Adult (tissue) stem cells

As opposed to embryonic stem cells (ESCs) that are only present in the embryo and are truly omnipotent (can give rise to all cells within the body), ASCs are only present in the mature organ and are already committed to the cell fates of a given organ * albeit giving rise to multiple cell lineages/types within the organ.  In order to ensure tissue turnover and regeneration throughout the lifespan of an organism, the ASCs must be endowed with three properties: immortality, self‑renewal and pluripotency.  The ability to live forever requires the presence of the enzyme telomerase that allows chromosomes in the ASCs to never shorten (which in all other cells of the body results in ultimate death of the cell, organ and organism).  Self‑renewal refers to the ability of the ASC to divide and generate a perfect copy of itself to ensure preservation of the ASC pool.  Pluripotency refers to the undifferentiated/uncommitted nature of the ASC that can be induced to differentiate into a variety of cell types within the organ.