title: Cyclic strain inhibits acute pro-inflammatory gene expression in aortic valve interstitial cells.
abstract: Mechanical in vitro preconditioning of tissue engineered heart valves is viewed as an essential process for tissue development prior to in vivo implantation. However, a number of pro-inflammatory genes are mechanosensitive and their elaboration could elicit an adverse response in the host. We hypothesized that the application of normal physiological levels of strain to isolated valve interstitial cells would inhibit the expression of pro-inflammatory genes. Cells were subjected to 0, 5, 10, 15 and 20% strain. Expression of VCAM-1, MCP-1, GM-CSF and OPN was then measured using qRT-PCR. With the exception of OPN, all genes were significantly up regulated when no strain was applied. MCP-1 expression was significantly lower in the presence of strain, although strain magnitude did not affect the expression level. VCAM-1 and GM-CSF had the lowest expression levels at 15% strain, which represent normal physiological conditions. These findings were confirmed using confocal microscopy. Additionally, pSMAD 2/3 and IkappaBalpha expression were imaged to elucidate potential mechanisms of gene expression. Data showed that 15% strain increased pSMAD 2/3 expression and prevented phosphorylation of IkappaBalpha. In conclusion, cyclic strain reduces expression of pro-inflammatory genes, which may be beneficial for the in vitro pre-conditioning of tissue engineered heart valves.
authors.affiliation: Department of Agricultural and Biological Engineering, Mississippi State University, 130 Creelman Street, Mississippi State, MS, 39762, USA.
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Smith
authors.forename: Scott A
authors.initials: SA
authors.lastname: Metzler
authors.forename: James N
authors.initials: JN
authors.lastname: Warnock
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000378:metabolism* / Q000473:pathology*; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism*; D018613:Microscopy, Confocal; D053495:Osteopontin / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013314:Stress, Mechanical; D034421:Sus scrofa; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism
chemical_list: D018932:Chemokine CCL2; D018836:Inflammation Mediators; D012333:RNA, Messenger; D019010:Vascular Cell Adhesion Molecule-1; D053495:Osteopontin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor