Abstract: AIM To explore the expression and clinical significance of S100B neointima of carotid artery after balloon injury. METHODSSprague Dawley (SD) rats (400-500) g were divided into control group and experimental group. The rat left common carotid artery injury model was established in experimental group using 2F Fogarty catheter. Carotid arteries were harvested for histomorphology and molecular markers assay on days 1, 3, 7, 14 and 28 after balloon injury. Hematoxylin and eosin staining was used to assess the changes of neointimal formation in the carotid artery and S100B expression was evaluated using Western blotting, qRT-PCR and immunohistochemical staining. Rats were randomly allocated into three groups to detect impact on neointimal information, namely, sham group without balloon injury, Ad-GFP group and Ad-shS100B group, respectively, experiencing 200 μl Ad-GFP, Ad-shS100B incubation and balloon injury. RESULTSAs the time of carotid arteries injury progressed, neointimal hyperplasia in carotid arteries revealed a gradual increasing trend, achieving peak at day 14 (P<0.05) and intima/media ratio reached a maximum at day 28. QRT-PCR revealed that S100B-mRNA expressions increased at day 1, declined at days 3 and 7, increased again at day 14 and decreased again at day 28 in carotid arteries after injury (P<0.05). Western blotting showed that S100B expressions increased from day 1 to day 7. After reaching a peak at day 7, the expressions gradually decreased at day 14 and day 28 (P<0.05). Immunohistochemical analysis localized S100B protein mainly in neointima layer of carotid arteries after injury, reaching a maximum at day 7 after injury (P<0.05). Administration with Ad-shS100B significantly reduced neointimal formation and S100B expression. CONCLUSIONThe characteristics of S100B expressions may be associated with neointimal formation in carotid arteries after injury.