Composition of cartilagenous tissue with mineralized and non-mineralized zones formed in vitro.

We have previously shown that cartilagenous tissue with both non-mineralized and mineralized zones can be formed by chondrocytes which have been selectively isolated from the deep zone of bovine articular cartilage. In this study, we quantitate proteoglycan and collagen content, calcification, tissue thickness and cellularity over a 10 week culture period in order to study matrix accumulation and tissue formation. The cartilagenous tissue cellularity and proteoglycan and collagen accumulation continued up to 8 weeks and this was paralleled by an increase in tissue thickness. The amount of mineral in the tissue as well as the amount of collagen, in contrast to proteoglycan, was still increasing at 10 weeks. At the end of week 10, the amount of glycosaminoglycan and collagen as a percentage of dry weight of the tissue were 11.0 +/- 0.6% and 14.8 +/- 0.1%, respectively, compared with 10.5 +/- 1.2% and 35.1 +/- 5.8% for the in vitro deep articular cartilage. The amount of calcium as a percentage of dry weight of the cartilagenous tissue was 8.1 +/- 0.7% which was similar to the in vivo cartilage (9.1 +/- 1.6%). This data suggests that 8 weeks of culture may be necessary before the cartilagenous tissue is suitable for use as a transplant.