Behavior of Adult Canine Annulus Fibrosus Cells in Collagen-gag Scaffolds Whencultured in a Rotating Wall Bioreactor

INTRODUCTION: Annulus fibrosus (AF) cell-seeded collagenglycosaminoglycan (CG) scaffolds could be of benefit as implants to facilitate reparative processes following discectomy. In part this work parallels other studies [1] that have demonstrated that articular chondrocyte-seeded type II CG scaffolds induced a greater amount of reparative tissue in cartilage defects than implantation of the CG matrix or cells alone. Better results were achieved when the cell-seeded constructs were cultured for a long enough period prior to implantation for newly synthesized matrix to accumulate in the scaffold. Prior work has shown that the rate of matrix synthesis of cells in certain systems can be significantly increased by culturing the constructs in a rotating wall “bioreactor” [2]. Such culture reactors randomize the gravity vector allowing for suspension of cultured substrates while reducing the shear stress applied. The successful use of this apparatus for other types of cell-seeded scaffolds [3] prompted this study. The objective was to evaluate the biosynthetic behavior of AF-seeded type II CG scaffolds cultured in this type of bioreactor for comparison with conventional static culture. While the AF is principally type I collagen, prior work has shown certain benefits of growing AF cells in a type II CG matrix [4].