These replacement joints can be made of combinations of metal alloys, plastic and ceramic, but new research shows that it might be possible to regenerate damaged joints using a patient's own stem cells.

VOA: standard.2010.08.11

And they do not regenerate.

而且不会再生。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选

(MOLINA CONTINUESTALKING INDISTINCTLY) ...regenerate.

VOA: standard.other