Multiple genetically modified <scp>GTKO</scp>/<scp>hCD</scp>46/<scp>HLA</scp>‐E/hβ2−mg porcine hearts are protected from complement activation and natural killer cell infiltration during ex vivo perfusion with human blood

Lipiński

et al. 2020

Genes

Progress in genetic engineering over the past few decades has made it possible to develop methods that have led to the production of transgenic animals. The development of transgenesis has created new directions in research and possibilities for its practical application. Generating transgenic animal species is not only aimed towards accelerating traditional breeding programs and improving animal health and the quality of animal products for consumption but can also be used in biomedicine. Animal studies are conducted to develop models used in gene function and regulation research and the genetic determinants of certain human diseases. Another direction of research, described in this review, focuses on the use of transgenic animals as a source of high-quality biopharmaceuticals, such as recombinant proteins. The further aspect discussed is the use of genetically modified animals as a source of cells, tissues, and organs for transplantation into human recipients, i.e., xenotransplantation. Numerous studies have shown that the pig (Sus scrofa domestica) is the most suitable species both as a research model for human diseases and as an optimal organ donor for xenotransplantation. Short pregnancy, short generation interval, and high litter size make the production of transgenic pigs less time-consuming in comparison with other livestock species This review describes genetically modified pigs used for biomedical research and the future challenges and perspectives for the use of the swine animal models.

Section: Cellular Xenograft Rejectionmentioning

confidence: 99%

Application of Genetically Engineered Pigs in Biomedical Research

Lipiński

et al. 2020

Genes

“…Genetically engineered pigs with swine leukocyte antigen (SLA) class I knock‐out (SLA‐1 KO), or expression of a mutant human class II transactivator gene (CIITA‐DN), have been produced to reduce pig antigen expression, and thus reduce the recipient's immune response, but are not yet being used consistently in experiments in NHPs. Pigs with transgenic expression of human HLA‐E/β2m and CD178 (FasL) have been produced to inhibit NK cell cytotoxicity, while the transgenic human CD47 gene contributes to regulate macrophage activation and phagocytosis . In addition, transgenic human CTLA4‐Ig (CD152) and CD253 (TRAIL) expression interrupt T‐cell activation and induce T‐cell apoptosis, respectively.…”

Section: Genetic Modification Of the Organ‐source Pigmentioning

confidence: 99%

A review of pig liver xenotransplantation: Current problems and recent progress

Zhang

Yang

et al. 2019

Xenotransplantation

Pig liver xenotransplantation appears to be more perplexing when compared to heart or kidney xenotransplantation, even though great progress has been achieved. The relevant molecular mechanisms involved in xenogeneic rejection, including coagulopathy, and particularly thrombocytopenia, are complex, and need to be systematically investigated. The deletion of expression of Gal antigens in the liver graft highlights the injurious impact of nonGal antigens, which continue to induce humoral rejection. Innate immunity, particularly mediated by macrophages and natural killer cells, interplays with inflammation and coagulation disorders. Kupffer cells and liver sinusoidal endothelial cells (LSECs) together mediate leukocyte, erythrocyte, and platelet sequestration and phagocytosis, which can be exacerbated by increased cytokine production, cell desialylation, and interspecies incompatibilities. The coagulation cascade is activated by release of tissue factor which can be dependent or independent of the xenoreactive immune response. Depletion of endothelial anticoagulants and anti-platelet capacity amplify coagulation activation, and interspecies incompatibilities of coagulation-regulatory proteins facilitate dysregulation. LSECs involved in platelet phagocytosis and transcytosis, coupled with hepatocyte-mediated degradation, are responsible for thrombocytopenia. Adaptive immunity could also be problematic in long-term liver graft survival. Currently, relevant evidence and study results of various genetic modifications to the pig donor need to be fully determined, with the aim of identifying the ideal transgene combination for pig liver xenotransplantation. We believe that clinical trials of pig liver xenotransplantation should initially be considered as a bridge to allotransplantation. K E Y W O R D Scoagulation dysregulation, genetically engineered, liver, pig, xenotransplantation

“…In support of their hypothesis, expression of PD‐L1 significantly reduced human immune cell proliferation and improved cell survival. Similarly, Abicht et al genetically engineered pigs for hearts expressing combinations of transgenes. Using an ex vivo model in human blood, they demonstrate how the human immune system might respond to a porcine donor graft.…”

Section: Basic Researchmentioning

confidence: 99%

Xenotransplantation literature update, September/October 2018

Taylor

Levy

Burlak

2018

Xenotransplantation

Damage from hypoxia is a significant hurdle for effect islet transplantation. Past studies have shown that porcine islet cells are protected from hypoxic damage when cultured with human mesenchymal stem cells (MSCs). To better understand how MSCs protect islet cells, Nie et al evaluated the contribution of MSC-secreted factors. MSC-conditioned media (CM) and exosomes reduced cellular apoptosis leading to enhanced cell survival. 1 Additionally, CM and exosomes activated transcriptional programs in islet cells associated with hypoxia tolerance, including hypoxia-inducible factor 1 alpha (Hif1-alpha). The review article by Smith et al 2 focuses on cellular encapsulation to protect recipients from antigenic donor grafts. They discuss new discoveries, issues, and strategies for wrapping up the donor cells, including an overview of device characteristics. 2 of 2 | TAYLOR eT AL. Non-Gal antigens in porcine cells have long been of interest for engineering an optimal porcine donor graft to use in clinical xenotransplantation. The review written by Byrne et al provides detailed and supportive information on a critical non-Gal antigen, B4GalNT2, and illustrates that when deleted, porcine cells are targeted less by the immune system. 10 2 | IMMUNE SUPPRE SS ION Corneal transplants using porcine tissues are a promising solution to a global need for corneal tissue to correct blindness. Descemet's membrane endothelial keratoplasty (DMEK) is an innovative transplantation technique that benefits from low rejection rates and requisite immunosuppression and results in superior vision recovery compared to other surgical techniques. Indeed, in current issue, Kim et al 11 demonstrate that immunosuppression with the common agent tacrolimus can lead to asymptomatic thrombotic microangiopathy that can lead to a number of problems including organ damage. Minimizing the need for immunosuppression by improved graft quality, genetics, and preparation may therefore enhance tissue survival long term. Liu et al 12 tested the feasibility of porcine xenografts using the DMEK technique. Here, the group used two techniques, mechanical stripping and liquid bubble, to prepare the ultra-thin DMEK prior to transplantation. The data, including a comparison of endothelial growth, were promising and indicate that corneal xenografts using DMEK are a viable future option. The authors plan next to test the xeno-DMEK in a non-human primate model. Successful xenotransplantation currently requires immunosuppression. Unfortunately, the immunosuppression regimen may be lethal, by a yet unidentified mechanism, though often linked with anti-CD154 antibody treatment. Ock et al 13 used a non-human primate model (cynomolgus macaques) to evaluate the transcriptional changes prior to and after the standard immunosuppression protocol for porcine cardiac xenotransplantation (alpha-1,3-galactosyltransferase KO pigs). The regimen included cobra venom factor, anti-thymocyte globulin, and rituximab, in the presence or absence of anti-CD154 antibodies. The authors identified a...