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