Comparative transfection studies of human ovarian carcinoma cells in vitro, ex vivo and in vivo with poly(2-(dimethylamino)ethyl methacrylate)-based polyplexes.

Background: Poly(2-(dimethylamino)ethyl methacrylate) (p(DMAEMA)) can be used successfully for in vitro transfection of different cell lines, including the OVCAR-3 human ovarian carcinoma cell line. The aim of this study was to investigate whether it is possible to transfect OVCAR-3 cells in vivo with polyplexes containing p(DMAEMA).

Methods: In order to understand the generally observed gap between in vitro and in vivo transfection, we gradually went from in vitro to in vivo transfection of OVCAR-3 cells, while keeping the exposure conditions the same, as far as possible. To find the reason for the negligible degree of in vivo transfection, in vitro cultured OVCAR-3 cells were transfected in the presence of peritoneal ascites fluid. Next, the influence of hyaluronic acid, one of the ascites components, on the transfection efficiency was studied.

Results: P(DMAEMA)-containing polyplexes can transfect OVCAR-3 cells in vitro with an overall transfection efficiency of 10%. Cells grown in vivo can be transfected ex vivo with p(DMAEMA)/plasmid complexes with an overall transfection efficiency of approximately 1-2%. When transfection complexes are injected i.p. into nude mice bearing OVCAR-3 cells in the peritoneal cavity, the degree of in vivo transfection efficiency achieved is negligible. In vitro cultured OVCAR-3 cells were also transfected with polyplexes in the presence of peritoneal ascites fluid. The results indicate that one or more components of ascites had a negative effect on the transfection efficiency of p(DMAEMA)-containing polyplexes. To elucidate which component(s) of ascites may have interfered, the influence of hyaluronic acid, one of the ascites components, on the transfection efficiency was studied. The outcome suggests that hyaluronic acid may have induced a negative effect on the transfection capability of p(DMAEMA)-containing polyplexes.

Conclusion: P(DMAEMA) is an efficient transfectant in vitro and ex vivo. However, transfected cells were not detected in vivo which may be caused by a negative influence of components of the ascites fluid.