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  • 1
    In: Xenotransplantation, Wiley, Vol. 28, No. 1 ( 2021-01)
    Abstract: Successful preclinical transplantations of porcine hearts into baboon recipients are required before commencing clinical trials. Despite years of research, over half of the orthotopic cardiac xenografts were lost during the first 48 hours after transplantation, primarily caused by perioperative cardiac xenograft dysfunction (PCXD). To decrease the rate of PCXD, we adopted a preservation technique of cold non‐ischemic perfusion for our ongoing pig‐to‐baboon cardiac xenotransplantation project. Methods Fourteen orthotopic cardiac xenotransplantation experiments were carried out with genetically modified juvenile pigs (GGTA1‐ KO/hCD46/hTBM) as donors and captive‐bred baboons as recipients. Organ preservation was compared according to the two techniques applied: cold static ischemic cardioplegia (IC; n = 5) and cold non‐ischemic continuous perfusion (CP; n = 9) with an oxygenated albumin‐containing hyperoncotic cardioplegic solution containing nutrients, erythrocytes and hormones. Prior to surgery, we measured serum levels of preformed anti‐non‐Gal‐antibodies. During surgery, hemodynamic parameters were monitored with transpulmonary thermodilution. Central venous blood gas analyses were taken at regular intervals to estimate oxygen extraction, as well as lactate production. After surgery, we measured troponine T and serum parameters of the recipient’s kidney, liver and coagulation functions. Results In porcine grafts preserved with IC, we found significantly depressed systolic cardiac function after transplantation which did not recover despite increasing inotropic support. Postoperative oxygen extraction and lactate production were significantly increased. Troponin T, creatinine, aspartate aminotransferase levels were pathologically high, whereas prothrombin ratios were abnormally low. In three of five IC experiments, PCXD developed within 24 hours. By contrast, all nine hearts preserved with CP retained fully preserved systolic function, none showed any signs of PCXD. Oxygen extraction was within normal ranges; serum lactate as well as parameters of organ functions were only mildly elevated. Preformed anti‐non‐Gal‐antibodies were similar in recipients receiving grafts from either IC or CP preservation. Conclusions While standard ischemic cardioplegia solutions have been used with great success in human allotransplantation over many years, our data indicate that they are insufficient for preservation of porcine hearts transplanted into baboons: Ischemic storage caused severe impairment of cardiac function and decreased tissue oxygen supply, leading to multi‐organ failure in more than half of the xenotransplantation experiments. In contrast, cold non‐ischemic heart preservation with continuous perfusion reliably prevented early graft failure. Consistent survival in the perioperative phase is a prerequisite for preclinical long‐term results after cardiac xenotransplantation.
    Type of Medium: Online Resource
    ISSN: 0908-665X , 1399-3089
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2011995-1
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  • 2
    In: Transplantation, Ovid Technologies (Wolters Kluwer Health), Vol. 105, No. 8 ( 2021-08), p. 1747-1759
    Abstract: The lymphatic system plays an active role in modulating inflammation in autoimmune diseases and organ rejection. In this work, we hypothesized that the transfer of donor lymph node (LN) might be used to promote lymphangiogenesis and influence rejection in vascularized composite allotransplantation (VCA). Methods. Hindlimb transplantations were performed in which (1) recipient rats received VCA containing donor LN (D:LN + ), (2) recipient rats received VCA depleted of all donor LN (D:LN − ), and (3) D:LN + transplantations were followed by lymphangiogenesis inhibition using a vascular endothelial growth factor receptor-3 (VEGFR3) blocker. Results. Our data show that graft rejection started significantly later in D:LN + transplanted rats as compared to the D:LN − group. Moreover, we observed a higher level of VEGF-C and a quicker and more efficient lymphangiogenesis in the D:LN + group as compared to the D:LN − group. The presence of donor LN within the graft was associated with reduced immunoactivation in the draining LN and increased frequency of circulating and skin-resident donor T regulatory cells. Blocking of the VEGF-C pathway using a VEGFR3 blocker disrupts the lymphangiogenesis process, accelerates rejection onset, and interferes with donor T-cell migration. Conclusions. This study demonstrates that VCA LNs play a pivotal role in the regulation of graft rejection and underlines the potential of specifically targeting the LN component of a VCA to control graft rejection.
    Type of Medium: Online Resource
    ISSN: 0041-1337
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2021
    detail.hit.zdb_id: 2035395-9
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  • 3
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    Frontiers Media SA ; 2022
    In:  Frontiers in Cardiovascular Medicine Vol. 9 ( 2022-5-13)
    In: Frontiers in Cardiovascular Medicine, Frontiers Media SA, Vol. 9 ( 2022-5-13)
    Abstract: The physiological, anti-inflammatory, and anti-coagulant properties of endothelial cells (ECs) rely on a complex carbohydrate-rich layer covering the luminal surface of ECs, called the glycocalyx. In a range of cardiovascular disorders, glycocalyx shedding causes endothelial dysfunction and inflammation, underscoring the importance of glycocalyx preservation to avoid disease initiation and progression. In this review we discuss the physiological functions of the glycocalyx with particular focus on how loss of endothelial glycocalyx integrity is linked to cardiovascular risk factors, like hypertension, aging, diabetes and obesity, and contributes to the development of thrombo-inflammatory conditions. Finally, we consider the role of glycocalyx components in regulating inflammatory responses and discuss possible therapeutic interventions aiming at preserving or restoring the endothelial glycocalyx and therefore protecting against cardiovascular disease.
    Type of Medium: Online Resource
    ISSN: 2297-055X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2781496-8
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  • 4
    In: The Journal of Heart and Lung Transplantation, Elsevier BV, Vol. 39, No. 8 ( 2020-08), p. 751-757
    Type of Medium: Online Resource
    ISSN: 1053-2498
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
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  • 5
    In: Xenotransplantation, Wiley, Vol. 30, No. 5 ( 2023-09)
    Abstract: Xenotransplantation is a promising approach to reduce organ shortage, while genetic modification of donor pigs has significantly decreased the immunogenic burden of xenotransplants, organ rejection is still a hurdle. Genetically modified pig organs are used in xenotransplantation research, and the first clinical pig‐to‐human heart transplantation was performed in 2022. However, the impact of genetic modification has not been investigated on a cellular level yet. Endothelial cells (EC) and their sugar‐rich surface known as the glycocalyx are the first barrier encountering the recipient's immune system, making them a target for rejection. We have previously shown that wild type venous but not arterial EC were protected against heparan sulfate (HS) shedding after activation with human serum or human tumor necrosis factor alpha (TNF 𝛼 ). Using a 2D microfluidic system we investigated the glycocalyx dynamics of genetically modified porcine arterial and venous EC (Gal 𝛼 1,3 Gal knock‐out, transgenic for human CD46 and thrombomodulin, GTKO/hCD46/hTM) after activation with human serum or human TNF 𝛼 . Interestingly, we observed that GTKO/hCD46/hTM arterial cells, additionally to venous cells, do not shed HS. Unscathed HS on GTKO/hCD46/hTM EC correlated with reduced complement deposition, suggesting that protection against complement activation contributes to maintaining an intact glycocalyx layer on arterial EC. This protection was lost on GTKO/hCD46/hTM cells after simultaneous perfusion with human serum and human TNF 𝛼 . HS shedding on arterial cells and increased complement deposition on both arterial and venous cells was observed. These findings suggest that GTKO/hCD46/hTM EC revert to a proinflammatory phenotype in an inflammatory xenotransplantation setting, potentially favoring transplant rejection.
    Type of Medium: Online Resource
    ISSN: 0908-665X , 1399-3089
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 2011995-1
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  • 6
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 10, No. 1 ( 2020-10-16)
    Abstract: Xenotransplantation using pig organs has achieved survival times up to 195 days in pig orthotopic heart transplantation into baboons. Here we demonstrate that in addition to an improved immunosuppressive regimen, non-ischaemic preservation with continuous perfusion and control of post-transplantation growth of the transplant, prevention of transmission of the porcine cytomegalovirus (PCMV) plays an important role in achieving long survival times. For the first time we demonstrate that PCMV transmission in orthotopic pig heart xenotransplantation was associated with a reduced survival time of the transplant and increased levels of IL-6 and TNFα were found in the transplanted baboon. Furthermore, high levels of tPA-PAI-1 complexes were found, suggesting a complete loss of the pro-fibrinolytic properties of the endothelial cells. These data show that PCMV has an important impact on transplant survival and call for elimination of PCMV from donor pigs.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2020
    detail.hit.zdb_id: 2615211-3
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  • 7
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 13, No. 1 ( 2023-03-18)
    Abstract: Endothelial dysfunction is an early event of vascular injury defined by a proinflammatory and procoagulant endothelial cell (EC) phenotype. Although endothelial glycocalyx disruption is associated with vascular damage, how various inflammatory stimuli affect the glycocalyx and whether arterial and venous cells respond differently is unknown. Using a 3D round-channel microfluidic system we investigated the endothelial glycocalyx, particularly heparan sulfate (HS), on porcine arterial and venous ECs. Heparan sulfate (HS)/glycocalyx expression was observed already under static conditions on venous ECs while it was flow-dependent on arterial cells. Furthermore, analysis of HS/glycocalyx response after stimulation with inflammatory cues revealed that venous, but not arterial ECs, are resistant to HS shedding. This finding was observed also on isolated porcine vessels. Persistence of HS on venous ECs prevented complement deposition and clot formation after stimulation with tumor necrosis factor α or lipopolysaccharide, whereas after xenogeneic activation no glycocalyx-mediated protection was observed. Contrarily, HS shedding on arterial cells, even without an inflammatory insult, was sufficient to induce a proinflammatory and procoagulant phenotype. Our data indicate that the dimorphic response of arterial and venous ECs is partially due to distinct HS/glycocalyx dynamics suggesting that arterial and venous thrombo-inflammatory disorders require targeted therapies.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2615211-3
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