Transplantation of isolated chondrocytes.

Intramuscular transplantation of isolated syngeneic chondrocytes from hyaline and elastic cartilage results in formation of cartilage with various degrees of similarity to the original tissue. Cells from cartilage with a simple structure, such as nasal septal cartilage, form islands of tissue with flattened chondrocytes at the periphery and more rounded ones in the center. Chondrocytes from auricular (elastic) cartilage taken from young animals produce islands of tissue with an arrangement of cells and fibers similar to that of the material used for isolation of chondrocytes. Cartilage produced by elastic chondrocytes from older animals has an irregular arrangement of cells and contains fewer elastic fibers than cartilage produced by chondrocytes of corresponding age in situ. Chondrocytes from epiphyseal cartilage produce tissue with an irregular arrangement of cells, but nevertheless, are treated with endochondral ossification. Transplants of allogeneic chondrocytes evoke a strong immune response in the recipient. Such chondrocytes produce cartilage that is surrounded and slowly resorbed by infiltrating cells and does not ossify. Short-term immunosuppression (procarbazine and antithymocyte serum) prevents rejection of such cartilage and allows endochondral ossification.