Culture of chondrocytes in alginate beads

A classic method for the encapsulation and culture of chondrocytes in alginate beads is described. Chondrocytes are released from cartilage matrix by collagenase/dispase digestion and mixed with a solution of 1.25% alginic acid until a homogenous suspension is obtained. The suspension is drawn into a syringe and pushed gently through a needle, so that drops fall into a solution of calcium chloride. Beads form instantaneously and further polymerize after 5 min in the calcium chloride solution. Chondrocytes from any species, including human osteoarthritic chondrocytes, can be cultured with this technique. Under these conditions, chondrocytes maintain a high degree of differentiation. Beads can be dissolved by chelation of calcium with EDTA. In this way, chondrocytes can be recovered and further separated from the matrix by centrifugation. Almost all molecular and biochemical techniques, as well as a number of biological assays, are compatible with the culture of chondrocytes in alginate.