Chondrocyte extraction, proliferation, and characterization for construct development

To date, many efforts to engineer cartilage have focused on matrix construc tion with the goal of producing a durable construct as cartilage replaces t he resorbing matrix. However, the importance of matrix construction is at l east matched by the challenge of efficient chondrocyte extraction, culture expansion, and prevention of dedifferentiation. This challenge is underscor ed by the large number of chondrocytes needed for a clinically significant construct such as an ear, Because human rib provides a large, readily avail able source of hyaline cartilage, the authors evaluated human rib chondrocy te extraction and found that maximum viable cell yield occurred after a 6-h our digestion. They also evaluated human microtic auricular remnant chondro cyte extraction and identified fibroblast contamination as a shortcoming of this potential source of chondrocytes. Initially, rib chondrocytes prolife rated in vitro with a doubling time of approximately 1 week. As the cells w ere passaged, proliferation decreased such that the cells stopped prolifera ting and adopted a large, spindle-shaped morphology by passage 6. Interesti ngly, no increase in proliferation was noted when rib chondrocytes were sti mulated with transforming growth factor beta 1, bone morphogenetic protein 2, and basic fibroblast growth factor. The major obstacles to the use of au tologous rib chondrocytes in matrix construction are the low cell yield fro m a small piece of rib and the limited proliferation that these cells wilt undergo in vitro. Further investigation of culture systems and mitogenic cy tokines may help resolve these limitations.