The Effect Of BFGF On ICAM-1 Expression Of Human Vascular Endothelial Cells

IntroductionTrauma is a health hazard in developed countries and thus tissue repair after trauma is an hot issue in medical research. Repair in trauma is a complicated but sequential biological process, which involves inflammatory cells, fibro-blasts, inflammatory mediators, growth factors, extracellular matrix and so on. In tissue repair research, regulatory mechanism of growth factors is on the spotlight. Fibroblast growth factor ( FGF) , especially basic fibroblast growth factor (bFGF) , plays a cruial role in the whole repair process via producing mitogens, inducing chemotaxis and protein activity regulation. It is well known that bFGF can promote endothelial cell proliferation, regulate protein expression, promote angiogenesis and enhance granulation. However, study of the effect of bFGF on endothelial adhesive factor expression in the early inflammatory stage is rare. In this experiment, we studied the time - dependent effect of bFGF on ICAM - 1 expression of human umbilicalvascular endothelial cells as well as determined the effect of Dexamethasone ( Dex) on bFGF - induced ICAM - 1 expression, aiming to uncovering the underlying mechanism of bFGF related early inflammatory reaction in the wound repair.Methods1. EC culture: HUVEC were obtained according to according to a method modified from Jaffe et al. Immunofluorescence staining with specific antisera a-gainst Ⅷ factor was used to identify the cultured cells as epithelial cells. HU-VEC ( sub - confluence, passage 1 - 3 ) were exposed in serum - free culture medium for 24h, then transferring to culture condition containing experimental factors.2. HUVECICAM - 1 expression determination;grouping: ( 1 ) for time - dependent effect;control (serum-free DMEM);positive control;bFGF (500ng/ml) 12h% 16hx 24h^ 48h(2)experimental groups(16h) : control (serum-free DMEM);bFGF(500ng/ml) x Dex(0. l|xmol/L) > bFGF + Dex. ICAM - 1 expression was determined by immunostaining and flow cytometry. 3. all the data were analyzed by SPSS software.ResultsImmunostaining results: ICAM — 1 was located on the cell membrane, presenting brown staining. Time - dependent effect;bFGF (12h , 16h) induced stronger ICAM - 1 expression as compared with control ( P < 0. 05 );bFGF (16h) stimulated even stronger ICAM - 1 expression than bFGF (12h) (P <0. 05);however, ICAM — 1 expression was absent in bFGF group (24h, 48h) with no statistical significance (P >0. 05).Experimental groups ( 16h);in contrast to control, immunostaining was stronger (P <0.05);there was no significant difference between Dex and control (p > 0.05);bFGF + Dex led to the decreased ICAM - 1 expression as compared with bFGF group (P <0. 05). Flow cytometry: bFGF (12h , 16h) induced stronger ICAM - 1 fluorescence intensity as compared with control (P < 0.05);bFGF (16h) stimulated even stronger ICAM -1 fluorescence intensity than bFGF (12h) (P<0.05)DiscussionPrevious studies indicated that bFGF for external use can promote wound healing. bFGF can affect the whole healing process. Inflammatory reaction is an initative link of wound repair. It is unclear how bFGF can affect early inflamma-tion. In this study, the time - dependent effect of bFGF on ICAM - 1 expression of human umbilical vascular endothelial cells was determined to uncover the underlying mechanism of bFGF related early inflammatory reaction in the wound repair. Intercellular adhesion molecule - 1 (ICAM - 1) is a transmembrane glyco-protein and belongs to immunoglobin super family, functioning as an adhesion molecule in leukocyte - to - endothelium adhesion. Our study showed that bFGF upregulated EC ICAM - 1 during 12h - 16h but down - regulation occurred after 24h, suggesting that bFGF - induced ICAM - 1 expression promotes neutrophil adhesion and migration to kill or inhibit microbes in the wound and that ICAM -1 down — regulation after 24 h may inhibit neutraphil adhesion and reduce transd-uatation to facilitate granulation. Thus, bFGF enhances EC ICAM - 1 expression , which possibly initiate healing process. ICAM -1 expression is dependent on NF - kB. Dex is a non - specific NF - kB inhibitor.This experiment indicated that Dex had the inhibitory effect on bFG - induced ICAM - 1 upregulation, which is associated with NF - kB inactivation.Conclusion1. bFGF first upregulates ICAM - 1 expression in 12h - 16h and then downregulates it after 24 h.2. Dex can inhibit the upregulation of bFGF - induced ICAM -1 expression.3. bFGF upregulates ICAM -1 expression in the early stage , which possibly initiate healing process.