Responses during cell preparation for functional analyses in mouse bone marrow-derived cultured mast cells

Murine bone marrow-derived cultured mast cells (BMMCs) are most widely used in in vitro experiments for evaluation of mast cell functions. The present study has shown that cell preparation procedure, i.e., cell collection by centrifugation and the subsequent adjustment and culture of cell density at the desired concentrations, transiently induced gene expression of plasminogen activator inhibitor-1 (PAI-1) and the AP-1 components (c-fos, c-jun, and junB). The level of PAI-1 gene transcript was closely related to the cell density and the gene expression was enhanced by pretreatment with okadaic acid, an inhibitor of protein phosphatases 1 (PP1) and 2A (PP2A). The cell preparation procedure also caused dephosphorylation of MAP kinases, i.e., ERK, p38, and JNK, resulting from PP1/PP2A activation. In view of the cell responses to the cell preparation procedure itself, care is needed in the interpretation of in vitro data using BMMCs.