Elimination of pluripotent stem cells from differentiated cells is critical prior to downstream in vivo experiments. The most simple method would involve using bead-conjugated antibodies against the pluripotent surface marker SSEA4 (see link below). http://www.lifetechnologies.com/us/en/home/references/protocols/proteins-expression-isolation-and-analysis/cell-separation-methods/embryonic-stem-cell-isolation-protocols/dynabeads-ssea-4.html
Using flow cytometry, SSEA4 negative population can be further assessed for the presence of cells expressing SSEA4 and other pluripotent markers such as TRA-1-60 and TRA-1-180.
Recently, alternate methods are emerging that are summarized in a recently publication in Nature Protocols {Ben-David & Benvenisty Nature Protocols (2014) 9, 729-740}.