Abstract 9256: Overexpression of C-Terminal Domain of Talin-1 Enhances Survival, Migration, and Differentiation of Human Cardiac Stem Cells
Background: Cardiac stem cells (CSCs) have emerged as a promising therapy for cardiac repair after acute MI. Talin-1 is a key downstream signaling mediator of integrins. The C-terminal part of the talin rod, talin C, contains binding sites and regulatory elements that convey essential aspects of talin function in cells. In this study, we aimed to investigate the role of talin C in the survival and migration of CSCs and their differentiation into adult cardiomyocytes.
Methods: Utilizing a baculovirus-mediated protein expression system in mammals (BacMam), we overexpressed talin C in c-kit-positive CSCs isolated from human right atrial appendages. In a TNF-α -treated cell culture system, we examined the survival of talin C-expressing CSCs by measuring LDH release. Adhesion of CSCs to fibronectin was measured by colorimetric Azur dye assay. Cell migration at baseline and with high glucose (HG) was studied by in vitro scratch assay. Differentiation of CSCs to adult cardiomyocytes was measured by flow cytometry using troponin I as cardiac lineage marker.
Results: Overexpressed talin C was localized to intracellular adhesion complexes and actin filaments. Overexpression of talin C inhibited TNF-α-induced cytotoxicity of CSCs (optical density: TNF-α, 0.713±0.11; TNF-α+talin C, 0.33±0.02, P<0.001, N=10, each group). Talin C overexpression prevented HG-induced loss of cell adhesion (optical density: HG, 0.92±0.07; HG+talin C, 1.05±0.046; p=0.04, N=8, each group), and enhanced CSC migration (migration index: HG, 15.34±2.7; HG+talin C, 34±4.7; p=0.03, N=3-4, each group). Furthermore, talin C overexpression increased the commitment of CSCs to a cardiac lineage (% of troponin-I positivity: control, 66.13±4.07; talin C, 80.53±1.79; p=0.05).
Conclusions: This study demonstrates a novel role for talin C in mediating i) increased CSC survival in a high pro-inflammatory environment, ii) increased CSC migration in HG cell growth environment, and 3 iii) enhanced commitment of CSCs to a cardiac lineage in vitro. These findings suggest that talin C enhancement may improve CSC survival, homing and differentiation after transplantation.
- © 2011 by American Heart Association, Inc.