lipofussiini

Lipofussiini, also known as lipofuscin, is a granular, yellow-brown autofluorescent pigment that accumulates in the lysosomes of aging cells. It is one of the hallmarks of cellular aging and is most prominent in postmitotic cells such as neurons, cardiac muscle fibers, and retinal pigment epithelium.

Lipofussiini is a heterogeneous complex composed of lipid-containing residues of lysosomal digestion, cross-linked proteins, and trace metals. It forms through incomplete lysosomal degradation of damaged cell components during autophagy, aided by oxidative stress and lipid peroxidation. The material is resistant to lysosomal enzymes and tends to accumulate, occupying lysosomal space and potentially impairing degradation.

Clinical and biological significance: Lipofussiini accumulation increases with age and has been observed in various tissues, correlating with functional decline. In the nervous system and retina, a higher burden is associated with aging-related conditions and some neurodegenerative diseases, though it is generally considered a biomarker rather than a primary driver of disease.

Detection and properties: Lipofussiini is intrinsically autofluorescent; under fluorescence microscopy it emits light over a broad range, typically excited by blue to green light and emitting in the yellow to red spectrum. Its presence can be observed in histological sections and can be influenced by tissue fixation and imaging.