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Kidney International Apr 2023Given their accessibility and relevance to established clinical workflows, blood and urine have been the major focus of investigation in metabolomics studies of human...
Given their accessibility and relevance to established clinical workflows, blood and urine have been the major focus of investigation in metabolomics studies of human kidney disease. In this issue, Liu et al. describe the application of metabolomics to perfusate from donor kidneys subjected to hypothermic machine perfusion. In addition to providing an elegant model for investigating kidney metabolism, this study highlights the limitations of allograft quality assessment and identifies metabolites of interest in kidney ischemia.
Topics: Humans; Kidney Transplantation; Kidney; Transplantation, Homologous; Metabolomics; Tissue Donors; Perfusion
PubMed: 36948766
DOI: 10.1016/j.kint.2022.12.025 -
The Journal of Trauma and Acute Care... Feb 2022Ex vivo normothermic limb perfusion (EVNLP) preserves amputated limbs under near-physiologic conditions. Perfusates containing red blood cells (RBCs) have shown to...
BACKGROUND
Ex vivo normothermic limb perfusion (EVNLP) preserves amputated limbs under near-physiologic conditions. Perfusates containing red blood cells (RBCs) have shown to improve outcomes during ex vivo normothermic organ perfusion, when compared with acellular perfusates. To avoid limitations associated with the use of blood-based products, we evaluated the feasibility of EVNLP using a polymerized hemoglobin-based oxygen carrier-201 (HBOC-201).
METHODS
Twenty-four porcine forelimbs were procured from Yorkshire pigs. Six forelimbs underwent EVNLP with an HBOC-201-based perfusate, six with an RBC-based perfusate, and 12 served as static cold storage (SCS) controls. Ex vivo normothermic limb perfusion was terminated in the presence of systolic arterial pressure of 115 mm Hg or greater, fullness of compartments, or drop of tissue oxygen saturation by 20%. Limb contractility, weight change, compartment pressure, tissue oxygen saturation, oxygen uptake rates (OURs) were assessed. Perfusate fluid-dynamics, gases, electrolytes, metabolites, methemoglobin, creatine kinase, and myoglobin concentration were measured. Uniformity of skin perfusion was assessed with indocyanine green angiography and infrared thermography.
RESULTS
Warm ischemia time before EVNLP was 35.50 ± 8.62 minutes (HBOC-201), 30.17 ± 8.03 minutes (RBC) and 37.82 ± 10.45 (SCS) (p = 0.09). Ex vivo normothermic limb perfusion duration was 22.5 ± 1.7 hours (HBOC-201) and 28.2 ± 7.3 hours (RBC) (p = 0.04). Vascular flow (325 ± 25 mL·min-1 vs. 444.7 ± 50.6 mL·min-1; p = 0.39), OUR (2.0 ± 1.45 mL O2·min-1·g-1 vs. 1.3 ± 0.92 mL O2·min-1·g-1 of tissue; p = 0.80), lactate (14.66 ± 4.26 mmol·L-1 vs. 13.11 ± 6.68 mmol·L-1; p = 0.32), perfusate pH (7.53 ± 0.25 HBOC-201; 7.50 ± 0.23 RBC; p = 0.82), flexor (28.3 ± 22.0 vs. 27.5 ± 10.6; p = 0.99), and extensor (31.5 ± 22.9 vs. 28.8 ± 14.5; p = 0.82) compartment pressures, and weight changes (23.1 ± 3.0% vs. 13.2 ± 22.7; p = 0.07) were not significantly different between HBOC-201 and RBC groups, respectively. In HBOC-201 perfused limbs, methemoglobin levels increased, reaching 47.8 ± 12.1% at endpoint. Methemoglobin saturation did not affect OUR (ρ = -0.15, r2 = 0.022; p = 0.45). A significantly greater number of necrotic myocytes was found in the SCS group at endpoint (SCS, 127 ± 17 cells; HBOC-201, 72 ± 30 cells; RBC-based, 56 ± 40 cells; vs. p = 0.003).
CONCLUSION
HBOC-201- and RBC-based perfusates similarly support isolated limb physiology, metabolism, and function.
Topics: Animals; Erythrocyte Transfusion; Feasibility Studies; Forelimb; Hemoglobins; Organ Preservation; Perfusion; Swine
PubMed: 34510075
DOI: 10.1097/TA.0000000000003395 -
Perfusion Nov 2023To explore impact of various periods of ischemia and reperfusion on the severity of myocardial injury.
BACKGROUND
To explore impact of various periods of ischemia and reperfusion on the severity of myocardial injury.
METHODS
Langendorff model of isolated cardiac perfusion system was established in 56 rat hearts. They were randomly assigned into four groups with four different ischemia (perfusion-pause) time and reperfusion time. The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and creatine kinase-MB (CK-MB) were measured and the size of myocardial infarction was assessed by 2,3,5-triphenyltetrazolium chloride (TTC) staining.
RESULTS
The levels of AST, ALT, LDH, and CK-MB in the heart tissues and perfusate were lowest in the group I (shortest time of perfusion-pause and reperfusion) followed by the groups II, III, and IV (longest time of perfusion-pause and reperfusion) ( < 0.05). The myocardial infarction size was smallest in the group I (6.63 ± 0.47) followed by group II (15.12 ± 1.03), group III (20.32 ± 2.18), and group IV (32.29 ± 5.42) ( < 0.05). Two-way ANOVA analysis revealed that period of perfusion-pause and reperfusion independently and significantly affected the levels of AST and ALT in both heart tissues and perfusate ( < 0.001). The interaction of pausing period and reperfusion significantly affected the level of AST ( = 0.046) and CK-MB ( = 0.001) in the perfusate. In addition, perfusion-pause period significantly affected levels of LDH and CK-MB only in the perfusate ( < 0.001). Neither perfusate nor heart tissue LDH level was significantly affected by the interaction of perfusion-pause and reperfusion period ( > 0.05).
CONCLUSION
The severity of myocardial injury in the Langendorff model was affected by the period of perfusion-pause and reperfusion. The longer period of perfusion-pause followed by the longer the period of reperfusion, the severe myocardial injury was found.
Topics: Rats; Animals; Myocardial Reperfusion Injury; Heart; Myocardial Infarction; Heart Injuries; Reperfusion; Perfusion; L-Lactate Dehydrogenase
PubMed: 36059244
DOI: 10.1177/02676591221122349 -
Scandinavian Journal of Trauma,... Dec 2023Selective aortic arch perfusion (SAAP) is a novel endovascular technique that combines thoracic aortic occlusion with extracorporeal perfusion of the brain and heart....
BACKGROUND
Selective aortic arch perfusion (SAAP) is a novel endovascular technique that combines thoracic aortic occlusion with extracorporeal perfusion of the brain and heart. SAAP may have a role in both haemorrhagic shock and in cardiac arrest due to coronary ischaemia. Despite promising animal studies, no data is available that describes SAAP in humans. The primary aim of this study was to assess the feasibility of selective aortic arch perfusion in humans. The secondary aim of the study was to assess the feasibility of achieving direct coronary artery access via the SAAP catheter as a potential conduit for salvage percutaneous coronary intervention.
METHODS
Using perfused human cadavers, a prototype SAAP catheter was inserted into the descending aorta under fluoroscopic guidance via a standard femoral percutaneous access device. The catheter balloon was inflated and the aortic arch perfused with radio-opaque contrast. The coronary arteries were cannulated through the SAAP catheter.
RESULTS
The procedure was conducted four times. During the first two trials the SAAP catheter was passed rapidly and without incident to the intended descending aortic landing zone and aortic arch perfusion was successfully delivered via the device. The SAAP catheter balloon failed on the third trial. On the fourth trial the left coronary system was cannulated using a 5Fr coronary guiding catheter through the central SAAP catheter lumen.
CONCLUSIONS
For the first time using a perfused cadaveric model we have demonstrated that a SAAP catheter can be easily and safely inserted and SAAP can be achieved using conventional endovascular techniques. The SAAP catheter allowed successful access to the proximal aorta and permitted retrograde perfusion of the coronary and cerebral circulation.
Topics: Humans; Aorta; Aorta, Thoracic; Heart Arrest; Perfusion; Shock, Hemorrhagic; Feasibility Studies
PubMed: 38087352
DOI: 10.1186/s13049-023-01148-z -
Metabolomics : Official Journal of the... Feb 2023Our untargeted metabolic data unveiled that Acyl-CoAs undergo dephosphorylation, however little is known about these novel metabolites and their physiology/pathology...
INTRODUCTION
Our untargeted metabolic data unveiled that Acyl-CoAs undergo dephosphorylation, however little is known about these novel metabolites and their physiology/pathology relevance.
OBJECTIVES
To understand the relationship between acyl-CoAs dephosphorylation and energy status as implied in our previous work, we seek to investigate how ischemia (energy depletion) triggers metabolic changes, specifically acyl-CoAs dephosphorylation in this work.
METHODS
Rat hearts were isolated and perfused in Langendorff mode for 15 min followed by 0, 5, 15, and 30 minutes of global ischemia. The heart tissues were harvested for metabolic analysis.
RESULTS
As expected, ATP and phosphocreatine were significantly decreased during ischemia. Most short- and medium-chain acyl-CoAs progressively increased with ischemic time from 0 to 15 min, whereas a 30-minute ischemia did not lead to further change. Unlike other acyl-CoAs, propionyl-CoA accumulated progressively in the hearts that underwent ischemia from 0 to 30 min. Progressive dephosphorylation occurred to all assayed acyl-CoAs and free CoA regardless their level changes during the ischemia.
CONCLUSION
The present work further confirms that dephosphorylation of acyl-CoAs is an energy-dependent process and how this dephosphorylation is mediated warrants further investigations. It is plausible that dephosphorylation of acyl-CoAs and limited anaplerosis are involved in ischemic injuries to heart. Further investigations are warranted to examine the mechanisms of acyl-CoA dephosphorylation and how the dephosphorylation is possibly involved in ischemic injuries.
Topics: Animals; Rats; Acyl Coenzyme A; Heart; Metabolomics; Myocardial Ischemia; Myocardial Reperfusion Injury; Phosphorylation; Perfusion
PubMed: 36750484
DOI: 10.1007/s11306-023-01975-2 -
The Journal of Thoracic and... Feb 2021
Topics: Adsorption; Extracorporeal Circulation; Humans; Lung; Perfusion; Seasons
PubMed: 31959447
DOI: 10.1016/j.jtcvs.2019.12.012 -
Journal of Applied Physiology... Nov 2021In recent years, it has become common to experiment with ex vivo perfused lungs for organ transplantation and to attempt regenerative pulmonary engineering using...
In recent years, it has become common to experiment with ex vivo perfused lungs for organ transplantation and to attempt regenerative pulmonary engineering using decellularized lung matrices. However, our understanding of the physiology of ex vivo organ perfusion is imperfect; it is not currently well understood how decreasing microvascular barrier affects the perfusion of pulmonary parenchyma. In addition, protocols for lung perfusion and organ culture fluid-handling are far from standardized, with widespread variation on both basic methods and on ideally controlled parameters. To address both of these deficits, a robust, noninvasive, and mechanistic model is needed which is able to predict microvascular resistance and permeability in perfused lungs while providing insight into capillary recruitment. Although validated mathematical models exist for fluid flow in native pulmonary tissue, previous models generally assume minimal intravascular leak from artery to vein and do not assess capillary bed recruitment. Such models are difficult to apply to both ex vivo lung perfusions, in which edema can develop over time and microvessels can become blocked, and to decellularized ex vivo organomimetic cultures, in which microvascular recruitment is variable and arterially perfused fluid enters into the alveolar space. Here, we develop a mathematical model of pulmonary microvascular fluid flow which is applicable in both instances, and we apply our model to data from native, decellularized, and regenerating lungs under ex vivo perfusion. The results provide substantial insight into microvascular pressure-flow mechanics, while producing previously unknown output values for tissue-specific capillary-alveolar hydraulic conductivity, microvascular recruitment, and total organ barrier resistance. We present a validated model of pulmonary microvascular fluid mechanics and apply this model to study the effects of increased capillary permeability in decellularized and regenerating lungs. We find that decellularization alters microvascular steady-state mechanics and that re-endothelialization partially rescues key biologic parameters. The described model provides powerful insight into intraorgan microvascular dynamics and may be used to guide regenerative engineering experiments. We include all data and derivations necessary to replicate this work.
Topics: Capillaries; Lung; Microvessels; Perfusion
PubMed: 34554016
DOI: 10.1152/japplphysiol.00286.2020 -
Annals of Surgery Nov 2023To develop a protocol for the defatting of steatotic liver grafts during long-term ex situ normothermic machine perfusion.
OBJECTIVE
To develop a protocol for the defatting of steatotic liver grafts during long-term ex situ normothermic machine perfusion.
BACKGROUND
Despite the alarming increase in donor organ shortage, the highly prevalent fatty liver grafts are often discarded due to the risk of primary nonfunction. Effective strategies preventing such outcomes are currently lacking. An exciting new avenue is the introduction of ex situ normothermic machine perfusion (NMP), enabling a liver to remain fully functional for up to 2 weeks and providing a unique window of opportunity for defatting before transplantation.
METHODS
Over a 5-year period, 23 discarded liver grafts and 28 partial livers from our resection program were tested during ex situ normothermic machine perfusion. The steatosis degree was determined on serial biopsies by expert pathologists, and triglyceride contents were measured simultaneously.
RESULTS
Of 51 liver grafts, 20 were steatotic, with up to 85% macrovesicular steatosis, and were perfused for up to 12 days. Ten livers displayed marked (5 of which almost complete) loss of fat, while the other 10 did not respond to long-term perfusion. Successful defatting was related to prolonged perfusion, automated glucose control, circadian nutrition, and L-carnitine/fenofibrate supplementation. Pseudopeliotic steatosis and the associated activation of Kupffer/stellate cells were unexpected processes that might contribute to defatting. Synthetic and metabolic functions remained preserved for most grafts until perfusion ended.
CONCLUSION
Ex situ long-term perfusion effectively reduces steatosis while preserving organ viability and may in the future allow transplantation of primarily unusable high-risk grafts, significantly increasing the number of organs available for transplantation.
Topics: Humans; Organ Preservation; Liver; Fatty Liver; Liver Transplantation; Perfusion
PubMed: 37497663
DOI: 10.1097/SLA.0000000000006047 -
Hearing Research Jul 2016The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or...
The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawn from basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner's membrane (RM), while in cochleae perfused with 0.125% and 0.25% HA RM was torn. Thus, the CAP threshold elevation was likely due to the broken RM, likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed, perhaps due to the presence and then clearance of viscous fluid within the cochlea, or to a temporary position shift of the Organ of Corti. After 0.5% HA perfusion, a short latency positive peak (P0) appeared in the CAP waveform. This P0 might be due to a change in the cochlea's traveling-wave pattern, or distortion in the cochlear microphonic.
Topics: Action Potentials; Animals; Cochlea; Cochlear Duct; Cochlear Implantation; Cochlear Implants; Cochlear Microphonic Potentials; Female; Gerbillinae; Hyaluronic Acid; Organ of Corti; Perfusion; Perilymph; Round Window, Ear; Scala Vestibuli; Shear Strength; Viscosity
PubMed: 27220484
DOI: 10.1016/j.heares.2016.05.007 -
Scandinavian Journal of Clinical and... 2018Within the scope of transplantation research, ex vivo kidney perfusion has been proven an attractive model to study ischemia-reperfusion and preservation injury. Renal...
Within the scope of transplantation research, ex vivo kidney perfusion has been proven an attractive model to study ischemia-reperfusion and preservation injury. Renal perfusion techniques also occupy scientists with the aim to optimize organ reconditioning and preparation prior to transplantation. This study investigated the influence of a pulsatile perfusion pattern that brings flow conditions closer to physiological situations, on renal perfusion characteristic and kidney function in the isolated perfused kidney. Kidneys were perfused via a roller pump at constant pressure set to 90 mmHg, or with addition of pulsatile pressure peaks (90/70 mmHg; 60/min) using an adjustable positive displacement pump. It was found that pulsatile pressure significantly enhanced renal flow rates as compared to non-pulsatile perfusion mode, especially after preceding preservation of the kidney by static cold storage. The improved vascular conductivity went along with a notable improvement of clearance of creatinine, sodium reabsorption and reduced tubular cell injury (Loss of fatty acid binding protein). The better vascular conductance upon pulsatile perfusion could be attributed to improved endothelial release of nitic oxide and reduced secretion of endothelin-1 into the perfusate. It is concluded, that pulsatile perfusion mode should be preferred in isolated kidney perfusion as resulting in better preservation/recovery of renal perfusion and function.
Topics: Animals; Blood Pressure; Kidney; Kidney Function Tests; Perfusion; Pulsatile Flow; Renal Artery; Sus scrofa
PubMed: 29301417
DOI: 10.1080/00365513.2017.1422539