Extracorporeal shock wave treatment modulates skin fibroblast recruitment and leukocyte infiltration for enhancing extended skin-flap survival.

Extracorporeal shock wave (ESW) treatment has a positive effect of rescuing ischemic skin flaps. This study assessed whether ESW treatment rescues the compromised flap tissue by suppressing the apoptosis of ischemic tissue and recruiting tissue remodeling. We used a random-pattern extended dorsal-skin-flap (10 x 3 cm) rodent model. Thirty-six male Sprague-Dawley rats were divided into three groups. Group I, the control group, received no treatment. Group II received one session of ESW treatment (500 impulses at 0.15 mJ/mm(2)) immediately after surgery. Group III received two sessions of ESW treatment, immediately and the day after the surgery. Results indicated that the necrotic area in the flaps in group II was significantly smaller than that of the flaps in group I (p<0.01). Transferase dUTP-nick end labeling (TUNEL) analysis revealed a significant decrease in the number of apoptotic cells in group II. Hydrogen peroxide (H(2)O(2)) expression in circulation blood was significantly decreased in group II on the day after ESW treatment. Immunohistochemical staining indicated that compared with no treatment, ESW treatment could substantially increase proliferating cell nuclear antigen (PCNA), endothelial nitric oxide synthase, and prolyl 4-hydroxylase (rPH) expression, reduce CD45 expression, and suppress 8-hydroxyguanosine (8-OG) expression in the ischemic zone of the flap tissue. In conclusion, ESW treatment administered at an optimal dosage exerts a positive effect of rescuing ischemic extended skin flaps. The mechanisms of action of ESWs involve modulation of oxygen radicals, attenuation of leukocyte infiltration, decrease in tissue apoptosis, and recruitment of skin fibroblasts, which results in increased flap tissue survival.