RELATIONSHIP BETWEEN CELL FUNCTION AND INITIAL CELL SEEDING DENSITY OF PRIMARY PORCINE CHONDROCYTES IN VITRO

Maintenance of differentiated functional phenotype within in vitro chondrocyte culture requires seeding at high densities with large numbers of cells. However, optimal cell seeding numbers and densities remain elusive due to multiple varying parameters and different methodologies utilized in previous studies. In the current study, we tried to investigate the relationship between cell seeding number and differentiated functional phenotype of in vitro cultured chondrocytes. Varying numbers of primary porcine chondrocytes (0.25, 2.5, 25 and 250 K) were seeded in 96 well-plates and cultured for 4 weeks. Cell proliferation, glycosaminoglycan (GAG) production and gene expression levels of Sox9, aggrecan, COL II and COL I were evaluated. The results showed that GAG content was high in the 0.25 and 25K groups, gene expression of Sox9 was high in the 2.5, 25 and 250K groups and expression of COL II was high in the 25K group, whereas expression of COL I was low in the 0.25, 25 and 250K groups. It is concluded that the seeding number and density of the 25K (78K cells/cm(2)) group achieved the optimal balance between functional phenotype of individual cells and the total ECM production for in vitro cultured chondrocytes.