A translational rat model for ex vivo lung perfusion of pre-injured lungs after brain death

Male versus female inflammatory response after brain death model followed by ex vivo lung perfusion

BACKGROUND

Ex vivo lung perfusion (EVLP) is a useful tool for assessing lung grafts quality before transplantation. Studies indicate that donor sex is as an important factor for transplant outcome, as females present higher inflammatory response to brain death (BD) than males. Here, we investigated sex differences in the lungs of rats subjected to BD followed by EVLP.

METHODS

Male and female Wistar rats were subjected to BD, and as controls sham animals. Arterial blood was sampled for gas analysis. Heart-lung blocks were kept in cold storage (1 h) and normothermic EVLP carried out (4 h), meanwhile ventilation parameters were recorded. Perfusate was sampled for gas analysis and IL-1β levels. Leukocyte infiltration, myeloperoxidase presence, IL-1β gene expression, and long-term release in lung culture (explant) were evaluated.

RESULTS

Brain dead females presented a low lung function after BD, compared to BD-males; however, at the end of the EVLP period oxygenation capacity decreased in all BD groups. Overall, ventilation parameters were maintained in all groups. After EVLP lung infiltrate was higher in brain dead females, with higher neutrophil content, and accompanied by high IL-1β levels, with increased gene expression and concentration in the culture medium (explant) 24 h after EVLP. Female rats presented higher lung inflammation after BD than male rats. Despite maintaining lung function and ventilation mechanics parameters for 4 h, EVLP was not able to alter this profile.

CONCLUSION

In this context, further studies should focus on therapeutic measures to control inflammation in donor or during EVLP to increase lung quality.

Zerumbone ameliorates the inflammatory response and organ damage in severe acute pancreatitis via the ROS/NF-κB pathway

OBJECTIVE

The aim of the current study was to determine the mechanism by which Zerumbone (ZER) ameliorates inflammation and organ damage in a rat model of severe acute pancreatitis (SAP).

METHODS

Different concentrations of ZER (10, 20 and 40 mg/kg) were administered by femoral vein puncture 30 min prior to establishment of the SAP model. Hematoxylin and eosin (H&E) staining was used to assess pathological changes in the pancreatic tissue of SAP-induced rats. The lung wet/dry (W/D) ratio was assessed and serum levels of amylase (AMY), alanine aminotransferase (ALT), creatinine (Cr), aspartate aminotransferase (AST) and phospholipase A2 (PLA2) were measured. Western blot analysis was used to examine changes in the expression of ROS/NF-κB pathway-associated proteins.

RESULTS

SAP was confirmed by significant histopathological damage to the pancreas. ZER (10, 20 and 40 mg/kg) was found to alleviate pancreatitis and decrease ascites volume, lung W/D ratio, pancreatic pathology score, oxidative stress and inflammatory damage. High concentrations (20 and 40 mg/kg) of ZER were shown to increase levels of hepatorenal toxicity. In contrast, 10 mg/kg ZER was found to attenuate liver enzyme levels, reduce pathological damage to the liver, and protect against extrapancreatic organ damage to the liver in SAP-induced rats. Moreover, ZER showed no significant side effects in normal rats. Finally, we demonstrated that ZER mediated its anti-inflammatory effects on SAP through the ROS/NF-κB signaling pathway.

CONCLUSION

ZER alleviated SAP-induced oxidative stress and inflammatory injury via the ROS/NF-κB pathway, and had a protective effect on lung injury and liver damage.

Design and Implementation of a Rat Ex Vivo Lung Perfusion Model

Ex vivo lung preparations are a useful model that can be translated to many different fields of research, complementing corresponding in vivo and in vitro models. Laboratories wishing to use isolated lungs need to be aware of important steps and inherent challenges to establish a setup that is affordable, reliable, and that can be easily adapted to fit the topic of interest. This paper describes a DIY (do it yourself) model for ex vivo rat lung ventilation and perfusion to study drug and gas effects on pulmonary vascular tone, independent of changes in cardiac output. Creating this model includes a) the design and construction of the apparatus, and b) the lung isolation procedure. This model results in a setup that is more cost-effective than commercial alternatives and yet modular enough to adapt to changes in specific research questions. Various obstacles had to be resolved to ensure a consistent model that is capable of being used for a variety of different research topics. Once established, this model has proven to be highly adaptable to different questions and can easily be altered for different fields of study.

Experimental Models of Ischemic Lung Damage for the Study of Therapeutic Reconditioning During Ex Vivo Lung Perfusion

Background.

Ex vivo lung perfusion (EVLP) may allow therapeutic reconditioning of damaged lung grafts before transplantation. This study aimed to develop relevant rat models of lung damage to study EVLP therapeutic reconditioning for possible translational applications.

Methods.

Lungs from 31 rats were exposed to cold ischemia (CI) or warm ischemia (WI), inflated at various oxygen fractions (FiO₂), followed by 3 h EVLP. Five groups were studied as follow: (1) C21 (control): 3 h CI (FiO₂ 0.21); (2) C50: 3 h CI (FiO₂ 0.5); (3) W21: 1 h WI, followed by 2 h CI (FiO₂ 0.21); (4) W50: 1 h WI, followed by 2 h CI (FiO₂ 0.5); and (5) W2h: 2 h WI, followed by 1 h CI (FiO₂ 0.21). Following 3 h EVLP, we measured static pulmonary compliance (SPC), pulmonary vascular resistance, lung weight gain (edema), oxygenation capacity (differential partial pressure of oxygen), and protein carbonyls in lung tissue (oxidative stress), as well as lactate dehydrogenase (LDH, lung injury), nitrotyrosine (nitro-oxidative stress), interleukin-6 (IL-6, inflammation), and proteins (permeability edema) in bronchoalveolar lavage (BAL). Perivascular edema was quantified by histology.

Results.

No significant alterations were noted in C21 and C50 groups. W21 and W50 groups had reduced SPC and disclosed increased weight gain, BAL proteins, nitrotyrosine, and LDH. These changes were more severe in the W50 group, which also displayed greater oxidative stress. In contrast, both W21 and W50 showed comparable perivascular edema and BAL IL-6. In comparison with the other WI groups, W2h showed major weight gain, perivascular edema, SPC reduction, drop of differential partial pressure of oxygen, and massive increases of BAL LDH and proteins but comparable increase of IL-6 and biomarkers of oxidative stress.

Conclusions.

These models of lung damage of increasing severity might be helpful to evaluate new strategies for EVLP therapeutic reconditioning. A model combining 1 h WI and inflation at FiO₂ of 0.5 seems best suited for this purpose by reproducing major alterations of clinical lung ischemia-reperfusion injury.