As a result of the low yield of cartilage from primary patient harvests and a high demand for autologous cartilage for reconstructive surgery and structural repair, primary explant cartilage must be augmented by tissue engineering techniques. In this study, chondrocytes seeded on PLLA/PGA scaffolds in static culture and a direct perfusion bioreactor were biochemically and histologically analyzed to determine the effects of fluid flow and media pH on matrix assembly. A gradual media pH change was maintained in the bioreactor within 7.4-6.96 over 2 weeks compared to a more rapid decrease from 7.4 to 6.58 in static culture over 3 days. Seeded scaffolds subjected to 1 microm/s flow demonstrated a 118% increase (p < 0.05) in DNA content, a 184% increase (p < 0.05) in GAG content, and a 155% (p < 0.05) increase in hydroxyproline content compared to static culture. Distinct differences were noted in tissue morphology, including more intense staining for proteoglycans by safranin-O and alignment of cells in the direction of media flow. Culture of chondrocyte seeded matrices thus offers the possibility of rapid in vitro expansion of donor cartilage for the repair of structural defects, tracheal injury, and vascularized tissue damage.

The objective of this study was to determine the effects of scaffold composition on the physical properties, adhesion, and growth of bovine articular chondrocytes on polylactic acid (PLA)/polyglycolic acid (PGA) composites. Nonwoven meshes of PGA were coated with PLA, using a solvent evaporation technique that resulted in composites with fractional PLA contents ranging from 0 to 68%. The compressive modulus of scaffolds increased linearly with the addition of PLA, ranging from less than 1 kPa for PGA to approximately 20 kPa for scaffolds with 68% PLA content. The characteristic degradation time of these scaffolds also increased from approximately 5 days for 0% PLA to 45 days for 68% PLA. Addition of PLA decreased cell seeding efficiency from 48% for 0% PLA scaffolds to 27% for 68% PLA scaffolds. Cells seeded onto 27% PLA scaffolds increased 3-fold in number over 4 weeks in culture, whereas cells seeded onto 68% PLA increased only 2-fold in number. Scanning electron microscopy indicated that cells attached to PGA appeared flat with many small processes, whereas those attached to PLA were more rounded. These studies provide important information for the design of scaffolds for cartilage tissue engineering.