Lheh Luc Snoeckx

Dynamic Straining Combined with Fibrin Gel Cell Seeding Improves Strength of Tissue-Engineered Small-Diameter Vascular Grafts

Vascular tissue engineering represents a promising approach for the development of living small-diameter vascular grafts that can be used for replacement therapy. The culture of strong human tissue-engineered (TE) vascular grafts has required long culture times, up to several months, whether or not combined with gene therapy. This article describes the culture of strong, genetically unmodified, human TE vascular grafts in 4 weeks Small-diameter vascular grafts were engineered using a fast-degrading polyglycolic acid scaffold coated with poly-4-hydroxybutyrate combined with fibrin gel and seeded with myofibroblasts isolated from discarded saphenous veins from patients undergoing coronary bypass surgery. The TE grafts were subjected to dynamic strain conditions. After 28 d of in vitro culture, the grafts demonstrated burst pressures of 903 +/- 123 mmHg. Comparison with native vessels (intact human left internal mammary arteries (LIMAs) and saphenous veins) showed no significant differences in the amount of DNA, whereas the TE vessels contained approximately 50% of the native collagen content. In the physiological pressure range, up to 300 mmHg, the mechanical properties of the TE vessels were comparable to the LIMA. In this study, we showed that dynamic conditioning combined with fibrin gel cell seeding enhances the mechanical properties of small-diameter TE grafts. These grafts might provide a promising alternative to currently used vascular replacements.

Anisotropic, three-dimensional deformation of single attached cells under compression

Quantifying three-dimensional deformation of cells under mechanical load is relevant when studying cell deformation in relation to cellular functioning. Because most cells are anchorage dependent for normal functioning, it is desired to study cells in their attached configuration. This study reports new three-dimensional morphometric measurements of cell deformation during stepwise compression experiments with a recently developed cell loading device. The device allows global, unconfined compression of individual, attached cells under optimal environmental conditions. Three-dimensional images of fluorescently stained myoblasts were recorded with confocal microscopy and analyzed with image restoration and three-dimensional image reconstruction software to quantify cell deformation. In response to compression, cell width, cross-sectional area, and surface area increased significantly with applied strain, whereas cell volume remained constant. Interestingly, the cell and the nucleus deformed perpendicular to the direction of actin filaments present along the long axis of the cell. This strongly suggests that this anisotropic deformation can be attributed to the preferred orientation of actin filaments. A shape factor was introduced to quantify the global shape of attached cells. The increase of this factor during compression reflected the anisotropic deformation of the cell.