TED科普：如何3D打印人体组织？

There are currently hundreds of thousands of people on transplant lists, waiting for critical organs like kidneys, hearts, and livers that could save their lives.

目前有数十万人在器官移植的名单上，等待如肾、心及肝脏的重要器官来挽救他们的生命。

Unfortunately, there aren’t nearly enough donor organs available to fill that demand.

很不幸地，捐赠器官的数量远远供不应求。

What if instead of waiting, we could create brand-new, customized organs from scratch?

如果不要用等待方式，我们能从零开始，制造全新客制化器官呢？

That’s the idea behind bioprinting, a branch of regenerative medicine currently under development.

那正是生物列印的理念，它是再生医学的一分支，目前正在发展中。

We’re not able to print complex organs just yet, but simpler tissues including blood vessels and tubes responsible for nutrient and waste exchange are already in our grasp.

我们尚无法列印复杂的器官，但简单的组织，例如血管或负责营养及废物交换的管道等，已有办法列印出。

Bioprinting is a biological cousin of 3-D printing, a technique that deposits layers of material on top of each other to construct a three-dimensional object one slice at a time.

生物列印和3D立体列印是相关的，是一种将材料层层叠加的技术，一次一层，建构出一个立体的物件。

Instead of starting with metal, plastic, or ceramic, a 3-D printer for organs and tissues uses bioink:a printable material that contains living cells.

不采用金属、塑胶或陶土等原料，器官及组织的3D立体列印机是用“生物墨水”：这是一种含有活体细胞的可列印物质。

The bulk of many bioinks are water-rich molecules called hydrogels.

许多生物墨水的主要组成是富含水的物质──即“水凝胶”。

Mixed into those are millions of living cells as well as various chemicals that encourage cells to communicate and grow.

墨水混合著数百万的活体细胞和多种化学物质以刺激细胞交流及成长。

Some bioinks include a single type of cell, while others combine several different kinds to produce more complex structures.

有些生物墨水只含一种类型的细胞，而有些则结合多种细胞以制造较复杂的构造。

Let’s say you want to print a meniscus, which is a piece of cartilage in the knee that keeps the shinbone and thighbone from grinding against each other.

例如你想列印一个“半月板”，那是膝盖的一块软骨，它可减少小腿胫骨与大腿股骨间的摩擦。

It’s made up of cells called chondrocytes, and you’ll need a healthy supply of them for your bioink.

半月板是由“软骨细胞”所组成，所以你的生物墨水需要有很多软骨细胞。

These cells can come from donors whose cell lines are replicated in a lab.

这些细胞可能来自实验室复制捐赠者的细胞。

Or they might originate from a patient’s own tissue to create a personalized meniscus less likely to be rejected by their body.

或是取自病人的自体组织，制成专属的半月板，这样较不会有身体排斥的状况。

There are several printing techniques, and the most popular is extrusion-based bioprinting.

目前有数种列印技术，最常用的是“挤出式生物列印法”。

In this, bioink gets loaded into a printing chamber and pushed through a round nozzle attached to a printhead.

此法是将生物墨水装入列印管中，然后挤压通过一个附在喷头上的圆形喷嘴。

It emerges from a nozzle that’s rarely wider than 400 microns in diameter, and can produce a continuous filament roughly the thickness of a human fingernail.

它从一个直径几近 400 微米的喷嘴挤出，且能形成连续的细线，其厚度与人的指甲相仿。

A computerized image or file guides the placement of the strands, either onto a flat surface or into a liquid bath that’ll help hold the structure in place until it stabilizes.

以电脑图像或档案来导引细线的位置，墨汁被挤到一个平面上或液体容器中，如此可协助构造成形，直到稳定。

These printers are fast, producing the meniscus in about half an hour, one thin strand at a time.

列印机的速度很快，一次一缕细线，约半小时就可制出半月板。

After printing, some bioinks will stiffen immediately; others need UV light or an additional chemical or physical process to stabilize the structure.

列印后，有些生物墨水会立刻变硬，而有些需借助紫外线或特别的化学、物理方法来稳定结构。

If the printing process is successful, the cells in the synthetic tissue will begin to behave the same way cells do in real tissue:signaling to each other, exchanging nutrients, and multiplying. We can already print relatively simple structures like this meniscus.

如果列印成功，人造组织上的细胞会开始如同真正组织细胞般地运作：互通讯息、交换营养以及繁殖。我们已能列印比较简单的构造，例如这个半月板。

Bioprinted bladders have also been successfully implanted, and printed tissue has promoted facial nerve regeneration in rats.

生物列印的膀胱已成功地被植入人体，而列印组织已能加速老鼠颜面神经的再生。

Researchers have created lung tissue, skin, and cartilage, as well as miniature, semi-functional versions of kidneys, livers, and hearts.

研究人员已能制造出肺组织、皮肤、软骨以及微型、具部分功能的肾、肝及心脏。

However, replicating the complex biochemical environment of a major organ is a steep challenge.

然而，复制一个重要器官的复杂生化环境是项艰难的挑战。

Extrusion-based bioprinting may destroy a significant percentage of cells in the ink if the nozzle is too small, or if the printing pressure is too high.

挤出式生物列印法可能破坏墨水中许多细胞，如果喷嘴过小或挤压的压力太高的话。

One of the most formidable challenges is how to supply oxygen and nutrients to all the cells in a full-size organ.

最难以克服的挑战之一是如何让氧气及养分供应到实际大小器官的每个细胞。

That’s why the greatest successes so far have been with structures that are flat or hollow — and why researchers are busy developing ways to incorporate blood vessels into bioprinted tissue.

这就是为何目前最大的成就只在扁平或中空的构造上──也是为什么研究人员忙于研发在列印组织中加入血管的方法。

There’s tremendous potential to use bioprinting to save lives and advance our understanding of how our organs function in the first place.

使用生物列印来拯救生命具有极大潜能，并可让我们更了解器官如何运作。

And the technology opens up a dizzying array of possibilities, such as printing tissues with embedded electronics.

科技开拓了极多的无限可能，例如内置电子设备的列印组织。

Could we one day engineer organs that exceed current human capability, or give ourselves features like unburnable skin?

有朝一日，我们能否制造超越目前人体性能的器官，或制造具特色的物件，例如不可燃的皮肤吗？

How long might we extend human life by printing and replacing our organs?

借由列印及置换器官，人类的生命能延长多久呢？

And exactly who—and what— will have access to this technology and its incredible output?

到底是谁──是什么东西──能使用到这项科技与它惊人的产品呢？

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