The expression of Col I in fibroblasts. A) Immunostaining of Col I in NL and SSc dermal fibroblasts (3 NL and 4 SSc subjects). B) Hydroxyproline content was measured in cell culture media. Similar to Figure 3A, hydroxyproline levels were elevated in SSc dermal fibroblasts compared to NL cells. PDGF significantly increased hydroxyproline in both NL and SSc cells. Addition of DHLA significantly reduced hydroxyproline in both NL and SSc cells. C) Col I mRNA levels with or without PDGF stimulation at various time points. D) The effect of TGF- β on hydroxyproline levels were examined. TGF- β significantly increased hydroxyproline levels in both NL and SSc dermal fibroblasts, while DHLA decreased it. E) TGF- β induced Col I mRNA levels in both NL and SSc fibroblasts, and DHLA decreased them significantly. Results are expressed as mean ± S.E. and p < 0.05 was considered significant. NL: normal; BM: basal medium; NS: non-stimulated.