The generation of induced pluripotent stem (iPS) cells has become a routine task in many laboratories. Across the globe, scientists are using published or commercial reprogramming methods to create iPS cells that further their studies in regenerative medicine, disease modeling, and drug discovery. As we noted in a previous blog post, questions about experimental reproducibility are percolating to the top of major issues that the stem cell field must address in order to confidently guide basic stem cell research into translational application. Extensive research is currently being conducted to uncover sources of variability and reproducibility across pluripotent stem cell lines, and it is becoming clear that not all iPS cells are created equal.
A recent article in Nature provides the latest peer-reviewed evidence of iPS cell line variability as well as some insights into its genomic etiology. Experiments orchestrated by the Human Induced Pluripotent Stem Cell Initiative, genetically and functionally assessed 711 iPSC cell lines (from over 300 healthy donors) for variations in genetic make-up and pluripotency capacity. Using this large sample population, this study suggests that donor variation is a major driver of heterogeneity, particularly identifying expression quantitative trait loci (eQTLs), or sequence variations, that impact gene expression.
iPS cell line variability is also a topic of interest for stem cell scientists at Bio-Techne. A recent set of experiments conducted by Fabrizio Rinaldi, Ph.D., investigated the variability of iPS cells when differentiated into the three germ layers (ectoderm, endoderm, and mesoderm) as well as further differentiated downstream cell types, including cardiomyocytes, hepatocytes, and neural progenitors. In this study, Dr. Rinaldi used 8 iPS cell lines, derived from peripheral blood mononuclear cells (PBMCs) or fibroblasts, as well as one embryonic stem cell line (BG01V human embryonic stem cells). Each cell line was differentiated into ectoderm, endoderm, and mesoderm using the Pluripotent Stem Cell Functional Identification Kit. The majority of cell lines were also differentiated into cardiomyocytes, hepatocytes, or neural progenitors using the Bio-Techne range of StemXVivo® Differentiation Kits. By utilizing kits that are optimized to drive lineage differentiation, Dr. Rinaldi was able to standardize the differentiation process, allowing for a clearer assessment of individual iPS cell line variability. In short, his findings provide evidence, at the level of functional pluripotency, that individual cell lines are variable in their ability to differentiate into specific lineages or cell-types.
Table 1: Induced Pluripotent Stem Cell Lines are variable in their efficiency to differentiate into intermediary and terminal cell types.
The data presented here suggest that, in addition to the expression of standard pluripotent stem cell markers, iPS cell line variability in differentiation capacity must be considered when outlining experiments. In particular, it is important to choose an iPS cell line that can generate the cell type you desire for your experiments. The Human Pluripotent Functional Identification Kit and our StemXVivo® Differentiation Kits can provide an easy way to screen for this. Screening reprogrammed iPS cell lines for differentiation into your desired cell type will ultimately provide you with a more robust iPS cell-based model for your downstream experiments.
Currently available StemXVivo® Differentiation Kits:
BG01V human embryonic stem cells are licensed for ViaCyte, Inc.