Innate Cellular Fluorescence Reflects Alterations in Cellular Proliferation

Background And Objective: The objective of this study was to examine the question of whether unique spectral patterns were associated with cell proliferation and could be identified by comparing the fluorescence pattern of slow to rapid growing cells.

Study Design/materials And Methods: Three in vitro model systems, (A431 cells inhibited by EGF, serum-starved 3T3 fibroblasts, and normal oral epithelial cells exposed to TGF beta), were analyzed using fluorescence spectroscopy. Growth status was monitored by cell number, 3H-thymidine incorporation, and flow cytometry.

Results: The excitation spectra (lambda ex 240-430 nm, lambda em 450 nm) effectively distinguished slow and rapid growing cells in all three systems. Statistical analysis of the ratios of the main broad peak (320-350 nm) to a point on the down-slope of the curve at 370 nm was statistically significant. Ratios in the emission scan (lambda ex 340 nm, lambda em 360-660 nm) could separate slow and rapid growing A431 and oral epithelial cells (P = 0.0001 and P = 0.023, respectively), but not slow and fast growing 3T3 cells (P = 0.56).

Conclusion: Innate cellular fluorescence has the potential to discriminate proliferating and nonproliferating cell populations.