Mechanical properties of a hierarchical electrospun scaffold for ovine anterior cruciate ligament replacement

Abstract

The anterior cruciate ligament (ACL) acts to stabilize the knee and prevent excessive motion of the tibia relative to the femur. Tears of the ACL are common and can result in pain and damage to surrounding tissues. Thus a torn ACL is often surgically replaced with an autograft or allograft material. Drawbacks to clinically available ACL grafts motivate the development of a tissue engineered ACL replacement. Our group has previously developed a polycaprolactone electrospun scaffold that mimics the hierarchical structure of the ACL. The goal of this study was to investigate the mechanical properties of the electrospun scaffold as an ACL replacement. Scaffold mechanical properties were assessed prior to implantation via stress relaxation and pull to failure testing. Following in vitro characterization, electrospun scaffolds and soft tissue grafts were implanted into ovine cadaver stifle joints as ACL replacements. Stifle joints with ACL replacements were tested via a simulated anterior drawer test as well as in situ stress relaxation and pull to failure tests and compared to stifle joints with the native ACL intact. Prior to implantation the scaffold matched the native ovine ACL well in the range of functional strains as evidenced by stress relaxation measures and the toe region stiffness. After implantation the scaffold was more similar to the native ACL than the soft tissue graft, particularly when it came to reducing joint laxity and matching stress relaxation measures. These results demonstrate that the electrospun scaffold has the potential to be a suitable material for ACL replacement. ß

Electrospinning of highly porous yet mechanically functional microfibrillar scaffolds at the human scale for ligament and tendon tissue engineering

“…Nevertheless, it has been demonstrated that electrospun PCL scaffolds are sufficiently mechanically robust to withstand in ex vivo models [54]. PLGA, PLLA, and PCL are among the most common synthetic biodegradable polymers (poly(α-hydroxy esters)) investigated for TE and have previously been used in certain FDA (US Food and Drug Administration) approved biomedical and drug-delivery devices [55,56].…”

3D printed mesh reinforcements enhance the mechanical properties of electrospun scaffolds

“…Substantial research is currently focused on the potential utility of electrospun scaffolds for clinical applications including the repair of diaphragm [1], bladder [2][3][4], and ligaments [5][6][7][8], as well as grafting procedures for bone [5,9], skin [10][11][12], and vascular [13,14] tissue. Electrospun scaffolds provide a 3-dimensional fibrous matrix with interconnecting pores, a feature that mimics the native extracellular matrix (ECM).…”

“…Other synthetic polymers used in electrospinning include poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) [22], poly (vinylidene fluoride) (PVD) [23], and poly (lactic acid) (PLA) [24]. While composite materials (e.g., PCL/collagen mixtures) are typically stronger than scaffolds composed solely of natural matrix molecules, the tensile strength of these composites rarely approaches the mechanical strength of tissues such as bone or tendon [8,12]. For many regenerative therapies, it is thought that the mechanical properties of an implanted scaffold should match that of the target tissue [25].…”

Biodegradable engineered fiber scaffolds fabricated by electrospinning for periodontal tissue regeneration

“…Poly (e-caprolactone) (PCL) is a semi-crystalline, hydrophobic, biodegradable polymer with satisfactory mechanical properties 41 and certificated by FDA. Compared with other polymers, PCL has more outstanding elastic property but lower tensile strength, making it a very good elastic biomaterial.…”