Research Team Member

Roger Markwald
University of South Carolina-Charleston
Roger Markwald The Co-PI is a developmental biologist with extensive experience in cardiovascular cellular and molecular morphogenesis. He has contributed to the description of the origin and mechanisms of cardiac cushion formation as well as studies on examining genes expressed during both heart/cushion and limb development. Much of his work has focused on the role of the extracellular matrix in embryonic cell proliferation, migration and differentiation. His work includes the first studies showing that a subset of cardiac endothelial cells acquire the potential to transform into cushion mesenchyme in response to a multicomponent complex secreted by the myocardium called adherons. The latter act as extracellular carriers for growth factors of the TGF beta gene family, which specifically activate endothelial transformation through BMP receptor 1b (Alk6) signaling. Recent microarray studies in his laboratory have identified two fasciclin genes - periostin and igH3 - which function as adhesive extracellular proteins that promote remodeling of cushion mesenchyme into mature valve leaflets through interactions with cell surface integrins and interplay with other matrix molecules such as fibronectin, fibrillins, collagen, hyaluronan, proteoglycans. Changes in the expression of periostin and igH3 correlate closely with changes in the viscoelastic properties of cushions over time. Collaborative studies with Dr. Forgacs and his team are in progress using genetically modified mice to confirm that viscoelastic changes in cushions are mediated through periostin and igH3 using tensiometric and interfacial surface tension assays. The Co-PI will provide embryological and molecular expertise and will supply samples of cushion and limb tissues from mice null for periostin or igH3. The Co-PI has developed in vivo-like dynamic assays in which the role of biomechanical signaling (cyclical stretch and sheer stress) upon regulation of periostin/ igH3 expression can be studied in cushions undergoing valvulogenesis. He is interested in using bioprinting as a means to extend these studies to include scaffolds seeded with cells and growth factors.