Anti-pig antibodies in swine veterinarian serum: Implications for clinical xenotransplantation.

Recent clinical xenotransplantation and human decedent studies demonstrate that clinical hyperacute rejection of genetically engineered porcine organs can be reliably avoided but that antibody mediated rejection (AMR) continues to limit graft survival. We previously identified porcine glycans and proteins which are immunogenic after cardiac xenotransplantation in non-human primates, but the clinical immune response to antigens present in glycan depleted triple knockout (TKO) donor pigs is poorly understood. In this study we use fluorescence barcoded human embryonic kidney cells (HEK) and HEK cell lines expressing porcine glycans (Gal and SDa) or proteins (tetraspanin-29 [CD9], membrane cofactor protein [CD46], protectin, membrane attack complex inhibition factor [CD59], endothelial cell protein C receptor, and Annexin A2) to screen antibody reactivity in human serum from 160 swine veterinarians, a serum source with potential occupational immune challenge from porcine tissues and pathogens.

Genetically engineered sheep: A new paradigm for future preclinical testing of biological heart valves.

Background: Heart valve implantation in juvenile sheep to demonstrate biocompatibility and physiologic performance is the accepted model for regulatory approval of new biological heart valves (BHVs). However, this standard model does not detect the immunologic incompatibility between the major xenogeneic antigen, galactose-α-1,3-galactose (Gal), which is present in all current commercial BHVs, and patients who universally produce anti-Gal antibody. This clinical discordance leads to induced anti-Gal antibody in BHV recipients, promoting tissue calcification and premature structural valve degeneration, especially in young patients.

Biological Equivalence of GGTA-1 Glycosyltransferase Knockout and Standard Porcine Pericardial Tissue Using 90-Day Mitral Valve Implantation in Adolescent Sheep.

Objective: There is growing interest in the application of genetically engineered reduced antigenicity animal tissue for manufacture of bioprosthetic heart valves (BHVs) to reduce antibody induced tissue calcification and accelerated structural valve degeneration (SVD). This study tested biological equivalence of valves made from Gal-knockout (GalKO) and standard porcine pericardium after 90-day mitral valve implantation in sheep.

Methods: GalKO (n = 5) and standard (n = 5) porcine pericardial BHVs were implanted in a randomized and blind fashion into sheep for 90-days.

A Case Series of Long-Term Surgical Outcomes of Primary Pulmonary Artery Sarcomas With Opportunities for 3D-Printed Models in Surgical Planning.

There are limited data regarding the surgical management of primary pulmonary artery sarcomas (PPAS) because of their rarity and complicated diagnostic history. The objective of this study was to analyze our institution's long-term surgical management outcomes for PPAS in the absence of a care pathway. From May 1997 to June 2013, 8 patients (mean age 60.

A Durable Porcine Pericardial Surgical Bioprosthetic Heart Valve: a Proof of Concept.

Bioprosthetic leaflets made from animal tissues are used in the majority of surgical and transcatheter cardiac valve replacements. This study develops a new surgical bioprosthesis, using porcine pericardial leaflets. Porcine pericardium was obtained from genetically engineered pigs with a mutation in the GGTA-1 gene (GTKO) and fixed in 0.

Proteomic Analysis of the Myocardium in Hypertrophic Obstructive Cardiomyopathy.

Background: Hypertrophic cardiomyopathy (HCM) is characterized by a complex phenotype that is only partly explained by the biological effects of individual genetic variants. The aim of this study was to use proteomic analysis of myocardial tissue to explore the postgenomic phenotype.

Methods: Label-free proteomic analysis was used initially to compare protein profiles in myocardial samples from 11 patients with HCM undergoing surgical myectomy with control samples from 6 healthy unused donor hearts.

B4GALNT2 and xenotransplantation: A newly appreciated xenogeneic antigen.

Analysis of non-Gal antibody induced after pig-to-baboon cardiac xenotransplantation identified the glycan produced by porcine beta-1,4-N-acetyl-galactosaminyltransferase 2 (B4GALNT2) as an immunogenic xenotransplantation antigen. The porcine B4GALNT2 enzyme is homologous to the human enzyme, which synthesizes the human SDa blood group antigen. Most humans produce low levels of anti-SDa IgM which polyagglutinates red blood cells from rare individuals with high levels of SDa expression.

Individualized surgical strategies for left ventricular outflow tract obstruction in hypertrophic cardiomyopathy.

Objectives: Surgical strategies to treat drug refractory left ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy include septal myectomy (SM) and, less frequently, mitral valve (MV) repair or replacement. The primary aim of this study was to report the surgical technique and management outcomes in a consecutive group of patients with variable phenotypes of hypertrophic cardiomyopathy in a broad national specialist practice.

Methods: A total of 203 consecutive patients, 132 men (mean age 48.

Porcine to Human Heart Transplantation: Is Clinical Application Now Appropriate?

Cardiac xenotransplantation (CXTx) is a promising solution to the chronic shortage of donor hearts. Recent advancements in immune suppression have greatly improved the survival of heterotopic CXTx, now extended beyond 2 years, and life-supporting kidney XTx. Advances in donor genetic modification (B4GALNT2 and CMAH mutations) with proven Gal-deficient donors expressing human complement regulatory protein(s) have also accelerated, reducing donor pig organ antigenicity.

Early and medium-term outcomes of Alfieri mitral valve repair in the management of systolic anterior motion during septal myectomy.

Background: This report studies the early and medium-term clinical and echocardiographic outcomes of the Alfieri edge-to-edge mitral valve repair, as adjunctive therapy, to prevent and treat systolic anterior motion (SAM) at the time of septal myectomy (SM) for left ventricular outflow tract obstruction in hypertrophic cardiomyopathy.

Methods: From 2009-2015, 11 consecutive patients had a trans-atrial Alfieri repair, to prevent (n = 7) or treat (n = 4) SAM at the time of SM.

Results: No patients were lost to follow-up.

Long-term outcomes for different surgical strategies to treat left ventricular outflow tract obstruction in hypertrophic cardiomyopathy.

Aims: Surgical intervention is used to treat dynamic left ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy. This study assesses the effect of different surgical strategies on long-term mortality and morbidity.

Methods And Results: In total, 347 patients underwent surgical intervention for LVOTO (1988-2015).

An acquired Gerbode defect from the left ventricle to the coronary sinus following mitral valve replacement.

We report the management of an acquired Gerbode defect, from the left ventricle to the coronary sinus, following mechanical mitral valve replacement. Following a failed percutaneous closure, surgical patch closure of the defect was performed.

Long term outcomes of cardiac transplant for immunoglobulin light chain amyloidosis: The Mayo Clinic experience.

Aim: To determine the outcome of orthotopic heart transplantation (OHT) in immunoglobulin light chain (AL) amyloidosis.

Methods: The medical records of patients with AL who underwent orthotopic heart transplantation at the Mayo Clinic in Rochester Minnesota from 1992 to 2011 were reviewed. Patients met at least one of the following at: New York Heart Association class IV heart failure, ventricular thickness > 15 mm, ejection fraction < 40%.

Physical equivalency of wild type and galactose α 1,3 galactose free porcine pericardium; a new source material for bioprosthetic heart valves.

Unlabelled: Humans make high levels of antibody to carbohydrates with terminal galactose α 1,3 galactose (Gal) modifications. This Gal antigen is widely expressed in other mammals and is present on an array of current animal derived biomedical devices including bioprosthetic heart valves. There is growing interest in using Gal-free animal tissues from Gal knockout pigs (GTKO) as these tissues would not be affected by anti-Gal antibody mediated injury.

Pre-clinical heterotopic intrathoracic heart xenotransplantation: a possibly useful clinical technique.

Background: As a step towards clinical cardiac xenotransplantation, our experimental heterotopic intrathoracic xenotransplantation model offers a beating and ejecting donor heart while retaining the recipient's native organ as a backup in case of graft failure. Clinically applicable immunosuppressive regimens (IS) were investigated first, then treatments known to be effective in hypersensitized patients or those with recalcitrant rejection reactions.

Methods: Consecutive experiments were carried out between 2009 and 2013.

A pig-to-mouse coronary artery transplantation model for investigating the pathogenicity of anti-pig antibody.

Background: Rejection of Gal-free (GTKO) donor pig cardiac xenografts is strongly associated with vascular non-Gal antibody binding, endothelial cell (EC) injury, and activation and microvascular thrombosis. We adopted a pig-to-SCID/beige small animal transplant model to compare the pathogenicity of baboon and human anti-pig antibody.

Methods: Wild-type (GT(+) ) or GTKO porcine coronary arteries (PCAs) were transplanted into the infrarenal aorta of SCID/beige mice.

Current status of pig heart xenotransplantation.

Significant progress in understanding and overcoming cardiac xenograft rejection using a clinically relevant large animal pig-to-baboon model has accelerated in recent years. This advancement is based on improved immune suppression, which attained more effective regulation of B lymphocytes and possibly newer donor genetics. These improvements have enhanced heterotopic cardiac xenograft survival from a few weeks to over 2 years, achieved intrathoracic heterotopic cardiac xenograft survival of 50 days and orthotopic survival of 57 days.

Recent investigations into pig antigen and anti-pig antibody expression.

Genetic engineering of donor pigs to eliminate expression of the dominant xenogeneic antigen galactose α1,3 galactose (Gal) has created a sea change in the immunobiology of xenograft rejection. Antibody mediated xenograft rejection of GGTA-1 α-galactosyltransferase (GTKO) deficient organs is now directed to a combination of non-Gal pig protein and carbohydrate antigens. Glycan analysis of GTKO tissues identified no new neo-antigens but detected high levels of N-acetylneuraminic acid (Neu5Gc) modified glycoproteins and glycolipids.

A retrospective analysis of myocardial preservation techniques during coronary artery bypass graft surgery: are we protecting the heart?

Background: Retrograde perfusion into coronary sinus during coronary artery bypass graft (CABG) surgery reduces the need for cardioplegic interruptions and ensures the distribution of cardioplegia to stenosed vessel territories, therefore enhancing the delivery of cardioplegia to the subendocardium. Peri-operative myocardial injury (PMI), as measured by the rise of serum level of cardiac biomarkers, has been associated with short and long-term clinical outcomes. We conducted a retrospective analysis to investigate whether the combination of antegrade and retrograde techniques of cardioplegia delivery is associated with a reduced PMI than that observed with the traditional methods of myocardial preservation.

Development of a consensus protocol to quantify primate anti-non-Gal xenoreactive antibodies using pig aortic endothelial cells.

Background: Scientists working in the field of xenotransplantation do not employ a uniform method to measure and report natural and induced antibody responses to non-Galα(1,3)Gal (non-Gal) epitopes. Such humoral responses are thought to be particularly pathogenic after transplantation of vascularized GalTKO pig organs and having a more uniform assay and reporting format would greatly facilitate comparisons between laboratories.

Methods: Flow cytometry allows examination of antibody reactivity to intact antigens in their natural location and conformation on cell membranes.

Cloning and expression of porcine β1,4 N-acetylgalactosaminyl transferase encoding a new xenoreactive antigen.

Background: Xenograft rejection of pigs organs with an engineered mutation in the GGTA-1 gene (GTKO) remains a predominantly antibody mediated process which is directed to a variety of non-Gal protein and carbohydrate antigens. We previously used an expression library screening strategy to identify six porcine endothelial cell cDNAs which encode pig antigens that bind to IgG induced after pig-to-primate cardiac xenotransplantation. One of these gene products was a glycosyltransferase with homology to the bovine β1,4 N-acetylgalactosaminyltransferase (B4GALNT2).

Histopathologic insights into the mechanism of anti-non-Gal antibody-mediated pig cardiac xenograft rejection.

The histopathology of cardiac xenograft rejection has evolved over the last 20 yr with the development of new modalities for limiting antibody-mediated injury, advancing regimens for immune suppression, and an ever-widening variety of new donor genetics. These new technologies have helped us progress from what was once an overwhelming anti-Gal-mediated hyperacute rejection to a more protracted anti-Gal-mediated vascular rejection to what is now a more complex manifestation of non-Gal humoral rejection and coagulation dysregulation. This review summarizes the changing histopathology of Gal- and non-Gal-mediated cardiac xenograft rejection and discusses the contributions of immune-mediated injury, species-specific immune-independent factors, transplant and therapeutic procedures, and donor genetics to the overall mechanism(s) of cardiac xenograft rejection.