The enigma that is the nucleus pulposus cell: the search goes on

The development of an effective treatment for degenerative disc disease has been hampered for many years by what seems a fundamental problem; what exactly defines a nucleus pulposus (NP) cell? The paper by Gilson and colleagues elegantly re-opens the debate concerning the lineage and identity of NP cells that are alike yet different from chondrocytes. As we pursue novel investigations and treatment strategies for degenerative disc disease, how do we isolate these unique cells and what is the role of the primordial notochordal cell that may well linger within the NP far longer and perhaps in a different phenotypic appearance than previously thought? The paper by Gilson and colleagues that is the subject of the present editorial presents compelling data concerning the heterogeneity of the cells of the NP, and their origin, development, maturation and function.