Self-organization of skin cells in three-dimensional electrospun polystyrene scaffolds

Much research in tissue engineering focuses on the synthesis of complex three-dimensional polymer scaffolds containing functional biomolecules to which cells are introduced. Typical scaffolds for skin tissue engineering are macroscopically porous with struts or fibers approximately 10 microm thick at a packing fraction of approximately 0.1. We made a polystyrene scaffold without cell signaling or spatial information by electrospinning and studied the growth of skin fibroblasts, keratinocytes, and endothelial cells, as single and cocultured populations in the presence and absence of fetal calf serum. In the absence of serum, keratinocytes, fibroblasts, and endothelial cells did not grow when cultured alone. However, when fibroblasts were cocultured with keratinocytes and endothelial cells, expansion of keratinocytes and endothelial cells occurred even in the absence of serum. Furthermore, cells displayed native spatial three-dimensional organization when cultured at an air-liquid interface, even when all three cell types were introduced at random to the scaffold. This study shows that coculture with fibroblasts enables keratinocytes and endothelial cells to proliferate without serum, but also to self-organize according to the native epidermal-dermal structure given the symmetry-breaking field of an air-liquid interface.