Hypothermic storage and cryopreservation of cartilage. An experimental study

Osteochondral autografts of femoral condyles in dogs were frozen at different cooling velocities after exposure to either glycerol or dimethyl sulfoxide to determine the freezing regimen best suited for preservation of intact cartilage. Autografts were also subjected to hypothermic storage in tissue culture media for ascertainment of how long they can be stored under these conditions. Autografts maintained in vitro under various conditions of storage were examined after transplantation. Autografts were chosen for this portion of the investigation in order to study the effects of storage uncomplicated by immunologic interactions. No differences were found between the cryoprotective actions of glycerol and dimethyl sulfoxide. The freezing rate that produced the least damage in the cartilage was 2 degrees/min. Cartilage survived ten days of hypothermic storage in tissue culture medium. Allografts frozen by the standard method of glycerolization and cooling at 1 degree/min were also studied. These showed eventual loss of chondrocytes and conversion of hyaline cartilage to fibrocartilage.