Application of shear flow stress to chondrocytes or chondrocyte stem

Abstract

Mammalian cells capable of producing cartilage are cultured under a shear flow stress of about 1 to about 100 dynes/cm.sup.2 to produce artificial cartilage for surgical transplantation to replace damaged or missing cartilage. Shear flow stressed cells display enhanced maintenance of chondrocyte phenotype and produce an extracellular matrix containing an enhanced ratio of type II collagen to type I collagen. The cells may be chondrocytes, chondrocyte stem cells or cells such as myoblasts or fibroblasts that transdifferentiate into chondrocytes. A bioreactor is used containing a growth chamber having a substrate on which the cells capable of producing cartilage are attached, and means for applying relative movement between a liquid culture medium and the substrate to provide the shear flow stress. The substrate may be a scaffold, or a nonporous surface such as the surface of a rotatable drum or disc, or the surface of a static plate that supports cell growth in a monolayer. Cartilage is produced by covering the substrate with a liquid growth medium, inoculating into the medium cells capable of producing cartilage, allowing the cells to attach to the substrate, applying and maintaining relative movement between the growth medium and the cells to provide the shear flow stress to produce shear flow stressed cells, and culturing the shear flow stressed cells to produce cartilage.