Characterizing Pluripotent Stem Cells Using the TaqMan® hPSC Scorecard(TM) Panel

Rapid technological developments for the efficient generation of footprint-free induced pluripotent stem cells (iPSC) enabled the creation of patient-specific iPSC for downstream applications in drug discovery and regenerative medicine. However, the large number of iPSCs, generated from diverse genetic backgrounds using various methods and culture conditions, created a steep challenge for rapid characterization and a demand for standardized methods. Current methods rely on a combination of in vitro and in vivo cellular analyses based on the expression of markers of self-renewal and the ability of the cells to differentiate into cell types representative of the three germ layers as a confirmation of functional pluripotency. These methods, though informative and extensively used, are not ideal for parallel analyses of large numbers of samples and hence not amenable to high-throughput environments. Recently, genetic and epigenetic expression signatures were used to define and confirm cell states, thus providing a surrogate molecular assay that can potentially replace complex in vivo cellular assays such as teratoma formation. In this chapter, we describe a molecular assay for rapid characterization and standardization of pluripotent stem cells. The TaqMan(®) hPSC Scorecard™ Panel is a comprehensive gene expression real-time PCR assay that consists of 94 individual q-PCR assays comprised of a combination of control, housekeeping, self-renewal, and lineage-specific genes. The resulting expression data set is analyzed using cloud-based analysis software that compares the expression pattern against a reference standard composed of multiple functionally validated ESC and iPSC lines. This system was successfully used to test several ESC and iPSC lines in their undifferentiated states to confirm their signatures of self renewal, as well as their terminally differentiates states, via spontaneous differentiation and directed differentiation into specific lineages, to determine the lines' differentiation potential. This genetic analysis tool, together with the flexibility to utilize varying sample inputs and preparation methods, provides a rapid method to confirm functional pluripotency of ESCs and iPSCs.