veno-venous-extracorporeal-membrane-oxygenation-in-a-mouse

Veno-Venous Extracorporeal Membrane Oxygenation in a Mouse

The use of extracorporeal membrane oxygenation (ECMO) has increased substantially in recent years. ECMO has become a reliable and effective therapy for ...

Hannover medical school

Clinically, selective antegrade cerebral perfusion (SACP) seems to be associated with a better neurological outcome compared to hypothermic circulatory arrest (HCA) alone, but the pathophysiological mechanisms are not well understood. Therefore, this study was undertaken to assess the effects of HCA with and without SACP on the cerebral integrity using multimodal neurophysiological monitoring.

Hypothermic circulatory arrest with and without cold selective antegrade cerebral perfusion: impact on neurological recovery and tissue metabolism in an acute porcine model.

The production of viable biological heart valves is of central interest in tissue engineering (TE). The aim of this study was to generate decellularized heart valves with an intact ultra-structure and to repopulate these with endothelial cells (EC) under simulated physiological conditions. Decellularization of ovine pulmonary valve conduits was performed under agitation in detergents followed by six wash cycles. Viability of EC cultures exposed to washing solution served to prove efficiency of washing. Resulting scaffolds were free of cells with preserved extracellular matrix. Biomechanical standard tension tests demonstrated comparable parameters to native tissue. Luminal surfaces of decellularized valvular grafts were seeded with ovine jugular vein EC in dynamic bioreactors. After rolling culture for 48 h, pulsatile medium circulation with a flow of 0.1 L/min was started. The flow was incremented 0.3 L/min/day up to 2.0 L/min (cycle rate: 60 beats/min), while pH, pO2, pCO2, lactate and glucose were maintained at constant physiological levels. After 7 days, a monolayer of cells covered the inner valve surface, which expressed vWF, indicating an endothelial origin. A complete endothelialization of detergent decellularized scaffold can be achieved under simulated physiological circulation conditions using a dynamic bioreactor system, which allows continuous control of the culture environment.

In vitro re-endothelialization of detergent decellularized heart valves under simulated physiological dynamic conditions.

The Bentall procedure is the 'gold standard' for the repair of a combined pathology of ascending aorta and aortic valve. Because there is no need for long-term anticoagulation, biological-valved conduits have become increasingly popular; however, the possible need for reoperation due to valve degeneration is a major disadvantage. The aim of this animal-based study was to prove the feasibility of an isolated replacement of the aortic valve prosthesis six months after a previous implantation of a biological valved conduit (BioValsalva) in a sheep model. A total aortic root replacement, using the BioValsalva conduit, was performed in 10 juvenile sheep. After six months, the surviving sheep were reoperated on, and the stentless valve was replaced with a stented biological valve placed inside the previously implanted vascular conduit.

Aortic valve re-replacement after Bentall procedure with a biological valved conduit in a sheep model.

The generation of tissue-engineered blood vessel substitutes remains an ongoing challenge for cardiovascular tissue engineering. Full biocompatibility and immediate availability have emerged as central issues for clinical use. To address these issues, we developed a technique that allows the generation of highly stable tubular fibrin segments. The process is based on the compaction of fibrin in a custom-made high-speed rotation mold. In an automated process, fibrin is precipitated from plasma by means of the Vivostat® system. Following application to the rotating mold, the fibrin was compacted by centrifugal force and excess fluid was pressed out. This compaction results in increasing cross-links between the fibrin fibrils and a corresponding significant increase of biomechanical stability up to a burst strength of 230mm of mercury. The molding process allows for a simultaneous seeding procedure. In a first in vivo evaluation in a sheep model, segments of the carotid artery were replaced by tissue-engineered vascular grafts, generated immediately prior to implantation (n=6). Following subjection to the body's remodeling mechanisms, the segments showed a high structural similarity to a native artery after explantation at 6months. Thus, this technique may represent a powerful tool for the generation of biomechanically stable vascular grafts immediately prior to implantation.

Novel method for the generation of tissue-engineered vascular grafts based on a highly compacted fibrin matrix.

Aortic valve replacement in patients with a small aortic annulus may result in patient-prosthesis mismatch (PPM). Aortic root enlargement (ARE) can reduce PPM, but leads to extended cardiac ischaemia times. Sutureless valves have the potential to prevent PPM while reducing cardiac ischaemia times.

Aortic valve replacement with sutureless prosthesis: better than root enlargement to avoid patient-prosthesis mismatch?

The concept of oligometastases is the medical rationale for a local treatment of a limited number of metastatic tumor manifestations. Patients with pulmonary oligometastases are candidates for surgery or radiotherapy, however there are a number of technical issues that limit treatment. Technical issues relating to radiotherapy include organs at risk of irradiation, chest wall toxicity and decreased precision of tumor targeting because of breathing movements. Technical issues relating to surgery include loss of lung parenchyma and unresectability. We propose the hypothesis that ex-vivo radiosurgery as new hybrid technique in thoracic oncology has the capability to overcome these technical issues and will expand the medical spectrum in thoracic oncology. The proposed - highly complex - technique consists of surgical lung explantation, followed by stereotactic radiotherapy during ex-vivo perfusion followed by surgical re-implantation. 

A new era of thoracic oncology? Ex-vivo stereotactic ablative radiosurgery within Ex-vivo Lung Treatment System as a hybrid therapy for unresectable locally advanced pulmonary malignancies.

Solid organs may differ in their potential to induce and maintain a state of donor-specific tolerance. Previously, we induced stable immunological tolerance in a lung transplantation model in miniature swine. Here, we wished to transfer this established protocol into a heart transplantation model in miniature swine. Heterotopic heart transplantation (HTX) was performed in four and left-sided lung transplantation (LTX) in seven minipigs from gender- and SLA-mismatched donors. All recipients received nonmyeloablative irradiation, donor splenocyte infusion and intravenous pharmacologic immunosuppression for 28 postoperative days. All transplanted hearts were rejected within 95 days. In contrast, four animals of the LTX group developed stable tolerance surviving beyond 500 days, and three further animals rejected 119, 239 and 360 days post-transplantation. In both groups, peripheral blood donor leucocyte chimerism peaked 1 h after reperfusion of the allograft. Importantly, the early chimerism level in the LTX group was significantly higher compared to the HTX group and remained detectable throughout the entire observation period. In conclusion, lungs and hearts vary in their potential to induce a state of tolerance after transplantation in a protocol with pre-operative recipient irradiation and donor splenocyte co-transplantation. This could be due to differential early levels of passenger leucocyte chimerism.

Irradiation before and donor splenocyte infusion immediately after transplantation induce tolerance to lung, but not heart allografts in miniature swine.

The objective of this study was to evaluate surgical handling, in vivo hemodynamic performance and morphological characteristics of decellularized mitral valves (DMVs) in a long-term sheep model.

Decellularized mitral valve in a long-term sheep model.

The emergence of multi-drug resistant bacteria threatens to end the era of antibiotics. Drug resistant bacteria have evolved mechanisms to overcome antibiotics at therapeutic doses and further dose increases are not possible due to systemic toxicity. Here we present a pilot study of ex vivo lung perfusion (EVLP) with high dose antibiotic therapy followed by autotransplantation as a new therapy of last resort for otherwise incurable multidrug resistant lung infections. Severe Pseudomonas aeruginosa pneumonia was induced in the lower left lungs (LLL) of 18 Mini-Lewe pigs. Animals in the control group (n = 6) did not receive colistin. Animals in the conventional treatment group (n = 6) received intravenous application of 2 mg/kg body weight colistin daily. Animals in the EVLP group (n = 6) had their LLL explanted and perfused ex vivo with a perfusion solution containing 200 μg/ml colistin. After two hours of ex vivo treatment, autotransplantation of the LLL was performed. All animals were followed for 4 days following the initiation of treatment. In the control and conventional treatment groups, the infection-related mortality rate after five days was 66.7%. In the EVLP group, there was one infection-related mortality and one procedure-related mortality, for an overall mortality rate of 33.3%. Moreover, the clinical symptoms of infection were less severe in the EVLP group than the other groups. Ex vivo lung perfusion with very high dose antibiotics presents a new therapeutic option of last resort for otherwise incurable multidrug resistant pneumonia without toxic side effects on other organs.

Treatment of infected lungs by ex vivo perfusion with high dose antibiotics and autotransplantation: A pilot study in pigs.

Ex vivo lung perfusion (EVLP) has become routine practice in lung transplantation. Still, running periods exceeding 12 hours have not been undertaken clinically to date, and it remains unclear how the perfusion solution for extended running periods should be composed and which parameters may predict outcomes. Twenty-four porcine lungs underwent EVLP for 24 hours using the Organ Care System (OCS). Lungs were ventilated and perfused with STEEN's solution enriched with erythrocytes (n = 8), acellular STEEN's solution (n = 8), or low-potassium dextran (LPD) solution enriched with erythrocytes (n = 8). After 24 hours, the left lungs were transplanted into recipient pigs. After clamping of the contralateral lung, the recipients were observed for 6 hours. The most favorable outcome was observed in organs utilizing STEEN solution enriched with erythrocytes as perfusate, whereas the least favorable outcome was seen with LPD solution enriched with erythrocytes for perfusion. Animals surviving the observation period showed lower peak airway pressure (PAWP) and pulmonary vascular resistance (PVR) during OCS preservation. The results suggest that transplantation of lungs following 24 hours of EVLP is feasible but dependent on the composition of the perfusate. PAWP and PVR during EVLP are early and late predictors of transplant outcome, respectively.

Prediction of transplant outcome after 24-hour ex vivo lung perfusion using the Organ Care System in a porcine lung transplantation model.

Disparities at the major histocompatibility antigens (MHC) and associated minor antigens trigger harmful immune responses leading to graft rejection after transplantation. We showed that MHC-silenced cells and tissues are efficiently protected against rejection. In complex vascularized organs the endothelium is the major interface between donor and recipient. We therefore aimed at reducing the immunogenicity of the lung by silencing MHC expression on the endothelium. In porcine lungs short-hairpin RNAs targeting beta-2-microglobulin and class II-transactivator transcripts were delivered by lentiviral vectors during normothermic ex vivo perfusion to permanently silence Swine Leukocyte Antigen (SLA) I and II expression. The results demonstrated the feasibility to genetically engineer all lung regions achieving the targeted silencing effect of SLA I and II of 67% and 52%, respectively, without affecting cell viability or tissue integrity. This decrease of immunogenicity carries the potential to generate immunologically invisible organs to counteract the burden of rejection and immunosuppression.

Article	Year
Hypothermic circulatory arrest with and without cold selective antegrade cerebral perfusion: impact on neurological recovery and tissue metabolism in an acute porcine model. European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery\| PubMed ID: 15200982	2004
In vitro re-endothelialization of detergent decellularized heart valves under simulated physiological dynamic conditions. Biomaterials\| PubMed ID: 16620956	2006
Aortic valve re-replacement after Bentall procedure with a biological valved conduit in a sheep model. The Journal of heart valve disease\| PubMed ID: 22474735	2012
Novel method for the generation of tissue-engineered vascular grafts based on a highly compacted fibrin matrix. Acta biomaterialia\| PubMed ID: 26472610	2016
Aortic valve replacement with sutureless prosthesis: better than root enlargement to avoid patient-prosthesis mismatch? Interactive cardiovascular and thoracic surgery\| PubMed ID: 26920726	2016
A new era of thoracic oncology? Ex-vivo stereotactic ablative radiosurgery within Ex-vivo Lung Treatment System as a hybrid therapy for unresectable locally advanced pulmonary malignancies. Medical hypotheses\| PubMed ID: 27241251	2016
Irradiation before and donor splenocyte infusion immediately after transplantation induce tolerance to lung, but not heart allografts in miniature swine. Transplant international : official journal of the European Society for Organ Transplantation\| PubMed ID: 28095640	2017
Decellularized mitral valve in a long-term sheep model. European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery\| PubMed ID: 29385428	2018
Treatment of infected lungs by ex vivo perfusion with high dose antibiotics and autotransplantation: A pilot study in pigs. PloS one\| PubMed ID: 29505574	2018
Prediction of transplant outcome after 24-hour ex vivo lung perfusion using the Organ Care System in a porcine lung transplantation model. American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons\| PubMed ID: 30106236	2018
Immunoengineering of the vascular endothelium to silence MHC expression during normothermic ex vivo lung perfusion. Human gene therapy\| PubMed ID: 30261752	2018

Klaus Hoeffler

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