Fig. 4

Regulation of Bmp-2 and -4 gene expression and phospho-smad5 in response to mechanical stimulation. a–c Dynamic stretch was applied for 2 h or 6 h to cultured chondrocytes (black bars), osteoblasts (white bars), and tenocytes (gray bars). Gene expression of Bmp-2 (a) and -4 (b) and the Bmp-2/Bmp-4 ratio (c) were compared to non-stretched control cells. d–f Cultured chondrocytes were stimulated 6 h by stretch (white bars), or 10 ng/mL of TNF-α (gray bars) separately or simultaneously (black bars). Gene expression of Bmp-2 (d) and -4 (e) and the Bmp-2/Bmp-4 ratio (f) were compared to non-stretched untreated control cells. g Immunostaining of phospho-smad5 in sane mouse ankle sections. The section comprises the enthesis -E- of the Achilles tendon -T- insertion into the calcaneus bone -B-. Some chondrocytes of the sesamoid cartilage zone were positive, as revealed by an intracellular brown staining. Sections were slightly counter-stained with Mayer’s hematoxylin staining. *p < 0.05 in comparison to the control resting condition; p values are indicated for the differences between the other conditions, ns: not significant (p > 0.1)