The role of integrin α2 in cell and matrix therapy that improves perfusion, viability and function of infarcted myocardium

Injectable delivery matrices hold promise in enhancing engraftment and the overall efficacy of cardiac cell therapies; however, the mechanisms responsible remain largely unknown. Here we studied the interaction of a collagen matrix with circulating angiogenic cells (CACs) in a mouse myocardial infarction model. CACs + matrix treatment enhanced CAC engraftment, and improved myocardial perfusion, viability and function compared to cells or matrix alone. Integrin-linked kinase (ILK) was up-regulated in matrix-cultured CACs. Integrin alpha 2 beta 1 blocking prevented ILK up-regulation, significantly reduced the adhesion, proliferation, and paracrine properties of matrix-cultured CACs, and negated the benefits of CACs + matrix therapy in vivo. Furthermore, integrin alpha 5 was essential for the angiogenic potential of CACs on matrix. These findings indicate that the synergistic therapeutic effect of CACs + matrix therapy in MI requires the matrix to enhance CAC function via alpha 2 beta 1 and alpha 5 integrin signaling mechanisms, rather than simply delivering the cells. (C) 2014 Elsevier Ltd. All rights reserved.