Introduction:Distinct from the serum LDL lowering mechanism of proprotein convertase subtilisin/kexin 9 (PCSK9) antagonists, shRNA knockdown of PCSK9 decreases atherosclerotic lesion size and inflammatory markers in ApoE-/- mice without altering serum LDL. This suggests that PCSK9 contributes to cardiovascular disease (CVD) risk through an LDL-independent inflammatory mechanism. Here, we use a novel humanized tissue-engineered blood vessel (TEBV) system composed of PCSK9 over- and under-expressing human induced pluripotent stem cell (hiPSC)-derived endothelial (viECs) and smooth muscle cells (viSMCs) to investigate the role of PCSK9 in inflammatory CVD risk.Methods/Results:hiPSCs were transduced with a dCas9 VP64 PCSK9 over-expression (P+) or PCSK9 shRNA under-expression (P-) lentiviral vector. RT-PCR revealed an increase in PCSK9 expression in P+ viECs (26.2?0.6 fold p<0.0001). PCSK9 expression (6.9?0.3 fold p=0.001) was also elevated in P+ viSMCs as was TNF-? expression (2.0?0.1 fold p<0.0001). In addition, TNF-?, IL-1?, and MCP-1 expression was elevated in primary human macrophages cultured in P+ viSMC conditioned media (TNF-? 15.1?0.1 fold p<0.0001, IL-1? 64.3?0.1 fold p<0.0001, and MCP-1 3.6?0.2 fold p<0.0001) compared to control. Conversely, PCSK9 expression decreased by 70?30% (p=0.0003) in P- viECs and 70?30% (p<0.0001) in P- viSMCs. Furthermore, TNF-? expression decreased by 90?10% (p=0.0003) in P- viECs. PCSK9 shRNA decreased immunofluorescence staining intensity for intercellular adhesion molecule-1 (ICAM-1) in enzyme modified LDL (eLDL) treated viECs (821,454?49,512U vs. 683,751?20,739U p<0.0001). Four TEBVs each, fabricated by plastic compression of collagen from either P- or WT viSMCs and viECs were perfused with eLDL and U937 monocytes. Fewer monocytes accumulated in the wall of P- TEBVs (2059 cells/cm2?751 vs. 8,010 cells/cm2?726 p<0.0001), whole TEBV TNF-? expression decreased by 40?30% (p=0.02), and ICAM-1 positive cells decreased by 24?5% (p=0.01).Conclusions:In our novel human TEBV model, blood vessel specific knockdown of PCSK9 decreases monocyte accumulation and expression of ICAM-1 and TNF-?. This suggests potential for development of PCSK9 antagonists to decrease inflammatory CVD risk.