The longest survival of a nonhuman primate with a life-supporting kidney graft to date has been 90 days, though graft survival >30 days has been unusual. A baboon received a kidney graft from an α1,3-galactosyltransferase gene-knockout pig transgenic for two human complement- and three human coagulation- regulatory proteins (though only one was expressed in the kidney). Immunosuppressive therapy was with ATG+anti-CD20mAb (induction) and anti-CD40mAb+rapamycin+corticosteroids (maintenance). Anti-TNF-α and anti-IL-6R were administered. The baboon survived 136 days with a generally stable serum creatinine (0.6–1.6mg/dL) until terminally. No features of a consumptive coagulopathy (e.g., thrombocytopenia, decreased fibrinogen) or of a protein-losing nephropathy were observed. There was no evidence of an elicited anti-pig antibody response. Death was from septic shock (Myroides spp). Histology of a biopsy on day 103 was normal, but by day 136 the kidney showed features of glomerular enlargement, thrombi, and mesangial expansion. The combination of (i) a graft from a specific genetically-engineered pig, (ii) an effective immunosuppressive regimen, and (iii) anti-inflammatory agents prevented immune injury and a protein-losing nephropathy, and delayed coagulation dysfunction. This outcome encourages us that clinical renal xenotransplantation may become a reality.

Background Three costimulation-blockade-based regimens have been explored after transplantation of hearts from pigs of varying genetic backgrounds to determine whether CTLA4-Ig (abatacept) or anti-CD40mAb+CTLA4-Ig (belatacept) can successfully replace anti-CD154mAb. Methods All pigs were on an α1,3-galactosyltransferase gene-knockout/CD46 transgenic (GTKO.CD46) background. Hearts transplanted into Group A baboons (n=4) expressed additional CD55, and those into Group B (n=3) expressed human thrombomodulin (TBM). Immunosuppression included anti-thymocyte globulin with anti-CD154mAb (Regimen 1: n=2) or abatacept (Regimen 2: n=2) or anti-CD40mAb+belatacept (Regimen 3: n=2). Regimens1/2 included induction anti-CD20mAb and continuous heparin. One further baboon in Group B (B16311) received a modified Regimen 1. Baboons were followed by clinical/laboratory monitoring of immune/coagulation parameters. At biopsy, graft failure, or euthanasia, the graft was examined by microscopy. Results Group A baboons survived 15–33 days, whereas Group B survived 52, 99 and 130 days, respectively. Thrombocytopenia and reduction in fibrinogen occurred within 21 days in Group A, suggesting thrombotic microangiopathy (TM), confirmed by histopathology. In Group B, with follow-up for >4m, areas of myofiber degeneration and scarring were seen in 2 hearts at necropsy. A T cell response was documented only in baboons receiving Regimen 2. Conclusions The combination of anti-CD40mAb+belatacept proved effective in preventing a T cell response. Expression of TBM prevented thrombocytopenia, and may possibly delay the development of TM and/or consumptive coagulopathy.

Introduction In pig-to-baboon heart/artery patch transplantation models, adequate costimulation blockade prevents a T cell response. After heart transplantation, coagulation dysfunction (thrombocytopenia, reduced fibrinogen, increased D-dimer) and inflammation (increased C-reactive protein [CRP]) develop. We evaluated whether coagulation dysfunction and/or inflammation can be detected following pig artery patch transplantation. Methods Baboons received heart (n=8) or artery patch (n=16) transplants from genetically-engineered pigs, and a costimulation blockade-based regimen. Heart grafts functioned for 15–130d. Artery recipients were euthanized after 28–84d. Platelet counts, fibrinogen, D-dimer, and CRP were measured. Results Thrombocytopenia and reduced fibrinogen developed only in recipients of hearts not expressing a coagulation-regulatory protein (n=4), but not in other heart or patch recipients. However, in heart recipients (n=8), there were sustained increases in D-dimer (<0.5–1.9ug/mL [p<0.01]), and CRP (0.26–2.2mg/dL [p<0.01]). In recipients of artery patches, there were also sustained increases in D-dimer (<0.5–1.4ug/mL [p<0.01]), and CRP (0.26–1.5mg/dL [p<0.001]). An IL-6R antagonist suppressed the increase in CRP, but not D-dimer. Conclusion The pig artery patch model has proved valuable for determining immunosuppressive regimens that prevent sensitization to pig antigens. This model also provides information on the sustained systemic inflammation seen in xenograft recipients (SIXR). An IL-6R antagonist may help suppress this response.

Background Baboons have natural antibodies against pig antigens. We have investigated whether there are differences in anti-nonGal pig antibody levels between baboons maintained under specific pathogen-free (SPF) conditions and those housed under conventional conditions (NonSPF) that might be associated with improved outcome after pig-to-baboon organ transplantation. Methods Baboons (n=40) were housed indoors (SPF n=8) or in indoor/outdoor pens (NonSPF n=32) in colonies of similar size and structure. NonSPF colonies harbor a number of pathogens common to nonhuman primate species, whereas many of these pathogens have been eliminated from the SPF colony. Complete blood cell counts (CBC), blood chemistry, and anti-nonGal IgM and IgG levels were monitored. Results There were no significant differences in CBC or blood chemistry between SPF and NonSPF baboons. Anti-nonGal IgM levels were significantly lower in the SPF baboons than in the NonSPF baboons (MFI 7.1 vs 8.8, p<0.05). One SPF and two NonSPF baboons had an MFI >20; if these 3 baboons are omitted, the mean MFIs were 4.8 (SPF) vs 7.5 (NonSPF) (p<0.05). Anti-nonGal IgG was minimal in both groups (MFI 1.0 vs 1.0). Conclusions As their levels of anti-nonGal IgM are lower, baboons maintained under SPF conditions may be beneficial for xenotransplantation studies as the initial binding of anti-pig IgM to an α1,3-galactosyltransferase gene-knockout pig organ may be less, thus resulting in less complement and/or endothelial cell activation. However, even under identical SPF conditions, an occasional baboon will express a high level of anti-nonGal IgM, the reason for which remains uncertain.

Background Hepatocyte transplantation is a potential therapy for certain diseases of the liver, including hepatic failure. However, there is a limited supply of human livers as a source of cells and, after isolation, human hepatocytes can be difficult to expand in culture, limiting the number available for transplantation. Hepatocytes from other species, e.g., the pig, have therefore emerged as a potential alternative source. We searched the literature through the end of 2014 to assess the current status of experimental research into hepatocyte xenotransplantation. Literature search and results The literature search identified 51 reports of in vivo cross-species transplantation of hepatocytes in a variety of experimental models. Most studies investigated the transplantation of human (n=23) or pig (n=19) hepatocytes. No studies explored hepatocytes from genetically-engineered pigs. The spleen was the most common site of transplantation (n=23), followed by the liver (through the portal vein [n=6]) and peritoneal cavity (n=19). In 47 studies (92%), there was evidence of hepatocyte engraftment and function across a species barrier. Conclusions The data provided by this literature search strengthen the hypothesis that xenotransplantation of hepatocytes is feasible and potentially successful as a clinical therapy for certain liver diseases, including hepatic failure. By excluding vascular structures, hepatocytes isolated from genetically-engineered pig livers may address some of the immunological problems of xenotransplantation.

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Fungal diseases have posed a great challenge to global health, but have fewer solutions compared to bacterial and viral infections. Development and application of new treatment modalities for fungi are limited by their inherent essential properties as eukaryotes. The microorganism identification and drug sensitivity analyze are limited by their proliferation rates. Moreover, there are currently no vaccines for prevention. Polymer science and related interdisciplinary technologies have revolutionized the field of fungal disease management. To date, numerous advanced polymer-based systems have been developed for management of fungal diseases, including prevention, diagnosis, treatment and monitoring. In this review, we provide an overview of current needs and advances in polymer-based strategies against fungal diseases. We high light various treatment modalities. Delivery systems of antifungal drugs, systems based on polymers’ innate antifungal activities, and photodynamic therapies each follow their own mechanisms and unique design clues. We also discuss various prevention strategies including immunization and antifungal medical devices, and further describe point-of-care testing platforms as futuristic diagnostic and monitoring tools. The broad application of polymer-based strategies for both public and personal health management is prospected and integrated systems have become a promising direction. However, there is a gap between experimental studies and clinical translation. In future, well-designed in vivo trials should be conducted to reveal the underlying mechanisms and explore the efficacy as well as biosafety of polymer-based products.

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