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  • Can you grow a human bone outside the human body?

    你能夠在人體外培育一個人類的骨頭嗎?

  • The answer may soon be yes,

    答案可能很快就會是肯定的

  • but before we can understand how that's possible,

    但在我們理解那是如何做到之前,

  • we need to look at how bones grow naturally inside the body.

    我們必須先著眼於骨頭如何在體內自然生長

  • Most bones start in a growing fetus as a soft, flexible cartilage.

    成長的胎兒中,最初多數的骨頭是柔軟又有彈性的軟骨

  • Bone-forming cells replace the cartilage with a spongy mineral lattice

    製造骨頭的細胞會用海綿狀礦物晶格取代軟骨

  • made of elements like calcium and phosphate.

    晶格是由鈣和磷酸鹽等元素所組成

  • This lattice gets harder, as osteoblasts,

    晶格會變得更硬,當造骨細胞

  • which are specialized bone-forming cells,

    一種專門製造骨頭的細胞

  • deposit more mineral, giving bones their strength.

    在其中加入更多礦物質,增加骨頭強度

  • While the lattice itself is not made of living cells,

    雖然晶格本身並非由活的細胞所構成,

  • networks of blood vessels, nerves and other living tissues

    可是血管、神經及其他活組織的網絡,

  • grow through special channels and passages.

    可長入它的特殊管道和通路中

  • And over the course of development,

    在成長發育過程中,

  • a legion of osteoblasts reinforce the skeleton

    大量的造骨細胞強化骨骼,

  • that protects our organs, allows us to move,

    以保護我們的器官,使我們能行動,

  • produces blood cells and more.

    製造血液細胞等等

  • But this initial building process alone

    但單靠這初始建構過程,

  • is not enough to make bones strong and functional.

    是不足以使骨頭強韌且具功能性的

  • If you took a bone built this way,

    假如你拿一個以這種方式做的骨頭,

  • attached muscles to it,

    將肌肉固定上去,

  • and tried to use it to lift a heavy weight,

    然後嘗試用它提重物,

  • the bone would probably snap under the strain.

    骨頭大概會在應力下,啪一聲被折斷

  • This doesn't usually happen to us

    這通常不會在我們身上發生

  • because our cells are constantly reinforcing and building bone

    因為我們的細胞會持續地強化及造骨

  • wherever they're used,

    不論被使用在哪個部位

  • a principle we refer to as Wolff's Law.

    這種原理叫做「沃爾夫定律」

  • However, bone materials are a limited resource

    然而骨質資源是有限的

  • and this new, reinforcing bone

    這個新的用來強化的骨頭

  • can be formed only if there is enough material present.

    只能在有足夠的資源時形成

  • Fortunately, osteoblasts, the builders,

    幸好,造骨細胞,也就是建造者

  • have a counterpart called osteoclasts, the recyclers.

    有一個制衡的對手叫蝕骨細胞,也就是回收者

  • Osteoclasts break down the unneeded mineral lattice using acids and enzymes

    蝕骨細胞用酸和酵素分解不需要的礦物晶格

  • so that osteoblasts can then add more material.

    讓造骨細胞能接著添加更多骨質

  • One of the main reasons astronauts must exercise constantly in orbit

    太空人必須在外太空軌道持續運動的主要原因之一

  • is due to the lack of skeletal strain in free fall.

    是因為在無重力情況下缺乏骨頭應力

  • As projected by Wolff's Law,

    如沃爾夫定律所預測

  • that makes osteoclasts more active than osteoblasts,

    這會使蝕骨細胞比造骨細胞更活躍

  • resulting in a loss of bone mass and strength.

    造成骨頭質量和力量喪失

  • When bones do break, your body has an amazing ability

    當骨頭斷裂,你的身體有一種神奇的能力,

  • to reconstruct the injured bone as if the break had never happened.

    重建受傷的骨頭,讓它仿佛從未斷掉過一樣

  • Certain situations, like cancer removal, traumatic accidents,

    某些特殊狀況,如因癌症切除、意外創傷

  • and genetic defects exceed the body's natural ability for repair.

    及基因的缺陷,超出人體的自然修復能力

  • Historical solutions have included filling in the resulting holes with metal,

    過去修復方法包括,用金屬填補上述原因造成的骨洞

  • animal bones, or pieces of bone from human donors,

    或用動物的骨頭、或人類捐獻的骨頭

  • but none of these are optimal as they can cause infections

    但這些都不是最好的,因為他們會造成感染

  • or be rejected by the immune system,

    或被免疫系統排斥

  • and they can't carry out most of the functions of healthy bones.

    而且無法執行健康骨頭大部份的功能

  • An ideal solution would be to grow a bone made from the patient's own cells

    一個理想的方法就是,用病人自己的細胞培育骨頭

  • that's customized to the exact shape of the hole,

    且量身訂做出與骨洞相符的形狀與大小

  • and that's exactly what scientists are currently trying to do.

    這正是科學家目前嘗試在做的事

  • Here's how it works.

    作法如下

  • First, doctors extract stem cells from a patient's fat tissue

    首先,醫生從病人的脂肪組織抽取幹細胞

  • and take CT scans to determine the exact dimensions of the missing bone.

    及用電腦斷層掃描判斷出缺失骨頭的尺寸大小

  • They then model the exact shape of the hole,

    接著他們做出正確形狀的骨洞模型

  • either with 3D printers,

    不是用 3D 印表機

  • or by carving decellularized cow bones.

    就是雕刻去細胞化的牛骨

  • Those are the bones where all of the cells have been stripped away,

    那些所有細胞都被去掉的骨頭

  • leaving only the sponge-like mineral lattice.

    只留下像海綿的礦物晶格

  • They then add the patient's stem cells to this lattice

    隨後他們將病人的幹細胞加入到這個晶格

  • and place it in a bioreactor,

    並放入一座生物反應器 ~

  • a device that will simulate all of the conditions found inside the body.

    一個會模擬身體內所有情況的機器

  • Temperature, humidity, acidity and nutrient composition all need to be just right

    溫度、濕度、酸度及營養組成都必須剛剛好

  • for the stem cells to differentiate into osteoblasts and other cells,

    幹細胞才能分化成造骨細胞及其他的細胞

  • colonize the mineral lattice,

    長入礦物晶格各部位

  • and remodel it with living tissue.

    並用活組織重新塑造它

  • But there's one thing missing.

    但別忘一件事

  • Remember Wolff's Law?

    記得沃爾夫定律嗎?

  • An artificial bone needs to experience real stress,

    人造骨頭必須體驗真正壓力

  • or else it will come out weak and brittle,

    否則將會變得軟弱易碎

  • so the bioreactor constantly pumps fluids around the bone,

    所以生物反應器持續在骨頭周圍泵出液體

  • and the pressure tells the osteoblasts to add bone density.

    壓力會指示造骨細胞增加骨質密度

  • Put all of this together, and within three weeks,

    將全部綜合起來,在三週之內

  • the now living bone is ready to come out of the bioreactor

    現在具有生命力的骨頭已可以移出生物反應器

  • and to be implanted into the patient's body.

    及被植入病人的身體

  • While it isn't yet certain that this method will work for humans,

    雖然尚未確定此方法是否對人類有效

  • lab grown bones have already been successfully implanted in pigs and other animals,

    但實驗室培育出來的骨頭已成功地移植在豬及其他動物身上

  • and human trials may begin as early as 2016.

    而人體實驗最早可能在2016實施

Can you grow a human bone outside the human body?

你能夠在人體外培育一個人類的骨頭嗎?

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B2 中高級 中文 美國腔 TED-Ed 骨頭 細胞 礦物 沃爾夫 反應器

TED-Ed】如何長出骨頭--Nina Tandon。 (【TED-Ed】How to grow a bone - Nina Tandon)

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    Ann 發佈於 2021 年 01 月 14 日
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