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  • 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.

  • Unfortunately,

  • there aren't nearly enough donor organs available to fill that demand.

  • What if instead of waiting,

  • we could create brand-new, customized organs from scratch?

  • That's the idea behind bioprinting,

  • a branch of regenerative medicine currently under development.

  • 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.

  • 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.

  • 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.

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

  • Mixed into those are millions of living cells

  • as well as various chemicals that encourage cells to communicate and grow.

  • Some bioinks include a single type of cell,

  • while others combine several different kinds to produce more complex structures.

  • 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.

  • It's made up of cells called chondrocytes,

  • and you'll need a healthy supply of them for your bioink.

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

  • Or they might originate from a patient's own tissue

  • to create a personalized meniscus less likely to be rejected by their body.

  • There are several printing techniques,

  • and the most popular is extrusion-based bioprinting.

  • In this, bioink gets loaded into a printing chamber

  • and pushed through a round nozzle attached to a printhead.

  • 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.

  • 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.

  • These printers are fast, producing the meniscus in about half an hour,

  • one thin strand at a time.

  • After printing, some bioinks will stiffen immediately;

  • others need UV light or an additional chemical or physical process

  • to stabilize the structure.

  • 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.

  • Bioprinted bladders have also been successfully implanted,

  • and printed tissue has promoted facial nerve regeneration in rats.

  • Researchers have created lung tissue, skin, and cartilage,

  • as well as miniature, semi-functional versions of kidneys, livers, and hearts.

  • However, replicating the complex biochemical environment

  • of a major organ is a steep challenge.

  • 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.

  • One of the most formidable challenges

  • is how to supply oxygen and nutrients to all the cells in a full-size organ.

  • 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.

  • There's tremendous potential to use bioprinting

  • to save lives and advance our understanding

  • of how our organs function in the first place.

  • And the technology opens up a dizzying array of possibilities,

  • such as printing tissues with embedded electronics.

  • Could we one day engineer organs that exceed current human capability,

  • or give ourselves features like unburnable skin?

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

  • And exactly whoand what

  • will have access to this technology and its incredible output?

There are currently hundreds of thousands of people on transplant lists,

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ヒトの組織を3Dプリントする方法 - Taneka Jones (How to 3D print human tissue - Taneka Jones)

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    shuting1215 に公開 2021 年 01 月 14 日
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