Characterization of Protein Expression and Signaling Pathway Activation That May Contribute to Differential Biological Functions in Porcine Arterial and Venous Smooth Muscle Cells

Arteriovenous fistulae (AVF) are the preferred mode of dialysis vascular access but have a maturation failure rate of over 50%. Venous segment stenosis is one of the main reasons. However, the reasons for the prevalence of stenosis in the venous segment, as opposed to the arterial segment, remain unknown. We hypothesize that differences in the protein expression profiles and in the activation of key signaling pathways of the vascular smooth muscle cells (VSMCs) in these two segments may contribute to this difference. In this study, arterial porcine VSMCs (ApSMCs) and venous porcine VSMCs (VpSMCs) were isolated to examine relevant protein expression and cell signaling pathway activation via Western blots and immunofluorescent staining. Our results revealed that growth-medium-stimulated cell proliferation was significantly higher in VpSMCs compared to ApSMCs, but no difference was detected in PDGF-BB-stimulated proliferation. VpSMCs migration was significantly greater than ApSMCs under both the serum-free condition and in the growth medium condition. In addition, VpSMCs appeared more susceptible to PDGF-BB-stimulated cell dedifferentiation. Furthermore, P53, vitronectin, collagen 1A1 and integrin β3 had lower expression in VpSMCs, whereas fibronectin, FAK, VCAM-1, MMP-9, TIMP-2 and TIMP-3 had higher expression as compared to ApSMCs. Meanwhile, PDGF-BB stimulated P38, JNKs and AKT activation, which were more potent in VpSMCs. Our results identify significant differences between VpSMCs and ApSMCs in the expression of functional proteins and the activation of signaling pathways, which may be responsible for more aggressive venous-as compared to arterial-stenosis in the clinical setting of arteriovenous access or other similar procedures.