“…In fact, based on the current view on in vitro behaviour of a given stem cell population, the culture conditions used by White et al (White et al, 2012) to expand the VASA pos cell population look like a differentiation system instead of a self-renewing system. The preliminary culture on a MEF feeder layer, a step mandatory to allow the subsequent cell expansion in liquid phase culture (White et al, 2012), may have contributed to de-differentiate the cells sorted by VASA antibodies by altering the gene and stem cell marker expression (Allegrucci and Young, 2007;Shoji et al, 2018).…”