['Pulsed Acoustic Cellular Expression (PACE) treatment is a novel technology with potential to improve tissue perfusion, but the mechanism of this action is unknown. We assessed in vivo the effect of PACE therapy on muscle microcirculatory hemodynamics, neovascularization, and proangiogenic and proinflammatory gene expression.', 'Cremaster muscles were prepared for standard intravital microscopy in 42 Lewis rats divided into five groups: (1) control (n = 10); acute PACE treatment 15 minutes before surgery with (2) 200 impulses (n = 8) and (3) 500 impulses (n = 8); and PACE treatment 24 hours before surgery with (4) 200 impulses (n = 8) and (5) 500 impulses (n = 8).Microcirculatory hemodynamics of red blood cell velocity and capillary perfusion were recorded for 4 hours. Gene expression levels of proinflammatory (inductible nitric oxide synthase [iNOS]) and proangiogenic factors (endothelial nitric oxide synthase [eNOS], vascular endothelial growth factor [VEGF], chemokine (C-X-C motif) ligand 5 [CXCL5], chemokine (C-C motif) ligand 2 [CCL2], and chemokine (C-C motif) receptor 2 [CCR2] were measured using Taqman real-time Polymerase Chain Reaction (PCR). Immunohistochemistry assessed expression of proangiogenic factors: VEGF, von Willebrand factor (vWF), and vessel density by CD31.', 'PACE treatment resulted in an increase of arteriolar diameters in acute groups 2 and 3 (p < 0.05). In group 5, vessel densities assessed by CD31, VEGF, and vWF expression increased significantly 24 hours after PACE treatment compared with control (p < 0.05). PACE application downregulated proinflammatory iNOS gene expression and upregulated proangiogenic genes expression of eNOS, VEGF, CXCL5, and CCL2.'] Does pulsed acoustic cellular treatment induce expression of proangiogenic factors and chemokines in muscle flaps?