Tissue transglutaminase is essential for integrin-mediated survival of bone marrow-derived mesenchymal stem cells

¹ Cardiovascular Research Institute, Cardiology Division, Yonsei University College of Medicine, Seoul, Korea
² Department of Thoracic and Cardiovascular Surgery, Yonsei University College of Medicine, Seoul, Korea
³ Department of Chemical Engineering, Hanyang University, Seoul, Korea
⁴ Department of Orthopedic Surgery and department of Molecular Science and Technology, Ajou University, Suwon, Korea
⁵ Department of Applied Statistics, Yonsei University, Seoul, Korea

^* To whom correspondence should be addressed. E-mail: kchwang{at}yumc.yonsei.ac.kr.

	Abstract

Autologous mesenchymal stem cell (MSC) transplantation therapy for repair of myocardial injury has inherent limitations due to the poor viability of the stem cells after cell transplantation. Adhesion is a prerequisite for cell survival and also a key factor for the differentiation of MSCs. As a novel pro-survival modification strategy, we genetically engineered MSCs to over-express tissue transglutaminase (tTG), with intention to enhance adhesion and ultimately cell survival after implantation. tTG-transfected MSCs showed a 2.7-fold and greater than a 2-fold increase of tTG expression and surface tTG activity, respectively, leading to a 20% increased adhesion of MSCs on fibronectin (Fn). Spreading and migration of tTG-MSCs were increased 4.75% and 2.52%, respectively. Adhesion of tTG-MSCs on cardiogel, a cardiac fibroblast-derived 3D matrix, showed a 33.1% increase. Down-regulation of tTG by transfection of small interfering RNA (siRNA) specific to the tTG resulted in markedly decreased adhesion and spread of MSCs on Fn or cardiogel. tTG-MSCs on Fn significantly increased phosphorylation of focal adhesion related kinases, FAK, Src and PI3K. tTG-MSCs showed significant retention in infarcted myocardium by forming a focal adhesion complex and developed into cardiac myocyte-like cells by the expression of cardiac-specific proteins. Transplantation of 1 X 10⁶ MSCs transduced with tTG into the ischemic rat myocardium restored normalized systolic and diastolic cardiac function. tTG-MSCs further restored cardiac function of infarcted myocardium as compared to MSC transplantation alone. These findings suggested that tTG may play an important role in integrin-mediated adhesion of MSCs in implanted tissues.