Validating a Microbiopsy Sampling Technique for Morphological Analysis of Human Muscles

Biopsy of muscle tissue has been a valuable method for clinical diagnostics and research. Traditionally, samples of muscle tissue are obtained via the Bergstrom needle biopsy, which is considered a moderately invasive technique as it requires an incision through the skin ranging from 5 mm to 10 mm. As an alternative, a minimally invasive microbiopsy technique that relies on fine needle aspiration has been introduced more recently. Originally, it was meant to produce samples for biochemical analyses. In this study, we want to make a case that the micorbiopsy method is a valuable approach to obtain samples for morphological analysis. We have processed 7 biopsies from young males and 8 biopsies from elderly males, obtained with the microsampling technique. On average, muscle sample sizes varied from 9 mg to 20 mg. Each biopsy produced sufficient amount of muscle tissue for three independent blocks of frozen tissue and an additional amount that could be used for molecular analysis. Frozen samples were sectioned and stained by immunofluorescence to reveal individual fiber types. Stained slides were imaged with confocal miscopy and subjected to morphological analysis. We report that the microsampling technique has produced approximately 1,000 fibers per sample, on average. Batches of muscle tissue from the same person produced similar muscle fiber type ratios. Moreover, the samples provided enough statistical power to detect changes in fiber type composition, described in the literature for aging muscles: we detected size reduction for type 2X fibers and fiber type groupings. Overall, our result confirms that the microsampling technique can be used for supplying material for morphological analysis of muscles