| 1. |
- Li, Mei, et al.
(författare)
-
Development and prevention of ischemic contracture (“stone heart”) in the pig heart
- 2023
-
Ingår i: Frontiers in Cardiovascular Medicine. - : Frontiers Media SA. - 2297-055X. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Stone heart (ischemic contracture) is a rare and serious condition observed in the heart after periods of warm ischemia. The underlying mechanisms are largely unknown and treatment options are lacking. In view of the possibilities for cardiac donation after circulatory death (DCD), introducing risks for ischemic damage, we have investigated stone heart in pigs. Following cessation of ventilation, circulatory death (systolic pressure <8 mmHg) occurred within 13.1 ± 1.2 min; and a stone heart, manifested with asystole, increased left ventricular wall thickness and stiffness, established after a further 17 ± 6 min. Adenosine triphosphate and phosphocreatine levels decreased by about 50% in the stone heart. Electron microscopy showed deteriorated structure with contraction bands, Z-line streaming and swollen mitochondria. Synchrotron based small angle X-ray scattering of trabecular samples from stone hearts revealed attachment of myosin to actin, without volume changes in the sarcomeres. Ca2+ sensitivity, determined in permeabilized muscle, was increased in stone heart samples. An in vitro model for stone heart, using isolated trabecular muscle exposed to hypoxia/zero glucose, exhibited the main characteristics of stone heart in whole animals, with a fall in high-energy phosphates and development of muscle contracture. The stone heart condition in vitro was significantly attenuated by the myosin inhibitor MYK-461 (Mavacamten). In conclusion, the stone heart is a hypercontracted state associated with myosin binding to actin and increased Ca2+ sensitivity. The hypercontractile state, once developed, is poorly reversible. The myosin inhibitor MYK-461, which is clinically approved for other indications, could be a promising venue for prevention.
|
|
| 2. |
- Arlock, Per, et al.
(författare)
-
Excitation and contraction of cardiac muscle and coronary arteries of brain-dead pigs
- 2023
-
Ingår i: FASEB BioAdvances. - : Wiley. - 2573-9832. ; 5:2, s. 71-84
-
Tidskriftsartikel (refereegranskat)abstract
- Excitability and contraction of cardiac muscle from brain-dead donors critically influence the success of heart transplantation. Membrane physiology, Ca2+-handling, and force production of cardiac muscle and the contractile properties of coronary arteries were studied in hearts of brain-dead pigs. Cardiac muscle and vascular function after 12 h brain death (decapitation between C2 and C3) were compared with properties of fresh tissue. In both isolated cardiomyocytes (whole-cell patch clamp) and trabecular muscle (conventional microelectrodes), action potential duration was shorter in brain dead, compared to controls. Cellular shortening and Ca2+ transients were attenuated in the brain dead, and linked to lower mRNA expression of L-type calcium channels and a slightly lower ICa,L, current, as well as to a lower expression of phospholamban. The current–voltage relationship and the current above the equilibrium potential of the inward K+ (IK1) channel were altered in the brain-dead group, associated with lower mRNA expression of the Kir2.2 channel. Delayed K+ currents were detected (IKr, IKs) and were not different between groups. The transient outward K+ current (Ito) was not observed in the pig heart. Coronary arteries exhibited increased contractility and sensitivity to the thromboxane analogue (U46619), and unaltered endothelial relaxation. In conclusion, brain death involves changes in cardiac cellular excitation which might lower contractility after transplantation. Changes in the inward rectifier K+ channel can be associated with an increased risk for arrhythmia. Increased reactivity of coronary arteries may lead to increased risk of vascular spasm, although endothelial relaxant function was well preserved.
|
|
| 3. |
- Critchley, William R., et al.
(författare)
-
Non-ischemic Heart Preservation via Hypothermic Cardioplegic Perfusion Induces Immunodepletion of Donor Hearts Resulting in Diminished Graft Infiltration Following Transplantation
- 2020
-
Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Many donor organs contain significant leukocyte reservoirs which upon transplantation activate recipient leukocytes to initiate acute rejection. We aimed to assess whether non-ischemic heart preservation via ex vivo perfusion promotes immunodepletion and alters the inflammatory status of the donor organ prior to transplantation. Methods: Isolated porcine hearts underwent ex vivo hypothermic, cardioplegic perfusion for 8 h. Leukocyte populations were quantified in left ventricle samples by flow cytometry. Cell-free DNA, cytokines, and chemokines were quantified in the perfusate. Tissue integrity was profiled by targeted proteomics and a histological assessment was performed. Heterotopic transplants comparing ex vivo hypothermic preservation and static cold storage were utilized to assess graft infiltration as a solid clinical endpoint. Results: Ex vivo perfusion significantly immunodepleted myocardial tissue. The perfusate displayed a selective, pro-inflammatory cytokine/chemokine pattern dominated by IFN-γ. The tissue molecular profile was improved following perfusion by diminished expression of nine pro-apoptotic and six ischemia-associated proteins. Histologically, no evidence of tissue damage was observed and cardiac troponin I was low throughout perfusion. Cell-free DNA was detected, the source of which may be necrotic/apoptotic leukocytes. Post-transplant graft infiltration was markedly reduced in terms of both leucocyte distribution and intensity of foci. Conclusions: These findings demonstrate that ex vivo perfusion significantly reduced donor heart immunogenicity via loss of resident leukocytes. Despite the pro-inflammatory cytokine pattern observed, a pro-survival and reduced ischemia-related profile was observed, indicating an improvement in graft viability by perfusion. Diminished graft infiltration was observed in perfused hearts compared with those preserved by static cold storage following 48 h of transplantation.
|
|
| 4. |
- Längin, Matthias, et al.
(författare)
-
Cold non-ischemic heart preservation with continuous perfusion prevents early graft failure in orthotopic pig-to-baboon xenotransplantation
- 2021
-
Ingår i: Xenotransplantation. - : Wiley. - 0908-665X .- 1399-3089. ; 28:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: 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.
|
|
| 5. |
- Längin, Matthias, et al.
(författare)
-
Xenografts Show Signs of Concentric Hypertrophy and Dynamic Left Ventricular Outflow Tract Obstruction after Orthotopic Pig-to-baboon Heart Transplantation
- 2023
-
Ingår i: Transplantation. - 0041-1337. ; 107:12, s. 328-338
-
Tidskriftsartikel (refereegranskat)abstract
- Background. Orthotopic cardiac xenotransplantation has seen substantial advancement in the last years and the initiation of a clinical pilot study is close. However, donor organ overgrowth has been a major hurdle for preclinical experiments, resulting in loss of function and the decease of the recipient. A better understanding of the pathogenesis of organ overgrowth after xenotransplantation is necessary before clinical application. Methods. Hearts from genetically modified (GGTA1-KO, hCD46/hTBM transgenic) juvenile pigs were orthotopically transplanted into male baboons. Group I (control, n = 3) received immunosuppression based on costimulation blockade, group II (growth inhibition, n = 9) was additionally treated with mechanistic target of rapamycin inhibitor, antihypertensive medication, and fast corticoid tapering. Thyroid hormones and insulin-like growth factor 1 were measured before transplantation and before euthanasia, left ventricular (LV) growth was assessed by echocardiography, and hemodynamic data were recorded via a wireless implant. Results. Insulin-like growth factor 1 was higher in baboons than in donor piglets but dropped to porcine levels at the end of the experiments in group I. LV mass increase was 10-fold faster in group I than in group II. This increase was caused by nonphysiological LV wall enlargement. Additionally, pressure gradients between LV and the ascending aorta developed, and signs of dynamic left ventricular outflow tract (LVOT) obstruction appeared. Conclusions. After orthotopic xenotransplantation in baboon recipients, untreated porcine hearts showed rapidly progressing concentric hypertrophy with dynamic LVOT obstruction, mimicking hypertrophic obstructive cardiomyopathy in humans. Antihypertensive and antiproliferative drugs reduced growth rate and inhibited LVOT obstruction, thereby preventing loss of function.
|
|
| 6. |
- Major, Triin, et al.
(författare)
-
Pro-IL-1β Is an Early Prognostic Indicator of Severe Donor Lung Injury During Ex Vivo Lung Perfusion
- 2021
-
Ingår i: Transplantation. - 1534-6080. ; 105:4, s. 768-774
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Ex vivo lung perfusion (EVLP) is used to evaluate and recondition extended criteria donor lungs for transplantation. Interleukin-1β (IL-1β) has been identified as a prognostic indicator of nonrecovery during EVLP. This may be an effect of inflammasome activation or cellular necrosis following donation and graft preservation. Delineating the mechanism of IL-1β release is required. METHODS: The inactive intracellular precursor molecule, pro-IL-1β, was characterized along with the pro-IL-1β processing enzyme, caspase-1, in the perfusate of n = 20 human lungs that had undergone EVLP (n = 10 lungs that failed to recover and were discarded versus n = 10 lungs that reconditioned and were transplanted). In an experimental porcine model, n = 8 lungs underwent EVLP and were randomized to receive either a specific NLRP3 inflammasome inhibitor or control. RESULTS: Significant increases in pro-IL-1β and caspase-1 were observed in the perfusate from human lungs that did not recondition during EVLP compared with those that successfully reconditioned and were used for transplantation. Within the porcine EVLP, NLRP3 inflammasome inhibition reduced IL-1β within the perfusate compared with controls, but this had no impact on lung function, hemodynamics, or inflammation. CONCLUSIONS: Our data suggest that pro-IL-1β is passively released following cellular necrosis of the donor lung.
|
|
| 7. |
- Nilsson, Johan, et al.
(författare)
-
A nonrandomized open-label phase 2 trial of nonischemic heart preservation for human heart transplantation
- 2020
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Pre-clinical heart transplantation studies have shown that ex vivo non-ischemic heart preservation (NIHP) can be safely used for 24 h. Here we perform a prospective, open-label, non-randomized phase II study comparing NIHP to static cold preservation (SCS), the current standard for adult heart transplantation. All adult recipients on waiting lists for heart transplantation were included in the study, unless they met any exclusion criteria. The same standard acceptance criteria for donor hearts were used in both study arms. NIHP was scheduled in advance based on availability of device and trained team members. The primary endpoint was a composite of survival free of severe primary graft dysfunction, free of ECMO use within 7 days, and free of acute cellular rejection ≥2R within 180 days. Secondary endpoints were I/R-tissue injury, immediate graft function, and adverse events. Of the 31 eligible patients, six were assigned to NIHP and 25 to SCS. The median preservation time was 223 min (IQR, 202–263) for NIHP and 194 min (IQR, 164–223) for SCS. Over the first six months, all of the patients assigned to NIHP achieved event-free survival, compared with 18 of those assigned to SCS (Kaplan-Meier estimate of event free survival 72.0% [95% CI 50.0–86.0%]). CK-MB assessed 6 ± 2 h after ending perfusion was 76 (IQR, 50–101) ng/mL for NIHP compared with 138 (IQR, 72–198) ng/mL for SCS. Four deaths within six months after transplantation and three cardiac-related adverse events were reported in the SCS group compared with no deaths or cardiac-related adverse events in the NIHP group. This first-in-human study shows the feasibility and safety of NIHP for clinical use in heart transplantation. ClinicalTrial.gov, number NCT03150147.
|
|
| 8. |
- Persson, G. Rutger, et al.
(författare)
-
Impact of an Okinawa/Nordic based diet on endocrinological and periodontal conditions in individuals with type 2 diabetes. A randomized case–control study
- 2023
-
Ingår i: BMC Oral Health. - : BioMed Central Ltd.. - 1472-6831. ; 23:1
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To assess if the results following intake of a diet using an Okinawan-based Nordic diet (OBND) over one month differs in endocrinological, periodontal clinical outcome, and serum cytokine levels compared to a standard hospital care diet in individuals with diabetes type 2 (T2D) (control group). Background: Scientific evidence suggests that the use of diet for individuals with T2D may be beneficial. Methods: Participating individuals with T2D were randomly assigned to a test (OBND) (n = 14), or control group (n = 16). Anthropometric data, blood glucose levels, HbA1c levels, lipids, serum inflammation markers (CRP, and a routine panel of 24 cytokines), blood pressure, gingival bleeding on probing (BOP), probing pocket depths (PPD), and clinical attachment levels (CAL) were studied. Results: Statistical analyses of baseline study data failed to demonstrate study group differences. The mean weight reduction was greater in the OBND group (4.1 kg) versus the control group (1.3 kg) (p < 0.01). The reduction in BMI was 1.4 kg/m2 in OBND (p < 0.001) and 0.5 kg/m2 in the control group, respectively (p < 0.01). Diastolic and systolic blood pressure reductions were greater in the OBND group than in the control group (p < 0.01). Periodontal study parameters (BOP % scores) and (PPD values) decreased (p < 0.001) overall with no between group differences. The OBND resulted in reduction of serum levels of IFNγ, Eotaxin IL-9, IP10,IL17a, MCP-1,m and PDFBB compared to the control diet. Conclusions: A strict T2D- diet provides an association between reduction in serum HbA1c and BOP scores. Serum levels decreases in IFNγ, Eotaxin IL-9, IP-10, IL17a. MCP-1, and PDFBB were only found in the test group.
|
|
| 9. |
- Pigot, Henry, et al.
(författare)
-
A novel nonlinear afterload for ex vivo heart evaluation: Porcine experimental results
- 2022
-
Ingår i: Artificial Organs. - : Wiley. - 0160-564X .- 1525-1594. ; 46:9, s. 1794-1803
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Existing working heart models for ex vivo functional evaluation of donor hearts often use cardiac afterloads made up of discrete resistive and compliant elements. This approach limits the practicality of independently controlling systolic and diastolic aortic pressure to safely test the heart under multiple loading conditions. We present and investigate a novel afterload concept designed to enable such control. Methods: Six ∼70 kg pig hearts were evaluated in vivo, then ex vivo in left-ventricular working mode using the presented afterload. Both in vivo and ex vivo, the hearts were evaluated at two exertion levels: at rest and following a 20 μg adrenaline bolus, while measuring aortic pressure and flow, left ventricular pressure and volume, and left atrial pressure. Results: The afterload gave aortic pressure waveforms that matched the general shape of the in vivo measurements. A wide range of physiological systolic pressures (93 to 160 mm Hg) and diastolic pressures (73 to 113 mm Hg) were generated by the afterload. Conclusions: With the presented afterload concept, multiple physiological loading conditions could be tested ex vivo, and compared with the corresponding in vivo data. An additional control loop from the set pressure limits to the measured systolic and diastolic aortic pressure is proposed to address discrepancies observed between the set limits and the measured pressures.
|
|
| 10. |
- Pigot, Harry, et al.
(författare)
-
Advantage of new ventilation method for cardiopulmonary resuscitation qualitatively captured by simple respiratory mechanics models
- 2020
-
Ingår i: 2020 American Control Conference (ACC). - 9781538682661 ; , s. 1317-1322
-
Konferensbidrag (refereegranskat)abstract
- First responders to cardiac arrest depend on cardiopulmonary resuscitation to keep patients alive. A new ventilation method, phase-controlled intermittent insufflation of oxygen, was previously shown to improve heart perfusion during cardiopulmonary resuscitation in a large-animal study, outperforming the best currently known ventilation method. This paper investigates whether the advantage of the new method can be explained using standard linear lumped-parameter models of respiratory mechanics. The simple models were able to qualitatively capture the improvement.
|
|
