Engineering of Functional Tendon

TLDR

Tendon repair is constrained by limited viable tissue, and its avascular nature makes it a suitable target for engineered tissue replacement. Cells isolated from rat Achilles tendon were cultured to confluence and self‑assembled into a scaffold‑free cylinder between two anchor points. The resulting scaffold‑free tissue displayed aligned, small‑diameter collagen fibrils, abundant cells, excess noncollagenous ECM, and a stress–strain response resembling immature tendons with an ultimate tensile strength of ~2 MPa, indicating the first viable engineered tendons without scaffolding.

Abstract

Surgical tendon repair is limited by the availability of viable tissue for transplantation. Because of its relatively avascular nature, tendon is a prime candidate for engineered tissue replacement. To address this problem, cells isolated from rat Achilles tendon were grown to confluence in culture and allowed to self-assemble into a cylinder between two anchor points. The resulting scaffold-free tissue was composed of aligned, small-diameter collagen fibrils, a large number of cells, and an excess of noncollagenous extracellular matrix; all characteristics of embryonic tendon. The stress–strain response of the constructs also resembles the nonlinear behavior of immature tendons, and the ultimate tensile strength is approximately equal to that of embryonic chick tendon, roughly 2 MPa. These physical and mechanical properties indicate that these constructs are the first viable tendons engineered in vitro, without the aid of artificial scaffolding.