经济学人下载:可移植的血管现可随意培育

Science and Technology A not-so-hard graft
科技 一个不那么难的移植

Transplantable blood vessels can now be grown as desired
可移植的血管现可随意培育

Medical technology
医学技术

ANOTHER advance in the emerging technology of regenerative medicine has just been announced.
新兴再生医学技术的又一项进展刚刚被公布。

It should soon be possible to make blood vessels that can be stored and used "off the shelf" for surgery that requires arteries or veins to be bypassed.
该项技术应该不久就可能制造血管，这种血管可以储存，需要进行绕过动静脉的外科手术时可以"现货供应"。

The vessels, prototypes of which are described this week in a paper in Science Translational Medicine, are made by Humacyte, a small firm based in Durham, North Carolina, that was founded by Shannon Dahl, the paper's principal author, and two colleagues.
本周《科学转化医学》上的一篇论文描述了这种血管的原型，它是由北卡罗来纳州达勒姆的一家小公司Humacyte制造的，而公司的创立者为该论文的主要作者夏伦?达尔和其两位同事。

The recipe Dr Dahl and her colleagues concocted begins with smooth-muscle cells. Smooth muscle is different from the familiar sort that cloaks bones and enables bodily movement. It is a component of organs such as the gut and the blood vessels that sometimes need to change shape while they are functioning.
达尔博士及其同事的制做方法是由平滑肌细胞开始。平滑肌不同于我们熟悉的那种包覆骨骼并使身体运动的肌肉。它是肠道和血管等器官的组成部分，这些器官有时需要改变形状才能行使功能。

To make artificial blood vessels the team took smooth-muscle cells from fresh corpses and cultured them on tubular scaffolds made of a material called polyglycolic acid. Grown this way, smooth muscle secretes collagen, a structural protein that is, among several other things in the body, an important component of the walls of blood vessels. The polyglycolic acid degrades spontaneously over the course of a few weeks with the consequence that it is, in effect, replaced by the collagen. The result is a tube of the length and diameter of the original scaffold, that is composed of collagen and smooth-muscle cells—a structure similar to a natural blood vessel.
为了制造人造血管，这个小组从新鲜尸体上采集平滑肌细胞，将其放在聚羟基乙酸材料制成的管式支架上培养。采取这种方式生长，平滑肌可分泌胶原，一种结构蛋白，是人体中除其它几种物质外组成血管壁的重要成分。聚羟基乙酸在几个星期内自发降解，实际结果就是被胶原蛋白取代了。所得物保持原来支架的长度和直径，由胶原蛋白和平滑肌细胞组成，其结构类似天然血管。

Transplanting that into a patient, however, would risk provoking an immune reaction, since the muscle cells are "foreign" tissue. To get around this, Dr Dahl and her colleagues wash the muscle cells away with a detergent, leaving just the collagen. Though the end product is a nonliving simulacrum of a blood vessel rather than an artificial version of the real, biologically active thing, experiments on animals suggest that it works well enough to substitute for a diseased natural vessel (for example, a clogged coronary artery that might otherwise cause a heart attack). It can also act as a "tap" from which the blood of people whose kidneys have failed might be drawn for dialysis.
不过将其移植到患者身上会有引发免疫反应的风险，因为人造血管上的肌肉细胞是"外来"组织。为了避免这个问题，达尔博士和其同事用洗涤剂洗去这些肌肉细胞，只留下胶原蛋白。虽然最终产品是无生命的模拟血管，而不是真正的、具有生物活性的人造血管，但是动物实验表明，它足以代替患病的天然血管（例如，冠状动脉，阻塞的血管可能导致心脏病发作）。它也可以充当肾病患者"龙头"，引出患者的血液进行透析。

At the moment, the optons for either of these things are limited. The best approach is to use a length of vessel taken from elsewhere in the patient's body (commonly, his leg). But that requires such transplants to be healthy themselves—and each length of transplanted vessel can be used only once. Synthetic vessels made of Teflon exist, but they are prone to infection and blockage by blood clots, and tend to work for only a few months.
目前，适合这些用途的任一用途的血管选择都很有限。最好的方法就是采用来自病患身体其它部位（通常为腿部）的一段血管。但这要求这样的移植对患者无害，而且每根移植的血管只能使用一次。现已存在聚四氟乙烯制成的人造血管，但它们很容易感染和形成血栓，且往往只能起几个月的作用。

The animal experiments suggest the new, all-collagen vessels are capable of lasting at least a year without noticeable deterioration. They are also, once implanted, able to remodel themselves in ways that improve their function—changing shape in response to blood flow, being colonised by cells from the patient's body, and showing signs of incorporating elastin, another structural protein found in natural vessels.
动物实验表明，新型全胶原蛋白的血管有能力至少维持一年而没有明显恶化。一旦植入，它们也能按照提高其功能的方式自我改造——针对血流改变形状，让病患的身体细胞在其上生长，并显示出混合了天然血管中发现的另一个结构蛋白弹性蛋白的迹象。

Also, if kept in a suitable saline buffer at 4°C, they can be transplanted a year after they were made without a perceptible degradation of their properties. So, if human trials confirm these results, the surgical-repairer's toolkit will have acquired a useful additional instrument—and the age of the cyborg will be just that little bit nearer.
此外，如果保存在4 ° C合适的盐水缓冲液中，它们可以在制成一年后被移植，而没有可察觉的性能退化。所以，如果人体试验证实了这些结果，外科修复师的工具包就会增添一个有用的额外工具，且生控体系统时代的来临就又接近了一点点。