D. S. Kaplan1 , V. M. Hitchins1 , P. V. Phan2 , R. Y. Au2 , M. W. Hungerford3 , C. G. Frondoza3 , 1CDRH, FDA, Rockville, MD 20850, 2Nutramax Laboratories, Edgewood, MD, 3Johns Hopkins Univ., Dept. Orthopaedic Surgery, Good Samaritan Hosp., Baltimore, MD
A critical obstacle in the use of cell-based therapies is the limited number of chondrocytes available to repair cartilage defects. Chondrocytes isolated from the extracellular matrix of cartilage and propagated in monolayer culture dedifferentiate into a fibroblastic phenotype. These cells shift from producing type II to type I collagen and shift from producing high molecular weight (MW) aggrecan to low MW proteoglycans. Analysis of growth characteristics and phenotype changes at the gene level may help identify tissue culture conditions favoring proliferation and maintenance of chondrocyte cellular functions. In the present study human chondrocytes derived from three cell lines were seeded and propagated on natural polymers as scaffolds and the propagated chondrocytes were evaluated for type II collagen and aggrecan production.
Articular chondrocyteswere grown on 1) control polystyrene (PS) tissue culture flasks, 2) type I collagen, and 3) alginate gels. Cells growing on both PS and collagen gels appeared refractile with well defined morphology, and all cells remained 100% viable. In contrast, chondrocytes seeded on the alginate gel were sparsely distributed throughout the scaffold and did not appear as healthy as cells cultured on PS and collagen. Evaluation of phenotypic markers using reverse transcriptase polymerase chain reaction showed that all three lines expressed a fibroblastic phenotype, characterized by expression of type I collagen. Aggrecan expression patterns varied according to the cell line.
The present study demonstrates that these two natural scaffold materials, type I collagen and alginate gels, did not consistently enhance retention of the chondrocyte phenotype.
Acknowledgements: Supported by the FDA Office of Science and Health Coordination and the Good Samaritan Hospital.