Summary
A bioRxiv preprint reports a Tris-EDTA-supplemented photobleaching workflow that reduced autofluorescence by 58–70% in fresh-frozen aged human brain sections while preserving tissue architecture and cellular content. The study also introduces a 28-plex antibody panel for spatial proteomics.
Researchers have described a workflow that reduced autofluorescence by 58–70% in fresh-frozen sections from aged human brain while preserving tissue architecture and cellular content. The finding, reported in a bioRxiv preprint posted on September 18, 2026, addresses a technical obstacle in multiplexed spatial proteomics: light emitted by the tissue itself can interfere with signals used to locate many proteins at once.
A workflow for fresh-frozen brain sections
Multiplexed spatial proteomics combines antibody-based protein detection with imaging to show both which proteins are present and where they are located across cells and tissue compartments. Autofluorescence—the natural emission of light from molecules in a specimen—can overlap with measurement signals. The problem is especially important when the background varies between brain regions or between grey and white matter.
The researchers characterized autofluorescence across four brain regions from 21 human donors. They found broad spectral emission, differences between regions and tissue compartments, and an association between autofluorescence and donor age.
The team then tested photobleaching conditions previously adopted for formalin-fixed, paraffin-embedded tissue. In fresh-frozen brain sections, those conditions caused marked damage that varied by region and compartment. The researchers developed a Tris-EDTA-supplemented photobleaching workflow instead. In the reported experiments, it reduced autofluorescence by 58–70% while preserving the tissue’s architecture and cellular content.
The workflow was paired with a custom 28-plex DNA-barcoded antibody panel targeting neuronal, glial, immune and vascular markers. DNA barcodes allow different antibodies to be distinguished within a multiplexed measurement, enabling many protein targets to be analysed in the same tissue section. Together, the optimized preparation and antibody panel enabled spatial proteomic analysis across fresh-frozen brain regions.
Autofluorescence also showed spatial structure
The study treated autofluorescence as more than a general background signal. By co-registering autofluorescence images acquired before photobleaching with multiplexed protein maps, the researchers built a cellular-resolution framework for describing where autofluorescent material occurs.
This analysis revealed region-dependent relationships between autofluorescence and protein markers. Autofluorescent particles were preferentially enriched near nuclei and within microglial and CD68-positive regions. These observations indicate that the background signal has a spatial organisation that can be mapped alongside the proteins being measured.
That combination is useful for studies of aged human brain because it provides two related resources: a preparation method intended to reduce interference during imaging, and a way to account for the autofluorescence that remains. The work is a method-development and tissue-characterisation study in fresh-frozen human brain sections, rather than a clinical study of a diagnostic or treatment effect.
The report is currently a bioRxiv preprint. Its immediate contribution is a workflow and antibody-panel resource for spatial proteomics in this type of specimen. The biological identity and origin of the autofluorescent particles themselves remain to be determined, so their distribution should be interpreted as a mapped tissue feature rather than as an established disease marker.