Articles by Nicky de Jonge in JoVE
Engineering Fibrin-based Tissue Constructs from Myofibroblasts and Application of Constraints and Strain to Induce Cell and Collagen Reorganization Nicky de Jonge1, Frank P. T. Baaijens1, Carlijn V. C. Bouten1 1Department of Biomedical Engineering, Eindhoven University of Technology This model system starts from a myofibroblast-populated fibrin gel that can be used to study endogenous collagen (re)organization real-time in a nondestructive manner. The model system is very tunable, as it can be used with different cell sources, medium additives, and can be adapted easily to specific needs.
Other articles by Nicky de Jonge on PubMed
Age-related Changes in Material Behavior of Porcine Mitral and Aortic Valves and Correlation to Matrix Composition Tissue Engineering. Part A. Mar, 2010 | Pubmed ID: 19814589 Recent studies showing significant changes in valvular matrix composition with age offer design criteria for age-specific tissue-engineered heart valves. However, knowledge regarding aging-related changes in valvular material properties is limited. Therefore, 6-week, 6-month, and 6-year-old porcine aortic valves (AV) and mitral valves (MV) were subjected to uniaxial tensile testing. In addition to standard material parameters, the radius of transition curvature (RTC) was measured to assess the acuteness of the transition region of the tension-strain curve. Radially, the MV had greater stiffness and a smaller RTC compared with the AV. Circumferentially, the center of the MV anterior leaflet (MVAC) had the highest stiffness (MVAC > AV > MV free edge [MVF]), greater stress relaxation (MVAC > MVF/AV), lowest extensibility (MVAC < AV < MVF), and smaller RTC compared with MVF (AV < MVAC < MVF). AV and MV radial strips had a larger RTC compared with circumferential strips. Aging elevated stiffness for MV and AV radial and circumferential strips, elevated stress relaxation in AV and MVF circumferential strips, and increased RTC for MV radial and MVF circumferential strips. In conclusion, there are significant age-related differences in the material properties of heart valves, which parallel differences in tissue composition and structure, likely impact valve function, and highlight the need for age-specific design goals for tissue-engineered heart valves.
Strain-induced Collagen Organization at the Micro-level in Fibrin-based Engineered Tissue Constructs Annals of Biomedical Engineering. Nov, 2012 | Pubmed ID: 23184346 Full understanding of strain-induced collagen organization in complex tissue geometries to create tissues with predefined collagen architecture has not been achieved. This is mainly due to our limited knowledge of collagen remodeling in developing tissues. Here we investigate strain-induced collagen (re)organization in fibrin based engineered tissues using nondestructive time-lapse imaging. The tissues start from a biaxially constrained myofibroblast-populated fibrin gel and are used to study: (A) remodeling from a static equi-biaxial loading condition to static uniaxial loading; and (B) remodeling of a biaxially constrained tissue under uniaxial cyclic straining before and after a change in strain direction. Under static conditions, collagen oriented parallel to the direction of strain, whereas under cyclic conditions the orientation in the constrained tissue was perpendicular to the direction of strain. It is concluded that due to the biaxial constraints the uniaxially, cyclically strained cells can exert forces in two directions and strain shield themselves. A subsequent change in the direction of cyclic straining resulted in a rapid reorientation of collagen at the tissue surface. Reorientation was significantly slower in deeper tissue layers, where tissue remodeling was dominated by contact guidance provided by the endogenous matrix. These findings emphasize the relevance of achieving a functional collagen organization right from the start of tissue culture.
Matrix Production and Organization by Endothelial Colony Forming Cells in Mechanically Strained Engineered Tissue Constructs PloS One. 2013 | Pubmed ID: 24023827 Tissue engineering is an innovative method to restore cardiovascular tissue function by implanting either an in vitro cultured tissue or a degradable, mechanically functional scaffold that gradually transforms into a living neo-tissue by recruiting tissue forming cells at the site of implantation. Circulating endothelial colony forming cells (ECFCs) are capable of differentiating into endothelial cells as well as a mesenchymal ECM-producing phenotype, undergoing Endothelial-to-Mesenchymal-transition (EndoMT). We investigated the potential of ECFCs to produce and organize ECM under the influence of static and cyclic mechanical strain, as well as stimulation with transforming growth factor β1 (TGFβ1).