title: Induced elastin regeneration by chronically activated smooth muscle cells for targeted aneurysm repair.
abstract: Elastin breakdown in vascular aneurysms is mediated by cytokines such as tumor necrosis factor alpha (TNF-alpha, which induces vascular smooth muscle cell (SMC) activation and regulates their deposition of matrix. We previously demonstrated that exogenous supplementation with TGF-beta1 (1 ng ml(-1)) and hyaluronan oligomers (0.786 kDa, 0.2 microg ml(-1)) cues the upregulation of elastin matrix synthesis by healthy cultured SMCs. Here, we determine whether these cues likewise enhance elastin matrix synthesis and assembly by TNF-alpha-stimulated SMCs, while restoring their healthy phenotype. Adult rat aortic SMCs were treated with TNF-alpha alone or together with TGF-beta1/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 cross-linking efficiency, while immunofluorescence and electron microscopy were used to analyze the elastin matrix quality. It was observed that SMC activation with TNF-alpha (10 ng ml(-1)) induced matrix calcification and promoted production of elastolytic MMP-2 and MMP-9. However, these effects were attenuated by the addition of TGF-beta1 and HA oligomer cues to TNF-alpha-stimulated cultures, which also enhanced tropoelastin and collagen production, improved elastin matrix yield and cross-linking, promoted elastin fiber formation and suppressed elastase activity, although the release of MMP-2 and MMP-9 was not affected. Overall, the results suggest that TGF-beta1 and HA oligomers are potentially useful in suppressing SMC activation and inducing regenerative elastin repair within aneurysms.
authors.affiliation: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Chandrasekhar R
authors.initials: CR
authors.lastname: Kothapalli
authors.forename: Anand
authors.initials: A
authors.lastname: Ramamurthi
mesh_terms: D000783:Aneurysm / Q000628:therapy*; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism; D049109:Cell Proliferation; D003094:Collagen / Q000737:chemistry; D004549:Elastin / Q000737:chemistry*; D005786:Gene Expression Regulation; D006820:Hyaluronic Acid / Q000737:chemistry; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods; D032389:Myocytes, Smooth Muscle / Q000166:cytology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012038:Regeneration; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014333:Tropoelastin / Q000737:chemistry; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D053773:Transforming Growth Factor beta1; D014333:Tropoelastin; D014409:Tumor Necrosis Factor-alpha; D006820:Hyaluronic Acid; D003094:Collagen; D004549:Elastin; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9