Novel Live Alkaline Phosphatase Substrate for Identification of Pluripotent Stem Cells

Abstract

Alkaline phosphatases (AP) are a class of enzymes that hydrolyze phosphate containing molecules under alkaline conditions. In humans, there are primarily four different types of this enzyme; intestinal, placental, placental-like and non-tissue specific forms. The non-tissue specific isozyme of AP is expressed in liver, bone and kidney. A similar isozyme was identified in pluripotent stem cells when monoclonal antibodies, TRA-2-49/6E, recognizing determinants of human embryonal carcinoma (EC) cells showed specific reactivity to this isoform. 1 AP is also known to be expressed at high levels in other pluripotent stem cell types such as embryonic germ cells (EG), embryonic stem cells (ESC) and induced pluripotent stem cells (iPSC). 2 – 5 Although definitive measures of pluripotency involves in-vitro tri-lineage differentiation and in-vivo teratoma formation, the most widely tested and validated panel for initial evaluation of ESC and iPSC consists of S tage S pecific E mbryonic A ntigen SSEA4; T umor R ejection A ntigens TRA-1-60, TRA-1-81; AP; Oct4 and Nanog. 6 , 7