[Transplantation of in vitro cultured cartilage materials: characterization of matrix synthesis]

Recently a three-dimensional model for the formation of cartilage in vitro was developed. The aim of this study was to investigate the amount and quality of newly synthesized matrix after graftig in vitro engineered cartilage into athymic nude mice.

Group I received transplants consisting of human chondrocytes, agarose, and E 200 (a bioabsorbable polymer fleece that offers mechanical stability. Ethicon Inc). Group II received chondrocytes and agarose only. At intervals of six, 12, and 24 weeks after subcutaneous transplantation we used azan blue staining and antibodies against collagen type I, collagen type II, and chondroitin-4sulfate to characterize the matrix synthesis. A quantitative analysis was performed using the computer image analyzing software photoshop (Adobe Inc).

In group I, the amounts of newly synthesized cartilage specific collagen type II and chondroitin-4 sulfate increased progressively. Twenty-four weeks after transplantation, these amounts were comparable to the original human cartilage from which the chondrocytes were derived. Collagen type I was detected only in small quantities in the periphery of the transplants. Gross examination revealed sufficient mechanical stability and unremarkable changes in size and form. In contrast to this, group II transplants showed markedly smaller amounts of cartilage specific matrix components as collagen type II and chondroitin-4 sulfate and at the same time greater amounts of collagen type I. It was found both in the periphery and in central parts of the transplants. There was a remarkable loss of volume in all transplants and mechanical stability was poor.

The absorbable cell carrier E 200 not only offers mechanical stability to in vitro engineered cartilage but also had a positive effect on the development of cartilage in our experiments. In conclusion, in vitro engineered cartilage is a promising pathway for the replacement of cartilage defects.