Xie Fangke, Tan Qiang, Yu Anyong, Guo Peiwen, Wang Ling, Zeng Zongwei, Liang Liang, Xian Jishu, Feng Hua, Chen Zhi
1Department of Emergency, Affiliated Hospital of Zunyi Medical University, Zunyi; and.
2Department of Neurosurgery, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China.
J Neurosurg. 2021 Jan 8;135(4):1105-1112. doi: 10.3171/2020.7.JNS201429. Print 2021 Oct 1.
Tissue plasminogen activator (tPA) fibrinolysis did not improve functional outcomes of patients with intraventricular hemorrhage (IVH), largely because of the unsatisfactory clot clearance. The presence of neutrophil extracellular traps (NETs) within the clot has been confirmed to impair tPA fibrinolysis, but the mechanism has been unclear. The authors hypothesized that cell-free DNA (cfDNA), the main framework of NETs, might be the important reason for the fibrinolysis resistance, and they validated the hypothesis, hoping to provide a new target to promote intraventricular fibrinolysis.
First, cfDNA was detected in IVH clots by immunofluorescence staining in a rat model of IVH. Second, after blood (with or without exogenous cfDNA) intraventricular injection, IVH rats were given intraventricular infusion of 2 μl of saline, tPA, or tPA + DNase1 randomly. Then, the ventricular volume, animal behavior, and reactive astrocyte proliferation were assessed. Third, the IVH clots were collected for fibrinolysis assay in vitro. Finally, the effects of exogenous cfDNA in IVH were evaluated.
The presence of cfDNA in clots was observed as early as 1 hour after IVH. Compared with the whole-blood model, blood + cfDNA caused more severe ventricular dilation (day 7: blood 32.47 ± 2.096 mm3 vs blood + DNA 40.09 ± 2.787 mm3, p < 0.05), increased fibrinolysis resistance to tPA (day 7: tPA + DNA 26.04 ± 1.318 mm3 vs tPA 22.15 ± 1.706 mm3, p < 0.05), and further deteriorated the functional defects in rats (blood vs blood + DNA, p < 0.05). Degradation of cfDNA by DNase1 further enhanced the fibrinolysis effects on relieving the ventricular dilation (day 7: tPA + DNase1 11.67 ± 2.023 mm3 vs tPA, p < 0.05), improving the functional outcome (tPA vs tPA + DNase1, p < 0.05) and reducing periventricular astrocyte proliferation.
cfDNA impaired tPA fibrinolysis for IVH, and degradation of cfDNA may be a new target to improve this condition.
组织型纤溶酶原激活剂（tPA）溶栓并不能改善脑室内出血（IVH）患者的功能结局，这主要是因为血块清除效果不尽人意。已证实血块中存在的中性粒细胞胞外陷阱（NETs）会损害tPA溶栓，但机制尚不清楚。作者推测，作为NETs主要框架的游离细胞DNA（cfDNA）可能是导致纤溶抵抗的重要原因，并对这一假设进行了验证，希望能为促进脑室内纤溶提供一个新靶点。
首先，通过免疫荧光染色在IVH大鼠模型中检测IVH血块中的cfDNA。其次，在脑室内注射血液（含或不含外源性cfDNA）后，将IVH大鼠随机给予脑室内输注2 μl生理盐水、tPA或tPA + DNase1。然后，评估脑室体积、动物行为和反应性星形胶质细胞增殖情况。第三，收集IVH血块进行体外溶栓试验。最后，评估外源性cfDNA在IVH中的作用。
早在IVH后1小时就观察到血块中存在cfDNA。与全血模型相比，血液 + cfDNA导致更严重的脑室扩张（第7天：血液组32.47 ± 2.096 mm³，血液 + DNA组40.09 ± 2.787 mm³，p < 0.05），增加了对tPA的纤溶抵抗（第7天：tPA + DNA组26.04 ± 1.318 mm³，tPA组22.15 ± 1.706 mm³，p < 0.05），并进一步恶化了大鼠的功能缺陷（血液组与血液 + DNA组，p < 0.05）。DNase1对cfDNA的降解进一步增强了溶栓对缓解脑室扩张的作用（第7天：tPA + DNase1组11.67 ± 2.023 mm³，tPA组，p < 0.05），改善了功能结局（tPA组与tPA + DNase1组，p < 0.05），并减少了脑室周围星形胶质细胞增殖。
cfDNA损害了IVH的tPA溶栓作用，cfDNA的降解可能是改善这种情况的一个新靶点。
