Abstract

Cell-based assays are a valuable tool to predict in vivo effects of drug candidates during early steps of development.Cell-based assays are performed using either cell lines or primary cells.Most cell lines are easy to handle and offer the advantage of infinite proliferation. This allows the generation of large cell banks and a facilitated use in screenings or long-term experiments. However, due to their transformed phenotype, many cell lines often exhibit a reduced physiological relevance but can be genetically modified to, for example, overexpress certain targets. In contrast, primary cells are more representative of the in vivo state when compared to cell lines. However, their use in vitro is hampered by: limited tissue availability, scarce cell yields, and a restriction or even lack of proliferation. Taken together, these factors may significantly compromise the: scope, length, and reproducibility of experiments and often circumvent their use for extended cell-based screenings. Here, we describe (1) the successful modification of various cell lines (HEK293, MDA-MB-231) to improve certain characteristics via lentiviral expression plasmids. In addition, we describe (2) the controlled expansion of human primary cells by lentiviral transduction, with proliferation-inducing genes, enabling production volumes of up to 2500 vials containing 5∙10⁶ cells each. As a proof of principle, primary cells from several relevant target tissues (liver, skin, muscle) as well different species (human, mouse) were transduced;