[Introduction of a MR-compatible system for extracorporal perfusion of vital organs for MR-guided procedures--first-experiences]. / Einsatz eines MR-kompatiblen Organperfusionssystems für physiologische Ex-vivo-Experimente im MRT--Erste Erfahrungen mit einem Tierversuchsersatzsystem.

PURPOSE: To represent a MRI-compatible perfusion-system for extracorporeal perfusion of vital organs which permits the realisation of realistic experiments in a MR scanner. MATERIAL AND METHODS: We performed MR examinations of explanted porcine livers and MR-guided interventions in porcine livers. Explanted organs were hemo-perfused under physiological conditions during the experiments. MR-sequences for diagnostic and interventional examinations were used. RESULTS: The evaluated system was MRI-compatible. The achieved image quality of the used sequences showed excellent anatomical resolution. Planned experiments can be carried out with relatively low expenditure. Diagnostic as well as interventional investigations can be carried out. The used organs showed a stable function within physiological parameters up to 4 hours. CONCLUSION: It is possible to perform ex vivo experiments under in vivo conditions with this system. With the used MR-compatible system MR-guided experimental interventions and thermal ablations can be carried out in explanted organs under in vivo conditions.

A model of isolated, autologously hemoperfused porcine slaughterhouse lungs.

INTRODUCTION: Models of isolated and perfused lungs study pathophysiological phenomena of the airways, but are limited by restricted resemblance to the human situation, non-physiological perfusates or the need for the use of high numbers of laboratory animals. The present model was established to address these difficulties. OBJECTIVES: Aim of the current study was the establishment of an animal model that uses slaughterhouse animals and closely resembles physiological conditions found in humans. METHODS: We used a model of hemoperfused isolated porcine slaughterhouse lungs using autologous blood, metabolically controlled via a dialysis system. Over a period of 135 minutes positive inspiratory pressure, pulmonary arterial pressure, pulmonary vein oxygen partial pressure and lung weight were assessed. RESULTS: Stable organ function was maintained over 135 minutes with an amount of 2,500-3,000 ml perfusate without fall in pulmonary arterial pressure. During the time the positive inspiratory pressure and lung weight increased, while pulmonary vein oxygen partial pressure decreased. CONCLUSIONS: The present model of isolated hemoperfused slaughterhouse lungs displays a useful new and economic approach to evaluate pulmonary function and toxicity of different substances on an organ level. As a major economic advantage in comparison to models using laboratory animals, the current model might be run using blood and organs obtained from slaughterhouse animals.

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.

Influence of cold storage on renal ischemia reperfusion injury after non-heart-beating donor explantation.

BACKGROUND: Due to the increasing need for kidney donors, transplantation from non-heart-beating donors (NHBD) is currently being practiced more extensively. As detailed studies on the reperfusion injury of these kidneys do not exist so far, a comparison of renal ischemia reperfusion injury scores immediately after organ explantation with injury scores after NHBD organ explantation with subsequent cold storage would be useful. METHODS: Non-stored kidneys were compared to a group of kidneys stored for 6.9 +/- 1.8 h. Functional analyses were made during 145 min of ex vivo perfusion. Quantitative histological analyses were performed in all kidneys after termination of perfusion. RESULTS: During ex vivo reperfusion, renal vascular resistance was elevated, while creatinine clearance, filtration fraction, renal oxygen consumption, and sodium reabsorption were below normal after non-heart-beating explantation and further decreased after subsequent washing and cold storage. In the kidneys subjected to cold preservation, histologically tubular damage was enhanced, and the total count, as well that for the intraglomerular neutrophil granulocytes were also elevated. CONCLUSIONS: Explantation from NHBD causes renal ischemia reperfusion injury. Cold storage augmented deterioration of the kidney as histologically and functionally demonstrated. Thus, preservation times for non-heart-beating kidneys should be carefully reappraised.