Fig. 2. Radiofrequency (RF)-induced collagen contraction and production in fibroblast-populated collagen lattices (FPCLs). (A) FPCL contraction assay diagram. As illustrated, cell-seeded matrices develop isometric tension during an initial attachment period (1∼2 days) that later dissipates when lattices are mechanically released. RF treatment performed at six sites on the FPCLs after mechanical release. (B) Plate map of the RF application sites on the FPCLs. At each site, RF was delivered for 1 to 20 minutes per site in a time-dependent manner. (C) Digital images of the contracting FPCLs were captured at 24 h and 48 h after RF application. (D) FPCL contraction diameters after an incubation period of 2 days. All plotted data represent the mean±standard error of the mean (SEM) values for all three FPCLs. Statistical pairwise comparisons were performed by using Student’s t-test. Statistical significance (p<0.05) was reached between normal and RF-treated FPCLs. (E) Percent change of FPCL surface area after RF treatment and an incubation period of 2 days. All plotted data represent the mean±SEM values for all three FPCLs. Statistical pairwise comparisons were performed by using Student’s t-test. Statistical significance (p<0.05) was reached between normal and RF-treated FPCLs. (F, G) Procollagen production after RF treatment and an incubation period of 2 days. All plotted data represent the mean±SEM values for all three FPCLs. Statistical pairwise comparisons were performed by using Student’s t-test. Statistical significance (p<0.05) was reached between normal and RF treated FPCLs. *p<0.05: significant.