How can I keep bronchial epithelial cell alive, while retaining the effect of PM exposure?

Objective of the study: Evaluate whether normal bronchial epithelial cells acquire invasiveness following exposure to particulate matter.

Initial approach: Expose the BEAS2B cell line to PM10 at concentrations of 50ug and 75ug for 48 hours. Subsequently, perform a wound healing assay and an invasion assay using matrigel.

Problem encountered: Post exposure, a significant number of cells died, resulting in inadequate cell viability. This has hindered our ability to observe if the non-malignant BEAS2B cells acquired invasiveness.

Query: Are there strategies to maintain cell viability post PM exposure while ensuring the effects of PM are still observable in the cell line? Would it be advisable to modify the PM exposure conditions, such as by reducing PM concentration and prolonging the exposure duration? Should I provide break for the cell lines to recover and reinitiate the PM exposure?