Protective effects of B2 preservation solution in comparison to a standard solution (histidine-tryptophan-ketoglutarate/Bretschneider) in a model of isolated autologous hemoperfused porcine kidney

Preservation Solutions for Kidney Transplantation: History, Advances and Mechanisms

Solid organ transplantation was one of the greatest medical advances during the past few decades. Organ preservation solutions have been applied to diminish ischemic/hypoxic injury during cold storage and improve graft survival. In this article, we provide a general review of the history and advances of preservation solutions for kidney transplantation. Key components of commonly used solutions are listed, and effective supplementations for current available preservation solutions are discussed. At cellular and molecular levels, further insights were provided into the pathophysiological mechanisms of effective ingredients against ischemic/hypoxic renal injury during cold storage. We pay special attention to the cellular and molecular events during transplantation, including ATP depletion, acidosis, mitochondrial dysfunction, oxidative stress, inflammation, and other intracellular mechanisms.

An Improved Model of Isolated Hemoperfused Porcine Livers Using Pneumatically Driven Pulsating Blood Pumps

Existing liver perfusion models are largely limited by high degrees of ischemic and reperfusion injury and the lack of standardization. To establish a highly standardized perfusion model and minimize reperfusion injury, a porcine liver perfusion model was developed using an artificial heart pump (Buecherl Artificial Heart). This model is characterized by pneumatically driven and pressure controlled blood pumps with pulsating flow characteristics. The perfusion parameters and the integrity of the perfused organ were assessed using hemodynamic and hepatic function tests. In eight porcine liver perfusion experiments the system allowed maintaining stable and physiologic organ function over 3 hours by bile production (5.5 ±3.1 ml/30 minutes, resp. 22.9 ±8.4 ml cumulative at 180 minutes), oxygen consumption (2.2 ±0.2 ml/min/100 g overall mean) and significantly better liver enzyme levels (AST 19.5 ± 10.1 U/l/100 g, ALT 2.1 ± 0.8 U/l/min, LDH 57.8 ± 24.2 U/l/100 g) compared to previous studies. It was also possible to reduce the circulating blood volume to 1,000 ml and to create a compact perfusion system that is adoptable to other organ systems such as the kidneys. The compact size and the absence of magnetic components also allow a use for advanced imaging techniques. In conclusion this optimized perfusion system provides a sound basis for future studies in the area of hepatotoxicity and pharmacology.

Reference values and physiological characterization of a specific isolated pig kidney perfusion model

BACKGROUND

Models of isolated and perfused kidneys are used to study the effects of drugs, hazardous or toxic substances on renal functions. Since physiological and morphological parameters of small laboratory animal kidneys are difficult to compare to human renal parameters, porcine kidney perfusion models have been developed to simulate closer conditions to the human situation, but exact values of renal parameters for different collection and perfusion conditions have not been reported so far. If the organs could be used out of regular slaughtering processes animal experiments may be avoided.

METHODS

To assess renal perfusion quality, we analyzed different perfusion settings in a standardized model of porcine kidney hemoperfusion with organs collected in the operating theatre (OP: groups A-D) or in a public abattoir (SLA: group E) and compared the data to in vivo measurements in living animals (CON). Experimental groups had defined preservation periods (0, 2 and 24 hrs), one with additional albumin in the perfusate (C) for edema reduction.

RESULTS

Varying perfusion settings resulted in different functional values (mean +/- SD): blood flow (RBF [ml/min*100 g]: (A) 339.9 +/- 61.1; (C) 244.5 +/- 53.5; (D) 92.8 +/- 25.8; (E) 153.8 +/- 41.5); glomerular filtration (GFR [ml/min*100 g]: (CON) 76.1 +/- 6.2; (A) 59.2 +/- 13.9; (C) 25.0 +/- 10.6; (D) 1.6 +/- 1.3; (E) 16.3 +/- 8.2); fractional sodium reabsorption (RFNa [%] (CON) 99.8 +/- 0.1; (A) 82.3 +/- 8.1; (C) 86.8 +/- 10.3; (D) 38.4 +/- 24.5; (E) 88.7 +/- 5.8). Additionally the tubular coupling-ratio of Na-reabsorption/O2-consumption was determined (TNa/O2-cons [mmol-Na/mmol- O2] (CON) 30.1; (A) 42.0, (C) 80.6; (D) 17.4; (E) 23.8), exhibiting OP and SLA organs with comparable results.

CONCLUSION

In the present study functional values for isolated kidneys with different perfusion settings were determined to assess organ perfusion quality. It can be summarized that the hemoperfused porcine kidney can serve as a biological model with acceptable approximation to in vivo renal physiology, also if the organs originate from usual slaughtering processes.

Shift work and pathological conditions

Shift work exerts major influences on the physiological functions of the human body. These are primarily mediated by the disruption of circadian rhythms since most body functions are circadian rhythmic. Next to the disturbances caused by changes in the circadian system, shift work has also been suggested to be related to a number of other health disorders. The present study summarizes recently published data on the potential relationship between disorders and shift working.

Evaluation of renal functional parameters in different settings of isolated organ hemoperfusions

Isolated porcine kidneys are commonly used to study physiological and pathophysiological aspects of renal homeostasis but standardized evaluation procedures of renal function in this model do not exist so far. A double-logarithmical nomogram is established for filtration and reabsorption functions in isolated and hemoperfused porcine kidneys using different perfusion settings. Model validity was demonstrated by the levels of urine flow and sodium excretion showing expected alteration levels of lowering in the ADH-group and increasing in the furosemide-group of isolated kidneys. Creatinine-clearance values were in constant ranges within each specific perfusion group as indicated by the nomogram procedure. The present studies used a nomogram method to analyze the effects of different renal perfusion settings in a porcine model of kidney perfusion. The method may be of use to differentiate various kidney perfusion parameters both at the experimental and clinical levels.

Hepatotoxic effects of polidocanol in a model of autologously perfused porcine livers

Polidocanol is an effective sclerosing agent that consists of 95% hydroxypolyethoxydodecane and 5% ethyl alcohol and is known to have a low risk of complications. However, since the compound has been proposed for the local treatment of liver diseases, the potential for topical hepatic side effects should be examined. Therefore, the new model of normothermic-hemoperfused isolated porcine slaughterhouse livers was used to examine polidocanol-hepatotoxicity encompassing the advantages of slaughterhouse organs to reduce animal experiments and autologous blood as an optimal perfusate. Polidocanol was administered via the hepatic artery and portal vein and the effects of the sclerosant on organ function parameters were compared with those in an untreated control group. In contrast to the untreated control organs, significant differences were found in the polidocanol group for parameters such as alanine aminotransferase or organ weight after perfusion. The most striking differences were found for hepatic bile flow, which dropped in the polidocanol group to 0.24+/-0.02 ml/min per 1000 g after administration of the compound compared with 3.80+/-1.08 ml/min per 1000 g in the control group. In summary, the present observations indicate a risk of hepatotoxic effects of polidocanol. Clinicians should be aware of this problem and the use of polidocanol for intrahepatic sclerosing should be restricted to specialized centers.