骨髓间充质干细胞对中性粒细胞胞外诱捕网介导的体外循环相关急性肺损伤的保护作用与机制

As a common complication of cardiopulmonary bypass (CPB), acute lung injury is associated with the formation of neutrophil extracellular trap (NETs). Our previous study showed that bone marrow mesenchymal stem cells (MSCs) could decrease the neutrophil-derived circulating free DNA in the plasma of rats after undergoing CPB. We also found that the main force of NETs formation might be immature neutrophils. We therefore hypothesize that MSCs can attenuate the CPB-related acute lung injury by inhibiting the immature neutrophils formation of NETs. This study aims at investigating the impacts of MSCs on NETs formation and acute lung injury in vivo with the employment of a CPB rat model. With the coculture of MSCs and immature neutrophils, which are isolated from both the blood of patients and bone marrow of rats undergoing CPB, we will explore the effect of MSCs on NETs formation in vitro. We will further elucidate the molecular mechanism of the regulatory effect of MSCs on NETs by exploring the expression of superoxide dismutase 3 (SOD3) and observing the changes in NETs formation after silencing the SOD3 expression with small interfering RNA. Focusing on NETs, the latest discovered regulatory target, our study will discuss the protective effect and mechanism of MSCs on CPB-related acute lung injury, which will provide theoretical basis and experimental evidence for the future use of MSCs in the treatment of CPB-related acute lung injury.

体外循环相关急性肺损伤是体外循环(CPB)术后常见并发症，发生机制与中性粒细胞胞外诱捕网(NETs)介导的损伤有关。我们前期研究表明，骨髓间充质干细胞(MSCs)可降低CPB后大鼠血浆中游离胞外诱捕网DNA的水平，且幼稚中性粒细胞可能是形成NETs的主要细胞群体。据此，我们假设骨髓MSCs可通过抑制幼稚中性粒细胞形成NETs，减轻CPB相关急性肺损伤。本研究拟通过大鼠CPB模型，研究MSCs对NETs的形成和肺损伤的影响；通过分离CPB患者外周血和CPB大鼠骨髓幼稚中性粒细胞，与MSCs共培养，研究MSCs在体外对NETs形成的作用；并通过检测MSCs超氧化物歧化酶3(SOD3)的表达和沉默SOD3后NETs的变化，研究MSCs调控NETs形成的分子机制。本研究将从NETs这一新靶点探讨MSCs对CPB相关急性肺损伤的保护作用及机制，为临床应用MSCs进行CPB肺保护提供理论依据。

体外循环相关急性肺损伤是体外循环(CPB)术后常见并发症，最新研究显示其发生机制与中性粒细胞胞外诱捕网(NETs)介导的损伤有关。间充质干细胞(MSCs)可通过多种机制发挥肺保护作用，但对NETs介导的CPB相关急性肺损伤的调控作用不明。本研究通过建立大鼠CPB模型后静脉输注骨髓MSCs，结果表明骨髓 MSCs可降低CPB后大鼠血浆中游离胞外诱捕网DNA的水平，明确MSCs对CPB建立后NETs形成的抑制作用；体外实验中，通过分离CPB患者外周血中性粒细胞，与MSCs共培养，经佛波酯(PMA)诱导NETs形成，通过检测幼稚中性粒细胞活性氧(ROS)的水平，细胞上清中髓化过氧化物酶(MPO)的释放和活性，以及cf-DNA/NETs的含量，明确MSCs在体外可抑制中性粒细胞ROS水平和NETs的形成；并通过小干扰RNA(siRNA)沉默MSCs的超氧化物歧化酶3(SOD3)的表达，检测NETs形成的变化，探讨了MSCs调控NETs形成的分子机制，结果表明MSCs对中性粒细胞NETs的调控作用与其释放SOD3有关。本研究从NETs这一新靶点探讨了MSCs对CPB相关急性肺损伤的保护作用及机制，为临床应用MSCs进行CPB肺保护提供了理论依据。