Use of GapmeRs for gene expression knockdowns in human primary resting CD4+ T cells.

Human primary resting CD4+ T cells are difficult to transfect while preserving viability. The present study evaluated gymnotic delivery and RNase H1-dependent gene expression knockdown mediated by antisense oligonucleotides, called GapmeRs. Exposure of primary resting CD4+ T cells to GapmeRs did not cause cell activation or affect cell viability. Gene expression knockdowns were stable at least up to 48 h after removal of GapmeRs from culture. Exposure to GapmeRs resulted in comparable levels of degradation along the entire transcript, which could be important when studying function of regulatory long non-coding RNAs. Efficiency of transcript degradation was not solely dependent on the dose of GapmeR, RNA target and its localization. When using GapmeRs, some optimization is required, and all targets have to be individually tested; however, using GapmeRs is advantageous in experiments where preservation of the resting state of the human primary CD4+ T cells and targeting nuclear RNAs are desired. In certain cases, combining GapmeR with siRNA for the same target may improve knockdown efficiency.