Evaluation of a novel system for hypothermic oxygenated pulsatile perfusion preservation.

BACKGROUND: Recently, a novel innovative machine perfusion (MP) system for hypothermic oxygenated pulsatile perfusion called the Airdrive (AD) has been developed. The aim of the study was to evaluate the biological safety of the AD system for perfusion preservation of kidney grafts in a porcine autotransplantation model using the low-viscosity perfusion solution Polysol (PS) in comparison with cold storage (CS) using PS or the University of Wisconsin solution (UW). In addition, we evaluated real-time microcirculation parameters. At sacrifice, grafts were retrieved for histological analysis and immunohistochemistry. METHODS: After assessment of the microcirculation, left kidneys were retrieved. Following the washout, kidneys were preserved for 20 hr using AD-PS, CS-PS or CS-UW. Thereafter, contralateral kidneys were removed followed by heterotopic autotransplantation of the preserved graft. Seven days after transplantation animals were sacrificed with retrieval of the grafts for histological analysis. Renal function, renal microcirculation and tissue injury including the proliferative response of tubular epithelial cells (TECs) were compared. RESULTS: Preservation using AD-PS or CS-PS resulted in higher microcirculatory flow compared with CS-UW. Improved recovery of renal function was seen in the AD-PS and CS-PS groups compared with CS-UW. Structural integrity was better preserved using AD-PS compared with both CS groups. Proliferative response of TECs was higher in CS-UW preserved grafts compared to grafts preserved using AD-PS. CONCLUSION: This study demonstrates the biological safety of the AD system in a porcine autotransplantation model. Also, the microcirculation was better preserved and less morphological injury was observed after 20 hr MP compared with CS.

Improved preservation and microcirculation with POLYSOL after transplantation in a porcine kidney autotransplantation model.

BACKGROUND: The most widely used preservation method for kidney grafts is cold static storage (CS) using the University of Wisconsin (UW) solution. To date, new preservation solutions have not been able to significantly improve preservation quality of grafts. The aim of this study was to compare POLYSOL, a recently developed low viscosity preservation solution, and the UW solution for CS of porcine kidney grafts. METHODS: In a porcine autotransplantation model, real-time parameters of the renal microcirculation were evaluated using the novel oxygen-to-see (O2C) combined laser Doppler and flowmetry system. Thereafter, kidneys were retrieved and washed out with POLYSOL or UW followed by 20-h CS. After the preservation period, the contralateral kidneys were removed and the preserved kidneys autotransplanted. The microcirculation was re-assessed at 10 min after reperfusion and at 7 days posttransplant, prior to removal of the grafts for histological evaluation. RESULTS: POLYSOL was able to better preserve the microcirculation compared to UW as expressed by higher values of capillary blood flow, blood flow velocity and tissue oxygen saturation values. In addition, CS using POLYSOL resulted in improved functional recovery demonstrated by lower posttransplant serum creatinine and blood urea values in comparison to the UW group. Also, structural integrity was better preserved in the POLYSOL group, compared to UW. CONCLUSIONS: This study in a clinically relevant large animal model showed that a new preservation solution, POLYSOL, resulted in improved preservation quality of kidney grafts compared to the UW solution.

Preclinical evaluation of superantigen (staphylococcal enterotoxin B) in the intravesical immunotherapy of superficial bladder cancer.

Superantigens are potent activators of T lymphocytes; therefore, their characteristics can be exploited in diseases where immunomodulation is known to be effective. In this study, we evaluated a new approach for the intravesical therapy of superficial bladder cancer. We investigated in coculture experiments if staphylococcal enterotoxin B (SEB)-activated PBMCs are able to induce apoptosis in human transitional cell carcinoma (TCC) cells. Additionally, we tested the toxicity and efficacy of SEB dissolved in NaCl 0.9% administered intravesically once weekly for 6 weeks in a rat bladder cancer model. To validate the coculture in vitro findings, we evaluated tumor stage, grade, apoptotic cells in the urothelium and stroma of the bladder and infiltration of the bladder wall by lymphocytes, macrophages and mononuclear cells. Coculture experiments revealed that SEB-activated PBMCs are able to kill TCC cells by inducing apoptosis. The intravesical toxicity study with a maximum dose of 100 microg/ml SEB demonstrated no side effects. In the intravesically SEB-treated animals (10 microg/ml), only 3 tumors remained vs. 15 persisting tumors in the control group. The remaining tumors of the therapy group showed a significant amount of apoptosis and granulocytes, mainly in the urothelium, whereas no relevant apoptosis or infiltration of the bladder with lymphocytes or macrophages was found in the control group. These preclinical findings suggest that SEB might be an interesting candidate for further clinical evaluation.

Kidney transplantation from non-heart-beating donors after oxygenated low-flow machine perfusion preservation with histidine-tryptophan-ketoglutarate solution.

The aim of this study was to determine the potential benefit of aerobic machine preservation (MP) with non-colloidal histidine-tryptophan-ketoglutarate (HTK) solution compared with MP with Belzer machine perfusion solution (MPS) and standard cold storage, after marginal kidneys had been obtained from non-heart-beating donors. Cardiac arrest was electrically induced in anaesthetized German landrace pigs (20-25 kg bw). Their kidneys were harvested 40 min thereafter, flushed with HTK by gravity of 100 cm H2O via the renal artery and then stored in HTK for 18 h at 4 degrees C. Other organs were subjected to oxygenated (pO2>500 mmHg) hypothermic pulsatile low-flow machine perfusion with HTK or MP with Belzer MPS at P(max)=40 mmHg, yielding transrenal flow values of 0.2-0.3 ml/min per g with HTK and approximately twice that amount with Belzer MPS. A well-preserved vascular endothelium and intact tubular epithelium were documented by electron microscopy at the end of perfusion preservation in both solutions as well as after cold storage. Concentrations of ATP (in micromoles per gramme) in tissue homogenates at the end of perfusion preservation with HTK were 1.18+/-0.12 vs 0.16+/-0.02 (P<0.05) after simple cold storage and 2.43+/-0.23 after perfusion with Belzer MPS, thus documenting a relevant effect of low-flow perfusion on tissue oxygenation. Viability of the grafts was followed for 1 week after heterotopic transplantation and bilateral nephrectomy in the recipient pigs. Machine perfusion with HTK significantly improved cortical microcirculation upon early reperfusion in vivo, as well as maximal serum levels of urea and creatinine, compared to recipients receiving cold-stored grafts. No differences could be found between MP with HTK or Belzer MPS. In conclusion, provision of oxygen during storage is possible by low-flow perfusion with HTK as with Belzer MPS and apparently improves graft viability after transplantation.