Cellular alterations in cultured endothelial cells exposed to therapeutic ultrasound irradiation.

Restoration of blood supply to tissue with impaired perfusion depends on spontaneous or mediated angiogenesis, which among other mechanisms includes stimulation, migration, and proliferation of endothelial cells (ECs). Therapeutic ultrasound (US) irradiation is known as an inducer of cellular modifications and is used to accelerate wound healing. An in vitro setup was developed in order to allow for a comprehensive investigation of cellular alterations induced in cultured ECs after exposure to different modes of therapeutic US irradiation. Viability assays revealed a higher rate of proliferation in the sonicated groups, although cell death was not observed. Visualization of actin stress fibers demonstrated partial disassembly of the fibers immediately after US sonication, with a maximum after about 2 h. However, 24 h following sonication the fibers regain normal appearance. A similar behavior was observed with the microtubules and focal adhesion complexes. Utilizing a wound healing assay revealed that migration rate of ECs is enhanced by US irradiation. These findings hint that therapeutic US sonication of ECs results in temporarily cellular alterations, which may induce tissue remodeling via stimulation of EC proliferation and migration.