冲开血凝块

 Think of it as Liquid-Plumr for the circulatory system. Researchers have designed a clump of tiny particles that rides the current of the bloodstream, seeks out life-threatening blood clots, and obliterates them. The approach works in mice and could soon move on to human trials.

 可以称之为循环系统中的强化疏通剂。研究人员设计了成团的微型粒子，这些粒子能够沿着血流找到威胁生命的血凝块，然后将其摧毁。这个办法在老鼠中能够奏效，并且有可能很快就要进入人体试验阶段了。

 Blood clots are bad news for the brain, heart, and other organs. These masses of blood cells can grow big enough to choke off veins and arteries, preventing oxygen from flowing to critical organs. One of the chief obstacles to dealing with blood clots is finding where they have lodged in the body. Even if doctors locate clots, they're hard to get rid of. Doctors often prescribe blood thinners that slow down the time it takes a clot to form, but such medication can also cause excessive bleeding. Another method is stenting, a procedure in which a flexible wire or tube is used to reopen a vessel. Patients recover quickly but often spend at least 1 night in the hospital.

 血凝块对于大脑、心脏以及其他器官来说是一种祸害，这些血细胞凝块可以变大，变大后足以阻塞静脉和动脉血管，致使氧气不能够到达关键器官。处理血凝块的主要障碍之一就是要找到凝块在体内的位置；另外，即使医生们找到了凝块的位置，凝块也不易去除。医生们通常给病人吃血液稀释剂来延长血栓形成的时间，但是这样的药物也可能会引起过度出血。另外一个办法就是在血管内安装支架，在这个过程中医生利用可弯曲的线条或软管来重新打开血管的通道，病人回复很快，但通常至少要在医院里住一个晚上。

 Looking for a better approach, biomedical engineer Donald Ingber of Harvard University and colleagues turned to nanoparticles. Modeled after platelets—cells that circulate in the blood and help stop bleeding by forming clots—the nanoparticles are less than 100 nm wide and made of synthetic polymers stuck together like a ball of wet sand. Like platelets, clumps of the particles flow freely in the blood and gravitate toward blocked vessels by sensing a change in blood flow. Once there, they break apart into individual particles that stick to the clot, releasing a drug called tissue plasminogen activator (tPA) that dissolves it.

 在寻找更佳办法的过程中，哈佛大学的生物医学工程师唐纳德·英伯格及同事的研究转向纳米粒子。他们的纳米粒子模仿了血小板，直径不超过100纳米，由合成聚合物构成，粘在一起就像湿润的沙球。血小板是在血液里循环的细胞，能够通过形成凝块而帮助止血。跟血小板一样，这些纳米粒子团可以在血液中自由流动，通过对血流变化的觉察而被吸引到阻塞的血管中。一旦到了阻塞处，粒子团就分离成单个的粒子，吸附到凝块上，释放一种叫做组织型纤溶酶原激活剂（tPA）的药物，将凝块溶解。

 The researchers tested the approach on mice suffering from blood clots. After they injected the particles into the animals, the particles coated in tPA were able to reopen the blocked vessels quickly, despite harboring low dosages of medicine, the team reports online today in Science. None of the mice had uncontrolled bleeding, and because the particles are biodegradable, they are eventually broken down by the body.

 研究人员利用这种方法在拥有血凝块的老鼠中做试验。今天，研究小组在《科学》杂志在线版上报道：为老鼠注射这种纳米粒子之后，尽管含药量很低，这些涂有tPA的粒子能够快速地重新开通阻塞的血管。没有任何老鼠发生不可控制的出血；由于这种粒子具有生物降解性，最终可以被身体分解掉。

 "Making these particles so that they break apart at the right amount of force was a challenge," says Ingber. "The most exciting thing that we are able to do is deliver a clot-busting drug directly to a site where a clot is, without knowing where it is." He says that the particles could be used to deliver essentially any drug—an anti-inflammatory to a specific spot where inflammation was occurring, for example.

 “制造这些粒子团时，要想使它们分离后达到合适的药力是一种挑战，”英伯格说，“最令人兴奋的事情是：我们能够做到，在不知道凝血发生在什么地方的情况下，可以直接将抗凝血药物送到凝血处。”他说，从根本上来讲，这种粒子可以用来输送任何药物，如：将抗炎药送往特定的发炎部位。

 "The beauty of these nanoparticles is that they will not deliver this drug to any other place but the area of stress," says Heyu Ni, platelet biologist at St. Michael's Hospital in Toronto, Canada, specifically referring to blood clot sites. Another advantage of the approach, he says, is that it gets around the issue of estimating the amount of anticlotting medication to give a patient. High dosages are effective but could cause excessive bleeding, whereas small doses are much safer but may not get the job done. The nanoparticles skirt this problem by depositing a small amount of medication directly on the clot. He notes that the nanoparticles could be used as a diagnostic tool to seek out blockages that may need to be removed surgically, since places where the nanoparticles wind up are easier to spot with ultrasound. "This could change our concept of how to deliver drugs effectively. I would think of this study as possibly revolutionary."

 “这些纳米粒子的美妙之处在于，它们不会将药物输送到任何其他部位，只是送往应激反应区，”加拿大多伦多市圣迈克尔医院研究血小板的生物学家倪和宇（Heyu Ni）说，他特别提到了凝血部位的问题。他说：这个疗法的另外一个优点是，不必去考虑抗凝血药物的给药剂量问题。高剂量给药效果好，但可能会引起过度出血，而小剂量给药会安全得多，但或许起不到应有的作用。这些纳米粒子避开了这个问题：将少量的药物直接投放在凝块上。倪和宇指出，这些纳米粒子可以用作诊断工具，找出那些需要利用手术摘除的凝块，因为纳米粒子所到之处比较容易被超声波发现。“关于有效的给药方式，该疗法可能会改变我们的观念，我认为该研究具有创新性。”