罗格列酮对2型糖尿病大鼠肾皮质PAI-1表达的影响

目的研究罗格列酮对2型糖尿病大鼠血糖血脂的影响及肾皮质纤溶酶原激活物抑制物1（PAJ-1）表达的作用。方法采用高糖、高脂、高热量饲料喂食2月后予链脲佐菌素腹腔注射建立大鼠2型糖尿病模型。灌胃给药10周，测定血糖、血脂及24h尿蛋白，取。肾皮质提取总RNA，应用R个P（永检测肾皮质中PAI-1 mRNA表达，免疫组化检测肾脏PAI-1蛋白表达。结果罗格列酮能降低血浆血糖、尿蛋白水平，对血脂的影响不明显，三组肾皮质PAI-1 mRNA的相对值分别为0．67±0．03，147±0．07，0．83±0．05，相互间有统计学意义。免疫组化显示，糖尿病组肾小球PAI-1明显增强，罗格列酮能降低肾小球PAI-1表达。结论。罗格列酮能降低糖尿病大鼠血糖和尿蛋白水平，抑制肾脏PAI-1表达，这种作用可能是罗格列酮治疗效益的重要机制之一。     

罗格列酮对2型糖尿病患者血浆tPA和PAI1活性的影响

目的:运用胰岛素增敏剂罗格列酮治疗2型糖尿病患者,观察罗格列酮对2型糖尿病患者血浆tPA和PAI1活性水平的影响。方法:48例2型糖尿病患者,口服罗格列酮(文迪雅)4mg/d,共12周,观察治疗前后的血浆tPA和PAI1活性、血糖和胰岛素等,计算胰岛素敏感指数和胰岛素抵抗指数,并将各指标进行分析比较。结果:罗格列酮治疗后2型糖尿病患者血浆tPA活性升高(P<0.05),PAI1活性及PAI1/tPA活性比值降低(P<0.05,P<0.01)。血糖、胰岛素水平降低(均P<0.05);胰岛素敏感指数明显升高(P<0.05);胰岛素抵抗指数降低(P<0.05)。结论:罗格列酮在降低血糖、改善胰岛素抵抗、提高胰岛素敏感指数的同时,能增强糖尿病患者纤溶系统的活性,对心血管起到保护作用。     

螺内酯对2型糖尿病大鼠血管PAI-1mRNA表达的影响

[目的]探讨非选择性醛固酮(aldsterone,ALD)受体拮抗剂-螺内酯(Spironolactone,SPI)对2型糖尿病(type 2 diabetic mellitus,T2DM)大鼠血管纤溶酶原激活物抑制剂-1(plasminogen activator inhibitor-1,PAI-1)mRNA的表达的影响.[方法] 高脂高糖喂养加小剂量链脲佐菌素(streptozotocin,STZ)腹腔注射法建立2型糖尿病大鼠模型,将成膜的T2DM大鼠随机分为糖尿病对照组(DM-C组)和SPI干预组(DM-S组),继续高脂高糖喂养,正常对照组(NC组)大鼠继续给予普通饲料喂养,其中DM-S组每天给予SPI 40 mg/(kg·d)灌胃,NC组和DM-C组每天等量蒸馏水灌胃.每2周监测大鼠体重和血糖水平,第16周末处死大鼠,收集血液标本,检测空腹血糖(FBG)、糖化血红蛋白(HbA1c﹪)、甘油三酯(TG)、胆固醇(TG)、血钾(K+).用RT-PCR法检测各组大鼠胸主动脉PAI-1 mRNA表达.[结果]DM-C组和DM-S组大鼠FBG、HbA1c﹪、TG均显著高于NC组(P＜0.01),而DM-S组和DM-C组比较差异无统计学意义(P＞0.05);三组之间的血K+水平比较差异无统计学意义(P＞0.05);DM-C组和DM-S组大鼠胸主动脉PAI-1 mRNA的表达显著高于NC组(P＜0.01),且DM-C组高于DM-S组(P＜0.05).[结论] SPI能通过下调T2DM大鼠主动脉PAI-1mRNA的表达而发挥血管保护作用.     

电针对急性脑梗死大鼠血浆t-PA和PAI-1含量的影响

目的:研究电针对急性脑梗死大鼠血浆组织型纤溶酶原激活物(t-PA)及纤溶酶原激活物抑制物-1(PAI-1)含量的影响。方法:40只SD大鼠随机分为正常组、假手术组、模型组及电针组各10只,模型组及电针组大鼠制成脑梗死模型;假手术组手术步骤同前2组,但不线栓;正常组不作任何处理。造模成功后,4组大鼠均同步喂养,电针组大鼠于造模成功后即刻给予电针百会、水沟穴,每天1次,30min。治疗5d后,4组大鼠均采用ELISA法检测血浆t-PA及PAI-1含量。结果:与正常组及假手术组比较,模型组及电针组大鼠血浆t-PA、PAI-1含量均显著升高(P<0.01),但电针组低于模型组(P<0.05,0.01)。结论:电针能显著降低急性脑梗死大鼠血浆t-PA、PAI-1含量,调节机体纤溶系统活性,改善梗死区域的血液循环,促进功能恢复。     

替米沙坦对2型糖尿病合并高血压病患者纤溶活性的影响

目的：探讨替米沙坦对2型糖尿病（2DM）合并高血压病患者纤溶活性的影响。方法：将60例2DM合并高血压患者随机分为常规治疗组（n=30）和常规＋替米沙坦（80mg,qd）治疗组（n=30）,另选择20名年龄匹配的健康查体者为对照。治疗4周后测定血中组织型纤溶酶原激活物（t-PA）及其抑制物（PAI-1）的活性。结果：与对照组比较,2DM合并高血压患者纤溶功能显著低下,虽t-PA活性无显著改变,但PAI-1活性增加了约70%（P〈0.01）。常规治疗组t-PA及PAI-1活性无显著变化（P〉0.05）;替米沙坦治疗使PAI-1活性显著下降约60%（P〈0.01）,t-PA活性无显著变化。结论：2型糖尿病合并高血压病患者存在纤溶功能低下,替米沙坦可显著降低纤溶酶原激活物抑制物-1活性,提高纤溶功能。     

2型糖尿病患者健康后代PAI-1基因多态性的研究

目的:通过检测2型糖尿病(T2DM)患者及其健康后代(offsprings)血浆纤溶酶原激活物抑制物-1(PAI-1)基因型,并分析它们与血浆PAI-1活性、血脂、血糖、体重指数(BMI)、腰臀比(WHR)、胰岛素抵抗(IR)之间的关系。方法:采用PCR检测PAI-1基因多态,发色底物法检测PAI-1活性。结果:T2DM组和健康后代组与对照组相比4G/4G+4G/5G基因型频率和4G等位基因频率呈增高趋势,但差异无显著性意义(P>0.05)。3组间含4G等位基因组的血浆PAI-1活性显著高于不含4G等位基因组(P<0.05)。结论:在2型糖尿病患者及健康后代中PAI-14G等位基因的携带者有增高趋势。携带4G等位基因的人群PAI-1活性升高。PAI-14G等位基因的存在对2型糖尿病患者及后代PAI-1活性升高起一定作用。     

2型糖尿病患者血浆D-二聚体,t-PA,PAI-1水平与血管病变的相关性

2型糖尿病血管病变是其较常见的并发症,它是由许多原因引起,主要原因之一是由于高血糖及脂代谢异常所引起的血管内皮损伤,导致血栓或广泛的微血栓形成.我们通过对患者血浆中D-二聚体,纤溶酶原激活物(tPA),纤溶酶原激活物抑制物(PAI-1)水平的测定,了解这三种指标与2型糖尿病患者血管病变的相     

GSK3β抑制剂对糖尿病肾病大鼠肾组织TGF-β1和血清PAI-1表达的影响

目的观察糖原合成酶激酶-3β（GSK3β）抑制剂Licl对糖尿病肾病（DN）大鼠的影响,从而明确GSK-3β抑制剂对DN的作用机制。方法将60只雄性Wistar大鼠随机分为四组：正常对照组（NC组,n=10）,Licl组（n=10）,DN组（n=20）,DN＋Licl组（n=20）。通过一次性腹腔注射链脲佐菌素（STZ）联合长期高脂饮食,建立DN大鼠模型;通过腹腔注射GSK-3β抑制剂Licl进行药物干预。观察各组大鼠一般状态、体重、肾重/体重的变化;检测血糖、尿量、尿蛋白、血肌酐等指标;肾脏PAS染色观察各组大鼠肾脏病理改变;ELISA方法检测各组大鼠血清纤溶酶原激活物抑制物-1（PAI-1）的水平,IHC方法检测肾组织转化生长因子-β1（TGF-β1）的表达,进行组间比较。结果与NC相比,DN组大鼠一般状态、体重、肾重/体重、血糖、血肌酐、尿量、尿蛋白、肾脏病理均出现了DN特有的变化特征,血清PAI-1明显增高,肾组织TGF-β1的表达明显上调。DN＋Licl组较DN组大鼠存活率高,尿蛋白、血清PAI-1表达显著减少,肾脏病理较DN组明显减轻,而肾组织TGF-β1表达明显增加。结论 GSK-3β抑制剂Licl能够降低DN大鼠血清PAI-1水平、蛋白尿及死亡率。DN大鼠较正常大鼠肾组织TGF-β1表达明显上调,GSK-3β抑制剂Licl能进一步增加DN大鼠肾组织TGF-β1蛋白的表达。抑制GSK-3β,对治疗DN有积极的意义。但是GSK-3β抑制剂Licl作为药物治疗DN,应考虑其效应的两面性。     

上皮性卵巢癌组织uPA、uPAR及PAI-1表达及意义

目的探讨尿激酶型纤溶酶原激活剂（uPA）、uPA受体（uPAR）及其抑制剂（PAI-1）在上皮性卵巢癌组织中的表达及意义。方法采用免疫组织化学PV-9000法检测60例上皮性卵巢癌、30例良性卵巢肿瘤及30例正常卵巢组织中uPA、uPAR及PAI-1蛋白表达,并结合临床病理因素进行分析。结果 uPA、uPAR、PAI-1在上皮性卵巢癌中的表达率（75.0%、65.0%、66.7%）明显高于良性肿瘤（40.0%、33.3%、30.0%）及正常组织（30.0%、26.7%、33.3%）,差异均有显著性（χ2=11.779~19.510,P〈0.05）,而良性肿瘤与正常组织比较无明显差异。uPA、uPAR、PAI-1在上皮性卵巢癌组织表达与手术病理分期、组织分级和有无淋巴结转移有关（χ2=8.242~36.906,P〈0.05）。结论 uPA、uPAR、PAI-1在上皮性卵巢癌组织高表达,可能与卵巢癌发生、发展及浸润有关。     

伴有糖尿病的冠心病患者纤溶系统的变化及罗格列酮的干预研究

目的通过观察伴有糖尿病(DM)的冠心病(CHD)患者纤溶系统的变化,并以罗格列酮进行干预,由此对罗格列酮防止支架术后再狭窄机制作初步探讨。方法试验对象共分为3组:伴有2型DM的CHD患者48例;不伴有2型DM的CHD患者36例;正常对照组:同期我院体检健康成人20例;3组对象均在入院后清晨抽血、分离血浆。检测一氧化氮(NO)、组织型纤溶酶原激活物(t-PA)和纤溶酶原激活物抑制剂(PAI-1)的含量;培养上清中NO采用硝酸还原酶法测定;t-PA和PAI-1采用酶联免疫法(ELISA)测定;另外将合并DM的CHD组48例患者分为两组,一组针对CHD和DM常规治疗,另一组在此基础上加用罗格列酮,4 mg/d,口服。治疗3个月后复查上述指标。结果伴有或不伴有DM的CHD患者NO的浓度分别为(40.83±5.34)μmol/L、(50.31±5.34)μmol/L均低于正常对照组(73.37±6.46)μmol/L(P均<0.01);t-PA的浓度分别为(18.53±7.05)μg/L、(26.72±8.20)μg/L均低于正常对照组(40.17±8.30)μg/L(P均<0.01);PAI-1的浓度分别为(86.04±8.88)μg/L(、78.52±7.34)μg/L均高于正常对照组(48.86±5.41)μg/L(P<0.01);伴有DM的CHD患者NO和t-PA的浓度均低于不伴有DM的CHD患者组(P<0.05),PAI-1的浓度高于不伴有DM的CHD患者组(P<0.05)。伴有DM的CHD患者常规治疗和常规 罗格列酮治疗后NO,t-PA显著高于治疗前:NO治疗前后的变化值分别为(20.97±3.49)μmol/L、(30.32±3.36)μmol/L(P均<0.01);t-PA治疗前后的变化值分别为(11.97±2.07)μg/L、(21.32±2.21)μg/L(P均<0.01);伴有DM的CHD患者常规治疗和常规 罗格列酮治疗后PAI-1的浓度显著低于治疗前,PAI-1治疗前后的变化值分别为(-23.98±5.12)μg/L、(-34.02±5.64)μg/L(P<0.01);和常规组比较,常规 罗格列酮治疗组改善的幅度要高于常规组(P<0.01)。结论伴或不伴DM的CHD患者冠心病患者体内存在不同程度纤溶活性的降低,这种高凝状态会促进血栓形成和再狭窄的发生。对于冠心病患者,在常规冠心病治疗基础上,加用罗格列酮能促进纤溶系统的激活,防止血栓的形成,有效防止支架术后再狭窄,特别是对于伴有糖尿病的CHD患者。     

纤溶酶原激活物抑制因子-1在放射性肾纤维化中的作用及意义

【目的】为探讨纤溶酶原激活物抑制因子-1(PAI-1)在肾损伤后纤维化中的作用和意义,揭示其发病的分子病理机制。【方法】雄性健康的Wistar大鼠以30Gy^60Coγ／线单次双肾局部照射,于照射后4个不同时相点活杀,取肾组织进行常规病理学观察及原位分子杂交,观察PAI-1 mRNA表达的变化。【结果】纤维化的肾组织PAI-1表达较正常对照组增高,与纤维化程度呈正相关。【结论】PAI-1可能在肾损伤后纤维化的发生及发展中起重要的作用。     

Plasminogen activator inhibitor-1 predicts coronary in-stent restenosis of drug-eluting stents

Background : We tested the hypothesis that plasma levels of plasminogen activator inhibitor-1 (PAI-1) are influenced by percutaneous coronary intervention (PCI) with the implantation of drug eluting stents (DES) and are able to predict the occurrence of in-stent restenosis (ISR). Methods and results : PAI-1 active antigen plasma levels were determined in 75 patients before and 24 h after PCI with DES implantation. Patients with ISR after six to eight months (16%) showed significantly lower PAI-1 plasma levels before PCI (ISR, 11.7 ± 8.1 ng mL⁻¹; non-ISR, 22.8 ± 18.8 ng mL⁻¹; P  < 0.05). PAI-1 levels in the lowest tertile were associated with a 9.5-fold increased risk of ISR, independent of clinical risk factors, angiographic or procedural characteristics, compared to the highest tertile ( P  <   0.05). The induced change of PAI-1 active antigen 24 h after PCI was significantly higher in patients with ISR (ISR, +5.6 ± 8.0 ng mL⁻¹; non-ISR, −3.2 ± 12.1 ng mL⁻¹; P  <   0.05) with positive correlation to late lumen loss ( r  =   0.30; P  <   0.05). Conclusions : ISR after DES implantation is significantly related to plasma levels of PAI-1 active antigen before and after PCI. If confirmed by larger multicenter studies, the determination of PAI-1 plasma levels might be clinically helpful in the identification of patients at high risk of developing of ISR, even after DES implantation.     

Plasminogen activator inhibitor-1 4G/5G polymorphism is associated with metabolic syndrome parameters in Malaysian subjects

The plasminogen activator inhibitor-1 4G/5G and tissue plasminogen activator Alu-repeat insertion/deletion polymorphisms might be genetic determinations of increased or decreased of their plasma activities. The aim of this study was to investigate the association of plasminogen activator inhibitor-1 4G/5G and tissue plasminogen activator Alu-repeat I/D polymorphisms with metabolic syndrome parameters in normal Malaysian subjects and to assess the impact of these polymorphisms on their plasma activities and antigens. The genetic polymorphisms were genotyped in 130 normal subjects. In addition, the plasma activities and antigens of plasminogen activator inhibitor-1 and tissue plasminogen activator as well as levels of insulin, glucose, and lipid profile at fasting state were investigated. The subjects with homozygous 4G/4G showed association with an increased triglyceride (p = 0.007), body mass index (p = 0.01) and diastolic blood pressure (p = 0.03). In addition, the plasminogen activator inhibitor-1 4G/5G polymorphism modulates plasma plasminogen activator inhibitor-1 activity and antigen and tissue plasminogen activator activity (p = 0.002, 0.014, 0.003) respectively. These results showed that, the plasminogen activator inhibitor-1 4G/5G polymorphism is associated with metabolic syndrome parameters, plasminogen activator inhibitor-1 and tissue plasminogen activator activities in Malaysian subjects, and may serve to increase the risk of type 2 diabetes and cardiovascular disease in Malaysian subjects.     

Plasminogen activator inhibitor-1 contributes to the deleterious effect of obesity on the outcome of thrombotic ischemic stroke in mice

BACKGROUND: It is widely accepted that obesity is a risk factor for ischemic heart disease, but the association with stroke is less clear. Adipose tissue is an important source of plasminogen activator inhibitor-1 (PAI-1), the main inhibitor of plasminogen activation. OBJECTIVE: To test the hypothesis that elevated PAI-1 levels associated with obesity negatively affect the outcome of thrombotic ischemic stroke. METHODS: Middle cerebral artery (MCA) occlusion was induced photochemically in mice with nutritionally induced or genetically determined obesity and their lean counterparts. RESULTS: The MCA occlusion time (to obtain complete occlusion) was significantly shorter in obese (nutritionally induced) than in lean wild-type (WT) C57Bl/6 mice, whereas the infarct size was significantly larger and intracranial hemorrhage (ICH) was enhanced (all P < 0.05). Similar observations were made in genetically obese ob/ob mice, as compared to lean WT littermates. In both strains, obesity was associated with markedly elevated circulating PAI-1 levels, probably originating from the fat tissue. In contrast, PAI-1-deficient lean and obese mice did not display significant differences in MCA occlusion time, infarct volume or ICH. CONCLUSIONS: Plasminogen activator inhibitor-1 may play a functional role in the deleterious effect of obesity on the outcome of thrombotic ischemic stroke in mice.     

多囊卵巢综合症患者血浆PAI-1水平及基因4G5G多态性的研究

目的 研究多囊卵巢综合症（PCOS）纤溶酶原激活物抑制因子-1（PAI-1）基因启动子区4G5G多态性的分布,探讨其与PCOS发病关系.方法 96例PCOS患者和50例对照组,用PCR方法测定PAI-1基因启动子区4G5G基因多态性;ELISA法检测血浆PAI-1水平.结果 PCOS组4G/4G基因型明显高于对照组,而5G/5G基因型显著少于对照组.PCOS组的PAI-1水平较对照组明显升高（29.32±2.37ng/mL与22.42±0.65ng/mL,P〈0.05）.结论 PCOS患者PAI-1基因启动子区4G/4G基因型频率增高,致血浆PAI-1水平升高,其与PCOS的发病有关.     

tPA和PAI-1活性与自然流产的相关性

【目的】探讨组织型纤溶酶原激活剂（tPA）和纤溶酶原激活剂抑制剂-1（PAI-1）活性与自然流产的相关性。【方法】选择2003年10月至2004年3月中南大学湘雅二医院门诊有自然流产史患者71例（非孕50例．孕妇21侧）和对照组41例（非孕20侧,孕妇21例）进行研究,运用发色底物法测定血浆tPA和PAI-1活性。【结果】非孕有自然流产史的研究组tPA活性比对照组低（t=2．226,P=0．029〈0．05）,早孕研究组tPA活性比对照组低（t=2．166,P=0．036〈0．05）,差别均有统计学意义;研究组中,tPA活性早孕高于非孕（t=-2．937,P=0．005）,PAI-1活性早孕低于非孕（t=2．428,P=0．018）;在对照组中,tPA活性早孕也高于非孕（t=2．597,P=0．013）,PAI-1活性早孕也低于非孕者（t=2．653,P=0．012）。差别均有统计学意义。【结论】妊娠后tPA活性增高和PAI-1活性下降。有自然流产史者在非孕状态时tPA活性明显下降,且妊娠后呈低增长水平。tPA活性下降与引起自然流产的发病机制有关。     

The regulation by fibrinogen and fibrin of tissue plasminogen activator kinetics and inhibition by plasminogen activator inhibitor 1

BACKGROUND: Tissue plasminogen activator (tPA) is unusual in the coagulation and fibrinolysis cascades in that it is produced as an active single-chain enzyme (sctPA) rather than a zymogen. Two chain tPA (tctPA) is produced by plasmin but there are conflicting reports in the literature on the behaviour of sc- and tctPA and little work on inhibition by the specific inhibitor plasminogen activator inhibitor-1 (PAI-1) under physiological conditions. OBJECTIVES: To perform a systematic study on the kinetics of sctPA and tctPA as plasminogen activators and targets for PAI-1. METHODS: Detailed kinetic studies were performed in solution and in the presence of template stimulators, fibrinogen and fibrin, including native fibrin and partially digested fibrin. Numerical simulation techniques were utilized to cope with the challenges of investigating kinetics of activation and inhibition in the presence of fibrin(ogen). RESULTS: Enzyme efficiency (k(cat)/K(m)) was higher for tctPA than sctPA in solution with chromogenic substrate (3-fold) and plasminogen (7-fold) but in the presence of templates, such as fibrinogen and native or cleaved fibrin, the difference disappeared. sctPA was more susceptible to PAI-1 in buffer solution and in the presence of fibrinogen; however, in the presence of fibrin, PAI-1 inhibited more slowly and there was no difference between sc and tctPA. CONCLUSIONS: Fibrinogen and fibrin modulate the activity of tPA differently in regard to their activation of plasminogen and inhibition by PAI-1. Fibrinogen and fibrin stimulate tPA activity against plasminogen but fibrin protects tPA from PAI-1 to promote fibrinolysis.     

缺血性脑卒中患者血纤溶活性变化规律的研究

目的 研究脑梗死组和非脑梗死组患者急性期,亚急性期和恢复期组织型纤溶酶原激活物（tPA）,纤溶酶原激活物抑制物-1（PAI-1）的变化规律.方法 135例脑梗死组患者于发病96h内,病后14d、3月、6月、9月分别采血,77例非脑梗死组患者先采血一次,然后分别在第一次采血后14d、3月、6月、9月采血.结果 脑梗死急性期tPA含量明显升高,PAI-1的含量明显升高.恢复期脑梗死即发病后3月,6月,9月tPA的含量比急性期明显降低,且脑梗死后时间越长tPA含量越低,恢复期脑梗死PAI-1的含量比急性期明显降低.结论 在缺血性卒中的患者,高tPA含量提示纤溶活性的降低.高PAI-1代表纤溶抑制增强.     

Effect of pharmacologic plasminogen activator inhibitor-1 inhibition on cell motility and tumor angiogenesis

BACKGROUND: Plasminogen activator inhibitor-1 (PAI-1) is integrally involved in tumorigenesis by impacting on both proteolytic activity and cell migration during angiogenesis. OBJECTIVES: We hypothesized that an orally active small molecule inhibitor of PAI-1 (PAI-039; tiplaxtinin) could affect smooth muscle cell (SMC) attachment and migration in vitro on a vitronectin matrix, and exhibit antiangiogenic activity in vivo. METHODS: In vitro assays were used to assess the mechanism of inhibition of PAI-1 by PAI-039 using wild-type PAI-1 in the presence or absence of vitronectin and wild-type PAI-1 and specific PAI-1 mutants in SMC adhesion and migration assays. An in vivo tumor angiogenesis model was used to assess the effect of PAI-039 administration on neovascularization in a Matrigel implant. RESULTS: PAI-039 dose-dependently inhibited soluble, but not vitronectin-bound, PAI-1. Cell adhesion assays using PAI-1 mutants unable to bind vitronectin (PAI-1K) or inactivate proteases (PAI-1R) further suggested that PAI-039 inactivated PAI-1 by binding near its vitronectin domain. In a tumor angiogenesis model, PAI-039 treatment of wild-type mice dose-dependently decreased hemoglobin concentration and endothelial cell staining within the Matrigel implant, indicating reduced angiogenesis, but exhibited no in vivo efficacy in PAI-1 null mice. CONCLUSIONS: Administration of an orally active PAI-1 inhibitor prevented angiogenesis in a Matrigel implant. The lack of activity of PAI-039 against wild-type PAI-1 bound to vitronectin and PAI-1K suggests PAI-039 binding near the vitronectin-binding site. Our studies further substantiate a role for PAI-1 in cellular motility and tumor angiogenesis, and suggest for the first time that these effects can be modulated pharmacologically.     

Effect of Thrombin and Incubation Time on Porcine Whole Blood Clot Elasticity and Recombinant Tissue Plasminogen Activator Susceptibility

Deep vein thrombosis is a major source of morbidity and mortality worldwide. Catheter-directed thrombolytics are the frontline approach for vessel recanalization, though fibrinolytic efficacy is limited for stiff, chronic thrombi. Although thrombin has been used in preclinical models to induce thrombosis, the effect on lytic susceptibility and clot stiffness is unknown. The goal of this study was to explore the effect of bovine thrombin concentration and incubation time on lytic susceptibility and stiffness of porcine whole blood clots in vitro. Porcine whole blood was allowed to coagulate at 37°C in glass pipets primed with 2.5 or 15 U/mL thrombin for 15 to 120 min. Lytic susceptibility to recombinant tissue plasminogen activator (rt-PA, alteplase) over a range of concentrations (3.15–107.00 µg/mL) was evaluated using percentage clot mass loss. The Young's moduli and degrees of retraction of the clots were estimated using ultrasound-based single-track-location shear wave elasticity and B-mode imaging, respectively. Percentage mass loss decreased and clot stiffness increased with the incubation period. Clots formed with 15 U/mL and incubated for 2 h exhibited properties similar to those of highly retracted clots: Young's modulus of 2.39 ± 0.36 kPa and percentage mass loss of 8.69 ± 2.72% when exposed to 3.15 µg/mL rt-PA. The histological differences between thrombin-induced porcine whole blood clots in vitro and thrombi in vivo are described.