Journal of Biomechanics 41 (2008) 2396–2401 Quantitative evaluation of cardiomyocyte contractility in a 3D microenvironment Jinseok Kim a , Jungyul Park b , Kyounghwan Na a , Sungwook Yang a , Jeongeun Baek a , Euisung Yoon a , Sungsik Choi c , Sangho Lee c , Kukjin Chun d , Jongoh Park e , Sukho Park e,Ã a Nano-Bio Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, Republic of Korea b Department of Mechanical Engineering, Sogang University, #1 Shinsu-dong, Mapo-gu, Seoul 121-742, Republic of Korea c School of Life Science and Biotechnology, Korea University, Anam-dong, Seongbuk-gu, Seoul 136-701, Republic of Korea d School of Electrical Engineering, Seoul National University, San56-1, Shinlim-dong, Gwanak-gu, Seoul 151-742, Republic of Korea e School of Mechanical Systems Engineering, Chonnam National University, 300 Youngbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea Accepted 26 May 2008 Abstract Three-dimensional cultures in a microfabricated environment provide in vivo-like conditions for cells, and have been used in a variety of applications in basic and clinical studies. In this study, the contractility of cardiomyocytes in a 3D environment using complex 3D hybrid biopolymer microcantilevers was quantified and compared with that observed in a 2D environment. By measuring the deflections of the microcantilevers with different surfaces and carrying out finite element modeling (FEM) of the focal pressures of the microcantilevers, it was found that the contractile force of high-density cardiomyocytes on 3D grooved surfaces was 65–85% higher than that of cardiomyocytes on flat surfaces. These results were supported by immunostaining, which showed alignment of the cytoskeleton and elongation of the nuclei, as well as by quantitative RT-PCR, which revealed that cells on the grooved surface had experienced sustained stimuli and tighter cell-to-cell interactions. Crown Copyright r 2008 Published by Elsevier Ltd. All rights reserved. Keywords: Cardiomyocyte; Contractile force; Microcantilever; 3D microenvironment; Grooved surface; Cell-to-cell interactions 1. Introduction Three-dimensional (3D) cell cultures have a wide variety of applications in basic cell and tissue studies (Yin et al., 2004; Entcheva and Bien, 2003; Motlagh et al., 2003), in vivo tissue repair and clinical practice (Curtis et al., 2005; Stoklosowa, 2001). Previous studies have attempted to provide grooved surfaces for cardiomyocytes to mimic their in vivo 3D circumstances, and have shown that the alignment, orientation and shape of the cells were guided by the grooved surfaces (Yin et al., 2004; Entcheva and Bien, 2003; Motlagh et al., 2003). Grooved surfaces have also been shown to alter gene expression, protein localiza- tion, cell signaling, nuclear eccentricity and intracellular calcium dynamics (Yin et al., 2004; Entcheva and Bien, 2003; Motlagh et al., 2003; Dalby et al., 2003). However, until now, there has been no suitable tool to validate and measure the changes of the contractile force of the cardiomyocytes resulting from the topology of adhesion surface. Some studies have reported that the contractile force of cardiomyocytes can be measured by using microfabrication technology (Lin et al., 2000; Tan et al., 2003; Balaban et al., 2001), but they have focused on the measurements of a single cardiomyocyte and the dissected cardiac tissue. Therefore, studies concerning the 3D organi- zation of cardiomyocytes are needed for a more complete understanding of tissue engineering. ARTICLE IN PRESS www.elsevier.com/locate/jbiomech www.JBiomech.com 0021-9290/$ - see front matter Crown Copyright r 2008 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jbiomech.2008.05.036 Ã Corresponding author. Tel.: +82 62 530 1687; fax: +82 62 530 1689. E-mail addresses: jinseok@kist.re.kr (J. Kim), sortpark@sogang.ac.kr (J. Park), naguryong@kist.re.kr (K. Na), swyang@kist.re.kr (S. Yang), myworld100@hanmail.net (J. Baek), esyoon@kist.re.kr (E. Yoon), choi9125@hanmail.net (S. Choi), sangho@korea.ac.kr (S. Lee), kchun@mintlab.snu.ac.kr (K. Chun), jop@chonnam.ac.kr (J. Park), spark@chonnam.ac.kr (S. Park).