The role of extracellular matrix composition and mechanical properties in driving cardiac differentiation of mesenchymal stem cells.
myocardial infarction (MI) generates a scar within the myocardium that can result in
long-term complications for the patient. Considerable effort has been directed toward
cell-based therapies for cardiac repair and regeneration, but these approaches have been
hampered by the non-proliferative nature of adult cardiomyocytes. To overcome this
hurdle, a significant amount of... read moreresearch has been focused on generating cardiomyocytes
from a proliferating pluripotent cell population. A number of successes have been
achieved, but generally suffer from low rates of efficiency that obviate their use in
clinical therapies. However, two areas of research show promise for promoting directed
differentiation in pluripotent stem cells: 1) the use of decellularized extracellular
matrix as a culture substrate and 2) the demonstration that substrate stiffness alone
can direct differentiation. Our hypothesis was that using decellularized cardiac ECM to
mimic the composition of the developing heart in vitro would promote cardiogenesis in
mesenchymal stem cells (MSCs), and that this differentiation would be modulated by
physiologically relevant stiffnesses. Rat MSCs were cultured on polyacrylamide gels of
experimentally determined stiffness that incorporated rat cardiac ECM derived from
specific life points. MSCs were interrogated for expression of the cardiac transcription
markers Nkx2.5, GATA4, Tbx5, Mef2C, cTnI, and MHC at 1 and 3 weeks. MSCs cultured on
neonatal ECM demonstrate the highest expression levels, and the expression is positively
modulated by non-infarct-like stiffnesses. In addition, we began preliminary
investigations into the role of integrin-binding peptide domains on cell signaling, as
well as an exploration of alternate methods for solubilizing total ECM in order to
generate a three dimensional hydrogel from it. This novel, soluble factor-free, cell
culture platform advances the idea of ECM-mediated cell signaling and its ability to
effect pluripotent stem cell differentiation.
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Biomedical Engineering.
Advisor: Lauren Black.
Committee: David Kaplan, and Gordon Huggins.
Keyword: Biomedical engineering.read less