Induced Elastin Regeneration by Chronically-Activated Smooth Muscle Cells for Targeted Aneurysm Repair

摘要

Elastin breakdown in vascular aneurysms is mediated by cytokines such as tumor necrosis factor-α (TNF-α), which induces vascular smooth muscle cell (SMC) activation and regulates their deposition of matrix. We previously demonstrated exogenous supplement of TGF-β1 (1 ng/mL) and hyaluronan oligomers (0.786 kDa; 0.2 µg/mL) cues to upregulate elastin matrix synthesis by healthy cultured SMCs. Here, we determine if these cues likewise enhance elastin matrix synthesis and assembly by TNF-α-stimulated SMCs, while restoring their healthy phenotype. Adult rat aortic SMCs were treated with TNF-α alone or together with TGF-β1/ hyaluronan oligomeric cues, and the release of inflammatory markers were monitored during over a 21 day culture. Biochemical analysis was used to quantify cell proliferation, matrix protein synthesis and crosslinking efficiency, while immunofluorescence and electron microscopy techniques were used to analyze the elastin matrix quality. It was observed that SMC activation with TNF-α (10 ng/mL) induced matrix calcification and promoted production of elastolytic MMPs-2, 9. However, these effects were attenuated by the addition of TGF-β1 and HA oligomers cues to TNF-α-stimulated cultures, which also enhanced tropoelastin and collagen production, improved elastin matrix yield and crosslinking, promoted elastin fiber formation, and suppressed elastase activity, though release of the MMPs-2, 9 was not impacted. Overall, the results suggest that TGF-β1 and HA oligomers are potentially useful to suppress SMC activation and induce regenerative elastin repair within aneurysms.