Evaluation of the effects of clinical diagnostic ultrasound in combination with ultrasound contrast agents on cell stress: Single cell analysis of intracellular phospho-signaling pathways in blood cancer cells and normal blood leukocytes

Clinical diagnostic ultrasound has been known as one of the safest imaging modalities available, yet very little is known about the cellular response to such acoustic conditions. With the increased interest in therapeutic ultrasound it is becoming ever more important to understand the effects of ultrasound on cells.In our work here we investigate the effect of clinical diagnostic ultrasound on several cell signalling proteins (p38 p-Thr180/p-Tyr182, ERK 1/2 p-Thr202/p-Tyr204 and p53 ac-Lys382) on leukaemia cells (MOLM-13) and monocytes. Our results show that leukaemia cells and monocytes react differently to ultrasound and microbubbles. A relatively small increase in p38 signalling was seen in the leukemic cells, and only at higher intensities in combination with microbubbles. In contrast the monocytes showed an increase in p38 signalling at all acoustic intensities with microbubbles and at the high acoustic intensity without microbubbles. Furthermore, the leukemic cells showed an overall increase in ERK 1/2 signalling whereas the monocytes showed a decrease. These results indicate that the leukaemia cells are less sensitive to stress induced by ultrasound and microbubbles when compared to normal monocytes. In conclusion, our results show that clinical diagnostic ultrasound does have a measurable effect on intracellular signalling but may differ drastically between different cell types. This may affect the conditions necessary for therapeutic ultrasound.