Effect of storage conditions on the stability of recombinant human MCP-1/CCL2.

Monocyte chemoattractant protein-1 (MCP-1) is commercially available in a form of recombinant protein. This makes it more convenient to study the functions of MCP-1 and its involvement in many cell functions. However, when using MCP-1 in experimental studies, if the analysis is not performed immediately, the stability of recombinant MCP-1 may become an issue. In this study, the stability of recombinant MCP-1 at different concentrations and storage conditions was investigated. Results show that no significant loss of MCP-1 is observed when MCP-1 solutions were stored at non-freezing condition (4 °C) for seven days. However, for storage at freezing conditions (-20 °C or -81 °C), it appears that the first freeze-thaw cycle may contribute to some loss of MCP-1 in the solutions, and such loss may be concentration and time dependent. The effect of multiple freeze-thaw cycles for storage at freezing conditions was also examined. Data reveal that the second freeze-thaw cycle causes approximately 50% loss of MCP-1 in the solutions. This finding confirms that multiple freeze-thaw cycles should be avoided. The findings of this study provide an outline of how storage can affect the stability of recombinant proteins and should be taken into account during the evaluation of the concentration of recombinant proteins.