Topography-mediated myofiber formation and endothelial cell sprouting

Directional topography is often used in cell alignment. This thesis explores the influences of directional topography and topography-aligned differentiated myoblasts in combination with endothelial cells in triggering capillary network formation for tissue engineering of skeletal muscle. Directional topography gradients were used to study the optimum alignment of differentiated myoblasts i.e., myotubes. It was shown that human myoblasts aligned and differentiated irrespective of the topography section. Subsequently, endothelial cells (ECs) were added to the same directional topographic systems, showing that ECs formed unstable sprouting networks that aggregated on the smaller topographies and flat parts whereas ECs themselves aligned on the larger topographies. In addition, different coatings were investigated, such as gelatin, fibronectin, and instructive adipose tissue-derived stromal cell (ASC). We identified that the ASC coating stabilized newly the formed sprouting networks. In addition, we tested the hypothesis that “topography-driven aligned human myotubes promote and support vascular network formation as a prelude to in vitro engineered vascularized skeletal muscle”. As a result, we showed that pre-aligned myotubes support early network sprouting of microvascular endothelial cells by providing collagen fibers and laminin but require accessory cells such as pericytes to complete the vascularization process in vitro. In conclusion, our results showed that aligned topography has a tremendous impact on myotube development and endothelial cell guidance. Topographical cues can be stronger than chemical cues and need further study and consideration in tissue engineering of skeletal muscle.