Abstract
Regeneration is the process by which lost or damaged tissue is replaced in adult organisms. Some organisms exhibit robust regenerative capabilities, while others, including humans, do not. Understanding the molecular principles governing the regenerative malleability of different organisms is of fundamental biological interest. Further, this problem has clear impact for the field of "regenerative medicine," which aspires to understand how human cells, tissues, and organs may be restored to normal function in scenarios of disease, damage, or age-related decline. This review will focus on the planarian flatworm as a powerful model system for studying the role of Ca(2+) signals in regeneration. These invertebrate animals display an astounding innate regenerative capacity capable of regenerating complete organisms from tiny, excised fragments. New knowledge and methodological capabilities in this system highlight the potential for studying the role of Ca(2+) signaling at multiple stages of the regenerative blueprint that controls stem cell behavior in vivo.