Effects Of Ex Vivo Lung Perfusion For 2 Hours On Pulmonary Arterial Endothelium

Background and ObjectiveAs the society ages and the living environment continues to deteriorate,the number of patients with lung diseases continues to increase worldwide,and it is now one of the leading causes of death.End-stage lung disease is a serious threat to the health of modern people.Currently,the most effective method for end-stage lung disease is to perform a lung transplant.Lung transplant surgery can effectively improve the patient's physical condition while prolonging survival.However,the development of lung transplant surgery worldwide is not ideal.The factors restricting its development mainly include many aspects such as operation technology,insufficient number of transplant donors and poor postoperative recovery.The most important reasons for lung transplant surgery are limited when the lung transplant donor is insufficient.Currently,there are multiple methods for expanding donor donor libraries,including donors for cardiogenic death and donor lung that do not meet the transplant criteria by repair and evaluation.In the continuous practice,the in ex vivo lung perfusion technique has played a huge role in expanding the donor bank of lung transplantation and improving the survival of patients after transplantation.The ex vivo lung perfusion technique provides a platform for detecting the donor lung and predicting the clinical manifestation of the donor lung after transplantation;at the same time,repairing the donor lung that does not meet the transplant criteria,in order to expand the donor lung source.At present,it is not clear whether the donor pulmonary blood vessels receive injury during perfusion.In this experiment,the normal lung tissue and the vascular smooth muscle and endothelial function of the lung tissue after in vitro lung perfusion experiments were compared to detect whether the pulmonary artery was damaged during perfusion.Materials and MethodsTake 6 Swedish pigs,male or female,weighing 25-35 kg.After the animals were anesthetized,the chest was opened in the middle,and the right ventricle was placed in the tube with a perfusion pressure of 20 cmH2 O.The whole lung was perfused with 4 L of LPD solution at a temperature of about 2 L(60 mL/kg).At the end of the expiratory flow,the trachea was removed and the bilateral lungs were removed.The lungs were divided into two groups,the right lung was classified as a fresh control group,and the left side was classified as an in vitro perfusion group.In the fresh control group,the surrounding lung tissue of the right lower lobe was removed and placed in a 4 °C Krebs solution.A pulmonary artery approximately 1.8 mm in diameter was dissected under a surgical microscope and cut into segments approximately 1.5 mm long.The pulmonary artery segments were transferred to an organ bath containing Krebs solution(37 °C)bubbling with 95% O2 and 5% CO2.In the ex vivo perfusion group,the left lung tissue was placed in a perfusion machine and perfused for 2 hours using a standardized decellularization protocol,and the operation in the fresh control group was repeated after perfusion.The pulmonary artery vascular ring was suspended between the two metal stents in the organ bath,and the basic tension of the vascular ring was adjusted to 4 mN by repeated stretching,and the smooth depolarization contraction of the smooth muscle was induced twice with 127 mmol / L potassium-Krebs solution.U46619(thromboxane A2 analogue)with a concentration of 3×10-7 mol / L was used to induce contraction;when the platform was reached,the gradually increasing concentration of substance P(10-9~10-4 mol / L)was added to the bath.Finally,a nonendothelium-dependent vasodilator papaverine(10-4 mol / L)was added to the bath to determine if complete relaxation had been achieved.ResultsThe contractions induced by U-46619 were 22.4±2.2 mN and 24.5±2.9 mN,respectively.There was no significant difference between the two groups.The maximum diastolic caused by substance P was 97±0.67% and 97±0.68%,respectively.There was no statistical difference between them;the negative logarithm pEC50 of the molar concentration of substance P at 50% maximal diastole between the two groups was 6.74±0.07 and 6.76±0.07,respectively,and the difference was not statistically significant.The 10-4 mmoL/L papaverine-induced relaxation in the pulmonary artery ring was 105.2 ± 0.8% and 104.3 ± 0.5%,respectively,of U-46619-induced contraction(Table 2),there was no significant difference between the two groups.ConclusionsTwo hours after extracorporeal pulmonary perfusion,pulmonary endothelial cells and smooth muscle function were not damaged.