AN IN-VITRO MODEL FOR ABNORMAL SKELETAL DEVELOPMENT IN THE LYSOSOMAL STORAGE DISEASES

Lysosomal storage diseases such as G(M1)-gangliosidosis are associated with skeletal abnormalities. Radiological and histological studies, b oth in human and corresponding animal models, indicate retarded bone f ormation. Since cartilage maturation leads to bone formation, we devel oped an in vitro system to study and compare the biological features o f cartilage from dogs affected with G(M1)-gangliosidosis with age-matc hed controls. Costochondral chondrocytes were grown in monolayer and i n agarose culture. Both affected and control cells dedifferentiated in monolayer; however, in agarose culture they re-expressed the chondroc ytic phenotype. Cells from affected dogs were enlarged and contained n umerous large vacuoles when compared with control cells. This morpholo gy was similar to that seen in vivo. In addition, the affected cells a ppeared to have a reduction in mitosis and alcian blue staining proteo glycans. Cultures from affected animals contained fewer cells positive for alkaline phosphatase activity. Both affected and control cells ex pressed collagen types I and II and were positive for the lectin Ricin us communis agglutinin-I. However, the staining of the control culture for type II collagen was more prominent than in the affected cells. T hese findings suggest that culture of chondrocytes in agarose may be a useful method for studying the biology of cartilage which leads to sk eletal abnormalities in lyse somal storage diseases.