COL1A2 and intervertebral disk degenerative disorder: By comparing the molecular features of PC differentiational trajectories in healthy and degenerative IVDs, we found hypoxia related genes such as EGLN3, nerve growth related genes NGF were upgraded in fate3 in IDD while the expression of SERPINE1, TGFB2, COL1A2 and TNC showed less variation (Figure S3c).37, 48