IMR Press / FBL / Volume 26 / Issue 10 / DOI: 10.52586/4989
Open Access Original Research
The biological effect of cobalt chloride mimetic-hypoxia on nucleus pulposus cells and the comparability with physical hypoxia in vitro
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1 Department of Orthopedics, Xinqiao Hospital, Army Military Medical University, 400037 Chongqing, China
*Correspondence: (Chang-Qing Li)
Front. Biosci. (Landmark Ed) 2021, 26(10), 799–812;
Submitted: 21 July 2021 | Revised: 2 September 2021 | Accepted: 7 September 2021 | Published: 30 October 2021
Copyright: © 2021 The Author(s). Published by BRI.
This is an open access article under the CC BY 4.0 license (

Objective: Nucleus pulposus cells (NPCs) are cells extracted from the intervertebral disc and are important for research into intervertebral disc degeneration (IVDD). NPCs live in an avascular and relatively hypoxic environment. Cobalt chloride (CoCl2) has been used in many cell studies to mimic hypoxia. The objective of this study was to explore the possibility of using CoCl2 to induce mimetic-hypoxia for NPCs and the comparison with hypoxia (1% O2) in vitro. Materials and methods: Rat nucleus pulposus cells of Passage 3–5 were used in this research. Cell viability, rate of cell apoptosis, ROS (reactive oxygen species) generation, cell migration, extracellular pH and extracellular matrix metabolism were determined to compare the influence of hypoxia (1% O2) and CoCl2 on NPCs. Results: We found that the effects of CoCl2 on NPCs was dose-dependent. At the proper concentration, CoCl2 could be used to elicit chemical hypoxia for nucleus pulposus cells in vitro and many biological effects, analogous to physical hypoxia (1% O2), could be achieved such as enhanced cell viability, decreased apoptosis and activated extracellular matrix metabolism. On the other hand, CoCl2 mimetic-hypoxia did not affect NPCs glycolysis and migration compared to physical hypoxia. In addition, high concentration of CoCl2 (>200 μM) is harmful to NPCs with high rates of apoptosis and ECM (extracellular matrix) degradation. Conclusions: It is feasible and convenient to use CoCl2 to induce chemical mimetic hypoxia for culturing NPCs on the premise of appropriate concentration. But in aspects of cell migration and glycolysis, CoCl2 could not achieve similar results with physical hypoxia. This study may provide a convenient method and enlightenment to induce mimetic-hypoxia for researchers studying NPCs and IVVD.

Nucleus pulposus cells
Cobalt chloride
Extracellular matrix synthesis
Fig. 1.
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