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Arnold M, Méndez-Carmona N, Wyss RK, Joachimbauer A, Casoni D, Carrel T, Longnus S. Comparison of Experimental Rat Models in Donation After Circulatory Death (DCD): in-situ vs. ex-situ Ischemia. Front Cardiovasc Med 2021; 7:596883. [PMID: 33521061 PMCID: PMC7838125 DOI: 10.3389/fcvm.2020.596883] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 12/14/2020] [Indexed: 12/16/2022] Open
Abstract
Introduction: Donation after circulatory death (DCD) could substantially improve donor heart availability. However, warm ischemia prior to procurement is of particular concern for cardiac graft quality. We describe a rat model of DCD with in-situ ischemia in order to characterize the physiologic changes during the withdrawal period before graft procurement, to determine effects of cardioplegic graft storage, and to evaluate the post-ischemic cardiac recovery in comparison with an established ex-situ ischemia model. Methods: Following general anesthesia in male, Wistar rats (404 ± 24 g, n = 25), withdrawal of life-sustaining therapy was simulated by diaphragm transection. Hearts underwent no ischemia or 27 min in-situ ischemia and were explanted. Ex situ, hearts were subjected to a cardioplegic flush and 15 min cold storage or not, and 60 min reperfusion. Cardiac recovery was determined and compared to published results of an entirely ex-situ ischemia model (n = 18). Results: In donors, hearts were subjected to hypoxia and hemodynamic changes, as well as increased levels of circulating catecholamines and free fatty acids prior to circulatory arrest. Post-ischemic contractile recovery was significantly lower in the in-situ ischemia model compared to the ex-situ model, and the addition of cardioplegic storage improved developed pressure-heart rate product, but not cardiac output. Conclusion: The in-situ model provides insight into conditions to which the heart is exposed before procurement. Compared to an entirely ex-situ ischemia model, hearts of the in-situ model demonstrated a lower post-ischemic functional recovery, potentially due to systemic changes prior to ischemia, which are partially abrogated by cardioplegic graft storage.
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Affiliation(s)
- Maria Arnold
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Natalia Méndez-Carmona
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Rahel K Wyss
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Anna Joachimbauer
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Daniela Casoni
- Experimental Surgery Facility (ESF), Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Thierry Carrel
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
| | - Sarah Longnus
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital and Department for BioMedical Research (DBMR), University of Bern, Bern, Switzerland
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Mechanical Postconditioning Promotes Glucose Metabolism and AMPK Activity in Parallel with Improved Post-Ischemic Recovery in an Isolated Rat Heart Model of Donation after Circulatory Death. Int J Mol Sci 2020; 21:ijms21030964. [PMID: 32024002 PMCID: PMC7039237 DOI: 10.3390/ijms21030964] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 01/27/2020] [Accepted: 01/30/2020] [Indexed: 12/25/2022] Open
Abstract
Donation after circulatory death (DCD) could improve donor heart availability; however, warm ischemia-reperfusion injury raises concerns about graft quality. Mechanical postconditioning (MPC) may limit injury, but mechanisms remain incompletely characterized. Therefore, we investigated the roles of glucose metabolism and key signaling molecules in MPC using an isolated rat heart model of DCD. Hearts underwent 20 min perfusion, 30 min global ischemia, and 60 minu reperfusion with or without MPC (two cycles: 30 s reperfusion—30 s ischemia). Despite identical perfusion conditions, MPC either significantly decreased (low recovery = LoR; 32 ± 5%; p < 0.05), or increased (high recovery = HiR; 59 ± 7%; p < 0.05) the recovery of left ventricular work compared with no MPC (47 ± 9%). Glucose uptake and glycolysis were increased in HiR vs. LoR hearts (p < 0.05), but glucose oxidation was unchanged. Furthermore, in HiR vs. LoR hearts, phosphorylation of raptor, a downstream target of AMPK, increased (p < 0.05), cytochrome c release (p < 0.05) decreased, and TNFα content tended to decrease. Increased glucose uptake and glycolysis, lower mitochondrial damage, and a trend towards decreased pro-inflammatory cytokines occurred specifically in HiR vs. LoR MPC hearts, which may result from greater AMPK activation. Thus, we identify endogenous cellular mechanisms that occur specifically with cardioprotective MPC, which could be elicited in the development of effective reperfusion strategies for DCD cardiac grafts.
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Differential effects of ischemia/reperfusion on endothelial function and contractility in donation after circulatory death. J Heart Lung Transplant 2019; 38:767-777. [DOI: 10.1016/j.healun.2019.03.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 02/21/2019] [Accepted: 03/08/2019] [Indexed: 01/18/2023] Open
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Farine E, Egle MU, Boone AC, Christensen S, Carrel TP, Tevaearai Stahel HT, Longnus SL. Development of a cardiac loading device to monitor cardiac function during ex vivo graft perfusion. PLoS One 2018; 13:e0195721. [PMID: 29702648 PMCID: PMC5922540 DOI: 10.1371/journal.pone.0195721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 03/28/2018] [Indexed: 11/18/2022] Open
Abstract
Background Ex vivo heart perfusion systems, allowing continuous perfusion of the coronary vasculature, have recently been introduced to limit ischemic time of donor hearts prior to transplantation. Hearts are, however, perfused in an unloaded manner (via the aorta) and therefore, cardiac contractile function cannot be reliably evaluated. Objectives We aim to develop a ventricular loading device that enables monitoring of myocardial function in an ex vivo perfusion system. In this initial study, was to develop a prototype for rat experimentation. Methods We designed a device consisting of a ventricular balloon and a reservoir balloon, connected through an electronic check valve, which opens and closes in coordination with changes in ventricular pressure. All balloons were produced in our laboratory and their properties, particularly pressure-volume relationships, were characterized. We developed a mock ventricle in vitro test system to evaluate the device, which was ultimately tested in ex vivo perfused rat hearts. Results Balloon production was consistent and balloon properties were maintained over time and with use on the device. Results from in vitro and ex vivo experiments show that the device functions appropriately; hemodynamic function can be measured and compares well to measurements made in an isolated, working (loaded) rat heart preparation. Conclusions Our cardiac loading device appears to reliably allow measurement of several left ventricular hemodynamic parameters and provides the opportunity to control ventricular load.
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Affiliation(s)
- Emilie Farine
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Manuel U. Egle
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Alice C. Boone
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Sandro Christensen
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Thierry P. Carrel
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
| | | | - Sarah L. Longnus
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, Bern, Switzerland
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Niederberger P, Farine E, Arnold M, Wyss RK, Sanz MN, Méndez-Carmona N, Gahl B, Fiedler GM, Carrel TP, Tevaearai Stahel HT, Longnus SL. High pre-ischemic fatty acid levels decrease cardiac recovery in an isolated rat heart model of donation after circulatory death. Metabolism 2017; 71:107-117. [PMID: 28521863 DOI: 10.1016/j.metabol.2017.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/07/2017] [Accepted: 03/08/2017] [Indexed: 01/07/2023]
Abstract
RATIONALE Donation after circulatory death (DCD) could improve cardiac graft availability. However, strategies to optimize cardiac graft recovery remain to be established in DCD; these hearts would be expected to be exposed to high levels of circulatory fat immediately prior to the inevitable period of ischemia prior to procurement. OBJECTIVE We investigated whether acute exposure to high fat prior to warm, global ischemia affects subsequent hemodynamic and metabolic recovery in an isolated rat heart model of DCD. METHODS AND RESULTS Hearts of male Wistar rats underwent 20min baseline perfusion with glucose (11mM) and either high fat (1.2mM palmitate; HF) or no fat (NF), 27min global ischemia (37°C), and 60min reperfusion with glucose only (n=7-8 per group). Hemodynamic recovery was 50% lower in HF vs. NF hearts (34±30% vs. 78±8% (60min reperfusion value of peak systolic pressure*heart rate as percentage of mean baseline); p<0.01). During early reperfusion, glycolysis (0.3±0.3 vs. 0.7±0.3μmol*min-1*g dry-1, p<0.05), glucose oxidation (0.1±0.03 vs. 0.4±0.2μmol*min-1*g dry-1, p<0.01) and pyruvate dehydrogenase activity (1.8±0.6 vs. 3.6±0.5U*g protein-1, p<0.01) were significantly reduced in HF vs. NF groups, respectively, while lactate release was significantly greater (1.8±0.9 vs. 0.6±0.2μmol*g wet-1*min-1; p<0.05). CONCLUSIONS Acute, pre-ischemic exposure to high fat significantly lowers post-ischemic cardiac recovery vs. no fat despite identical reperfusion conditions. These findings support the concept that oxidation of residual fatty acids is rapidly restored upon reperfusion and exacerbates ischemia-reperfusion (IR) injury. Strategies to optimize post-ischemic cardiac recovery should take pre-ischemic fat levels into consideration.
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Affiliation(s)
- Petra Niederberger
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Emilie Farine
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Maria Arnold
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Rahel K Wyss
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Maria N Sanz
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Natalia Méndez-Carmona
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Brigitta Gahl
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Georg M Fiedler
- Center of Laboratory Medicine, University Institute of Clinical Chemistry, University Hospital, Inselspital, Bern, Switzerland.
| | - Thierry P Carrel
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Hendrik T Tevaearai Stahel
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
| | - Sarah L Longnus
- Department of Cardiovascular Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.
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Farine E, Niederberger P, Wyss RK, Méndez-Carmona N, Gahl B, Fiedler GM, Carrel TP, Tevaearai Stahel HT, Longnus SL. Controlled Reperfusion Strategies Improve Cardiac Hemodynamic Recovery after Warm Global Ischemia in an Isolated, Working Rat Heart Model of Donation after Circulatory Death (DCD). Front Physiol 2016; 7:543. [PMID: 27920725 PMCID: PMC5118653 DOI: 10.3389/fphys.2016.00543] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/28/2016] [Indexed: 12/12/2022] Open
Abstract
Aims: Donation after circulatory death (DCD) could improve cardiac graft availability, which is currently insufficient to meet transplant demand. However, DCD organs undergo an inevitable period of warm ischemia and most cardioprotective approaches can only be applied at reperfusion (procurement) for ethical reasons. We investigated whether modifying physical conditions at reperfusion, using four different strategies, effectively improves hemodynamic recovery after warm ischemia. Methods and Results: Isolated hearts of male Wistar rats were perfused in working-mode for 20 min, subjected to 27 min global ischemia (37°C), and 60 min reperfusion (n = 43). Mild hypothermia (30°C, 10 min), mechanical postconditioning (MPC; 2x 30 s reperfusion/30 s ischemia), hypoxia (no O2, 2 min), or low pH (pH 6.8–7.4, 3 min) was applied at reperfusion and compared with controls (i.e., no strategy). After 60 min reperfusion, recovery of left ventricular work (developed pressure*heart rate; expressed as percent of pre-ischemic value) was significantly greater for mild hypothermia (62 ± 7%), MPC (65 ± 8%) and hypoxia (61 ± 11%; p < 0.05 for all), but not for low pH (45 ± 13%), vs. controls (44 ± 7%). Increased hemodynamic recovery was associated with greater oxygen consumption (mild hypothermia, MPC) and coronary perfusion (mild hypothermia, MPC, hypoxia), and with reduced markers of necrosis (mild hypothermia, MPC, hypoxia) and mitochondrial damage (mild hypothermia, hypoxia). Conclusions: Brief modifications in physical conditions at reperfusion, such as hypothermia, mechanical postconditioning, and hypoxia, improve post-ischemic hemodynamic function in our model of DCD. Cardioprotective reperfusion strategies applied at graft procurement could improve DCD graft recovery and limit further injury; however, optimal clinical approaches remain to be characterized.
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Affiliation(s)
- Emilie Farine
- Clinic for Cardiovascular Surgery, Inselspital, Bern University HospitalBern, Switzerland; Department of Clinical Research, University of BernBern, Switzerland
| | - Petra Niederberger
- Clinic for Cardiovascular Surgery, Inselspital, Bern University HospitalBern, Switzerland; Department of Clinical Research, University of BernBern, Switzerland
| | - Rahel K Wyss
- Clinic for Cardiovascular Surgery, Inselspital, Bern University HospitalBern, Switzerland; Department of Clinical Research, University of BernBern, Switzerland
| | - Natalia Méndez-Carmona
- Clinic for Cardiovascular Surgery, Inselspital, Bern University HospitalBern, Switzerland; Department of Clinical Research, University of BernBern, Switzerland
| | - Brigitta Gahl
- Clinic for Cardiovascular Surgery, Inselspital, Bern University HospitalBern, Switzerland; Department of Clinical Research, University of BernBern, Switzerland
| | - Georg M Fiedler
- Center of Laboratory Medicine, University Institute of Clinical Chemistry, University Hospital Inselspital, Bern, Switzerland
| | - Thierry P Carrel
- Clinic for Cardiovascular Surgery, Inselspital, Bern University HospitalBern, Switzerland; Department of Clinical Research, University of BernBern, Switzerland
| | - Hendrik T Tevaearai Stahel
- Clinic for Cardiovascular Surgery, Inselspital, Bern University HospitalBern, Switzerland; Department of Clinical Research, University of BernBern, Switzerland
| | - Sarah L Longnus
- Clinic for Cardiovascular Surgery, Inselspital, Bern University HospitalBern, Switzerland; Department of Clinical Research, University of BernBern, Switzerland
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