Collagen Gel as Cell Extracellular Environment to Study Gene Electrotransfer

Abstract

Gene electrotransfer is a promising nonviral method that enables transfer of plasmid DNA into cells with electric pulses. Several in vitro and in vivo studies analyzed different pulse duration however the question of the mechanisms involved in gene electrotransfer remains open. One of main obstacles toward efficient gene electrotransfer in vivo is relatively poor mobility of DNA in tissues. Since cells in tissues are connected to their extracellular environment they behave differently than in standard in vitro conditions. We first grew cells on collagen layer and furthermore developed a three-dimensional (3-D) in vitro model of CHO cells embedded in collagen gel as an in vitro model of tissue. We analyzed gene electrotransfer efficiency and viability using different pulse duration. We obtained that gene electrotransfer efficiency of cells in 3-D collagen model has similar dependence on pulse duration as in in vivo studies. We suggest that our 3-D collagen model resembles the in vivo situation more closely than conventional 2-D cell cultures and thus provides an intermediate between in vitro and in vivo conditions to study mechanisms of gene electrotransfer.