Stimulation of Tissue Regeneration by Pulsed Plane-Wave Ultrasound

Abstract

Plane-wave ultrasound at certain dosages can cause a statistically significant increase in the rate at which tissue re- generates to replace that lost after injury. The experimental model used in this study is the replacement of tissue in the pinna of the ear of a rabbit after the removal of tissue of area 1 cm2 through the full thickness of the ear. The regenerate consists of skin and its derivatives and elastic cartilage. The method of irradiation and the effects of a range of dosages on the rate of tissue replacement are described. Experimental evidence indicates that the growth rate increases found are not due to thermal effects caused by ultrasound; it is thought that a mechanical factor, streaming, may be involved. Electron microscopic studies show changes in the irradiated tissue that may be interpreted as indicating an increase in protein synthesis and temporary interference with the polymerization of collagen precursors. Autoradiographic investigation of 3H-thymidine uptake shows that the rate of synthesis of DNA in the regenerating tissue is increased by treatment with ultrasound. ISTROUL-CTIOX HERE have been several reports that ultrasound at certain dosages can increase enzyme activity (l), (2) and thus generally increase metabolic ac- tivity. In plants this effect stimulates seed germination and the growth rate of young seedlings (3), (4). This stimulation of plant growth suggested the use of ultra- sound as a possible stimulant of tissue growth in animals. The control of regenerative growth, i.e., the replacement of lost tissue, is clinically important in the treatment of injuries and in post-operative care. It is possible to stimulate growth by systemic means, for example, by the repeated injection of anabolic hormones (5), but such treatment affects other sites as well as the regenerate and can produce undesirable side effects. The direct