Dacron Stimulation of Macrophage Transforming Growth Factor-β Release

Abstract

This study evaluated the effect of Dacron on the release of macrophage transforming growth factor-β (TGF-β), an endothelial cell growth inhibitor. Rabbit peritoneal macrophages were grown in minimum essential medium (MEM) with 10% fetal bovine serum (FBS) in the presence or absence of Dacron (0.5 mm x 3 mm particles). Media were collected three times each week for 7 weeks. For the TGF-β bioassay, mink lung epithelial cells (CCL64) were grown in MEM with 10% FBS. Test-conditioned media, 100 μl, were added (n = 4), and incubated 48 h. ³H-Thymidine (³H-TdR) uptake was determined and compared with ³H-TdR uptake using known pure TGF-β standards. Media samples were additionally pre-incubated with a neutralizing anti-TGF-β₁ antibody and the ³H-TdR uptake again quantitated. TGF-β activity in the conditioned media of macrophages exposed to Dacron exceeded the control media groups in all weeks, reaching significance (P<0.05) in weeks 3, 4, 5, 6 and 7. Pre-incubation of media samples with the anti-TGF-β₁ antibody inhibited this TGF-β activity in all weeks with statistical significance in weeks 1, 2, 3, 5 and 7. The inhibitory effects of Dacron on endothelialization may be explained by the Dacron-induced release of TGF-β from macrophages.