2-(DIMETHYLAMINO)ETHYL METHACRYLATE BASED (CO)POLYMERS AS GENE-TRANSFER AGENTS

Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) is a water-soluble cationic polymer, which is able to bind to DNA by electrostatic inter actions. At a polymer/plasmid ratio above 2 (w/w) positively charged c omplexes were formed with a size around 0.2 mu m. The transfection eff iciency of polymer/plasmid complexes was evaluated in cell culture (CO S-7 and OVCAR-3 cells) using a pCMV-lacZ plasmid, encoding for beta-ga lactosidase, as a reporter gene. The optimal transfection efficiency w as found at a PDMAEMA/plasmid ratio of 3-5 (w/w). Under these conditio ns 3-6% of the cells were actually transfected. Like other cationic po lymers, PDMAEMA is slightly cytotoxic. This activity was partially mas ked by complexing the polymer with DNA. A pronounced effect of the mol ecular weight of the polymer on the transfection efficiency was observ ed. An increasing molecular weight resulted in an increasing number of transfected cells. Dynamic light scattering experiments showed that h igh molecular weight polymers (M-w>300 kDa) were able to condense DNA effectively (particle size 0.15-0.20 mu m). In contrast, when plasmid was incubated with low molecular weight PDMAEMA, large complexes were formed (size 0.5-1.0 mu m). Copolymers of DMAEMA with methyl methacryl ate (MMA), ethoxytriethylene glycol methacrylate (triEGMA) or N-vinyl- pyrrolidone (NVP) also acted as transfection agents. A copolymer with 20 mol % of MMA showed a reduced transfection efficiency and a substan tial increased cytotoxicity compared with a homopolymer of the same mo lecular weight. A copolymer with triEGMA (48 mol %) showed both a redu ced transfection efficiency and a reduced cytotoxicity, whereas a copo lymer with NVP (54 mol %) showed an increased transfection efficiency and a decreased cytotoxicity as compared to a DMAEMA homopolymer. (C) 1998 Elsevier Science B.V.