Regeneration, the homeostatic ability to maintain tissue structure in the face of normal cell turnover or loss of tissue damaged by trauma or disease, is an essential developmental process that continues throughout life. As recently as a decade ago, any serious discussion of the possibility of regeneration becoming a practical medical tool in the near future had the air of science fiction or over-optimistic speculation. The term "regenerative medicine" was certainly on many lips but few actually expected to soon see it applied in a clinical setting. A tidal wave of discovery has changed...