FGF2 and limb ischemia: Through stimulation of angiogenic factors such as interleukin-8, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), via the extracellular signal-regulated kinase (ERK)/Akt/endothelial nitric oxide synthase/VEGF pathway, LIPUS exposure has the potential to provide beneficial cellular therapeutic effects on limb ischemia by inducing microvascular regeneration and to improve clinical symptoms in patients with CLI and reduce the risk of amputation [14].