Nucleus pulposus cells as competent phagocytes to clear apoptotic cells: mission applicable or impossible? Authors' response

  • Philip Jones1, 2,

    Affiliated with

    • Lucy Gardner1, 2,

      Affiliated with

      • Janis Menage1,

        Affiliated with

        • Gwyn T Williams2 and

          Affiliated with

          • Sally Roberts1, 2Email author

            Affiliated with

            Arthritis Research & Therapy200911:406

            DOI: 10.1186/ar2672

            Published: 6 May 2009

            We thank Dr Wang and Dr Luo for their interest in our paper demonstrating the ability of intervertebral disc cells to undergo phagocytosis [1], and we can certainly concur with some of the points they raise [2]. In fact, we addressed the first point in the last paragraph of the Discussion, stating that 'Although disc cells usually occur in isolation ...', disc cells do occur adjacent to each other in clusters of cells that are common in degenerate discs [1]. It is in this situation that we suggest our findings could have relevance in vivo in humans.

            We would suggest that the second point made by Wang and Luo has very little bearing on our study. In intact adult discs there is little evidence of T cells being present, and therefore this comment is of limited relevance.

            Wang and Luo's third point is certainly true and pertinent to all cell culture studies – the results of which can only be interpreted, bearing in mind all the limitations of making any deductions from in vitro studies to an in vivo situation.

            The objective of the study was to determine whether disc cells could undergo phagocytosis [1], a property that as far as we were aware had not previously been demonstrated. To this effect we believe our study produced novel findings and provides the foundation for further work defining the contribution of phagocytosis of apoptotic cells under both physiological and pathological conditions.


            Authors’ Affiliations

            Centre for Spinal Studies, Robert Jones & Agnes Hunt Orthopaedic & District Hospital NHS Trust
            Institute of Science and Technology in Medicine, Keele University


            1. Jones P, Gardner L, Menage J, Williams GT, Roberts S: Intervertebral disc cells as competent phagocytes in vitro : implications for cell death in disc degeneration. Arthritis Res Ther 2008, 10:R86.View ArticlePubMed
            2. Wang H-Q, Luo Z-J: Nucleus pulposus cells as competent phagocytes to clear apoptotic cells: mission applicable or impossible? Arthritis Res Ther 2009, 11:405.View ArticlePubMed


            © BioMed Central Ltd 2009