(145g) Evoking a Mature Smc Phenotype in Mouse Embryonic Progenitor Cells

The profound effects of ECM-associated
biochemical signals on cell behavior have long been recognized. However,
the impact of these biochemical signals on stem cell or progenitor cell
differentiation have proven difficult to explore in a controlled manner, since most synthetic and natural materials adsorb a range of
plasma proteins from the cell culture media. These adsorbed proteins are major
determinants of cell behavior, in addition to any molecule deliberately added
by the researcher. For controlled investigation of the effects of specific
biochemical stimuli on cellular response, we therefore need a scaffold material
that is essentially ?non-biofouling?. Poly(ethylene glycol) diacrylate (PEGDA)
is a ?non-biofouling? scaffold, and thus, in the absence of biochemical
modification, presents a biochemical ?blank slate? to cells. The photoactivity
of PEGDA permits desired biochemical moieties to be readily conjugated into the
PEGDA hydrogels at defined levels. In the present work, we investigated the
efficacy of defined biochemical stimuli on driving mouse embryonic progenitor (10T½)
cells toward a mature smooth muscle cell (SMC)
phenotype. To explore these effects, mouse embryonic progenitor cells
were incorporated into PEGDA hydrogels into which defined levels of collagen
type IV, fibronectin, laminin, fibrinogen, or heparin had been conjugated. Each
of these molecules have been implicated in SMC differentiation or in
maintenance of a mature SMC phenotype. 10T½ mouse embryonic progenitor cells
encapsulated in hydrogels containing heparin and fibrinogen showed
significantly higher levels of SMC markers SM-a-actin,
calponin h1, and SM-g-actin than gels
containing laminin or fibronectin. Similarly, collagen and elastin levels were
higher in the fibrinogen and heparin hydrogels than in laminin and fibronectin
gels. Focused microarray analyses indicate that variable modulation of the Wnt
pathway may underlie the differing responses observed in the present study.