Articular cartilage covers the bones in the major joints of the human body, e.g.knee and hip joints. It is composed of only one specialized cell type, Chondrocytes. Chondrocytes produce and maintain the extracellular matrix of cartilage, i.e. collagen (mostly type II) and proteoglycans. The isolated, differentiated cells express collagen type II; however, during prolonged in vitro cultivation, dedifferentiation begins and collagen type II expression declines. Creative Bioarray Human Chondrocytes (HCH) are produced at Creative Bioarray's cell culture facility and are available from knee and hip joint cartilage tissue. Shortly after isolation, all Creative Bioarray Human Chondrocytes are cryopreserved at passage 2 (P2) using Creative Bioarray's proprietary, serum-free freezing medium,Cryo-SFM. Each cryo vial contains more than 500,000 viable cells after thawing. Proliferating cell cultures are made from 500,000 cryopreserved cells that have been thawed and cultured for three days at Creative Bioarray.