Shock wave as biological therapeutic tool: From mechanical stimulation to recovery and healing, through mechanotransduction.

Extracorporeal Shock Wave Therapy (ESWT) is a form of "mechanotherapy", that, from its original applications as urological lithotripsy, gained the field of musculo-skeletal diseases as Orthotripsy (mainly tendinopaties and bone regenerative disorders) and Regenerative Medicine as well. The mechanisms of action of Shock Waves (SW), when applied in non-urological indications, are not related to the direct mechanical effect, but to the different pathways of biological reactions, that derive from that acoustic stimulations, through "mechano-transduction". So, the "mechanical model" of urological lithotripsy has been substituted by a "biological model", also supported by current knowledge in "mechanobiology", the emerging multidisciplinary field of science that investigates how physical forces and changes in cell/tissue mechanics can influence the tissue development, physiology and diseases. Although some details are still under study, it is known that SW are able to relief pain, as well to positively regulate inflammation (probably as immunomodulator), to induce neoangiogenesis and stem cells activities, thus improving tissue regeneration and healing. ESWT can be nowadays considered an effective, safe, versatile, repeatable, noninvasive therapy for the treatment of many musculo-skeletal diseases, and for some pathological conditions where regenerative effects are desirable, especially when some other noninvasive/conservative therapies have failed. Moreover, based on the current knowledge in SW mechanobiology, it seems possible to foresee new interesting and promising applications in the fields of Regenerative Medicine, tissue engineering and cell therapies.