Simultaneous reprogramming and gene editing of human fibroblasts.

The utility of human induced pluripotent stem cells (iPSCs) is enhanced by an ability to precisely modify a chosen locus with minimal impact on the remaining genome. However, the derivation of gene-edited iPSCs typically involves multiple steps requiring lengthy culture periods and several clonal events. Here, we describe a one-step protocol for reliable generation of clonally derived gene-edited iPSC lines from human fibroblasts in the absence of drug selection or FACS enrichment. Using enhanced episomal-based reprogramming and CRISPR/Cas9 systems, gene-edited and passage-matched unmodified iPSC lines are obtained following a single electroporation of human fibroblasts. To minimize unwanted mutations within the target locus, we use a Cas9 variant that is associated with decreased nonhomologous end-joining (NHEJ) activity. This protocol outlines in detail how this streamlined approach can be used for both monoallelic and biallelic introduction of specific base changes or transgene cassettes in a manner that is efficient, rapid (∼6-8 weeks), and cost-effective.