Aldehyded Dextran and ε-Poly(L-lysine) Hydrogel as Nonviral Gene Carrier

Background. The expression term of the gene transfected in cells needs to belong enough inorder to make a gene therapy clinically effective. The controlled release of the transfected gene can be utilized. The new biodegradable hydrogel material created by 20？w/w% aldehyded dextran and 10？w/w% ε-poly(L-lysine) (ald-dex/PLL) was developed. We examined whether it could be as a nonviral carrier of the gene transfer. Methods. A plasmid (Lac-Z) was mixed with ald-dex/PLL. An in vitro study was performed to assess the expression of Lac-Z with X-gal stain after gene transfer into the cultured 293 cells and bone marrow cells. As a control group, PLL was used as a cationic polymer. Results. We confirmed that the transfection efficiency of the ald-dex/PLL had a higher transfection efficiency than PLL in 293？cells (plasmid of 2？μg: ald-dex/PLL 1.1%, PLL 0.23%, plasmid of 16？μg: ald-dex/PLL 1.23%, PLL 0.48%). In bone marrow cells, we confirmed the expression of Lac-Z by changing the quantity of aldehyded dextran. In the groups using ald-dextran of the quantity of 1/4 and 1/12 of PLL, their transfection efficiency was 0.43% and 0.41%, respectively. Conclusions. This study suggested a potential of using ald-dex/PLL as a non-carrier for gene transfer. 1. Introduction Recently, many studies about gene therapy have been published. One of the achievements in gene therapy is safe and effective expression of the gene in the body. The naked DNA is the safe but rapidly degraded by nucleases, and it shows a poor cellular uptake. Success of gene therapy largely relies on gene delivery vectors [1, 2]. Although viral vectors have good transfer efficiency, the consequent immunogenic side effect is not negligible. On the other hand, advantages of safe nonviral carriers　include an ability to introduce DNA into nondividing cells, avoidability of integration into the chromosome, lack of infective risks, and an expense potentially lower cost than viral vectors. However, nonviral carriers display poorer transfer efficiency than viral vectors [3]. Therefore, nonviral gene carriers such as cationic polymer [4], cationic lipid [5], and polysaccharide [6] have been developed to improve this weak point [1]. A cationic polymer and lipid form complexes with DNA by electrostatic interactions between positively charged amine of the polycations and negatively charged phosphate groups of the DNA. This can condense DNA into a relatively small size via ionic interactions, which is important for gene transfer because a small size is favorable for cellular uptake [4, 7]. In addition, the interaction