and turning from just collections of cells into arterial tissue,

并且分化为只能形成动脉组织的细胞时
they were exposed to flowing blood

它们存在于流动的血液当中
because the embryonic heart was already beating,

因为胚心这时已经开始跳动
there's already an immature circulatory system.

不太成熟的循环系统已经形成了
These arteries developed in the presence of a beating heart.

在心脏跳动时动脉进行发育
What if you simulated that in cell culture

如果在细胞培养时就模拟这种条件
and took these tissue engineered structures

并在这种条件下培养充满合适的细胞的
that are polymer scaffolds filled with the right kinds of cells.

这种组织工程支架会是什么情况
You hook them up to--on both ends to a tube

你将这根管道的两侧吊起来
where you can expose them to blood flow and blood pressure and

置于血液流动并有血压的地方
build a reactor around these blood vessels,

在血管周围放置一个反应器
so that as they're developing outside the body.

这样的话当它们在体外发育时