Time-related changes in cell morphology and biomarker immunoreactivity for cells stored in a buffer-based cell medium.

Objective: Buffer-based cell media (BBCM) are a valuable tool in the post-collection processing of cytology samples, though with poorly defined effects on cell properties. In this study, time-related changes in cell morphology and biomarker immunoreactivity were evaluated for cells stored at room temperature in a BBCM prepared with bovine serum albumin (BSA) and ethylene diamine tetraacetic acid (EDTA).

Methods: Cytospins were prepared at five consecutive 24-hour intervals (0, 24, 48, 72, 96) from three human cell lines (MCF7, SK-MEL-28, FaDu) suspended and stored in BBCM. Preservation of cell morphology was evaluated on Papanicolaou-stained cytospins from the percentages of apoptotic cells. Preservation of immunoreactivity was evaluated for cytokeratins, oestrogen receptors, Ki67, and melanoma markers from the percentages of cells positive for the corresponding immunocytochemical reactions.

Results: Cell morphology was well preserved for the majority of cells of the three lines stored for 24 and 48 hours (93%, 97%, 98% and 62%, 81%, 88%, respectively), while the majority of cells were apoptotic after 72 and 96 hours (70%, 47%, 39% and 77%, 70%, 59%, respectively). The immunoreactivity of cytokeratins remained unchanged during the entire 96 hours, while that of melanoma markers (S100, HMB45, Melan-A) decreased by 27%, 2%, and 3%, respectively. The immunoreactivity of oestrogen receptors and Ki67 decreased by 29% and 17% after the first 24 hours, and was completely lost after 96 hours.

Conclusions: A BBCM with the addition of BSA and EDTA facilitates good preservation of cell morphology and immunoreactivity of biomarkers for up to 48 hours at room temperature.