Abstract

Objective Brain branks preserve extensive material relevant to neurodegenerative disease research. As these collections age, tissue becomes archival, raising the question of whether long-term fixed and stored human brain tissue remains suitable for contemporary immunohistochemical analyses.

Materials and Methods Forty-one autopsy brains collected between 1946 to 1980 were examined. For each case, midbrain and hippocampus were available both as original paraffin-embedded blocks and as tissue stored long term in fixative. New paraffin blocks were prepared from the long-term fixated tissue. Sections from original and newly prepared blocks were immunohistochemically stained for α-synuclein, hyperphosphorylated tau and amyloid-β. Immunoreactivity was assessed using semi-quantitative scoring.

Results Original blocks consistently showed good staining intensity and morphological preservation for each protein pathology. Newly prepared blocks showed slightly lower semi-quantitative scores for Lewy-related pathology, without statistically significant differences, except for astrocytic α-synuclein in the substantia nigra in cases from the 1960s. Tau pathology displayed modestly reduced labelling, particularly of the neuropil threads and neurofibrillary tangles, most evident in cases from the 1950s. Amyloid-β-positive senile plaques showed similar or slightly higher scores in newly prepared blocks, with no significant differences across regions.

Conclusion Human brain tissue preserved as paraffin-embedded blocks or stored in fixative for up to 78 years remains suitable for immunohistochemical analyses. Adequate-to-good detection of aggregated of α-synuclein, hyperphosphorylated tau and amyloid-β is achievable, indicating preserved pathological hallmarks of Lewy Body Disease and Alzheimer’s Disease in archival tissue.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

This study was funded by grants from the Lundbeck Foundation.

Author Declarations

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Scientific Ethics Committees for the Central Denmark Region gave ethical approval for this work.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Data Availability

All data produced in the study are available upon reasonable request to the authors.

AbbreviationsAβamyloid-betaADAlzheimer’s DiseaseαSynalpha-synucleinCAAcerebral amyloid angiopathyEnt Cxentorhinal cortexFAformic acidFFPEformalin-fixed paraffin-embeddedIHCimmunohistochemicalLBLewy bodyLBDLewy Body DiseaseLNLewy neuriteNFTneurofibrillary tangleNTneuropil threadPAGperiaqueductal greyPDParkinson’s DiseaseROIregion of interestSNsubstantia nigraSPsenile plaqueTO Cxtemporo-occipital cortex