Mechanical characterization of matrix-induced autologous chondrocyte implantation (MACI®) grafts in an equine model at 53 weeks

Abstract

There has been much interest in using autologous chondrocytes in combination with scaffold materials to aid in cartilage repair. In the present study, a total of 27 animals were used to compare the performance of matrix-assisted chondrocyte implantation (MACI®) using a collagen sponge as a chondrocyte delivery vehicle, the sponge membrane alone, and empty controls. A total of three distinct types of mechanical analyses were performed on repaired cartilage harvested from horses after 53 weeks of implantation: (1) compressive behavior of samples to measure aggregate modulus (HA) and hydraulic permeability (k) in confined compression; (2) local and global shear modulus using confocal strain mapping; and (3) boundary friction coefficient using a custom-built tribometer. Cartilage defects receiving MACI® implants had equilibrium modulus values that were 70% of normal cartilage, and were not statistically different than normal tissue. Defects filled with Maix™ membrane alone or left empty were only 46% and 51-63% of control, respectively. The shear modulus of tissue from all groups of cartilage defects were between 4 and 10 times lower than control tissue, and range from 0.2 to 0.4 MPa. The average values of boundary mode friction coefficients of control tissue from all groups ranged from 0.42 to 0.52. This study represents an extensive characterization of the mechanical performance of the MACI® grafts implant in a large animal model at 53 weeks. Collectively, these data demonstrate a range of implant performance, revealing similar compressive and frictional properties to native tissue, with inferior shear properties.

Mechanical properties and structure‐function relationships of human chondrocyte‐seeded cartilage constructs after in vitro culture

“…In this study, we showed improvement in the compressive and frictional properties of the constructs but no change in the shear properties. While a few studies have characterized the frictional and shear properties of tissue engineered articular cartilage constructs cultured with bovine or porcine cells, this study is the first to perform such analysis on human chondrocyte‐seeded implants. Additionally, only a few previous studies have characterized the compressive properties of human chondrocyte seeded implants .…”

Hyaline Articular Matrix Formed by Dynamic Self-Regenerating Cartilage and Hydrogels

“…Methods for analysis of the compressive properties of constructs in the murine model were based on those described previously [25]. Full thickness cylindrical plugs (3 mm diameter) were harvested from the constructs using a biopsy punch (Miltex, York, PA) applied perpendicular to the articular surface (n = 4-9…”

Mechanical properties and structure–function relationships in articular cartilage repaired using IGF‐I gene‐enhanced chondrocytes

“…IGF‐I transfection increased aggrecan and type II collagen content in cartilage repair and improved integration with surrounding cartilage matrix . Many studies have shown the benefits of grafts using autologous chondrocytes, but few have analyzed the mechanical properties of the repaired tissue . Particularly, there is little to no mechanical data on the restorative effects of IGF‐I in ACI grafts in a large animal model.…”