The FASEB Journal • Research Communication Pluripotency of mouse spermatogonial stem cells

ABSTRACT Recent studies indicate that neonatal sper-matogonial stem cells (SSCs) possess pluripotency. How-ever, the mechanisms that regulate the pluripotent differ-entiation capacity of SSCs remain unclear. Here, we describe a new method to clonally derive pluripotent SSCs from neonatal mouse testis. By coculturing with testicular stromal cells, SSCs can be maintained and expanded in serum-free conditions. Unlike endogenous SSCs, these in vitro expanded SSCs showed strong alka-line phosphatase (AP) activity and displayed characteris-tics of embryonic stem cells and primordial germ cells, which were therefore designated as AP germline stem cells (APGSCs). The pluripotency of APGSCs was confirmed by in vitro differentiation toward hepatic and neuronal lineages and formation of embryonic chimera