Quantification of collagen orientation in 3D engineered tissue

Tissue engineered heart valves are a promising alternative for current heart valve replacements. However, the mechanical properties of these valves are insufficient for implantation at the aortic position [1]. Collagen orientation is important to improve the mechanical properties of tissue engineered valves. Two-photon laser-scanning microscopy allows us to study the influence of strain on collagen orien-tation in 3D. A method based on the 2nd order derivative of the 3D image structure was used to determine the general orientation of the collagen fibers with automatic scale selection of the operator. We studied the effect of strain on collagen orientation. Alignment in the direction of the applied strain is seen. Histograms show that the distribution of orientations becomes smaller for increased strain. This indicates that the collagen fibers align more