High-energy shock waves: in vitro effects

To date, there have been multiple studies on the effects of high-energy shock waves (HESW) on benign and malignant cells under in vitro conditions. The major problem in comparing and contrasting these studies has been the wide range of mechanical, biological, and analytical variables facing the investigator. However, if one takes the time to select out only those studies in which a wide range of experimental variables have been defined or controlled, then it becomes possible to begin to understand the effects of HESW on cells in vitro. With this in mind, the literature has been thoroughly reviewed. It would appear that HESW do cause cellular damage regardless of the cell's doubling time. The cell damage is likely due to the impact of cavitation and the attendant shear forces and jets that are produced by the shock waves as it passes through the cell suspension. The damage occurs both at the cell membrane and within the cell itself. With regard to the latter, it would appear that the mitochondria are most sensitive to HESW; however, damage also occurs within the nucleus and along the endoplasmic reticulum and in other cell organelles (eg, lyosomes). Applications of HESW to other clinical situations are currently being studied. One example of interest is the in vitro combination of chemotherapeutic agents and HESW to enhance the effect of a specific chemotherapeutic regimen on a given tumor cell line. Several investigators have noted a beneficial effect of this combination therapy in vitro; however, similar favorable results have not been obtained when the same or similar tumor system was studied in vivo.