Time dependent transgenic Fas ligand (FasL) mRNA expression in human synovium in vivo. The 1011 virus particles of recombinant FasL adenovirus (Ad-FasL) and LacZ adenovirus (Ad-LacZ) were injected into the grafted human synovium in severe combined immunodeficiency (SCID) mice in vivo. The injected tissue samples were harvested at days 2, 5, 7, 10, and 20 after virus injection. Total tissue RNA was isolated and the first-strand cDNA of transgenic FasL was detected by RT-PCR as described in Materials and methods. (a) Lane 1, PBS injected tissue; lanes 2–6, Ad-FasL infected tissues harvested on day 2, 5, 7, 10, and 20, respectively, after virus injection; lanes 7–11, the Ad-LacZ infected tissues harvested at the same time points. Ethidium bromide staining of fractionated DNA at 688 base pairs (bp) represents transgenic FasL mRNA expression; the DNA fragments at 505 bp represent β-actin expression as the internal control for the quality of mRNA samples. (b) Transgenic FasL mRNA in vivo was highly expressed on days 2–10 (lanes 2–5), and obviously decreased on day 20 (lane 6), indicated by the ratio of luminosity between transgenic FasL cDNA and the endogenous β-actin cDNA.