Please cite this article in press as: Haeri, A., et al., Sirolimus-loaded stealth colloidal systems attenuate neointimal hyperplasia after balloon injury: A comparison of phospholipid micelles and liposomes. Int J Pharmaceut (2013), http://dx.doi.org/10.1016/j.ijpharm.2013.07.003 ARTICLE IN PRESS G Model IJP-13475; No. of Pages 11 International Journal of Pharmaceutics xxx (2013) xxx–xxx Contents lists available at ScienceDirect International Journal of Pharmaceutics j o ur nal ho me page: www.elsevier.com/locate/ijpharm Pharmaceutical nanotechnology Sirolimus-loaded stealth colloidal systems attenuate neointimal hyperplasia after balloon injury: A comparison of phospholipid micelles and liposomes Azadeh Haeri a,b , Saeed Sadeghian c , Shahram Rabbani c , Maryam Sotoudeh Anvari c , Afsaneh Lavasanifar d , Mohsen Amini e , Simin Dadashzadeh a,b,∗ a Department of Pharmaceutics, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran b Pharmaceutical Sciences Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran c Department of Cardiology, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran d Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada e Department of Medicinal Chemistry, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran a r t i c l e i n f o Article history: Received 29 April 2013 Received in revised form 29 June 2013 Accepted 4 July 2013 Available online xxx Keywords: DSPE–PEG micelles PEGylated liposomes Sirolimus Restenosis Local delivery a b s t r a c t Restenosis after angioplasty remains a serious complication in clinical cardiology. This study aims to investigate the stealth colloidal systems for local intra-arterial drug delivery. Micelles from polyethyl- ene glycol conjugated with phosphatidylethanolamine and PEGylated liposomes loaded with sirolimus were prepared and characterized with regard to their loading efficiency, particle size distribution, zeta potential, morphology, nuclear magnetic resonance spectroscopy, drug release profile and stability. The antirestenotic effects of the sirolimus-loaded micelles (14 nm) and liposomes (90 nm) were evaluated and compared in the rat carotid injury model following local intravascular delivery. In comparison to control groups, treatment of balloon injured rats with drug loaded micelles and nanoliposomes signifi- cantly reduced vascular stenosis by 42% and 19%, respectively (P < 0.05). In addition, the luminal area was significantly enlarged by 39% and 60% following treatment with sirolimus-loaded liposomes and micelles, respectively (P < 0.05). Immunohistochemistry revealed that sirolimus-loaded nanocarriers suppressed cell proliferation (Ki67-positive cells) as compared to control groups without affecting the density of smooth muscle actin staining. These results suggest that both colloidal nanocarriers could serve as effec- tive intramural drug delivery systems for the treatment of restenosis; however, phospholipid based micelles provided better antirestenotic effects than PEGylated liposomes. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Percutaneous transluminal balloon angioplasty is a minimally invasive method that is widely used to remove an atheroscle- rotic plaque and to restore the blood flow of the coronary, carotid, Abbreviations: Chol, cholesterol; DES, drug-eluting stent; DSPG, distearoyl-sn-glycerophosphoglycerol; DSPE–PEG, distearoyl-sn-glycero-3- phosphoethanolamine–N-[methoxy(polyethylene glycol)-2000]; EE, entrapment efficiency; EEL, external elastic lamina; EL, empty liposome; EPC, egg phos- phatidylcholine; FTIR, Fourier transform infrared; IEL, internal elastic lamina; IHC, immunohistochemistry; NMR, nuclear magnetic resonance; RBC, red blood cells; SGOT, serum glutamic oxaloacetic transaminase; SGPT, serum glutamic pyruvic transaminase; SIR, sirolimus; SMA, smooth muscle actin; TEM, transmission electron microscopy; WBC, white blood cell. ∗ Corresponding author at: Department of Pharmaceutics, School of Pharmacy, Shahid Beheshti University of Medical Sciences, P.O. Box: 14155-6153, Tehran, Iran. Tel.: +98 21 88200070; fax: +98 21 88209620. E-mail addresses: Sdadashzadeh@sbmu.ac.ir, dadashzadeh5@yahoo.com (S. Dadashzadeh). and peripheral arteries. However, a significant number of patients develop re-obstruction of the arteries following these interven- tions; this disease process is known as restenosis (Burt and Hunter, 2006; Melikian and Wijns, 2008). While the systemic administra- tion of antirestenosis drugs results in subtherapeutic arterial drug concentration (Popma et al., 1991), restenosis can be efficiently treated by the local delivery of a drug (e.g., paclitaxel or sirolimus) from drug eluting stents (DESs) because it provides a higher local- ized arterial drug levels (Hunter, 2006; Salam et al., 2006). However, despite the impressive short-term and intermediate- term clinical outcomes of DESs, the safety of DESs has been questioned because recent data have described late adverse events. Stent thrombosis (which can result in acute myocardial infarction and death) is a serious complication of DES implantation (Genereux and Mehran, 2009; Luscher et al., 2007; McFadden et al., 2004). The pathogenesis of this complication is still not fully understood and several factors are involved. The questionable hemocompa- tibility of stent coating materials seems to be one of key factors (Genereux and Mehran, 2009; Luscher et al., 2007; McFadden et al., 0378-5173/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ijpharm.2013.07.003