A pilot feasibility study of a minimally invasive technique to collect microbiopsies from sternocleidomastoid muscle for histological analysis in humans

Abstract

Background

The fine-needle (microbiopsy) technique may be suitable for sampling extradiaphragmatic respiratory muscles, but has so far never been used for this purpose. If feasible it would allow to study structural properties and adaptations of these muscles in response to disuse or loading interventions in humans. The sternocleidomastoid muscle (SCM) might be a promising target.

Aim

To assess the feasibility of the microbiopsy technique to obtain muscle tissue of good-quality with cross-sectionally oriented muscle fibres for immunohistochemical analyses of fibre type composition, number of capillaries and satellite cells in human SCM.

Methods

Three to five SCM microbiopsies were taken bilaterally under ultrasound guidance in four fresh-frozen human cadavers, and six recently deceased adult patients in the intensive care unit (ICU). Biopsies were frozen in liquid nitrogen-cooled isopentane. Sections were stained for presence and quality of muscle tissue (Hematoxylin&Eosin), fibre typing (myosin heavy chain immunostaining), capillaries (CD31 immunostaining), and satellite cells amount (Pax7 immunostaining).

Results

Biopsy collection was poor in fresh-frozen cadavers, while muscle biopsies were successfully collected in 87 % of all samples from recently deceased ICU patients. Good-quality muscle biopsies, with cross-sectionally oriented fibres (average:131 ± 79, range:30–343 fibres), were obtained from at least one sample per deceased subject. Staining procedures were successful, allowing analyses of fibre type composition, number of capillaries and satellite cells.

Conclusion

In six recently deceased ICU patients, it was feasible to collect good-quality muscle tissue with cross-sectionally oriented fibres from the human SCM for immunohistochemical analyses of fibre type composition, number of capillaries and satellite cells.