Effect of growth factors on cell proliferation, matrix deposition, and morphology of human nasal septal chondrocytes cultured in monolayer

Objectives: Tissue engineering of septal cartilage provides ex vivo growth of cartilage from a patient's own septal chondrocytes for use in craniofacial reconstruction. To become clinically applicable, it is necessary to rapidly expand a limited population of donor chondrocytes and then stimulate the production of extracellular matrix on a biocompatible scaffold. The objective of this study was to determine favorable serum-free culture conditions for proliferation of human septal chondrocytes using various concentrations and combinations of four growth factors. Study Design: Prospective, randomized, controlled study. Methods: Nasal septal chondrocytes from six patient donors were isolated by enzymatic digestion and expanded in monolayer culture in both serum-free media (SFM) and 2% fetal bovine serum (FBS). Both of these groups were exposed to varying concentrations and combinations of transforming growth factor (TGF)-beta 1, basic fibroblast growth factor (FGF)-2 both at 1, 5, and 25 ng/mL, and bone morphogenetic protein (BMP)-2 and insulin-like growth factor (IGF)-1, both at 5,25, and 125 ng/mL in the medium during the expansion phase. Cell morphology was assessed throughout the culture duration. After 7 days of monolayer growth, cultures were assessed for cellularity and glycosaminoglycan (GAG) content. Results: The addition of low-dose FBS in culture media consistently led to significantly greater cell proliferation and matrix deposition than the SFM cell cultures. FGF-2 and TGF-beta 1 both alone and in combination led to the greatest proliferative effect compared with the other growth factors. In contrast, BMP-2 and IGF-1 led to the least cell proliferation although was most effective in retaining chondrocyte cell morphology. Conclusions: With the addition of TGF-beta 1 and FGF-2 to culture media, the concentration of serum can be greatly decreased and possibly eliminated altogether without jeopardizing cell proliferation.