Developing an articular cartilage decellularization process toward facet joint cartilage replacement

Abstract

Objective: The facet joint has been identified as a significant source of morbidity in lower back pain. In general, treatments have focused on reducing the pain associated with facet joint osteoarthritis, and no treatments have targeted the development of a replacement tissue for arthritic facet articular cartilage. Therefore, the objective of this study was to develop a nonimmunogenic decellularized articular cartilage replacement tissue while maintaining functional properties similar to native facet cartilage tissue.

Methods: In vitro testing was performed on bovine articular cartilage explants. The effects of 2% sodium dodecyl sulfate (SDS), a detergent used for cell and nuclear membrane solubilization, on cartilage cellularity, biochemical, and biomechanical properties, were examined. Compressive biomechanical properties were determined using creep indentation, and the tensile biomechanical properties were obtained with uniaxial tensile testing. Biochemical assessment involved determination of the DNA content, glycosaminoglycan (GAG) content, and collagen content. Histological examination included hematoxylin and eosin staining for tissue cellularity, as well as staining for collagen and GAG.

Results: Treatment with 2% SDS for 2 hours maintained the compressive and tensile biomechanical properties, as well as the GAG and collagen content while resulting in a decrease in cell nuclei and a 4% decrease in DNA content. Additionally, treatment for 8 hours resulted in complete histological decellularization and a 40% decrease in DNA content while maintaining collagen content and tensile properties. However, a significant decrease in compressive properties and GAG content was observed. Similar results were observed with 4 hours of treatment, although the decrease in DNA content was not as great as with 8 hours of treatment.

Conclusion: Treatment with 2% SDS for 8 hours resulted in complete histological decellularization with decreased mechanical properties, whereas treatment for 2 hours maintained mechanical properties, but had a minimal effect on DNA content. Therefore, future studies must be performed to optimize a treatment for decellularization while maintaining mechanical properties close to those of facet joint cartilage. This study served as a step in creating a decellularized articular cartilage replacement tissue that could be used as a treatment for facet cartilage osteoarthritis.

Fig. 1

Gross morphological properties of (a) lumbar spine prior to dissection, (b) superior facet surfaces following dissection, (c) 3 mm sample for compressive testing, and (d) dog-bone shaped sample for tensile testing.

Fig. 2

Histological staining, representative of both lumbar spine levels. 10x original magnification. (a) Picrosirius red and (b) safranin-O staining demonstrate extensive production of collagen and GAG, respectively. (c) H&E stain.

Fig. 3

Tissue cellularity per mg of tissue.

Fig. 4

Collagen content per mg of tissue.

Fig. 5

GAG content per mg of tissue.

Fig. 6

Facet cartilage compressive properties.

Fig. 7

Facet cartilage tensile properties. (a) Young’s modulus and (b) ultimate tensile strength.