The overall experimental design. In brief, bovine meniscus cells were expanded through four passages in monolayer culture; 0.5 × 106 cells were expanded in a T-75 flask to confluence. At each passage time point, 0.2 × 106 cells were collected for RT-PCR, and 0.2 × 106 cells were plated on an aggrecan or collagen I two-dimensional surface coating or on a no coating control for 24 hours and then subsequently processed for RT-PCR. The gene expression profiles with passage and on the different protein coatings were then determined. n = 6 was used for all gene expression abundance evaluations.