Phenotype and biological activity of neonatal equine chondrocytes cultured in a three-dimensional fibrin matrix.

Equine neonatal chondrocytes were cultured in three-dimensional fibrin matrices under conditions of immediate implantation or implantation following monolayer culture for 6 days, and 3 cell concentrations (1 x 10(5), 1 x 10(6), and 5 x 10(6) chondrocytes/cm3). Equine fibrinogen was collected by cryoprecipitation and polymerized by use of activated bovine thrombin. The fibrin implants were harvested and analyzed histologically and biochemically at 3, 7, and 14 days after the chondrocytes were implanted in fibrin. The differentiation ratio (ratio of rounded, chondrocyte-like cells to stellate, fibroblast-like cells) was statistically higher for implants that received 5 x 10(6) precultured cells at all time periods than for implants that received 1 x 10(5) or 1 x 10(6) precultured cells. The differentiation ratio was statistically higher for implants that received 5 x 10(6) immediately implanted cells than for other implants at 7 days after implantation. At 14 days, implants that received 5 x 10(6) precultured chondrocytes had a higher differentiation ratio than did implants that received 5 x 10(6) chondrocytes that had not been precultured. Among implants that received precultured chondrocytes, total glycosaminoglycan and chondroitin sulfate content was lowest for implants that received only 1 x 10(5) cells. Among implants that received chondrocytes that had not been precultured, glycosaminoglycan content was not significantly different among the 3 cell concentrations, and chondroitin sulfate content was different only between implants that received 5 x 10(6) vs 1 x 10(6) cells. Only after the longest incubation period and at the highest cell concentration studied did preculturing of chondrocytes improve maintenance of phenotype. Preculturing did not appear to influence proteoglycan synthesis.