Iroxanadine

Background and Purpose— Myointimal hyperplasia (MIH) cells are related to permanent upregulated proliferation as tumor-like cells. The aim of this study is to assess whether treatment of cells after hypoxia by Iroxanadine heat-shock protein (HSP-coinducer) predicts recovery through cell proliferation. Methods— Vascular smooth muscle cells (VSMC) and brain capillary endothelial cells (HBEC) were isolated from human origin and MIH-cells from early carotid restenosis after surgery. Cell proliferation was quantified by bromuridine (BrdU) incorporation after hypoxia/reoxygenation. HSP72 and cyclin-dependent kinase (CDKN1A) mRNA expression was assessed by reverse transcription-polymerase chain reaction (PCR) and cell cycle distribution by flow cytometry (FACS) analysis. Results— After hypoxia/reoxygenation, the proliferation of MIH-cells increased, whereas endothelial cells decreased (MIH: 0.266±0.016 versus 0.336±0.024; P <0.05; HBEC: 1.249±0.10 versus 0.878±0.11; P <0.05). Whereas augmented proliferation of MIH-cells was reduced (40% to 45%) by HSP-coinducer, diminished HBEC proliferation increased (46.2%). Stress-activated-protein-kinase (SAPK)p38-dependent cell cycle redistribution was generated by an increase in HSP72 and CDKN1A mRNA levels in MIH-cells. Conclusions— The 2 key players of early restenosis (MIH, EC) were oppositely regulated and correspondingly after treatment by HSP-coinducer reverse recovered. Drug candidate may have therapeutic potential in (re)restenosis.

BRX-235 (Iroxanadine), a novel drug developed by Biorex (Hungary), was previously characterized as a vasculoprotector against atherosclerosis, an activator of p38 kinase, and an enhancer of stress-responsive heat shock protein (Hsp) expression. The present data demonstrate that BRX-235 may improve survival of vascular endothelial cells (ECs) following ischemia/reperfusion stress. ECs cultured from human umbilical veins were exposed to hypoxia/reoxygenation to mimic ischemia/reperfusion. Caspase activation and apoptosis were monitored in the reoxygenated cells. Addition of BRX-235 (0.1-1 microM) to culture medium prior to hypoxia or at start of reoxygenation significantly reduced the caspase-dependent apoptosis. The cytoprotection conferred by the pre-hypoxic drug administration was sensitive to quercetin and seems to be based on enhanced Hsp accumulation in stressed ECs. In the case of post-hypoxic drug administration, the cytoprotection was strongly inhibited by SB202190 and SB203580 and appears to be associated with enhanced p38 kinase activation in reoxygenated ECs.