Characterization of the regrowth behavior of amyloid-like fragmented fibrils decomposed by ultrasonic treatment

Ultrasonic treatment (UST) has been used not only to accelerate protein fibril growth and amplify infectious prion proteins from biological fluids, but also to break amyloid-like fibrils for treatment. Despite the applicability of UST to clinical treatment, both the decomposition characteristics of fibrils and the regrowthmechanisms of the decomposed fibrils remain unclear. Here, we report UST-driven decomposition of amyloid-like fibrils into shorter fibrils and the principles of fibril regrowth via conventional heating. Short fibrils decomposed by UST can be reconstructed into mature fibrils with the addition of monomeric protein, but the regrowth of short fibrils rarely occurs in the absence of monomeric protein. Interestingly, the reconstructed fibrils possess electric properties similar to those of the original fibrils. We propose a model that describes the regrowth process of amyloid-like fibrils decomposed by UST, which sheds light on future biomedical applications of UST for the treatment of amyloidogenic diseases.