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Objective: To determine the effects of bone morphogenetic proteins (BMP)-2 and -7, and serum, on extracellular matrix production by human septal chondrocytes in alginate., Study Design: Human nasal septal chondrocytes were expanded, suspended in alginate, and cultured in BMP-2 or 7, with and without serum. The optimal concentration of each growth factor was determined based on matrix production. Next, the synergistic effects of BMP-2 and -7 at optimal concentrations were determined on separate beads, based on matrix quantity and histology., Results: Matrix content was highest with concentrations of BMP-2 and -7 of 100 ng/ml and 20 ng/ml, respectively, with serum. Adding both BMP-2 and -7, with serum, increased matrix content by factors of 5.1 versus serum-only cultures, 2.7 versus only BMP-2 with serum, and 2.4 versus only BMP-7 with serum. All comparisons were statistically significant., Conclusion: BMP-2 and -7 significantly increase production of extracellular matrix by septal chondrocytes suspended in alginate. The presence of serum improves matrix production., Significance: BMP-2 and -7 have great potential for use in cartilage tissue engineering.

Objective: To analyze the growth patterns and differentiation of human septal chondrocyte monolayers of different seeding densities., Study Design: Chondrocytes from 8 donors were plated at densities ranging from 20,000 cells/cm(2) (high density) to 300 cells/cm(2) (very low density). Confluency, cellularity, and glycosaminoglycan content were determined from days 1 to 15., Results: Confluency was attained at 5.8, 8.3, 11.0, and 14.8 days for high-, intermediate-, low-, and very low-density monolayers, respectively (P < 0.001). Regression growth curves showed typical lag, logarithmic, and stationary phases. Confluent monolayers attained similar cellularity (power = 0.94) and differentiation (power = 0.88), regardless of initial density., Conclusions: Human septal chondrocyte monolayers reach confluency from very low initial densities. Growth patterns, cellularity, and differentiation are similar to other starting densities., Significance: Very low-density monolayers expanded cell number 838-fold in 1 passage and therefore are sufficient for tissue-engineering purposes. This is important because of the requirement of maintaining differentiation and the limitation of small tissue harvest specimens.