Hilfiker P R, Waugh J M, Li-Hawkins J J, Kuo M D, Yuksel E, Geske R S, Cifra P N, Chawla M, Weinfeld A B, Thomas J W, Shenaq S M, Dake M D
Stanford Institute of Bioengineering and Molecular Medicine, and Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA.
J Vasc Surg. 2001 Apr;33(4):821-8. doi: 10.1067/mva.2001.112323.
Indirect evidence suggests that tissue plasminogen activator (tPA) either limits or does not alter restenosis. However, tPA enhances tumor invasiveness through matrix remodeling, and several elements of degraded matrix enhance smooth muscle cell mitogenesis. We use either local adenoviral-mediated overexpression of tPA or systemic infusion of recombinant tPA combined with mechanical overdilation of rabbit common femoral arteries to evaluate the impact of tPA on neointima formation.
Left common femoral arteries of New Zealand white rabbits were transfected in situ either with an adenoviral-construct-expressing tPA or a viral control (adenoviral-construct-expressing beta-galactosidase) or nonviral (buffer) control after balloon angioplasty injury. At 7 and 28 days, left common femoral artery segments were harvested (n = 4 for each group and time point). Vessel segments were examined for intimato-media ratio, smooth muscle cell proliferation, extracellular matrix, and inflammatory response. Thrombus formation was evaluated after 3 days (n = 3 for each group). In a second experiment, New Zealand white rabbits (n = 3 per group, per time point) underwent mechanical dilation followed by buffer treatment or systemic tPA infusion according to a widely clinically used accelerated infusion protocol. Treated artery segments were harvested after 7 or 28 days and processed for intima-to-media ratio determination and class-wide histochemical determination of collagenous extracellular matrix and collagen content.
Both rate and degree of neointima formation increase dramatically with overexpression (250%-461% relative to controls at 7 and 28 days). Substantial early matrix degradation is observed in vessels treated with local overexpression of tPA, although no increases in local inflammation or in smooth muscle proliferation occur. Late enhancement of smooth muscle proliferation emerges, consistent with secondary impact of perturbed matrix components. Systemic infusion of tPA according to clinical protocols also results in early and late enhancement of neointima formation in this model (34%-52% relative to controls at at 7 and 28 days), with significant early collagenous matrix degradation. Systemic infusion, although significant, did not attain the degree of neointima formation present with overexpression.
With some evidence of dose-dependence, tissue plasminogen activator enhances neointima formation after angioplasty in a rabbit model. Early matrix degradation precedes change in rates of proliferation and underlies this effect in spite of several antirestenotic actions including decreased thrombus and decreased macrophage recruitment in this model.
间接证据表明组织型纤溶酶原激活剂（tPA）要么限制再狭窄，要么不改变再狭窄情况。然而，tPA通过基质重塑增强肿瘤侵袭性，且降解基质的几个成分可增强平滑肌细胞有丝分裂。我们采用局部腺病毒介导的tPA过表达或重组tPA全身输注联合兔股总动脉机械性过度扩张，以评估tPA对新生内膜形成的影响。
新西兰白兔的左股总动脉在球囊血管成形术损伤后，原位转染表达tPA的腺病毒构建体、病毒对照（表达β-半乳糖苷酶的腺病毒构建体）或非病毒（缓冲液）对照。在第7天和第28天，采集左股总动脉段（每组每个时间点n = 4）。检查血管段的内膜中膜比、平滑肌细胞增殖、细胞外基质和炎症反应。在第3天评估血栓形成情况（每组n = 3）。在第二个实验中，新西兰白兔（每组每个时间点n = 3）根据广泛临床应用的加速输注方案进行机械扩张，随后进行缓冲液处理或重组tPA全身输注。在第7天或第28天后采集处理过的动脉段，进行内膜中膜比测定以及全类胶原细胞外基质和胶原含量的组织化学测定。
随着tPA过表达，新生内膜形成的速率和程度均显著增加（在第7天和第28天相对于对照组增加250% - 461%）。在用局部tPA过表达处理的血管中观察到大量早期基质降解，尽管局部炎症或平滑肌增殖没有增加。晚期平滑肌增殖增强，这与受干扰的基质成分的继发影响一致。按照临床方案进行重组tPA全身输注在该模型中也导致新生内膜形成的早期和晚期增强（在第7天和第28天相对于对照组增加34% - 52%），伴有显著的早期胶原基质降解。全身输注虽然有显著效果，但未达到过表达时的新生内膜形成程度。
有一些剂量依赖性证据表明，在兔模型中，组织型纤溶酶原激活剂在血管成形术后会增强新生内膜形成。早期基质降解先于增殖速率的变化，尽管在该模型中有包括减少血栓和减少巨噬细胞募集在内的几种抗再狭窄作用，但早期基质降解仍是这种效应的基础。
