Injectable PLGA microspheres encapsulating WKYMVm peptide for neovascularization Young Hwan Choi a,1 , Soon Chul Heo b,1 , Yang Woo Kwon b , Hwan D. Kim a , Seung Hyun L. Kim a , Il Ho Jang b , Jae Ho Kim b,⇑ , Nathaniel S. Hwang a,c,⇑ a School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 152-742, Republic of Korea b Department of Physiology, School of Medicine, Pusan National University, Yangsan 626-870, Gyeongsangnam-do, Republic of Korea c N-Bio Institute, Seoul National University, Seoul 152-742, Republic of Korea article info Article history: Received 5 March 2015 Received in revised form 24 June 2015 Accepted 23 July 2015 Available online xxxx Keywords: WKYMVm peptide PLGA microsphere Drug delivery Outgrowth endothelial cells Neovascularization abstract Formyl peptide receptor-2 (FPR-2) is expressed in various cell types, such as phagocytes, fibroblasts, and endothelial cells. FPR-2 has been reported to play a significant role in inflammation and angiogenic response, and synthetic WKYMVm peptide has been identified as a novel peptide agonist for the FPR-2. In this study, we demonstrate that WKYMVm peptides stimulate the angiogenic potential of outgrowth endothelial cells (OECs). Upon WKYMVm peptide exposure, migration and proliferation of OECs were stimulated. WKYMVm effectively stimulated angiogenesis in tube formation assay and aortic ring assay. Furthermore, we fabricated injectable poly (lactide-co-glycolide) (PLGA) microspheres encapsulating WKYMVm peptides, which showed sustained release of cargo molecule. When WKYMVm peptide encap- sulated microspheres were injected into the hind limb ischemia model, a single injection of microspheres was as effective as multiple injections of WKYMVm peptide in restoring blood flow from ischemic injury and promoting capillary growth. These results demonstrate that sustained release of WKYMVm peptide from microspheres in the application to ischemic hind limb extended angiogenic stimulation. Statement of Significance Formyl peptide receptor (FPR) has been reported to play an important role in inflammation and angio- genic response. A synthetic WKYMVm peptide has been identified as a novel peptide activating the FPR-2 that is expressed in a various cell types, such as phagocytes, fibroblasts, and endothelial cells. In this manuscript we explored a unique property of high-affinity ligand for formyl peptide receptors-2 (FPR-2) (i.e., WKYMVm). WKYMVm-induced activation of FPR2 has been reported to be crucial in host defense and inflammation by activation of phagocytes, monocytes, and lymphocytes. In this study, high- light the efficacy of WKYMVm peptide’s role in inducing neovascularization in vivo hind limb ischemia model when the peptide was released from injected PLGA microspheres in sustained manner. Our results demonstrate that sustained release of WKYMVm peptide from microspheres have extended angiogenic stimulation capacity. Ó 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. 1. Introduction Angiogenesis, defined as functional collateral vessel formation out of preexisting vessels, contributes to enhanced tissue perfu- sion. Factors such as smoking, hypertension, hypercholesterolemia, atherosclerosis, and diabetes can cause insufficient blood flow to tissue and abnormal collateral vessel formation in ischemic tissue [1–3]. Among the disease caused by risk factors, peripheral artery diseases (PAD) is a narrowing of the arteries that supply the heart, brain or legs. PAD has been commonly known to affect the legs. In peripheral vascular defects, limbs that do not receive enough blood flow results in limb pain accompanied by necrosis and ulceration. Finally, amputation of the ischemic limb may be required [4]. To induce neovascularization in ischemic tissues, previous studies have utilized therapeutic angiogenic growth factors. To date, http://dx.doi.org/10.1016/j.actbio.2015.07.033 1742-7061/Ó 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. ⇑ Corresponding authors at: School of Chemical and Biological Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea (N.S. Hwang). E-mail addresses: jhkimst@gmail.com (J.H. Kim), nshwang@snu.ac.kr (N.S. Hwang). 1 These authors contributed equally. Acta Biomaterialia xxx (2015) xxx–xxx Contents lists available at ScienceDirect Acta Biomaterialia journal homepage: www.elsevier.com/locate/actabiomat Please cite this article in press as: Y.H. Choi et al., Injectable PLGA microspheres encapsulating WKYMVm peptide for neovascularization, Acta Biomater. (2015), http://dx.doi.org/10.1016/j.actbio.2015.07.033