Oldies, but goldies-preserved morphology and stability of antigenic determinants in decades-old cryosections of human m. vastus lateralis

Abstract

Fibre typing by immunohistochemistry on cryosections from human skeletal muscle biopsies is an essential tool in the diagnosis and research of muscular diseases, ageing, and responses to exercise training and disuse. Preserving a good quality in these frozen specimens can be challenging especially if they are stored for longer periods before histological processing, which is often the case in studies with a large number of test subjects and/or repeated sampling separated by multiple years. We demonstrate in this article that both, the morphology and reactivity of epitopes to myosin heavy chain isoforms and dystrophin are well preserved in up to 18-year-stored unfixed and unstained cryosections of human m. vastus lateralis (n = 241). Any variation in staining intensity between samples was unrelated to the age of the biopsy donor or the storage period of the unstained cryosections, and in all cases, the obtained images were appropriate for image analysis, such as the determination of the fibre type composition and the fibre cross-sectional area, and quantitative analysis of muscle capillarisation.

Keywords: epitope preservation; frozen sections; long term storage.

FIGURE 1

Immunofluorescent (IF) labelling of cryosections after different storage durations: Slow muscle fibres are depicted in blue (MyHC‐I), fast muscle fibres in green (MyHC‐IIa), the sarcolemma in red and capillaries in white. These cryosections of human m. vastus lateralis have been stored for 18 years, 66‐year‐old man (a), 9 years, 22‐year‐old man (b) and 2 weeks, 51‐year‐old woman (c) before IF labelling. Scale bar indicating 100 μm.