Selective deletion or preservation of tissue components via enzymatic digestion monitored by scanning acoustic microscopy

Detecting specific tissue components is valuable in histology. Scanning acoustic microscopy (SAM) measures the attenuation-of-sound (AOS) through tissue sections, enabling the generation of histological images without staining. AOS values decrease as tissues degrade. In this study, we enzymatically digested target components and monitored the process using AOS imaging over time. Additionally, we applied specific dyes and antibodies to inhibit enzyme activity and preserve target component. Collagenase digested the bone to clearly visualise the internal structure. The target component showed a distinct decline in AOS values. Actinase digested the artery except for amyloid deposits, which were detected by Congo red staining. Actinase-digested lymphoid cells remained positive for horseradish peroxidase (HRP) staining. Amylase digested some corpora amylacea (CA) in the brain, which became negative for periodic acid-Schiff (PAS) staining and diminished in size under electron microscopy. DNase digested and deleted cell nuclei, except for those stained with HRP. Residual nuclear images of AOS matched those of light microscopy. Enzyme-specific inhibition of enzymes preserved the target cells and materials. Our method offers a practical method for intentionally deleting or retaining target components in a section. Furthermore, it provides a means to adjust and compare the degree of degradation using AOS values.