Prevalence of Antibodies against Adeno-Associated Viruses (AAVs) in Göttingen Minipigs and Its Implications for Gene Therapy and Xenotransplantation.

Adeno-associated viruses (AAV) are widely used as delivery vectors in clinical trials for in vivo gene therapy due to their unique features. Göttingen minipigs are a well-established animal model for several diseases and can be used for the efficacy and safety testing of AAV-based gene therapy. Pre-existing antibodies against AAV may influence the results of testing and, therefore, the animals should be tested for the presence of antibodies against relevant AAV serotypes.

Monitoring for PERV Following Xenotransplantation.

Porcine endogenous retroviruses (PERVs) are integrated in the genome of all pigs. PERV-A, PERV-B and PERV-C can be released as infectious virus particles and PERV-A and PERV-B can infect human cells in culture. PERV-C does not infect human cells, but high-titer recombinant PERV-A/C can infect them.

Combination of Anti-CD40 and Anti-CD40L Antibodies as Co-Stimulation Blockade in Preclinical Cardiac Xenotransplantation.

The blockade of the CD40/CD40L immune checkpoint is considered essential for cardiac xenotransplantation. However, it is still unclear which single antibody directed against CD40 or CD40L (CD154), or which combination of antibodies, is better at preventing organ rejection. For example, the high doses of antibody administered in previous experiments might not be feasible for the treatment of humans, while thrombotic side effects were described for first-generation anti-CD40L antibodies.

An Approach to Controlling Inflammation and Coagulation in Pig-to-Baboon Cardiac Xenotransplantation.

Introduction: Inflammatory responses and coagulation disorders are a relevant challenge for successful cardiac xenotransplantation on its way to the clinic. To cope with this, an effective and clinically practicable anti-inflammatory and anti-coagulatory regimen is needed. The inflammatory and coagulatory response can be reduced by genetic engineering of the organ-source pigs.

The Endothelial Glycocalyx in Pig-to-Baboon Cardiac Xenotransplantation-First Insights.

Cardiac xenotransplantation has seen remarkable success in recent years and is emerging as the most promising alternative to human cardiac allotransplantation. Despite these achievements, acute vascular rejection still presents a challenge for long-term xenograft acceptance and new insights into innate and adaptive immune responses as well as detailed characterizations of signaling pathways are necessary. In allotransplantation, endothelial cells and their sugar-rich surface-the endothelial glycocalyx-are known to influence organ rejection.

[Xenotransplantation of solid organs].

Transplantation of genetically modified porcine hearts and kidneys could become a solution to the persistent shortage of human organ donors. Progress has been made in genetic engineering of donor pigs, preservation techniques after organ harvesting and immunosuppression using co-stimulation blockade with anti-CD40/CD40L monoclonal antibodies. Progress has also been made in in the development of methods that detect pathogenic porcine viruses and prevent their transmission to the recipient.

Limited availability of methods for the detection of xenotransplantation-relevant viruses in veterinary laboratories.

Background: The German Xenotransplantation Consortium is in the process to prepare a clinical trial application (CTA) on xenotransplantation of genetically modified pig hearts. In the CTA documents to the central and national regulatory authorities, that is, the European Medicines Agency (EMA) and the Paul Ehrlich Institute (PEI), respectively, it is required to list the potential zoonotic or xenozoonotic porcine microorganisms including porcine viruses as well as to describe methods of detection in order to prevent their transmission. The donor animals should be tested using highly sensitive detection systems.

Genetic diversity, growth and heart function of Auckland Island pigs, a potential source for organ xenotransplantation.

One of the prerequisites for successful organ xenotransplantation is a reasonable size match between the porcine organ and the recipient's organ to be replaced. Therefore, the selection of a suitable genetic background of source pigs is important. In this study, we investigated body and organ growth, cardiac function, and genetic diversity of a colony of Auckland Island pigs established at the Center for Innovative Medical Models (CiMM), LMU Munich.

Screening for Viruses in Indigenous Greek Black Pigs.

The successful advancement of xenotransplantation has led to the development of highly sensitive detection systems for the screening of potentially zoonotic viruses in donor pigs and preventing their transmission to the recipient. To validate these methods, genetically modified pigs generated for xenotransplantation, numerous minipigs and other pig breeds have been tested, thereby increasing our knowledge concerning the pig virome and the distribution of pig viruses. Of particular importance are the porcine cytomegalovirus, a porcine roseolovirus (PCMV/PRV) and the hepatitis E virus genotype 3 (HEV3).

Porcine endogenous retroviruses in xenotransplantation.

Xenotransplantation using pig cells, tissues or organs is under development to alleviate the shortage of human donor organs. Meanwhile, remarkably long survival times of pig organs in non-human primates have been reported, as well as the functionality of pig kidneys and hearts in brain-dead humans. Most importantly, two transplantations of pig hearts in patients were performed with survival times of the patients of 8 and 6 weeks.

Determination of the Copy Number of Porcine Endogenous Retroviruses (PERV) in Auckland Island Pigs Repeatedly Used for Clinical Xenotransplantation and Elimination of PERV-C.

Auckland Island pigs represent an inbred population of feral pigs isolated on the sub-Antarctic island for over 100 years. The animals have been maintained under pathogen-free conditions in New Zealand; they are well characterized virologically and have been used as donor sources in first clinical trials of porcine neonatal islet cell transplantation for the treatment of human diabetes patients. The animals do not carry any of the xenotransplantation-relevant viruses, and in the first clinical trials, no porcine viruses, including porcine endogenous retroviruses (PERVs) were transmitted to the human recipients.

Current Status of Cardiac Xenotransplantation: Report of a Workshop of the German Heart Transplant Centers, Martinsried, March 3, 2023.

This report comprises the contents of the presentations and following discussions of a workshop of the German Heart Transplant Centers in Martinsried, Germany on cardiac xenotransplantation. The production and current availability of genetically modified donor pigs, preservation techniques during organ harvesting, and immunosuppressive regimens in the recipient are described. Selection criteria for suitable patients and possible solutions to the problem of overgrowth of the xenotransplant are discussed.

The large extracellular loop is important for recruiting CD63 to exosomes.

Exosomes are small extracellular vesicles that are secreted from cells. To characterize exosome fraction marker proteins of the tetraspanin family in particular, CD9, CD63, and CD81 are routinely used. CD63 expression constructs were employed to investigate the influence of the large extracellular loop (LEL) of CD63 on sorting into exosomes.

Evidence for Microchimerism in Baboon Recipients of Pig Hearts.

Xenotransplantation, like allotransplantation, is usually associated with microchimerism, i.e., the presence of cells from the donor in the recipient.

Sensitive detection of lipopolysaccharides by monitoring of interleukin-10 secretion from human PBMCs.

Lipopolysaccharide (LPS) contaminations may falsify immunological experiments and are crucial for pharmaceutical products because they cause life-threatening immune reactions. Here, we present interleukin-10 (IL-10) as a reliable marker to measure LPS contents when the readout of pro-inflammatory cytokines is not favored. This animal free source assay is able to detect LPS with a limit of detection (LOD) of 0.

Microchimerism, PERV and Xenotransplantation.

Microchimerism is the presence of cells in an individual that have originated from a genetically distinct individual. The most common form of microchimerism is fetomaternal microchimerism, i.e.