Influence of species and anatomical location on chondrocyte expansion

Background: Bovine articular cartilage is often used to study chondrocytes in vitro. It is difficult to correlate in vitro studies using bovine chondrocytes with in vivo studies using other species such as rabbits and sheep. The aim of this investigation was to study the effect of species, anatomical location and exogenous growth factors on chondrocyte proliferation in vitro. Methods: Equine (EQ), bovine (BO) and ovine (OV) articular chondrocytes from metacarpophalangeal ( fetlock ( F)), shoulder ( S) and knee ( K) joints were cultured in tissue culture flasks. Growth factors (rh-FGFb: 10 ng/ml; rh-TGF : 5 ng/ml) were added to the cultures at days 2 and 4. On day 6, cells were counted and flow cytometry analysis was performed to determine cell size and granularity. A three factor ANOVA with paired Tukey's correction was used for statistical analysis. Results: After 6 days in culture, cell numbers had increased in control groups of EQ-F, OV-S, OVF and BO-F chondrocytes. The addition of rh-FGFb led to the highest increase in cell numbers in the BO-F, followed by EQ-F and OV-S chondrocytes. The addition of rh-TGF increased cell numbers in EQ-S and EQ-F chondrocytes, but showed nearly no effect on EQ-K, OV-K, OV-S, OVF and BO-F chondrocytes. There was an overall difference with the addition of growth factors between the different species and joints. Conclusion: Different proliferation profiles of chondrocytes from the various joints were found. Therefore, we recommend performing in vitro studies using the species and site where subsequent in vivo studies are planned.