Figure 4.

Soft and medium stiffness CHG-treated constructs suffer losses in aggregate modulus values despite no increases in TNF-α production. (A) GAG/WW was significantly affected by the ΜΦ factor, with significant decreases within the medium stiffness constructs between the construct-only control and LPS-stimulated co-culture group. (B) Trending with GAG/WW, aggregate modulus significantly decreased with the addition of macrophages (unstimulated or LPS-stimulated) in soft and medium stiffness constructs. (C) Conversely, after 48 hours of co-culture, only the stiff construct group had significant increases in TNF-α secretion between the construct-only control and the LPS-stimulated group. Statistics: Two-way ANOVA with post hoc Tukey’s HSD among groups within a stiffness (dotted lines), α = 0.05, n = 3-6 per group. CHG = chondrogenic medium; TNF-α = tumor necrosis factor alpha; GAG = glycosaminoglycan; WW = wet weight; ΜΦ = macrophage; LPS = lipopolysaccharide; ANOVA = analysis of variance; HSD = honestly significant difference.