The chronic decrease in the number and function of NPCs in NP under conditions of IDD and loss of ECM components, especially collagen II and aggrecan, is one of the pathological features of IDD (Antoniou et al., 1996; Roberts et al., 2006; Nicholas and George, 2011; Colombier et al., 2014; Risbud and Shapiro, 2014). The gene discussed is ACAN; the disease is intervertebral disk degenerative disorder.