Fig. 7: Variation of disc height and T2 MRI signal intensity of NP during the 16 weeks implantation, and mechanical properties of the discs at 16 weeks.

a X-ray and T2 MRI images of the discs at 0, 8, and 16 weeks (anatomical directions: H Head, F Foot, V Ventro, D Dorsal). The yellow arrow represents platinum ring on the PGD scaffold. b, d, and f Normalized DHI of the discs in NP injury disc and four experimental groups at 1 (b)(n = 4), 8 (d)(n = 4) and 16 weeks (f)(n = 4) after implantation. c, e, and g Normalized T2 signal intensity of NP in the discs of NP injury and four experimental NP groups at 1 (c)(n = 4), 8 (e)(n = 4), and 16 weeks (g)(n = 4) after implantation. h Variation of normalized DHI of NP Injury and four experimental groups (n = 4) during 16 weeks. i Variation of normalized T2 signal intensity in NP of NP injury disc and four experimental groups (n = 4) during 16 weeks. j Four-step compression stress relaxation for the collected L5-L6 discs after 16 weeks implantation. The discs are removed from peripheral tissue and fixed in the cured acrylate for mechanical experiments as shown in the upper left picture. k, l Effective instantaneous (k), and equilibrium moduli (l) are calculated based on stress-strain curves (n = 4). The above data are all presented as mean values ± SD. Transverse lines in figures indicate statistical differences between the two groups determined by the two-tailed t-test (P < 0.05), and the exact P-values are listed in the Supplementary Data 4, 5 and 6.