Decreased surface sialic acid content is a sensitive indicator of muscle damage

Abstract

The glycosylation state of the muscle sarcolemma is crucial for membrane strength and is thereby linked to pathologic conditions. No markers currently exist with sufficient sensitivity to detect muscle damage in biopsy samples. We aimed to determine whether surface sialic acid content is a useful criterion for estimating muscle injury. Sialic acid content was measured by comparing the fluorescence intensity of muscle sections stained with 2 types of lectins. One binds specifically to nonsialylated sugars, and the other binds to both sialylated and nonsialylated sugars. Sialic acid levels were markedly reduced (60-80%) in muscles from dystrophin-defective mice, δ-sarcoglycan-deficient hamsters, merosin-deficient mice, and patients with muscular dystrophy, when compared with their healthy counterparts. Testing for a marked decrease in sialic acid levels, which is caused by the release of trace amounts of sialidase from damaged muscles, is a sensitive detection method for muscle injury and could be commonly utilized for various subtypes of muscular dystrophy.