Neuropeptide Y3-36 incorporated into PVAX nanoparticle improves functional blood flow in a murine model of hind limb ischemia

Abstract

We generated a novel nanoparticle called PVAX, which has intrinsic antiapoptotic and anti-inflammatory properties. This nanoparticle was loaded with neuropeptide Y3–36 (NPY3–36), an angiogenic neurohormone that plays a central role in angiogenesis. Subsequently, we investigated whether PVAX-NPY3–36 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 NPY3–36, and Ischemia PVAX-NPY3–36. Ischemia was induced by ligation of the femoral artery in all groups except control and given relevant treatments (PBS, PVAX, NPY3–36, and PVAX-NPY3–36). 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 PVAX-NPY3–36 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 PVAX-NPY3–36 group compared with ischemia PBS group ( P = 0.023). Proapoptotic marker Smad5 was significantly decreased in the PVAX-NPY3–36 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-NPY3–36 group. In conclusion, we were able to show that PVAX-NPY3–36 can induce angiogenesis and arteriogenesis as well as improve functional blood flow in a murine model of hind limb ischemia. NEW & NOTEWORTHY Our research project proposes a novel method for drug delivery. Our patented PVAX nanoparticle can detect areas of ischemia and oxidative stress. Although there have been studies about delivering angiogenic molecules to areas of ischemic injury, there are drawbacks of nonspecific delivery as well as short half-lives. Our study is unique because it can specifically deliver NPY3–36 to ischemic tissue and appears to extend the amount of time therapy is available, despite NPY3–36’s short half-life.