A Proof-of-Concept Preclinical Study Using a Novel Thermal Insulation Device in a Porcine Kidney Auto-Transplantation Model.

Ischemia-reperfusion injury remains a fundamental problem during organ transplantation logistics. One key technical factor is the rapid allograft rewarming during the time of vascular reconstruction in the recipient. In this pilot study, a new thermal insulation bag (TIB) for organ transplantation was used. Insulation capacity, tissue compatibility, and usability were tested initially ex vivo on porcine kidneys (n = 24) followed by the first in vivo usage. Fourteen female German landrace pigs underwent kidney auto-transplantation after 24 h cold storage (4 °C). During the implantation process the kidney was either insulated with the new TIB, or it was not thermo-protected at all, which represents the clinical standard. In this proof-of-concept study, the usability (knife-to-skin-time) and the general thermal capacity (30 min warm storage at 38 °C ex vivo p < 0.001) was shown. The clinical outcome showed significant differences in the determination of CRP and pi-GST levels. Syndecan-1 Antibody staining showed clear significant higher counts in the control group (p < 0.01) indicating epithelial damage. However, the effect on renal outcomes in not severely pre-damaged kidneys does not appear to be conclusively significant. A close follow-up study is warranted, especially in the context of marginal organs or in cases where anastomosis-times are prolonged due to surgical complexity (e.g., multiple vessels and complex reconstructions).

The Benefits of Fibrinolysis Combined with Venous Systemic Oxygen Persufflation (VSOP) in a Rat Model of Donation after Circulatory Death and Orthotopic Liver Transplantation.

Organ shortage has led to the increasing utilization of livers retrieved from donors after circulatory death (DCD). These pre-damaged organs are susceptible to further warm ischemia and exhibit minimal tolerance for cold storage. The aim was thus to examine the effects of fibrinolysis combined with Venous Systemic Oxygen Persufflation (VSOP) on the preservation of DCD livers in vivo. Livers of male Lewis rats were explanted after 45 min of warm ischemia, cold-stored for 18 h, and transplanted into a recipient animal. Livers were left untreated or underwent either VSOP or fibrinolysis via Streptokinase (SK) or received combined SK and VSOP. Combined treatment exhibited improved microvascular flow at 168 h (p = 0.0009) and elevated microperfusion velocity at 24 h post-transplantation (p = 0.0007). Combination treatment demonstrated increased portal venous flow (PVF) at 3 and 24 h post-transplantation (p = 0.0004, p < 0.0001), although SK and VSOP analogously achieved increases at 24 h (p = 0.0036, p = 0.0051). Enzyme release was decreased for combination treatment (p = 0.0002, p = 0.0223) and lactate dehydrogenase (LDH) measurements were lower at 24 h post-transplantation (p = 0.0287). Further supporting findings have been obtained in terms of serum cytokine levels and in the alterations of endothelial injury markers. The combination treatment of SK + VSOP might provide improved organ integrity and viability and may therefore warrant further investigation as a potential therapeutic approach in the clinical setting of DCD.

Assessment of Plasma Coagulation on Liver Tissue in a Large Animal Model In Vivo.

Plasma coagulation as a form of electrocautery is used in liver surgery for decades to seal the large liver cut surface after major hepatectomy to prevent hemorrhages at a later stage. The exact effects of plasma coagulation on liver tissue are only poorly examined. In our porcine model, the coagulation effects can be examined close to the clinical application. A combined laser Doppler flowmeter and spectrophotometer documents microcirculation changes during coagulation at 8 mm tissue depth noninvasively, providing quantifiable information about hemostasis beyond the subjective clinical impression. The temperature at coagulation site is assessed with an infrared thermometer prior and post coagulation and with a thermographic camera during coagulation, a measurement of the gas beam temperature is not possible due to the upper threshold of the devices. The depth of coagulation is measured microscopically on hematoxylin/eosin stained sections after calibration with an object micrometer and gives an exact information about the power setting-coagulation depth-relation. The sealing effect is examined on the bile ducts as it is not possible for a plasma coagulator to seal larger blood vessels. Burst pressure experiments are carried out on explanted organs to rule out blood pressure related effects.

Argon and helium plasma coagulation of porcine liver tissue.

Objective Argon plasma coagulation (APC) and helium plasma coagulation (HPC) are electrosurgical techniques that provide noncontact monopolar electrothermal haemostasis. Although these techniques have been widely used clinically during the last three decades, their in vivo effects on liver tissue remain unclear. Methods We investigated the effects of different power levels (10-100 W) of APC and HPC on liver coagulation in 11 Landrace pigs. Capillary blood flow and capillary blood flow velocity were recorded with a combined laser Doppler flowmeter and spectrophotometer. The temperature, clinical biochemical parameters, blood gas parameters, bile duct-sealing effect, and coagulation depth were measured. Results APC and HPC significantly reduced the capillary blood flow and capillary blood flow velocity compared with baseline flow. No significant temperature change was measured on the liver surface immediately after coagulation. The clinical biochemical and blood gas parameters were not different before and after coagulation. The coagulation depth was positively correlated with the device power setting. Conclusions These results prove that APC and HPC provide sufficient superficial haemostasis. No significant systemic effects occurred following coagulation. The depth of the coagulation effect can be controlled through selection of the output power level.

Cyclooxygenase Inhibitors as a New Therapeutic Strategy in Small Bowel Transplantation.

BACKGROUND: The long-term outcome of intestinal transplantations is still not favorable, which is partly due to the intestinal susceptibility to ischemia. There are several indications that the inflammatory response to ischemia-reperfusion injury is mediated by cyclooxygenases and that their inhibition may be associated with improved organ function. The aim of this study was to analyze if cyclooxygenase (COX) inhibitors could improve the early posttransplant outcome after orthotopic small bowel transplantation. METHODS: Small bowel transplantation was performed between rats to test the impact of nonselective (Piroxicam), preferential (Meloxicam), and selective COX-2 inhibitors (Parecoxib). The donor intestines were either perfused and stored with inhibitor or had inhibitor administered intravenously after transplantation. RESULTS: Using COX inhibitors, a sequential increase of posttransplantation intestinal integrity could be shown, with Parecoxib the least effective and Meloxicam the most effective treatment. These differences were in line with the downregulation of COX-2 activity by the inhibitors. Functionally, the same tendency could be seen in diminished expression of proinflammatory molecules, decreased leucocyte inflammation, and significantly improved graft microcirculation. In most cases, the intravenous administration was more effective. However, the COX inhibitors used were shown to cause relevant hepatotoxicity under nearly all conditions, but particularly under intravenous administration. Only Meloxicam in histidine-tryptophan-ketoglutarate was demonstrated to be a safe drug without hepatotoxic side effects. CONCLUSIONS: The activity of COX contributes to ischemia-reperfusion injury after intestinal transplantation. In this comparative study, the administration of the preferential COX-2 inhibitor Meloxicam via histidine-tryptophan-ketoglutarate showed the best graft-protective attributes and the lowest hepatotoxic side effects.

Comparison of Aerobic Preservation by Venous Systemic Oxygen Persufflation or Oxygenated Machine Perfusion of Warm-Ischemia-Damaged Porcine Kidneys.

BACKGROUND/AIM: The global shortage of donor organs for transplantation has necessitated the expansion of the organ pool through increased use of organs from less ideal donors. Venous systemic oxygen persufflation (VSOP) and oxygenated machine perfusion (OMP) have previously demonstrated beneficial results compared to cold storage (CS) in the preservation of warm-ischemia-damaged kidney grafts. The aim of this study was to compare the efficacy of VSOP and OMP for the preservation of warm-ischemia-damaged porcine kidneys using the recently introduced Ecosol preservation solution compared to CS using Ecosol or histidine-tryptophan-ketoglutarate solution (HTK). MATERIALS AND METHODS: Kidneys from German Landrace pigs (n = 5/group) were retrieved and washed out with either Ecosol or HTK after 45 min of clamping of the renal pedicle. As controls, kidneys without warm ischemia, cold stored for 24 h in HTK, were employed. Following 24 h of preservation by VSOP, OMP, CS-Ecosol, or CS-HTK, renal function and damage were assessed during 1 h using the isolated perfused porcine kidney model. RESULTS: During reperfusion, urine production was significantly higher in the VSOP and OMP groups than in the CS-HTK group; however, only VSOP could demonstrate lower urine protein concentrations and fractional excretion of sodium, which did not differ from the non-warm-ischemia-damaged control group. VSOP, CS-Ecosol, and controls showed better maintenance of the acid-base balance than CS-HTK. Reduced lipid peroxidation, as reflected in postreperfusion tissue thiobarbituric acid-reactive substance levels, was observed in the VSOP group compared to the OMP group, and the VSOP and CS-Ecosol groups had concentrations similar to the controls. The ratio of reduced to oxidized glutathione was higher in the VSOP, OMP, and CS-Ecosol groups than in the CS-HTK group and controls, with a higher ratio in the VSOP than in the OMP group. CONCLUSION: VSOP was associated with mitigation of oxidative stress in comparison to OMP and CS. Preservation of warm-ischemia-damaged porcine kidneys by VSOP was improved compared to OMP and CS, and was comparable to preservation of non-warm-ischemia-damaged cold-stored kidneys.

Improved preservation of warm ischemia-damaged porcine kidneys after cold storage in Ecosol, a novel preservation solution.

BACKGROUND: Ecosol, an extracellular-type, colloid-based preservation solution, has recently been introduced for washout, cold storage, and machine perfusion preservation of kidney grafts. Here, we assessed the efficacy of Ecosol compared to the widely used Histidine-Tryptophan-Ketoglutarate solution (HTK) for 24-h cold storage preservation of warm ischemia-damaged kidney grafts. MATERIAL AND METHODS: Before recovery, warm ischemia was induced by clamping the renal pedicle for 45-min. Thereafter, kidneys were washed-out and cold-stored for 24-h in Ecosol or HTK solution. Kidneys recovered without warm ischemia and cold-stored for 24-h in HTK served as controls (n=5). Renal function and damage parameters were assessed during 1-h normothermic reperfusion using the isolated perfused porcine kidney model. RESULTS: Renal function did not differ between Ecosol and controls and was significantly reduced in HTK compared to controls. Total output of urine was higher in Ecosol compared to HTK. Intrarenal resistance and urine protein concentrations in Ecosol were lower compared to HTK and equal to controls. In the Ecosol group, oxygen consumption during reperfusion was higher and reduced tissue lipid peroxidation products were detected compared to HTK. CONCLUSIONS: The preservation quality of warm ischemia-damaged, cold-stored porcine kidneys was improved using the recently developed Ecosol preservation solution compared to HTK.

Determination of the preferred conditions for the isolated perfusion of porcine kidneys.

BACKGROUND: The isolated perfused porcine kidney (IPPK) model has been the method of choice for the early preclinical evaluation of kidney graft preservation techniques. The preferred reperfusion conditions have not yet been determined. Here, we examined the effects of pressure- or flow-controlled perfusion and oxygenation by pure oxygen or carbogen (95% O2/5% CO2) on normothermic reperfusion in the IPPK model. METHODS: Porcine kidneys were cold-stored for 24 h in histidine-tryptophan-ketoglutarate solution and reperfused for 1 h with normothermic whole blood/Krebs-Henseleit buffer medium (20/80%). Kidneys (n = 5/group) were flow-controlled reperfused with pure oxygen (1 ml/min/g; Flow-O2) or pressure-controlled reperfused (85 mm Hg mean arterial pressure) and oxygenated with either pure oxygen (Pressure-O2) or carbogen (Pressure-O2/CO2). Renal function and damage were assessed during reperfusion and NGAL and HIF-1α levels were analyzed using an ELISA. RESULTS: Pressure-O2 and Pressure-O2/CO2 were associated with significantly better renal hemodynamics and acid-base homeostasis compared to Flow-O2. Urine protein concentrations and the fractional excretion of sodium were lower with both Pressure-O2 and Pressure-O2/CO2 than with Flow-O2. NGAL and HIF-1α levels were also lower with Pressure-O2 and Pressure-O2/CO2 than with Flow-O2. Only Pressure-O2/CO2 could demonstrate a significantly increased urine production compared to Flow-O2. The structural integrity was well preserved in the Pressure-O2 and Pressure-O2/CO2 groups, whereas diffuse and global glomerular destruction was observed in the Flow-O2 group. CONCLUSION: In the IPPK model, the application of pressure-controlled reperfusion with carbogen oxygenation, and to a lesser extent with pure oxygen, maintained physiological renal function for 1 h, thus providing a reliable and reproducible ex vivo evaluation of kidney preservation quality.

Evaluation of the novel bipolar vessel sealing and cutting device BiCision® in a porcine model.

BACKGROUND: Energy-based technologies for tissue sealing and cutting are increasingly supplementing current standards used for haemostasis and dissection during laparoscopic surgery. For their safe and efficacious use in clinical practice, these instruments have to guarantee sufficient burst resistance and low thermal damage to adjacent tissue in combination with good cutting characteristics. MATERIAL AND METHODS: The novel laparoscopic, bipolar electrosurgical sealing and cutting instrument BiCision® was compared to a commercially available laparoscopic device (EnSeal(™)) on visceral and peripheral arteries and veins in an animal model. RESULTS: For all parameters investigated (burst pressure, cut quality, tissue adhering to the instrument, time needed to seal and cut the vessel and thermal damage), BiCision® was at least as good as EnSeal(™). Regarding the burst pressure, BiCision® was superior over EnSeal(™) in arteries: 600 mmHg (±478) versus 241 (±269) mmHg, respectively (p < 0.0001*). In veins, almost equivalent burst pressures of 155 ± 134 mmHg (BiCision®) and 173 ± 139 mmHg (EnSeal(™)) were obtained. CONCLUSION: BiCision® appeared to be as good as or even superior to EnSeal(™). Since EnSeal(™) has already been shown to be safe and has been successfully used in clinical practice, BiCision® is assumed to be as efficient and reliable as EnSeal(™) under pre-clinical conditions.