Fig. 2.

(A) Cells were treated as described in the legend to Fig. 1 and photographed at 72 h. Compared to treatment with control (serum-free), Ad-PDGF-1308, or recombinant human platelet-derived growth factor-BB, human gingival fibroblasts transduced with Ad-PDGF-B resulted in colony-like growth, as indicated by the arrows (20× magnification). (B) Human gingival fibroblast cells were seeded in 12-well plates at a concentration of 2 × 10⁴ cells per well. After different treatments (recombinant human platelet-derived growth factor-BB, Ad-PDGF-B, or Ad-PDGF-1308), the cells were cultured with serum-free Dulbecco’s modified Eagle’s minimal essential medium without medium change during the experiment. Two days later, 2 × 10⁵ counts per minute of [methyl-³H]thymidine was added to each well. On day 7, the medium was removed and each well was washed twice with cold phosphate-buffered saline. The DNA in each well was precipitated with 5% cold trichloroacetic acid at 4°C for 2 h, solubilized with 1% sodium dodecyl sulfate solution at 55°C for 2 h, then the radioactivity of [methyl-³H]thymidine in the solution was counted using a scintillation counter. Ad-PDGF-B stimulated robust DNA synthesis when compared with the other treatments. NS, no significant difference; (n = 6 samples).