Introduction: Brain death (BD) compromises graft quality by causing systemic changes and hormonal dysfunction. Hormonal replacement is already vastly applied in the clinical scenario with positive outcomes. Another alternative to increase donation is the recovery of marginal lungs using treatment during ex vivo lung perfusion (EVLP). Owing to the anti-inflammatory actions of 17β-estradiol (E2) and methylprednisolone (MP), we aimed to investigate the effect of E2 and MP combined treatment during EVLP.
Methods: Males and females Wistar rats underwent BD induction and were maintained for 4h. Naive animals were used as control. After BD, the pulmonary artery was cannulated, one third of the animals had the lungs flushed, collected and stored (BD) and the other animals had the heart-lung block collected, submitted to cold ischemia (1 h) and then placed in an EVLP system for normothermic perfusion (4 h). The solution used for perfusate was home-made STEEN added or not with the treatment (T: MP, 40 mg; E2: 5 µg/mL) During EVLP, volume-controlled ventilation was performed. Groups were defined as: male (n=22) and female (n=22) rats, divided as follows: BD (without perfusion), BD+EVLP (BD+EVLP without treatment), BD+EVLP+T (BD+EVLP with treatment). Lung tissue and perfusate samples were collected and data from perfusion flow and ventilatory parameters were recorded. IL-1β was measured in lung homogenate, perfusate and explant (lung culture – 24h). LDH was measured in perfusate.
Results: After BD, males presented higher IL-1β in comparison to females in lung homogenate (p=0.0011) however, after 24h lung tissue culture, females presented increased IL-1β levels in comparison to males (p=0.0403). In the perfused groups, treatment was able to improve perfusion flow in both male and female lungs (p<0.0001). LDH was increased in male groups in comparison to respective female groups (p<0.0001). Male perfused groups presented lower IL-1β in lung tissue after EVLP (p<0.0001) in comparison to BD, while no differences were observed among females. There were no differences in IL-1β among the groups in perfusate. In lung culture, female BD-EVLP+T group presented lower levels of IL-1β (p=0.0143) in comparison to BD. There were no differences in male groups. Regarding lung function analysis during EVLP, non-treated males needed increased peak inspiratory pressure and presented higher elastance, and reduced dynamic compliance in comparison to treated males and both female groups. Some results are represented in figure 1.
Conclusion: Our results point to a sex-dependent response to combined therapy of MP and E2 during EVLP after BD. Males presented improved lung function after treatment, evidenced by increased compliance and reduced elastance. Also, regarding the inflammatory profile, females responded positively to the treatment during EVLP, with reduced IL-1β levels in lung culture 24h later.