The effects of treatment using polydeoxyribonucleotide through extracorporeal shock wave therapy: synergic regeneration effects on atrophied calf muscles in immobilized rabbits

BACKGROUND: This study aimed to examine the synergic effects of polydeoxyribonucleotide (PDRN) through extracorporeal shock wave therapy (ESWT) on atrophied calf muscles in cast-immobilized rabbit models. METHODS: Twenty male New Zealand rabbits (aged 12 weeks) were allocated into four groups. Four types of procedures [0.7 mL normal saline to Group 1 (G1-NS); 0.7 mL PDRN to Group 2 (G2-PDRN); ESWT to Group 3 (G3-ESWT); and 0.7 mL PDRN with ESWT to Group 4 (G4-PDRN + ESWT)] were injected to the atrophied calf muscles of the rabbits after two weeks of cast immobilization. Radial ESWT (0.1 mJ/mm(2), 3 Hz, 1,500 shocks) was performed twice weekly. The circumference of the calves, compound muscle action potential (CMAP) of the tibial nerves, and thickness of the gastrocnemius (GCM) muscle were evaluated after two weeks of treatment. Type I and II GCM muscle fibers were immunohistochemically stained using monoclonal anti-myosin, anti-VEGF (vascular endothelial growth factor), and anti-PECAM-1 (platelet endothelial cell adhesion molecule-1) antibodies, and the cross-sectional area (CSA), VEGF ratio, and PECAM ratio were measured after 2 weeks of treatment. Statistical differences among the four groups were determined using analysis of variance (ANOVA). RESULTS: The G4-PDRN + ESWT group had a significantly greater circumference of calf muscles, thickness of the GCM muscle, CMAP of the tibial nerve, and CSA of the GCM muscle fibers (type I, II, and total) (hereinafter termed “the four categories”) than those in the remaining three groups (P<0.05). Rabbits in the G3-ESWT group had significantly higher results in the four categories than in G1-NS and G2-PDRN groups (P<0.05). G2-PDRN rabbits had significantly higher results in the four categories than those in G1-NS (P<0.05). The VEGF and PECAM-1 ratio of the medial GCM muscle fibers in G4-PDRN + ESWT were significantly higher than those in the remaining three groups (P<0.05). CONCLUSIONS: ESWT combined with PDRN injection was more effective in muscle regeneration than ESWT, PDRN injection alone, or normal saline injection on atrophied calf muscles in rabbit models.