*3.2. Modified MSCs Express Genes of Hepatitis C Virus*

MSCs were transfected with the pcNS3-NS5B plasmid and the expression of viral genes was analyzed by immunocytochemical methods. Transfection efficiency was 55% on average. Figure 2a,d show typical staining of the transfected cells with monoclonal antibody against NS5A protein; expression of the other target HCV proteins was also demonstrated (Figure S1). The cell lines, obtained by selection of the transfected cells in the presence of G-418 for two weeks, also demonstrated expression of the HCV proteins (Figure 2b,e), in contrast to the non-transfected MSC (Figure 2c,f). Finally, expression of the HCV proteins was also confirmed by western blotting (Figure S2).

**Figure 2.** Immunocytochemical staining of hepatitis C virus (HCV) NS5A in MSCs transfected with pcNS3-NS5B. Primary MSC cultures at third-fourth passages were transfected with the pcNS3-NS5B plasmid and later selected with G-418. The cells were stained with monoclonal antibody against HCV NS5A using immunoperoxidase (top panel) and immunofluorescence (bottom panel) methods. NS5A is located in cytoplasm (brown or green, respectively); nuclei were stained with hematoxylin or 4- ,6-diamidino-2-phenylindole (DAPI), respectively (blue). (**a**,**d**) 72 h post-transfection; (**b**,**e**) two weeks post-transfection and selection; (**c**,**f**) non-transfected MSC (scale bar, 25 μM).
