Bone Morphogenetic Protein 2 Gene Delivery via Polyethylene Imine Grafted Chondroitin Sulfate Non-viral Gene Carrier

Abstract

Background: Bone morphogenetic protein 2 (BMP-2) has been frequently used for bone regeneration. The purpose of this study was to design a gene vector to deliver the BMP-2 plasmid into cells. Polyethylene imine (PEI) is commonly used for gene transfer, however the high cytotoxicity often leads to decreased transfection efficiency. Solutions to this problem have been widely discussed, one of which being the grafting of a highly biocompatibility polymer such as chondroitin sulfate (CS). Methods: Different molecular weights (1,800 and 25,000 g/mol) of PEI were grafted onto CS (PEI1.8K-g-CS and PEI25K-g-CS, respectively) through the ethyldimethylaminopropyl carbodiimide/ N-hydroxysuccinimide reaction. This modification resulted in a non-viral gene carrier with improved biocompatibility as well as enhanced transfection efficiency compared to PEI alone. Cytotoxicity toward human embryonic kidney cell line (293T) was assayed. Results: Cell viability in the PEI-grafted-CS group was higher than that of the PEI group, and this was particularly evident at high concentrations. The efficiency of transfection and the amount of intracellular plasmid DNA were monitored using green fluorescent protein. The expression of BMP-2 was measured by enzyme-linked immunosorbent assay. A polymer:DNA weight ratio of 4:1 in the PEI25K-g-CS/DNA polyplexes exhibited the highest transfection efficiency. Conclusions: The low toxicity and high transfection efficiency of PEI25K-g-CS make it ideal for application in gene delivery and therapy.