DNA methylation analysis as a tool for cell typing.

Cell therapeutic approaches currently lack definitive quality control measures which guarantee safety in clinical applications and create consistent standards for regulatory approval. These approaches rely on isolation, purification and possibly ex vivo manipulation of donor cells. Since such cells are exposed to artificial environments, there is potential for deviations from natural growth processes. The resulting heterogeneity of cell cultures is an inherent problem. Therefore, verification of cell identity and quantification of subpopulations is mandatory. Focusing on cultured human primary cells, we tested whether DNA methylation patterns serve as distinctive cell type markers. We identified panels of cell type specific differentially methylated gene regions (CDMs) which produce unambiguous profiles for these cell types. Applying methylation sensitive single nucleotide primer extension generated binary cell type descriptors ("barcodes") which allow quantification of cell mixtures. Thus, methylation based analytics suggest themselves as promising tools for the characterization and quality control of ex vivo manipulated cells.