Intramuscular delivery of 3D aggregates of HUVECs and cbMSCs for cellular cardiomyoplasty in rats with myocardial infarction Ding-Yuan Chen a,g,1 , Hao-Ji Wei b,h,1 , Wei-Wen Lin c,1 , Kun-Ju Lin d,e,1 , Chieh-Cheng Huang a,g , Cheng-Tse Wu a,g , Shiaw-Min Hwang f , Yen Chang b,h, ⁎, Hsing-Wen Sung a,g, ⁎⁎ a Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC b Division of Cardiovascular Surgery, Veterans General Hospital at Taichung, Taipei, Taiwan, ROC c Division of Cardiology, Veterans General Hospital at Taichung, Taiwan, ROC d Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taoyuan, Taiwan, ROC e Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Linkou, Taiwan, ROC f Bioresource Collection and Research Center, Food Industry Research and Development Institute, Hsinchu, Taiwan, ROC g Institute of Biomedical Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC h College of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC abstract article info Article history: Received 12 April 2013 Accepted 23 June 2013 Available online 1 July 2013 Keywords: Myocardial infarction Cell-based therapy Cell delivery Neovascularization Tissue engineering Cell-based therapeutic neovascularization is a promising method for treating ischemic disorders. In this work, human umbilical vein endothelial cells (HUVECs) were thoroughly premixed with cord-blood mesenchymal stem cells (cbMSCs) and cultivated to form three-dimensional (3D) cell aggregates for cellular cardiomyoplasty. In the in vitro study, tubular networks were formed at day 1 after the co-culturing of dissociated HUVECs and cbMSCs on Matrigel; however, as time progressed, the grown tubular networks regressed severely. Conversely, when 3D cell aggregates were grown on Matrigel, mature and stable tubular networks were observed over time, under the influence of their intensive cell–extracellular matrix (ECM) interactions and cell–cell contacts. 3D cell aggregates were transplanted into the peri-infarct zones of rats with myocardial infarction (MI) via direct intramyocardial injection. Based on our pinhole single photon emission computed tomography (SPECT) myocardial-perfusion observations, echocardiographic heart-function examinations and histological analyses, the engrafted 3D cell aggregates considerably enhanced the vascular densities and the blood flow recovery in the ischemic myocardium over those of their dissociated counterparts, thereby reducing the size of perfusion defects and restoring cardiac function. These results demonstrate that the intramuscular delivery of 3D cell aggregates of HUVECs/cbMSCs can be a valuable cell-based regenerative therapeutic strategy against MI. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Massive cell death has commonly been observed following myocar- dial infarction (MI), as a result of the reduced or obstructed blood flow, resulting in the formation of fibrous non-contractile scars that ultimate- ly lead to progressive heart failure [1,2]. Cell-based neovascularization is emerging as an option to ensure sufficient tissue perfusion and pre- serve the viability of ischemic tissues, thereby restoring heart functions [3–6]. Therapeutic neovascularization can be achieved by transplanting the cellular components of vessel walls — endothelial cells (ECs) and vascular smooth muscle cells (SMCs) — directly into the ischemic tissues [7]. Neovascularization depends on not only specific cell– extracellular matrix (ECM) interactions but also cell–cell contacts [8]. Typical cell transplantation involves the administration of dissoci- ated cells via direct intramuscular injection. In this process, a large proportion of the transplanted cells are either washed away by local bleeding or squeezed out from the injected sites by cardiac contraction, due to their insufficiency in physical size [9,10]. Employing a thermo- responsive methylcellulose (MC) hydrogel system, we have previously developed a method in which human umbilical vein ECs (HUVECs) and cord-blood mesenchymal stem cells (cbMSCs) self-aggregate together in a three-dimensional (3D) organization. Our earlier study verified the potential of cbMSCs to differentiate into SMCs [11]. The developed 3D cell aggregates could reach adequate physical size to be trapped in the muscular interstices, thus enhancing the retention of the transplanted cells at the sites of the cell graft [12,13]. Additionally, by using a mouse model with hindlimb ischemia, we demonstrated that the transplantation of 3D HUVEC/cbMSC aggregates promoted ischemic neovascularization and the salvaging of limbs more effectively than their dissociated counter- parts [11]. Journal of Controlled Release 172 (2013) 419–425 ⁎ Corresponding author. ⁎⁎ Correspondence to: H.-W. Sung, Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan 30013. Tel.: +886 3 574 2504. E-mail addresses: ychang@vghtc.gov.tw (Y. Chang), hwsung@che.nthu.edu.tw (H.-W. Sung). 1 The first four authors (D.Y. Chen, H.J. Wei, W.W. Lin and K.J. Lin) contributed equally to this work. 0168-3659/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jconrel.2013.06.025 Contents lists available at ScienceDirect Journal of Controlled Release journal homepage: www.elsevier.com/locate/jconrel