Authors:
J. L. Young; A. J. Engler
Summary:
Recent studies have reported the importance of extracellular matrix (ECM) elasticity in directing adult stem cells toward a specific lineage. However, such tissue-specific ECM elasticity arises from developmental changes in matrix and suggests that traditional cultures on ECM-coated glass or gels with a static set of intrinsic parameters may not be the most appropriate physical environment, especially for highly contractile cells such as cardiomyocytes. Rather, such cells should be cultured in the appropriate physical conditions that mimic tissue progression, measured here by atomic force microscopy (AFM) as changing from soft, pre-cardiac mesoderm at E1, Emeso ~ 0.2 -1 kPa, to a contractile heart tube at E3, Etube ~ 3.4 ± 0.5 kPa, and finally to mature, less compliant cardiac tissue by E17, Ecardio ~ 8.2 ± 1.3 kPa. Limited differentiation or maintenance of a contractile phenotype even on compliant materials hints that such a dynamic property may be an important differentiation regulator, and to mimic this temporal ECM change in the myocardium, we have made an engineered “smart” material. Using the AFM measurements as design parameters, the elastic properties of collagen, fibronectin and hyaluronic acid (HA) matrices were tuned to mimic in situ temporal elasticity changes via time-dependent poly(ethylene glycol) diacrylate (PEGDA) crosslinking. Stem cells were plated onto these engineered matrices, and improved cardiomyocyte differentiation was characterized by immunofluorescence after staining for proteins that mark cardiogenesis. Results from this experiment will not only have a profound impact on the field of cardiovascular engineering, but will influence the way in which many cellular regenerative therapies are conducted.
Source:
2009 Annual Meeting of the American Society for Cell Biology (ASCB); ID# 2003/B382, Exhibit Halls D-H, 7:30AM-6:00PM (12/08/09)