Reduction in Xenogeneic Epitopes on Porcine Endothelial Cells by Periodate Oxidation.

Background: Patterns of humoral immune responses represent a major hurdle in terms of pig-to-human xenotransplantation approaches. The best-known xenogeneic glycan antigens present in pigs are the αGal (Galili antigen) and the non-human sialic acid Neu5Gc. As there are further differences between porcine and human cellular surface glycosylation, a much broader range of glycan epitopes with xeno-reactive relevance can be anticipated.

Serial assessment of early antibody binding to decellularized valved allografts.

Objectives: Decellularized homograft valves (DHV) appear to elicit an immune response despite efficient donor cell removal.

Materials And Methods: A semiquantitative Dot-Blot analysis for preformed and new recipient antibodies was carried out in 20 patients following DHV implantation on days 0, 1, 7, and 28 using secondary antihuman antibodies. Immune reactions were tested against the implanted DHV as well as against the stored samples of 5 non-implanted decellularized aortic (DAH) and 6 pulmonary homografts (DPH).

Immunological and functional features of decellularized xenogeneic heart valves after transplantation into GGTA1-KO pigs.

Decellularization of xenogeneic heart valves might lead to excellent regenerative implants, from which many patients could benefit. However, this material carries various xenogeneic epitopes and thus bears a considerable inherent immunological risk. Here, we investigated the regenerative and immunogenic potential of xenogeneic decellularized heart valve implants using pigs deficient for the galactosyltransferase gene (GGTA1-KO) as novel large animal model.

Residual immune response towards decellularized homografts may be highly individual.

Objectives: Decellularized homograft valves (DHVs) have shown promising clinical results, particularly in the treatment of congenital heart disease. However, DHV appears to elicit an immune response in a subset of young patients, indicated by early valve degeneration. As the decellularization process is quality controlled for each DHV, we hypothesized that there may be residual immunogenicity within the extracellular matrix of DHV.

Dot blots of solubilized extracellular matrix allow quantification of human antibodies bound to epitopes present in decellularized porcine pulmonary heart valves.

Background: The present study reports the development of a sensitive dot blot protocol for determining the level of preformed antibodies against porcine heart valve tissue derived from wild-type (WT) and α-Gal-KO (GGTA1-KO) pigs in human sera.

Methods: The assay uses decellularized and solubilized heart valve tissue; antibody binding found in this dot blot assay could be correlated with antibody titers of preformed anti-α-Gal and anti-Neu5Gc antibodies detected by a sensitive ELISA.

Results: The ultimate protocol had an inter-assay variance of 9.

Toward acellular xenogeneic heart valve prostheses: Histological and biomechanical characterization of decellularized and enzymatically deglycosylated porcine pulmonary heart valve matrices.

The use of decellularized xenogeneic heart valves might offer a solution to overcome the issue of human valve shortage. The aim of this study was to revise decellularization protocols in combination with enzymatic deglycosylation, in order to reduce the immunogenicity of porcine pulmonary heart valves, in means of cells, carbohydrates, and, primarily, Galα1-3Gal (α-Gal) epitope removal. In particular, the valves were decellularized with sodium dodecylsulfate/sodium deoxycholate (SDS/SD), Triton X-100 + SDS (Tx + SDS), or Trypsin + Triton X-100 (Tryp + Tx) followed by enzymatic digestion with PNGaseF, Endoglycosidase H, or O-glycosidase combined with Neuraminidase.

Decellularization combined with enzymatic removal of N-linked glycans and residual DNA reduces inflammatory response and improves performance of porcine xenogeneic pulmonary heart valves in an ovine in vivo model.

Background: Limited availability of decellularized allogeneic heart valve substitutes restricts the clinical application thereof. Decellularized xenogeneic valves might constitute an attractive alternative; however, increased immunological hurdles have to be overcome. This study aims for the in vivo effect in sheep of decellularized porcine pulmonary heart valves (dpPHV) enzymatically treated for N-glycan and DNA removal.

Decellularized pig pulmonary heart valves-Depletion of nucleic acids measured by proviral PERV pol.

Background: Decellularized human pulmonary heart valve (dhHV) scaffolds have been shown to be the gold standard especially for younger, adolescent patients. However, human heart valves are limited in availability. Xenogeneic decellularized pig heart valves (dpHV) may serve as alternative.

In vivo performance of freeze-dried decellularized pulmonary heart valve allo- and xenografts orthotopically implanted into juvenile sheep.

Unlabelled: The decellularization of biological tissues decreases immunogenicity, allows repopulation with cells, and may lead to improved long-term performance after implantation. Freeze drying these tissues would ensure off-the-shelf availability, save storage costs, and facilitates easy transport. This study evaluates the in vivo performance of freeze-dried decellularized heart valves in juvenile sheep.

Effects of combined cryopreservation and decellularization on the biomechanical, structural and biochemical properties of porcine pulmonary heart valves.

Unlabelled: Non-fixed, decellularized allogeneic heart valve scaffolds seem to be the best choice for heart valve replacement, their availability, however, is quite limited. Cryopreservation could prolong their shelf-life, allowing for their ideal match to a recipient. In this study, porcine pulmonary valves were decellularized using detergents, either prior or after cryopreservation, and analyzed.

Decellularized GGTA1-KO pig heart valves do not bind preformed human xenoantibodies.

Pre-clinical and clinical data have unequivocally demonstrated the usefulness of decellularized heart valve (HV) matrices implanted for HV replacement therapy. However, human donor valves applicable for decellularization are in short supply, which prompts the search for suitable alternatives, such as porcine grafts. Since decellularization might be insufficient to remove all xenoantigens, we analysed the interaction of human preformed antibodies with decellularized porcine HV in vitro to assess potential immune reactions upon implantation.

No evidence for αGal epitope transfer from media containing FCS onto human endothelial cells in culture.

Background: Current clinical applications of cell therapies and tissue engineered (TE) constructs aim to generate non-immunogenic cells in the best-case scenario of autologous origin. As the cells are cultured, it is theoretically possible that immunoreactive molecules present in xenogenic cell culture media components, such as fetal calf serum (FCS), are transmitted in the culturing process. This problem has propelled the search for xeno-free culture media; however, in vitro culturing of many cell types, especially TE constructs which consist of several cell types, still relies to a great extent on FCS.

Mesodermal origin of median fin mesenchyme and tail muscle in amphibian larvae.

Mesenchyme is an embryonic precursor tissue that generates a range of structures in vertebrates including cartilage, bone, muscle, kidney, and the erythropoietic system. Mesenchyme originates from both mesoderm and the neural crest, an ectodermal cell population, via an epithelial to mesenchymal transition (EMT). Because ectodermal and mesodermal mesenchyme can form in close proximity and give rise to similar derivatives, the embryonic origin of many mesenchyme-derived tissues is still unclear.

Sucrose Diffusion in Decellularized Heart Valves for Freeze-Drying.

Decellularized heart valves can be used as starter matrix implants for heart valve replacement therapies in terms of guided tissue regeneration. Decellularized matrices ideally need to be long-term storable to assure off-the-shelf availability. Freeze-drying is an attractive preservation method, allowing storage at room temperature in a dried state.

Successful re-endothelialization of a perfusable biological vascularized matrix (BioVaM) for the generation of 3D artificial cardiac tissue.

Generating cellularized 3D constructs with clinical relevant dimensions is challenged by nutrition supply. This is of utmost importance for cardiac tissue engineering, since cardiomyocytes are extremely sensitive to malnutrition and hypoxia in vitro and after implantation. To develop a perfusable myocardial patch, we have focused on seeding a decellularized biological vascularized matrix (BioVaM) with endothelial cells.