Figure 5From: Growth differentiation factor 6 and transforming growth factor-beta differentially mediate mesenchymal stem cell differentiation, composition, and micromechanical properties of nucleus pulposus constructsMean acoustic wave speed (a surrogate measure of tissue stiffness) assessed with scanning acoustic microscopy. (A) Acoustic wave-speed distribution maps of BM-MSC- and AD-MSC-seeded type I collagen hydrogels stimulated with TGF-β or GDF6. Scale bar, 50 μm. (B) Quantification of wave speed in BM-MSC- and AD-MSC-seeded constructs after stimulation with TGF-β or GDF6. GDF6 stimulation of AD-MSCs resulted in a significantly decreased acoustic-wave speed compared with TGF-β-stimulated constructs, suggesting that GDF6-stimulated AD-MSC produced a less-stiff ECM. N = 3. *P < 0.05. (C) Wave-speed distribution in AD-MSC-seeded constructs after stimulation with either TGF-β or GDF6. The GDF6-stimulated construct shows significantly reduced mean wave speed of 1,599 ms−1 compared with the TGF-β-stimulated counterpart, 1,644 ms−1.Back to article page