Role of heat shock protein 65 kDa on vascular smooth muscle cell proliferation

Abstract

Introduction. Proliferation of vascular smooth muscle cells (vSMC) is one of the most important pathological processes in atherosclerosis. Recently, heat-shock protein (Hsp65) has been implicated in the pathogenesis and propagation of this disease. The aim of this study was to examine the effect of Hsp65 on the proliferation of vSMCs. Materials/Methods. Male Dark Agouti rats were immunized with 200 gg of Hsp65 (n = 6) or saline control (n = 5) and then sacrificed at 10 weeks. The thoracic aortae were removed and from sections, vSMCs were grown using standard explant technique. Cells were grown to confluence using DMEM+ 10% fetal calf serum (FCS), trypsinized, plated into 96-well plates, and made quiescent. These were subsequently stimulated with FCS (0-20% concentration) over 24 and 48 h. Proliferation was determined by the uptake of 5-bromo-2' deoxyuridine using colorimetric ELISA. Results. At 24 h, there was no difference in proliferation in any of the groups. However, at 48 h, vSMC proliferation was significantly reduced in the rats immunized with Hsp65 compared to controls. Data are expressed as means?SEM (see Figure 1). Conclusions. These findings suggest that prior in vivo inoculation with Hsp65 subsequently inhibited smooth muscle cell proliferation in vitro. Therefore Hsp65 per se could not account for the proliferation of vSMC seen in atherosclerosis.