Laminar tendon composites with enhanced mechanical properties

A strong isotropic material that is both biocompatible and biodegradable is desired for many biomedical applications, including rotator cuff repair, tendon and ligament repair, vascular grafting, among others. Recently, we developed a technique, called “bioskiving” to create novel 2D and 3D constructs from decellularized tendon, using a combination of mechanical sectioning, and layered stacking and rolling. The unidirectionally aligned collagen nanofibers (derived from sections of decellularized tendon) offer good mechanical properties to the constructs compared with those fabricated from reconstituted collagen. In this paper, we studied the effect that several variables have on the mechanical properties of structures fabricated from tendon slices, including crosslinking density and the orientation in which the fibers are stacked. We observed that following stacking and crosslinking, the strength of the constructs is significantly improved, with crosslinked sections having an ultimate tensile strength over 20 times greater than non-crosslinked samples, and a modulus nearly 50 times higher. The mechanism of the mechanical failure mode of the tendon constructs with or without crosslinking was also investigated. The strength and fiber organization, combined with the ability to introduce transversely isotropic mechanical properties makes the laminar tendon composites a biocompatible material that may find future use in a number of biomedical and tissue engineering applications.