Background: The ability of human mesenchymal stem cells (hMSCs) to differentiate into specific cells holds promise for therapeutic use in cell- or gene-based therapy. Genetic modification of hMSCs by introduction of therapeutic genes is an important tool for successful cell-mediated gene therapy. Similar to most primary cells, hMSCs are difficult to transfect with currently available gene delivery methods. Viral vectors are the most efficient DNA delivery system in stem cells. However, the use of viral vectors has disadvantages involving safety. To overcome these problems, nonviral gene delivery has been studied as an alternative strategy, and the cationic peptide was an efficient vector for transfecting various mammalian cell types. However, little is known about the capacity of this delivery method to transfect to hMSCs. In the present study, we examined the use of a short arginine peptide as a carrier for DNA delivery in hMSCs.
Methods: Plasmids containing the enhanced green fluorescent protein (EGFP) were transfected into hMSCs by arginine peptide in vitro. pEGFP delivery and EGFP expression were assessed by the fluorescence-activated cell sorting technique.
Results: The hydrophobically modified arginine peptide, palmitic acid-R15 (PA-R15), formed a condensed complex with DNA and successfully delivered the gene into hMSCs without compromising cell survival rate. Complexes readily internalized into hMSCs after a 4 h incubation, and PA-R15 showed higher cellular uptake compared to the unmodified arginine peptide (R15). In addition, transfected cells retained their stem cell properties, including the ability to differentiate into adipogenic and osteogenic lineages. Moreover, the erythropoietin (EPO) gene was successfully transfected into hMSCs and the cells produced EPO for 4 weeks.
Conclusions: Hydrophobically modified arginine peptides are promising candidates with low toxicity. They comprise efficient nonviral gene delivery vectors for hMSCs and these may be used as a potential tool for basic research and the therapeutic application of hMSCs.