Investigation of Collagen Transplants Seeded with Human Autologous Chondrocytes at the Time of Transplantation

OBJECTIVE The treatment of cartilage defects with matrix-embedded autologous chondrocytes is a promising method to support the repair process. In this study we gathered quality parameters of collagen I matrices and embedded autologous chondrocytes at the time of transplantation We determined number, morphology, and distribution of matrix-embedded chondrocytes as well as their synthesis performance concerning sulphated glycosaminoglycans (sGAG) and collagen 1A1 and 2A1 mRNA levels. RESULTS Chondrocytes were equidistantly distributed in the collagen matrices, and cell numbers ranged from 6 to 34 × 10(4) cells/g wet weight. Significant amounts of sGAG were detected in all of the investigated transplants but did not correlate with the number of cells within the respective transplants. Moreover, collagen I mRNA levels exceeded that of collagen II up to 17-fold. Collagen I and II ratio and sGAG amounts indicated significant interindividual differences of chondrocytes. The variation of transplant-associated sGAG levels could be attributed to the differential biosynthesis performance of chondrocytes. CONCLUSIONS These results confirm the vitality and the chondrocytic phenotype of matrix-embedded cells (CaRes(®)) with respect to sGAG synthesis. However, chondrocytes showed collagen I mRNA expression partially far exceeding that of collagen II, indicating a rather dedifferentiated cellular status. In addition, sGAG synthesis performance of different patients' chondrocytes varied significantly. Nevertheless, a 2-year clinical study of chondrocyte-seeded collagen matrices as investigated in this work delivered promising results. However, future studies are planned to determine markers for the regenerative potential of donor chondrocytes.