Shockwave Treatment Enhances Proliferation and Improves WoundHealing via Purinergic Signaling- Induced Erk1/2 Pathway

In clinical settings, shockwave treatment (SWT) has proven to accelerate poor woundhealing of burn wounds or diabetic ulcers although the underlying principles of this beneficial effect remain to be fully elucidated. Therefore the aim of this study was to identify the underlying signaling pathways involved in the proliferative and wound-healing effect of SWT. Primary human adipose tissue-derived stem cells, mouse mesenchymal stem cells, and a human Jurkat T cell line were subjected to SWT in vitro and ATP release was measured. Proliferation after SWT was determined and immunoblotting was performed to evaluate mitogen activated protein kinase pathway activation. In addition, an in vivo rodent ischemic excision wound-healing model was used to assess the dependency of SWT-induced woundhealing on ERK1/2 signaling. SWT dose-dependently released ATP in all three cell types and significantly increased the number of proliferating cells. Hydrolysis of released ATP using the scavenging molecule apyrase diminished the proliferative effect of SWT. Shockwaves significantly activated ERK1/2 signaling, which was prevented by the P2 receptor antagonist suramin as well as by ATP depletion. Our in vivo study confirmed that SWT induced wound healing in an ERK1/2 dependent manner. We conclude that in vitro SWT releases cellular ATP, activating downstream ERK1/2 signaling via predominantly P2Y purinergic receptors, ultimately causing the proliferative effects of SWT. Our in vivo data endorse the ERK1/2 signaling pathway being essential in the SWT wound healing effect. Thus, this signaling cascade is one of the underlying principles of the beneficial effects of SWT and will aid to emphasize the application of SWT as a routine wound healing treatment.