Passive and active contributions to generated force and retraction in heart valve tissue engineering
- 566 Downloads
In tissue engineered heart valves, cell-mediated stress development during culture results in leaflet retraction at time of implantation. This tissue retraction is partly active due to traction forces exerted by the cells and partly passive due to release of residual stress in the extracellular matrix and the cells. Within this study, we unraveled the passive and active contributions of cells and matrix to generated force and retraction in engineered heart valve tissues. Tissue engineered rectangular strips, fabricated from PGA/P4HB scaffolds and seeded with human myofibroblasts, were cultured for 4 weeks, after which the cellular contribution was changed at different levels. Elimination of the active cellular traction forces was achieved with Cytochalasin D and inhibition of the Rho-associated kinase pathway. Both active and passive cellular contributions were eliminated by lysation and/or decellularization of the tissue. Maximum cell activity was reached by increasing the fetal bovine serum concentration to 50%. The generated force decreased ~20% after elimination of the active cellular component, ~25% when the passive cellular component was removed as well and remained unaffected by increased serum concentrations. Passive retraction accounted for ~60% of total retraction, of which ~15% was residual stress in the matrix and ~45% was passive cell retraction. Cell traction forces accounted for the remainder ~40% of the retraction. Full activation of the cells increased retraction by ~45%. These results illustrate the importance of the cells in the process of tissue retraction, not only actively retracting the tissue, but also in a passive manner to a large extent.
KeywordsHeart valve tissue engineering Stress generation Passive and active retraction Extracellular matrix Myofibroblasts
The authors gratefully acknowledge the support of the Smart Mix Program of the Netherlands Ministry of Economic Affairs and theNetherlands Ministry of Education, Culture and Science. The authors would like to thank Nicky de Jonge for the visualization of the actin staining and Linda Kock for performing the biochemical assays.
This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
- Cebotari S, Lichtenberg A, Tudorache I, Hilfiker A, Mertsching H, Leyh R, Breymann T, Kallenbach K, Maniuc L, Batrinac A, Repin O, Maliga O, Ciubotaru A, Haverich A (2006) Clinical application of tissue engineered human heart valves using autologous progenitor cells. Circulation 114(1): I-132–I-137CrossRefGoogle Scholar
- Dugina V, Fontao L, Chaponnier C, Vasiliev J, Gabbiani G (2001) Focal adhesion features during myofibroblastic differentiation are controlled by intracellular and extracellular factors. J Cell Sci 114(18): 3285–3296Google Scholar
- Hoerstrup SP, Sodian R, Daebritz S, Wang J, Bacha EA, Martin DP, Moran AM, Guleserian KJ, Sperling JS, Kaushal S, Vacanti JP, Schoen FJ, Mayer JE Jr (2000) Functional living trileaflet heart valves grown in vitro. Circulation 102(19 Suppl 3): III44–III49Google Scholar
- Mol A, Lieshout MI, Dam-de Veen CG, Neuenschwander S, Hoerstrup SP, Baaijens F, Bouten CV (2004) Fibrin as a cell carrier in cardiovascular tissue engineering applications. Biomaterials 26: 8Google Scholar
- Mol A, Rutten MC, Driessen NJ, Bouten CV, Zund G, Baaijens FP, Hoerstrup SP (2006) Autologous human tissue-engineered heart valves: prospects for systemic application. Circulation 114(1 Suppl): I152–I158Google Scholar
- Schmidt D, Dijkman PE, Driessen-Mol A, Stenger R, Mariani C, Puolakka A, Rissanen M, Deichmann T, Odermatt B, Weber B, Emmert MY, Zund G, Baaijens FP, Hoerstrup SP (2010) Minimally-invasive implantation of living tissue engineered heart valves: a comprehensive approach from autologous vascular cells to stem cells. J Am Coll Cardiol 56(6): 510–520CrossRefGoogle Scholar