The human auricular chondrocyte. Responses to growth factors

The first human auricular (elastic cartilage) chondrocyte cell culture model is presented. These chondrocytes, harvested from fresh human cadaver auricular cartilage, are easily grown in culture. They produce type II collagen and abundant alkaline phosphatase. Like growth plate chondrocytes, human auricular chondrocytes respond mitogenically to both transforming growth factor-beta and basic fibroblast growth factor by increasing proliferation twofold. The growth factors exert a synergistic effect on thymidine uptake in this model, with maximal stimulation occurring at the dose combination of basic fibroblast growth factor, 10 ng/mL, and transforming growth factor-beta, 3 ng/mL. Human nasal septal (hyaline cartilage) chondrocytes do not increase proliferation in response to these two growth factors. Human auricular chondrocytes also increase matrix production in response to transforming growth factor-beta, as indicated by increased proteoglycan production and increased collagen synthesis. The increased matrix production combined with increased proliferative rate elicited with transforming growth factor-beta and basic fibroblast growth factor indicates that human elastic cartilage chondrocytes harvested from the external ear are better suited for in vitro cartilage implant growth than human hyaline cartilage chondrocytes. Further biochemical and molecular biological characterization of the human auricular chondrocyte cell culture model is currently under way. Additional work is also under way to generate multilayer culture growth on absorbable frameworks, in the pursuit of the long-term goal of in vitro production of autogenous cartilage implants.