Establishment of a novel model to assess the function of proteins under in vivo conditions

We established a novel model to assess the function of proteins under in vivo conditions. The model relies on the expansion of HEK293 cells in immunodeficient NOD.Scid mice. To validate the novel model, we performed microarray gene expression profiling of NOD.Scid-expanded HEK293 cells relative to conventionally cultivated cells. Microarray analysis revealed that cell expansion in NOD.Scid mice restored an imbalanced chaperone system without inducing a major upregulation of the entire protein folding machinery. Human embryonic kidney (HEK293) cells were injected subcutaneously into immunodeficient NOD.Scid mice. After three weeks, the expanded cell pellet was isolated, and total RNA was extracted. In parallel, total RNA was prepared from HEK293 cells cultivated in vitro under standard cell culture conditions in a commercially available medium containing 450 mg/dl glucose (DMEM). Microarray gene expression profiling was performed to determine differential gene expression between in vivo expanded and in vitro cultivated HEK293 cells. Two biological replicates for each condition were made (in vitro cultivated HEK293 cells: Cells-1 and Cells-2; and NOD.Scid-expanded HEK293 cells: Scid-1 and Scid-2).