It was found that T2 MRI signal intensity of NP at 1 week after surgical treatment was used as the clinical indicator to reflect NP damage among each group (PGD, PGD + SDF-1α, HA, HA + SDF-1α, and NP Injury group) in this study, and they were all ~60% of their initial state before surgery with no statistical difference (Fig. 7c), which meant they had similar disc degeneration level after surgical treatment at the beginning. This evidence concerns the gene CXCL12 and intervertebral disk degenerative disorder.