Combining cell sheet technology and electrospun scaffolding for engineered tubular, aligned, and contractile blood vessels Shahrzad Rayatpisheh a , Daniel E. Heath b , Amir Shakouri c , Pim-On Rujitanaroj a , Sing Yian Chew a , Mary B. Chan-Park a, * a School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore b Biosystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology,1 CREATE Way, Singapore 138602, Singapore c School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore article info Article history: Received 15 November 2013 Accepted 13 December 2013 Available online 8 January 2014 Keywords: Cardiovascular tissue engineering Contractile phenotype Cell sheet engineering NIPAm Electrospinning abstract Herein we combine cell sheet technology and electrospun scaffolding to rapidly generate circum- ferentially aligned tubular constructs of human aortic smooth muscles cells with contractile gene expression for use as tissue engineered blood vessel media. Smooth muscle cells cultured on micro- patterned and N-isopropylacrylamide-grafted (pNIPAm) polydimethylsiloxane (PDMS), a small portion of which was covered by aligned electrospun scaffolding, resulted in a single sheet of unidirectionally aligned cells. Upon cooling to room temperature, the scaffold, its adherent cells, and the remaining cell sheet detached and were collected on a mandrel to generating tubular constructs with circumferentially aligned smooth muscle cells which possess contractile gene expression and a single layer of electrospun scaffold as an analogue to a small diameter blood vessel’s internal elastic lamina (IEL). This method improves cell sheet handling, results in rapid circumferential alignment of smooth muscle cells which immediately express contractile genes, and introduction of an analogue to small diameter blood vessel IEL. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The current gold standard in coronary artery bypass surgery is a blood vessel autograft where a vessel explanted from the patient is attached to the diseased artery in order to reroute blood around the obstruction and restore blood flow to the heart. However, this strategy is suboptimal due to second site morbidity, a limited supply of autografts, and loss of patency [1e5]. Similarly, the use of synthetic grafts in coronary artery (and other small diameter ar- teries) augmentation is clinically unsuccessful due to loss of patency which occurs due to thrombus accumulation on the lumen of the graft [6e8]. To address the current limitations in treating small diameter blood vessel disease, researchers in the medical community have strived to develop a tissue engineered small diameter artery for more than two decades [9e11]. Early approaches towards blood vessel tissue engineering are termed “top down” approaches and are based on seeding cells on porous scaffolds or embedding cells in hydrogels to support the cells and achieve the formation of tubular tissue engineered constructs. However, the archetypal approach of using biodegradable scaffolds to provide initial strength for the newly constructed vessels raises concerns about foreign body reaction, inflammation and infection due to bacterial colonization [12e15]. Furthermore, the blood vessel is a multi-layered and three dimensional tissue, and the successful function of the tissue is based on the complex anatomy of the vessel [16]. Recapitulating the complex structure of the blood vessel through top down tissue engineering techniques and generating clinically successful grafts for bypass surgery have yet to be achieved. “Bottom up” tissue engineering strategies were later developed. In this approach, individual sections of the tissue are generated and these sections are then brought together to generate a tissue engineered construct which replicates native tissue structure with higher fidelity. Furthermore, bottom up approaches tend to be scaffold free which promises less inflammation and toxicity which may occur due to scaffold degradation [17e21]. A scaffold-free and bottom up approach to human blood vessel tissue engineering e cell sheet tissue engineering e was introduced more than a decade ago by L’Heureux et al. [21]. In this technique non-aligned sheets of smooth muscle cells (SMCs) are cultured and rolled over a mandrel to create the medial layer of the blood vessel, sheets of non-aligned fibroblasts are then rolled outside SMCs to create the outer layer of the blood vessel (tunica adventitia), and * Corresponding author. Tel.: þ65 6790 6064; fax: þ65 6794 7553. E-mail address: mbechan@ntu.edu.sg (M.B. Chan-Park). Contents lists available at ScienceDirect Biomaterials journal homepage: www.elsevier.com/locate/biomaterials 0142-9612/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.biomaterials.2013.12.035 Biomaterials 35 (2014) 2713e2719