Lysosomal Profiling With LysoTracker For Quantitative Assessment of Cellular Senescence In Human Fibroblasts

Area of Science:

• Cell Biology
• Molecular Biology
• Aging Research

Background:

• Cellular senescence is a state of stable cell-cycle arrest.
• Senescent cells display characteristic phenotypes, including enlarged morphology and altered secretory signaling.
• Lysosomal remodeling, particularly the expansion of the acidic endo-lysosomal compartment, is a hallmark of senescence.

Purpose of the Study:

• To describe a live-cell imaging protocol for quantifying senescence-linked lysosomal remodeling.
• To provide a pH-dependent proxy for the acidic organelle compartment as a correlate of senescence burden.
• To offer a practical, quantitative complement to conventional senescence assays.

Main Methods:

• Utilized LysoTracker Deep Red, an acidotropic fluorescent dye, for live-cell imaging.
• Demonstrated the protocol in IMR-90 human lung fibroblasts undergoing replicative senescence.
• Detailed cell culture, LysoTracker staining, fluorescence imaging, and image-based quantification of lysosomal signal intensity and area per cell.

Main Results:

• Observed higher acidotropic fluorescent dye signal and larger lyso-positive regions in late-passage senescent cells compared to early-passage controls.
• Results are consistent with the expansion of the acidic organelle compartment during senescence.
• The readout serves as an indirect correlate of lysosomal remodeling.

Conclusions:

• The described protocol offers a simple, quantitative method for assessing senescence burden via lysosomal remodeling.
• The method is adaptable to other cell types and senescence-inducing stresses.
• This approach complements traditional senescence detection methods like SA-β-Gal staining.