Heart failure is a leading cause of mortality in the world. Current therapies seek to slow the progression of the disease or treat its symptoms, but no therapies are able to effectively stimulate the regeneration of diseased heart tissue. The heart has shown the limited ability to regenerate and the discovery of circulating and resident cardiac progenitor cells offers the new possibility of induced myocardial regeneration. My lab's previous work showed that myocardial injection of a cleavage resistant mutant of the protein SDF-1 was able to improve cardiac function after myocardial infarction. SDF-1 is thought to be important in the homing of progenitor cells to tissue regions and may be responsible for myocardial regeneration and the improvements in cardiac function. My research plan intends to further develop the role of SDF-1 in the migration and differentiation of cardiac progenitor cells. Microfluidic bioreactors will be used in these investigations. These bioreactors offer several advantages over conventional chemotaxis instruments (i.e. Boyden chambers). They allow careful monitoring and control of concentration gradients, direct visualization of migrating cells, and a 3-D scaffold through which cells and chemotactic agents traverse.
My first aim asks whether and to what degree cardiac stem cells exhibit a chemotactic response to SDF-1 and its variants. Chemotactic gradients will be established in the bioreactors and the migration of cells toward the stimulus will be compared to migration toward a control region.
The second aim asks if migrating cells will differentiate during their migratory path or if differentiation only occurs after a cell has reached its final destination. In these experiments both migrating and stationary cells will be induced to differentiate. The number of differentiated cells in each sub-group as well as the specific cellular phenotypes will be noted and compared.
The third aim asks whether the presence of a vascular structure will affect chemotaxis and survival. This phenomenon could explain why increased vascularization may improve cardiac function. Endothelial cells will be co-cultured with cardiac progenitor cells in microfluidics bioreactors. The endothelial cells will organize into tube-like structures and progenitor cells will be induced to migrate in the same direction as the tubular outgrowths. Both the degree of migration, cellular necrosis, and apoptosis shall be measured. The relevance of this project is immense. This work will further characterize how cardiac progenitor cells react to chemotactic stimuli. The work in my laboratory could lead to a chemotactic protein, mutatated and modified so that it can be injected intravenously and home to diseased heart tissue to begin the process of regeneration, perhaps even before a patient arrives at the hospital.
|Amadi, Ovid C; Steinhauser, Matthew L; Nishi, Yuichi et al. (2010) A low resistance microfluidic system for the creation of stable concentration gradients in a defined 3D microenvironment. Biomed Microdevices 12:1027-41|