In vitro characterization of porcine juvenile articular cartilage
Lamar, C.H.; Eller, L.L.; Turek, J.J.
American Journal of Veterinary Research 48(3): 515-518
1987
ISSN/ISBN: 0002-9645 PMID: 3565908 Document Number: 304979
Dispersed cell cultures were established from the articular cartilage of the proximal portion of the humerus of young pigs. Articular and epiphyseal portions of the cartilage were separated, minced, and enzymatically dispersed, using bacterial collagenase. Morphologically, 2 cell types were observed, using phase-contrast microsocpy. Smaller polygonal cells (32.5 .+-. 3.5 .mu.m diameter) containing cytoplasmic granules were found in both areas of the cartilage. In cultures from the articular region, cells grew as monolayer cultures and initially did not demonstrate contact inhibition. In cultures from the epiphyseal region, cells grew in a multilayered manner in a colonial arrangement with cells being released from the center of the colony into the culture medium. Small granular particles (0.03 to 0.08 .mu.m diameter) were secreted by cells in both culture systems. Particle secretion was greater in epiphyseal cultures than in articular cultures with the rate decreasin gas confluency was approached. These particles stained positively for lipid and alkaline phosphatase. Acridine orange was also incorporated into the granules. The 2nd cell type, a stellate-shaped cell (60 .+-. 7.6 .mu.m diameter), was found mainly surrounding the outside of colonial areas in epiphyseal cultures. These cells did not secrete small granular particles and stained positive for factor VIII. Evaluation of cultures by scanning and transmission electron microscopy further supported the presence of 2 cell types. With scanning electron microsopy, the smaller polygonal cell was characterized by varying sizes of blebs (0.03 to 0.1 .mu.m diameter) associated with the cell membrane and small cytoplasmic processes projecting from the cell's surface. Stellate-shaped cells presented a smooth-appearing cell surface. Using transmission electron microscopy, smaller cells were shown to contain a nonmembrane-bound, finely granular-to-amorphous cytoplasmic material reacting positively for proteoglycans. Blebs seen with a scanning electron microscope contained small vesicles (0.07 to 0.2 .mu.m diameter). Ultrastructural evaluation of vesicles isolated from the culture medium by ultracentrifugation revealed particles morphologically similar to matrix vesicles.