The delivery of nucleic acids into muscle tissue is a pressing issue that needs to be resolved to advance the field of gene therapy for neuromuscular diseases. The transfection of muscle tissue is highly challenging primarily due to the absence of mitotic divisions in myofibrils, making it difficult for plasmid DNA to enter the nucleus. We have developed non-viral carriers based on arginine-histidine-rich peptides, and have shown their ability to deliver DNA into the muscle cells. Anionic peptide coating was developed to increase the stability of the polyplexes. The main task of current study was to reduce polyplexes package volume in order to increase transfection efficiency in vivo. Arginine-histidine-rich and glutamic acid-containing peptides were synthesized and polyplexes were formed with plasmids carrying the