measured via flow cytometry from the peripheral blood of 16 rhesus monkeys before and after porcine islet xenotransplantation. The correlation between the graft survival and the absolute number or ratio of T cells was retrospectively analyzed. RESULTS: The ratio of CD4+ versus CD8+ T cells was significantly reduced due to CD8+ effector memory cells' increase. Correlation analyses revealed that CD4+ /CD8+ , CD4+ /CD8+ naïve, CD4+ naïve/CD8+ naïve, and CD4+ central memory/CD8+ naïve cell ratios negatively correlated with the duration of graft survival. Conversely, further analyses discovered strong, positive correlation of CD4+ /CD8+ cell ratios within the early graft-rejected monkeys (≤60 days). CONCLUSIONS: This retrospective study demonstrated that CD4+ /CD8+ ratios correlated with graft survival, especially in recipients which rejected the graft in early post-transplantation periods. CD4+ /CD8+ ratios could be used as a surrogate marker to predict the graft fate in pig-to-NHP islet xenotransplantation.

Bioinformatic analysis of peripheral blood RNA-sequencing sensitively detects the cause of late graft loss following overt hyperglycemia in pig-to-nonhuman primate islet xenotransplantation.

Clinical islet transplantation has recently been a promising treatment option for intractable type 1 diabetes patients. Although early graft loss has been well studied and controlled, the mechanisms of late graft loss largely remains obscure. Since long-term islet graft survival had not been achieved in islet xenotransplantation, it has been impossible to explore the mechanism of late islet graft loss. Fortunately, recent advances where consistent long-term survival (≥6 months) of adult porcine islet grafts was achieved in five independent, diabetic nonhuman primates (NHPs) enabled us to investigate on the late graft loss. Regardless of the conventional immune monitoring methods applied in the post-transplant period, the initiation of late graft loss could rarely be detected before the overt graft loss observed via uncontrolled blood glucose level. Thus, we retrospectively analyzed the gene expression profiles in 2 rhesus monkey recipients using peripheral blood RNA-sequencing (RNA-seq) data to find out the potential cause(s) of late graft loss. Bioinformatic analyses showed that highly relevant immunological pathways were activated in the animal which experienced late graft failure. Further connectivity analyses revealed that the activation of T cell signaling pathways was the most prominent, suggesting that T cell-mediated graft rejection could be the cause of the late-phase islet loss. Indeed, the porcine islets in the biopsied monkey liver samples were heavily infiltrated with CD3+ T cells. Furthermore, hypothesis test using a computational experiment reinforced our conclusion. Taken together, we suggest that bioinformatics analyses with peripheral blood RNA-seq could unveil the cause of insidious late islet graft loss.

JAK3 inhibitor-based immunosuppression in allogeneic islet transplantation in cynomolgus monkeys.

Islet transplantation is efficacious to prevent severe hypoglycemia and glycemic liability of selected patients of type 1 diabetes. However, since calcineurin inhibitor (CNI) causes ß-cell and nephrotoxicity, alternative drug(s) with similar potency and safety profile to CNI will be highly desirable. Here we tested whether JAK3 inhibitor, tofacitinib could be used instead of tacrolimus in CIT07 immunosuppression regimen in cynomolgus nonhuman primate (NHP) model. Five independent streptozotocin (STZ)-induced diabetic monkeys were transplanted with MHC-mismatched allogeneic islets and three animals were further re-transplanted upon insufficient glycemic control or early islet graft rejection. After islet transplantation, blood glucose levels were quickly stabilized and maximal islet graft survival as measured by serum C-peptide concentration was >330, 98, >134, 31, or 22 days, respectively, after transplantation (median survival day; 98 days). Cellular and humoral immune responses were efficiently suppressed by JAK3 inhibitor-based immunosuppression during the follow-up periods. Although intermittent increases of the genome copy number of cynomolgus cytomegalovirus (CMV) were detected by quantitative real-time PCR analyses, serious infections or posttransplant lymphoproliferative disease (PTLD) was not found in all animals. Taken together, we have shown that JAK3 inhibitor could be used in replacement of tacrolimus in a highly translatable NHP islet transplantation model and these results suggest that JAK3 inhibitor will be potentially incorporated in human allogeneic islet transplantation.

Absence of spontaneous regeneration of endogenous pancreatic ß-cells after chemical-induced diabetes and no effect of GABA on α-to-ß cell transdifferentiation in rhesus monkeys.

ß-cell deficiency is common feature of type 1 and late-stage of type 2 diabetes mellitus. Thus, ß-cell replacement therapy has been the focus of regenerative medicine past several decades. Particularly, evidences suggest that ß-cell regeneration via transdifferentiation from sources including α-cells is promising. However, data using higher mammals besides rodents are scarce. Here, we examined whether endogenous pancreatic ß-cells could regenerate spontaneously or under normoglycemia following porcine islet transplantation for varied periods up to 1197 days after streptozotocin-induced diabetes, and remaining α-cells transdifferentiate into ß-cells by GABA treatment in vivo and in vitro. The results showed that endogenous ß-cells rarely regenerate in both conditions as evidenced by stagnant serum C-peptide levels and ß-cell number in the pancreas, and the remaining α-cells did not transdifferentiate into ß-cells by GABA treatment. Collectively, we concluded that monkey ß-cells had relatively low regenerative potential compared with rodent counterpart and GABA treatment could not induce α-to-ß-cell transdifferentitation.

Senescent T Cells Predict the Development of Hyperglycemia in Humans.

Senescent T cells have been implicated in chronic inflammatory and cardiovascular diseases. In this study, we explored the relationship between senescent T cells and glycemic status in a cohort of 805 participants by investigating the frequency of CD57+ or CD28null senescent T cells in peripheral blood. Participants with normal glucose tolerance (NGT) with follow-up data (N = 149) were included to determine whether hyperglycemia (prediabetes or type 2 diabetes) developed during follow-up (mean 2.3 years). CD8+CD57+ and CD8+CD28null T-cell frequencies were significantly higher in prediabetes and type 2 diabetes compared with NGT. Increased CD57+ or CD28null cells in the CD8+ T-cell subset were independently associated with hyperglycemia. Furthermore, among participants with baseline NGT, the frequency of CD8+CD57+ T cells was an independent predictor of hyperglycemia development. Immunofluorescent analyses confirmed that CD8+CD57+ T-cell infiltration was increased in visceral adipose tissue of patients with prediabetes or type 2 diabetes compared with those with NGT. Our data suggest that increased frequency of senescent CD8+ T cells in the peripheral blood is associated with development of hyperglycemia.

Ascites formation accompanied by portal vein thrombosis after porcine islet xenotransplantation via the portal vein in Rhesus macaque (Macaca mulatta).

Pig-to-nonhuman primate (NHP) islet transplantation has been widely conducted as a preclinical xenotransplantation model prior to human clinical trial. Portal vein thrombosis is one of the complications associated with islet infusion through the portal vein into the liver. Here, we briefly report severe case of ascites formation accompanied by portal vein thrombi after pig-to-NHP islet xenotransplantation in a rhesus monkey. Meticulous prophylactic treatment such as continuous heparin infusion should be implemented to prevent portal vein thrombi in pig-to-NHP islet transplantation models.

Tacrolimus-induced asymptomatic thrombotic microangiopathy diagnosed by laboratory tests in pig-to-rhesus corneal xenotransplantation: A case report.

Tacrolimus-associated thrombotic microangiopathy (TA-TMA) is a rare complication. TA-TMA is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ damage due to thrombus. We report asymptomatic TA-TMA diagnosed by laboratory tests in pig-to-rhesus corneal xenotransplantation. Corneal transplantation had been conducted from a wild-type SNU miniature pig to a rhesus macaque. The veterinary records were retrospectively reviewed in this case. The immunosuppressive regimen consisted of rituximab, basiliximab, and IVIg as inductive therapies, and steroids with tacrolimus (0.1 mg/kg/day) as maintenance therapies. Although there were no clinical symptoms, increased levels of lactate dehydrogenase, total bilirubin, blood urea nitrogen, and creatinine and decreased levels of hemoglobin and platelet were observed in laboratory tests on Day (D) 61. Systemic TA-TMA was tentatively diagnosed. Tacrolimus was discontinued starting on D71. Dalteparin, clopidogrel bisulfate (D77-D99), and IVIg (D72) were administered as a conservative treatment. Abnormal laboratory results were reversed on D99. When low-dose tacrolimus (0.07 mg/kg/day) was re-administered on D131 to prevent rejection of the graft, TMA was detected again by laboratory tests on D161, confirming the initial diagnosis. Discontinuation of tacrolimus on D162 and re-administration of Dalteparin (D161-D196) corrected the laboratory values on D161. This report shows that in pig-to-rhesus corneal xenotransplantation, clinically asymptomatic TMA can be induced by tacrolimus, and the discontinuation of tacrolimus and administration of anticoagulant seems sufficient to correct the laboratory TMA.

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

BACKGROUND: 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. METHODS: Pig islets were isolated from designated pathogen-free (DPF) SNU miniature pigs and transplanted via portal vein into five streptozotocin-induced diabetic monkeys. One group (n = 2, basal group) was treated with anti-thymoglobulin (ATG), anti-CD40 antibody (2C10R4), sirolimus, and tacrolimus, and the other group was additionally given tocilizumab on top of basal immunosuppression (n = 3, Tocilizumab group). To confirm IL-6 blocking effect, C-reactive protein (CRP) levels and serum IL-6 concentration were measured. Scheduled biopsy of the margin of the posterior segment right lobe inferior of the liver was performed at 3 weeks after transplantation to assess the degree of revascularization of the transplanted islets. Immunohistochemical staining using anti-insulin, anti-CD31 antibodies, and lectin IB4 was conducted to find the origin of endothelial cells in the islet graft. RESULTS: CRP significantly increased at 1~2 days after transplantation in Basal group, but not in Tocilizumab group, and higher serum IL-6 concentration was measured in latter group, showing the biological potency of tocilizumab. In Basal group, well-developed endothelial cells were observed on the peri- and intraislet area, whereas the number of CD31+ cells in the intraislet space was significantly reduced in Tocilizumab group. Finally, new endothelial cells in the pig islet graft were positive for CD31, but not for lectin IB4, suggesting that they are originated from the recipient monkey. CONCLUSIONS: Our results demonstrated that tocilizumab can delay revascularization of the transplanted islet, although this effect had no significant correlation to the overall islet graft survival. In the pig to NHP islet xenotransplantation model, the endothelial cells from recipient monkey form new blood vessels in and around pig islets.

Pre-clinical results in pig-to-non-human primate islet xenotransplantation using anti-CD40 antibody (2C10R4)-based immunosuppression.

BACKGROUND: Islet transplantation is an effective therapy for selected patients with type 1 diabetes with labile glycemic control and hypoglycemic unawareness, but donor organs are limited. Islet xenotransplantation using porcine islets will potentially solve this problem. Although successful proof of concept studies using clinically inapplicable anti-CD154 monoclonal antibody (mAb) in pig-to-non-human primate (NHP) islet xenotransplantation has been demonstrated by several groups worldwide, potentially clinically applicable anti-CD40 (2C10R4) mAb-based studies have not been reported. METHODS: Nine streptozotocin (STZ)-induced diabetic rhesus monkeys were transplanted with adult porcine islets isolated from designated pathogen-free (DPF) miniature pigs. They were treated with anti-CD40 mAb-based immunosuppressive regimen and were divided into 3 groups: anti-CD40 only group (n = 2), belatacept group (anti-CD40 mAb+belatacept, n = 2), and tacrolimus group (anti-CD40 mAb+tacrolimus, n = 5). All monkeys received anti-thymocyte globulin (ATG), cobra venom factor (CVF), adalimumab, and sirolimus. Blood glucose levels (BGL) and serum porcine C-peptide concentrations were measured. Humoral and cellular immune responses were assessed by ELISA and ELISPOT, respectively. Liver biopsy and subsequent immunohistochemistry were conducted. RESULTS: All animals restored normoglycemia immediately after porcine islet transplantation and finished the follow-up without any severe adverse effects except for one animal (R092). Most animals maintained their body weight. Median survival, as defined by a serum porcine C-peptide concentration of >0.15 ng/mL, was 31, 27, and 60 days for anti-CD40 only, belatacept, and tacrolimus groups, respectively. Anti-αGal IgG levels in serum and the number of interferon-γ secreting T cells in peripheral blood mononuclear cells did not increase in most animals. CONCLUSION: These results showed that anti-CD40 mAb combined with tacrolimus was effective in prolonging porcine islet graft survival, but anti-CD40 mAb was not as effective as anti-CD154 mAb in terms of preventing early islet loss.

Computed tomography or necropsy diagnosis of multiple bullae and the treatment of pneumothorax in rhesus macaques (Macaca mulatta).

Pulmonary bullae and pneumothorax have various etiologies in veterinary medicine. We diagnosed multiple pulmonary bullae combined with or without pneumothorax by computed tomography (CT) or necropsy in seven rhesus macaques (Macaca mulatta) imported from China. Two of seven rhesus macaques accompanied by pneumothorax were cured by fixation of ruptured lung through left or right 3rd intercostal thoracotomy. Pneumonyssus simicola, one of the etiologies of pulmonary bullae, was not detected from tracheobronchiolar lavage. To the best of our knowledge, this is the first case report on the CT-aided diagnosis of pulmonary bullae and the successful treatment of combined pneumothorax by thoracotomy in non-human primates (NHPs).

D-dimer level, in association with humoral responses, negatively correlates with survival of porcine islet grafts in non-human primates with immunosuppression.

BACKGROUND: Several immunosuppression (IS) regimens achieve long-term graft survival in non-human primates (NHPs) after porcine islet transplantation (PITx), but their success rates vary. To understand the mechanism of graft loss, we investigated the relationships between graft survival and humoral or inflammatory responses for maintenance IS in NHPs after PITx. METHODS: Islets purified from adult wild-type pigs were intraportally transplanted into streptozotocin-induced diabetic rhesus monkeys. Three monkeys received an IS regimen without anti-CD154 monoclonal antibody (mAb, transplant [Tpl]-control) and 11 received IS with anti-CD154 mAb (Tpl-aCD154). Blood samples were obtained weekly from the recipients until graft function ceased and weekly from three healthy monkeys (non-Tpl-control) for 6 months. Levels of D-dimer, C-reactive protein (CRP), and anti-Galα1,3Gal (Gal) IgG, IgG1, IgG2, and IgM were measured. Liver biopsy sections were immunostained for fibrin, insulin, and human CD31. RESULTS: Tpl-control monkeys had higher time-weighted average levels (levelstwavrg ) of Δanti-Gal IgG (Δ, difference from level at day 0) and D-dimer than Tpl-aCD154 or non-Tpl-control. The levelstwavrg of Δanti-Gal IgG, IgG1, IgG2, and IgM did not differ between Tpl-aCD154 and non-Tpl-control. The levelstwavrg of D-dimer and Δanti-Gal IgG2 negatively correlated with graft survival. Liver biopsy sections revealed many spots of fibrin deposition inside islet grafts that were well vascularized by human CD31-positive cells. Level of D-dimer positively correlated with Δanti-Gal IgG1 in Tpl-control and with Δanti-Gal IgG2 in Tpl-aCD154. CONCLUSIONS: Intravascular coagulation, in association with immune responses against xenografts, may partly contribute to loss of islet grafts in NHPs after PITx.

Gastrostomy tube placement for long-term oral drug administration in non-human primates.

BACKGROUND: Non-human primates (NHPs) are often used as recipients in preclinical transplantation research that in most cases involves administration of various drugs including immunosuppressants. Long-term oral drug administration, particularly tacrolimus, is challenging in the transplant recipient NHPs. Oral drug administration method using the mixture of drug and fruit juice has been used in NHPs, but this is not always effective in all monkeys. To those monkeys who are poorly compliant, oral drug administration in restraint or administration using gastrostomy tube should be necessary. The aim of this study was to compare the efficacy of between oral drug administration in restraint and administration using gastrostomy tube and to report complications and solutions to overcome the problems related to gastrostomy tube for long-term oral drug dosing in rhesus monkeys. METHODS: Fifteen of 4- to 5-year-old male and female healthy rhesus monkeys weighing 5.0-6.8 kg were used as recipients for porcine pancreatic islet transplantation. Oral drug administration in restraint was used for four monkeys, and gastrostomy tube was placed to other 11 monkeys (8-French Feeding tube, n=6; Tri-Funnel Replacement Gastrostomy tube, n=5). Oral immunosuppressive drugs such as sirolimus and tacrolimus were administered through the tube. The efficacy and the extent of ease for administration and related complications were compared between two groups. RESULTS AND CONCLUSIONS: The complication of gastrostomy included a transient inflammation in the skin and peritonitis caused by a leakage around implantation site (one case), which could be overcome by changing suture method and tube type to interlocking box suture and Tri-Funnel Replacement Gastrostomy tube, respectively. Despite these complications, oral drug administration using gastrostomy tube allowed us to perform accurate dosage of drug administration and to reduce the stress that both the monkey and the researcher may experience. Taken together, this study showed that gastrostomy tube placement is a better alternative to oral drug administration in restraint for long-term oral drug administration in rhesus monkeys who tend to refuse to eat the mixture of drug and fruit juice.

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

BACKGROUND: Diabetes mellitus (DM) model using streptozotocin (STZ) which induces chemical ablation of ß 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. METHODS: Streptozotocin (immediately dissolved in normal saline, 110 mg/kg) was slowly infused via central catheter for 10 minutes in 22 rhesus monkeys. Clinical signs, complete blood count and blood chemistry were monitored to evaluate toxicity for 1 week after STZ injection. Monkey basal C-peptides were measured and intravenous glucose tolerance test was performed to confirm complete induction of DM. Exogenous insulin was subcutaneously injected to maintain blood glucose in diabetic rhesus monkeys and the complications were recorded while in insulin treatment. RESULTS: Severe salivation and vomiting were observed within 1 hour after STZ injection in 22 rhesus monkeys. One monkey died at 6 hours after STZ injection and the reason for the death was unknown. Pancreatitis was noticed in one monkey after STZ injection, but the monkey recovered after 5 days by medical treatment. Serum total protein and albumin decreased whereas the parameters for the liver function such as aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase significantly increased (P<.05) after STZ injection, but they were resolved within 1 week. Azotemia was not observed. Monkey fasting C-peptide levels after STZ injection were <0.1 ng/mL in 18 rhesus monkeys, but 0.34, 0.22, 0.16 ng/mL in three monkeys, respectively. The value of daily insulin requirement was 0.92±0.26IU/kg/d (range=0.45-1.29) in the monkeys. Diabetic ketoacidosis was observed in one rhesus monkeys, but the monkey recovered after 24 hours by fluid and insulin treatment. CONCLUSIONS: Streptozotocin was effective for inducing DM in rhesus monkeys, but various adverse effects such as pancreatitis, liver toxicity or death were observed. Therefore, careful and suitable medical managements should be implemented to eliminate the risks of mortality and severe adverse effects.