IGF1 and intervertebral disk degenerative disorder: Further in vivo studies have found that the reduction of IGF1 bioavailability can reduce the senescence of intervertebral disc cells and the decomposition of extracellular matrix [14], and promote the synthesis of proteoglycan and type II collagen in intervertebral disc cells [15], which was consistent with the results of IDD development caused by the down-regulation of IGF1 in this study.