Fluorescent nanoswitch for monitoring specific pluripotency-related microRNAs of induced pluripotent stem cells: Development of polyethyleneimine- oligonucleotide hybridization probes

The isolation of high-grade (i.e. high-pluripotency) human induced pluripotent stem cells (hiPSCs) is a decisive factor for enhancing the purity of hiPSC populations or differentiation efficiency. A non-invasive imaging system that can monitor microRNA (miRNA) expression provides a useful tool to identify and analyze specific cell populations. However, previous studies on the monitoring/isolation of hiPSCs by miRNA expression have limited hiPSCs' differentiation system owing to long-term incubation with miRNA imaging probe-nanocarriers. Therefore, we focused on monitoring high-grade hiPSCs without influencing the pluripotency of hiPSCs. We reduced nanoparticle transfection time, because hiPSCs are prone to spontaneous differentiation under external factors during incubation. The fluorescent nanoswitch ("ON" with target miRNA), which can be applied for either imaging or sorting specific cells by fluorescence signals, contains an miRNA imaging probe (miP) and a PEI-PEG nanoparticle (miP-P). Consequently, this nanoswitch can sense various endogenous target miRNAs within 30 min in vitro, and demonstrates strong potential for not only imaging but also sorting pluripotent hiPSCs without affecting pluripotency. Moreover, miP-P-treated hiPSCs differentiate well into endothelial cells, indicating that miP-P does not alter the pluripotency of hiPSCs. We envisage that this miRNA imaging system could be valuable for identifying and sorting high-grade hiPSCs for improved practical applications.