Royal College of Surgeons in Ireland
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The impact of the extracellular matrix environment on sost expression by the MLO-Y4 osteocyte cell line

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journal contribution
posted on 2022-11-11, 14:05 authored by Robert Thomas Brady, Fergal O'BrienFergal O'Brien, David A Hoey
Bone is a dynamic organ that can adapt its structure to meet the demands of its biochemical and biophysical environment. Osteocytes form a sensory network throughout the tissue and orchestrate tissue adaptation via the release of soluble factors such as a sclerostin. Osteocyte physiology has traditionally been challenging to investigate due to the uniquely mineralized extracellular matrix (ECM) of bone leading to the development of osteocyte cell lines. Importantly, the most widely researched and utilized osteocyte cell line: the MLO-Y4, is limited by its inability to express sclerostin (Sost gene) in typical in-vitro culture. We theorised that culture in an environment closer to the in vivo osteocyte environment could impact on Sost expression. Therefore, this study investigated the role of composition and dimensionality in directing Sost expression in MLO-Y4 cells using collagen-based ECM analogues. A significant outcome of this study is that MLO-Y4 cells, when cultured on a hydroxyapatite (HA)-containing two-dimensional (2D) film analogue, expressed Sost. Moreover, three-dimensional (3D) culture within HA-containing collagen scaffolds significantly enhanced Sost expression, demonstrating the impact of ECM composition and dimensionality on MLO-Y4 behaviour. Importantly, in this bone mimetic ECM environment, Sost expression was found to be comparable to physiological levels. Lastly, MLO-Y4 cells cultured in these novel conditions responded accordingly to fluid flow stimulation with a decrease in expression. This study therefore presents a novel culture system for the MLO-Y4 osteocyte cell line, ensuring the expression of an important osteocyte specific gene, Sost, overcoming a major limitation of this model.


European Research Council under the European Community’s Seventh Framework (FP7/2007-2013)

Horizon 2020 Programmes under ERC grant agreement no. 239685, no. 788753 and no.336882

Science Foundation Ireland (SFI/19/FFP/6533)

EU BlueHuman Interreg Atlantic Area Project (EAPA_151/2016)



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Published Citation

Brady RT, O'Brien FJ, Hoey DA. The impact of the extracellular matrix environment on sost expression by the MLO-Y4 osteocyte cell line. Bioengineering (Basel). 2022;9(1):35.

Publication Date

13 January 2022

PubMed ID



  • Anatomy and Regenerative Medicine
  • Tissue Engineering Research Group (TERG)
  • Amber (Advanced Material & Bioengineering Research) Centre

Research Area

  • Chemistry and Pharmaceutical Sciences
  • Biomaterials and Regenerative Medicine
  • Immunity, Infection and Inflammation




  • Published Version (Version of Record)