Brain tissue microarrays in neurodegenerative diseases: validation of methodology and immunohistochemical study of growth-associated protein-43 and calretinin.

A tissue microarray (TMA) was constructed using 47 neurodegenerative diseases (NDD), including Alzheimer's disease (AD; n = 30) and non-AD NDD (n = 17), and from seven controls. For validation of the methodology, the following three immunostains were used. Tau and beta-amyloid-related pathologies were more significantly recognized in tauopathies/AD compared to non-tauopathies/controls, and these results were comparable to the assessment of the whole brain sections. But no alpha-synuclein pathologies were observed despite five cases of dementia with Lewy bodies. It was concluded that the TMA technique is useful for NDD with diffuse pathological processes but not for those with patchy and occasional lesions or in early stages. Growth-associated protein (GAP)-43 and calretinin were also immunostained. A significant reduction in GAP-43 expression was seen in the frontal lobe and hippocampus in AD compared to non-AD cases, but not in other areas. No significant difference in number of anticalretinin immunoreactive neurons or in density of immunoreactive neurites was observed between any of the NDD and controls, which may indicate that calretinin-positive neurons are spared in the degenerative process. These results are compatible with the previous studies. These analyses were performed rapidly in a large number of cases using a single slide under uniform staining conditions.