Cell based cardiac repair offers an innovative strategy to repair the heart and all its damaged components. Achieving targeted trafficking of resident stem cell is critical for effective cardiac repair. More recent approaches have focused on taking lessons from molecular programming of cardiac progenitors (CPC) that build the developing heart. During vertebrate development, the heart is the first organ to function and cardiac progenitors are among the first cell lineages to be established from the mesoderm. However, migrations of cardiac progenitors have never been directly observed and the factor(s) controlling their movement are still unknown. We previously described niches of different CPCs in the left atrial appendage (LAA).
Objectives and Methods: We aimed to characterize the LAA CPCs migration factors signatures using their genetic blueprint by gene array combined with both protein Orbitrape MS/MS analysis Osteopontin (OPN) is the most abundant factor related to migratory pathways in CPC lineages(by gene array). This multifunctional molecule enhances motility and chemotaxis of various cells (smooth muscles cells, neuronal stem cells, lymphocytes) and is involved in inflammation, cell adhesion, migration, proliferation and cell survival.
Methods and Results: We have identified several factors that attract CPC in a consistent fashion. Hence, we studied and validated the migration rate of CPC in LAA organotypic slices in 2D and 3D chemotaxis assays. We have identified OPN as an efficient 3D chemotactic agent which also promote CPC spreading, migration and proliferation in vitro by time lapse videomicroscopy, second harmonic multiphoton imaging and impedance on chip measurement. Homig and differentiation of CPC was seen to be consistently enhanced by OPN in Ex vivo organotypic culture of LAA slice in agarose gel for 3D invasion assay, collagen membrane cell morphology assay by SEM analysis, ECM remodeling investigation using HE, MT and PAS-Alcian blue staining.
Conclusion: OPN is a potent factor enhancing migration, homing and proliferationof CPC, which is an important step towards recruiting the heart's own repair capability to address cardiac injuries and prevent heart failure.