In Vitro Evaluation of the Biocompatibility and Stability of Fluorescent Dil Dye on Mouse Embryonic Fibroblast Cells

Background: There are few methods for cell labeling in basic studies of cell-migration, tissue engineering, and cell therapy. Recent progress in cell trackers has led to an increasing number of clinical trials involving the treatment of various diseases based on cell transplantation. Objectives: In this study, we investigated the effects of different concentrations of DiI as a cell labeling dye on the viability and proliferation of mouse embryonic fibroblasts (MEFs). Methods: MEFs were divided into two groups of control and experimental (treated with Dil dye). We treated MEFs with three concentrations of the dye and after 1, 5, 7 and 14 days, these cells were analyzed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and 4’, 6-diamidino-2-phenylindole (DAPI) staining. Also, the stability of the dye in treated MEFs was examined by immunofluorescence. Results: Our results showed that cell viability was significantly different between the groups that received Dil at the concentrations of 1 and 2 µg/mL and the control group. However, cell viability was not significantly different between the group that received Dil (0.5 µg/mL) and the control group. Conclusions: Therefore, Dil at concentrations higher than 0.5 µg/mL was toxic for MEFs. We suggest that Dil dye, which is concentration-dependent, can be used as a safe and stable fluorescent dye for cell labeling both in-vivo and in-vitro.