how to maintain these cells in culture,

如何培养这些细胞
how to propagate them,

如何繁殖这些细胞
how to increase them in number

如何增加它们的数量
using the same techniques we talked about

就用我们在这门课刚一开始
very near the beginning of the course.

讲过的那些技术
They've also discovered how to genetically modify these cells

他们也发现了如何对细胞进行基因修饰
so that they perform better in culture.

这样它们在培养基中能长得更好
One of these modifications is

其中一种修饰方法是
to add a gene called Bcl-2.

添加一个叫Bcl-2的基因
Bcl-2 is a survival gene

Bcl-2是存活基因
that allows these cells to live beyond

能够让细胞一直生存下去
when you would expect them to live.

如果你期望它们活下去的话