Microvascular response to shock wave application in striated skin muscle

Background: This study aims to quantify by intravital microscopy the microhemodynamic response after extracorporeal shock wave application (ESWA) to the physiologic microcirculation of the mouse dorsal skinfold chamber. Materials and Methods: ESWA was carried out using an electrohydraulic shock wave source. Two different shock wave doses of 500 and 1000 pulses at an energy flux rate of 0.08 mJ/mm2 and a frequency of 4 Hz were compared with sham-operated animals. Microcirculatory analyses were performed at baseline (BL) and during a 3 d observation period after ESWA. The expression of caspase-3 (casp-3), proliferating cell nuclear antibody (PCNA), von Willebrand factor (vWF), and endothelial nitric oxide synthase (eNOS) were analyzed semiquantitatively by immunohistochemistry. Results: ESWA provoked a significant and persistent increase of functional capillary density (FCD) throughout the observation period, reaching a maximum (140% ± 5% of BL, P < 0.05 versus sham) after 1 d when animals were treated with 1000 pulses. ESWA induced a slight increase of leukocyte rolling (not, vert, similar2- to not, vert, similar3.5-fold, P < 0.05) and leukocyte adherence (not, vert, similar1.5- to not, vert, similar2-fold, P < 0.05) to the endothelial lining of postcapillary venules. One day following ESWA, we observed enhanced expression of casp-3 (not, vert, similar3- to not, vert, similar4-fold), PCNA (not, vert, similar9- to not, vert, similar14-fold), vWF (not, vert, similar11- to not, vert, similar14-fold), and eNOS (not, vert, similar3-fold), all P < 0.05. Conclusion: This study shows that ESWA provokes a favorable persistent increase of patent capillaries, however accompanied by a transient and slight inflammatory response but also by dose-dependant apoptotic cell death. Our data suggest that ESWA might represent a noninvasive biomechanical tool to treat critically perfused and endangered tissues, but certainly warrants further investigation