A semi‐degradable composite scaffold for articular cartilage defects

Abstract

Few options exist to replace or repair damaged articular cartilage. The optimal solution that has been suggested is a scaffold that can carry load and integrate with surrounding tissues; but such a construct has thus far been elusive. The objectives of this study were to manufacture and characterize a non-degradable hydrated scaffold. Our hypothesis was that the polymer content of the scaffold can be used to control its mechanical properties, while an internal porous network augmented with biological agents can facilitate integration with the host tissue. Using a two-step water-in-oil emulsion process a porous poly-vinyl alcohol (PVA) hydrogel scaffold combined with alginate microspheres was manufactured. The scaffold had a porosity of 11–30% with pore diameters of 107–187 μm, which readily allowed for movement of cells through the scaffold. Alginate microparticles were evenly distributed through the scaffold and allowed for the slow release of biological factors. The elastic modulus (Es) and Poisson’s ratio (υ), Aggregate modulus (Ha) and dynamic modulus (ED) of the scaffold were significantly affected by % PVA, as it varied from 10% to 20% wt/vol. Es and υ were similar to that of articular cartilage for both polymer concentrations, while Ha and ED were similar to that of cartilage only at 20% PVA. The ability to control scaffold mechanical properties, while facilitating cellular migration suggest that this scaffold is a potentially viable candidate for the functional replacement of cartilage defects.

A Novel Macroporous Polyvinyl Alcohol Scaffold Promotes Chondrocyte Migration and Interface Formation in anIn VitroCartilage Defect Model

“…To achieve these goals we developed a nonbiodegradable porous hydrogel (polyvinyl alcohol [PVA]) scaffold, the composition of which is stable over time and whose mechanical properties can be varied by changing the PVA polymer content. 16,17 The use of a nonbiodegradable porous hydrogel scaffold for cartilage repair may provide initial properties similar to the native cartilage extracellular matrix (ECM) while allowing for tissue ingrowth to facilitate long-term stability, function, and integration. In orthopedic applications, this concept is embodied in the use of porous metal scaffolds for bone repair.…”

Experimental method to characterize the strain dependent permeability of tissue engineering scaffolds

“…Each swelled scaffold was cut with a 8 mm diameter punch and the thickness was sized to 3 mm using a custom made cutting tool. The equilibrium Young modulus of hydrated scaffolds were determined through applying successive compressive strains (10%, 15% and 20%) with the Instron uniaxial testing machine (Instron E3000, Norwood, Massachusetts, USA) as described elsewhere (Scholten et al, 2011). Unconfined stress relaxation tests of 20% strain were also performed for fine and coarse pore size scaffolds at 50 mm/s and 5 mm/s compression rates as schematically depicted in Fig.…”

“…For this, a thick cylindrical sealant (3.5 mm thickness, 7 mm internal and 15 mm outer diameter) was designed to guarantee the sample seal while maintaining a uniform deformation. It was made of a silicon rubber (Elastosoil M4601, Wacker Chemie, Munich, Germany) and we obtained its equilibrium Young modulus by sequential compressive strains of 5%, 10%, 15% and 20% considering stress relaxation after each step (Scholten et al, 2011). The pre-strain resulting in required sealing force to prevent any leakage under the applied experimental conditions was evaluated using Hooke's law and Lamé's equations for thick walled cylinders.…”

Biomaterials for Cartilage Tissue Engineering

“…Fibrin-PLGA Chondrocytes In vitro [45] Collagen-PLC Chondrocytes In vivo [46] Alginate/PVA Chondrocytes In vitro [47] Collagen/PEG Human mesenchymal stem cells…”