CXCL12 and intervertebral disk degenerative disorder: On the contrary, there were substantial numbers of miRNAs were down-regulated and most likely exert anti-apoptotic effects in IDD, mainly involving miR-129-5p/BMP2 (23), miR-623/CXCL12 (24) and miR-155-3p/KDM3A/HIF1α (25).