LAUSR

Cell‐penetrating peptides (CPPs) are short amino acid sequences known to act as a vehicle for enhancing the intracellular translocating efficiency of extracellular molecules. Although many groups have attempted to develop peptides with high cell‐penetrating efficiencies, very few have demonstrated efficient cellular uptake of CPPs at low concentrations. Here, we describe a newly synthesized peptide derived from Arabidopsis, Ara‐27, which exhibits significant improvement in cell‐penetrating efficiency compared to existing CPPs. The cell‐penetrating efficiency of Ara‐27 was compared with the commonly used Tat‐protein transduction domain (Tat‐PTD) and membrane translocating sequence (MTS) in human dermal fibroblast (HDF) and human dental pulp stem cells (hDPSC). Cell‐penetrating efficiency of fluorescein isothiocyanate (FITC)‐labeled CPPs were assessed by flow cytometry and visualized by confocal microscopy. Flow cytometric analysis revealed >99% cell‐penetrating efficiency for 2 μM Ara‐27 in both HDF and hDPSC. In contrast, 2 μM Tat‐PTD and MTS showed <10% cell‐penetrating efficiency in both cells. In support, relative fluorescence intensities of FITC‐labeled Ara‐27 were around 8 to 22 times higher than those of Tat‐PTD and MTS in both cells. Confocal analysis revealed internalization of 0.2 and 2 μM Ara‐27 in both human cells, which was not observed for Tat‐PTD and MTS at either concentration. In conclusion, this study describes a novel CPP, Ara‐27, which exhibit significant improvement in intracellular uptake compared to conventional CPPs, without affecting cell viability. Thus, development of Ara‐27 based peptides may lead to improved delivery of functional cargo such as small molecules, siRNA, and drugs for in vivo studies.