The anterior cruciate ligament (ACL) is the most commonly injured ligament, and due to its limited blood supply and poor healing potential frequently requires surgical intervention to achieve a successful outcome. A tissue-engineered ligament is a promising alternative to autograft for ACL reconstruction, and we propose that this material can be formed by culturing ligament progenitor cells on electrospun fiber meshes. Attachment, proliferation, and differentiation of the progenitor cells on biomaterial scaffolds is critical for the development of a clinically effective engineered tissue, and we postulate that oriented electrospun fiber meshes have unique capacity to induce cell orientation and the deposition of an oriented extracellular matrix through a contact guidance phenomenon.

In this study fused fiber meshes were produced from poly(ester-urethane-urea) (PEUU) elastomers with controlled fiber diameters and degrees of orientation. Meshes with different fiber diameters were produced by electrospinning with varying solution concentrations, and different degrees of macroscopic orientation were produced by varying the rotational speeds of the target. Bone marrow stromal cells (BMSCs) were cultured on substrates to determine how mesh topography (i.e., fiber diameter and orientation) affects cell morphology and proliferation. The extracellular matrix protein collagen type I was measured through quantitative PCR and immunostaining. Concurrently, PEUU meshes with different mechanical properties were produced by varying the soft segment content, and BMSCs were cultured on the meshes to determine the effect of mechanical properties. Tensile modulus and creep behavior of the meshes were tested.