Neuropeptide Y_3-36 incorporated into PVAX nanoparticle improves functional Blood flow in a murine model of hind limb ischemia

We generated a novel nanoparticle called PVAX, which has intrinsic antiapoptotic and anti-inflammatory properties. This nanoparticle was loaded with neuropeptide Y_3-36 (NPY_3-36), an angiogenic neurohormone that plays a central role in angiogenesis. Subsequently, we investigated whether PVAX-NPY_3-36 could act as a therapeutic agent and induce angiogenesis and vascular remodeling in a murine model of hind limb ischemia. Adult C57BL/J6 mice (n = 40) were assigned to treatment groups: control, ischemia PBS, ischemia PVAX, ischemia NPY_3-36, and Ischemia PVAX-NPY_3-36. Ischemia was induced by ligation of the femoral artery in all groups except control and given relevant treatments (PBS, PVAX, NPY_3-36, and PVAX-NPY_3-36). Blood flow was quantified using laser Doppler imaging. On days 3 and 14 posttreatment, mice were euthanized to harvest gastrocnemius muscle for immunohistochemistry and immunoblotting. Blood flow was significantly improved in the PVAXNPY3-36 group after 14 days. Western blot showed an increase in angiogenic factors VEGF-R2 and PDGF-β (P = 0.0035 and P = 0.031, respectively) and antiapoptotic marker Bcl-2 in the PVAXNPY3-36 group compared with ischemia PBS group (P = 0.023). Proapoptotic marker Smad5 was significantly decreased in the PVAXNPY3-36 group as compared with the ischemia PBS group (P = 0.028). Furthermore, Y₂ receptors were visualized in endothelial cells of newly formed arteries in the PVAX-NPY_3-36 group. In conclusion, we were able to show that PVAX-NPY_3-36 can induce angiogenesis and arteriogenesis as well as improve functional blood flow in a murine model of hind limb ischemia.