Microenvironment Design for Stem Cell Fate Determination - Tissue Engineering: Cell-Surface Interactions for Tissue Culture - page 239

Fig. 4 Upper panel Alginate scaffolds containing short motifs of ECM adhesion proteins such as
RGD encouraged hMSCs to spread and attach to the matrix (left), whereas on unmodified
scaffolds (right) only cell-cell interactions were seen in 1-week hMSC constructs (collagen
fibers, green; nuclei, red). Lower panel In the RGD-immobilized cell constructs, the production/
secretion of collagen type II, a major component in the cartilaginous ECM, was more pronounced
and the cells had the round morphology of committed chondrocytes (left), compared to
unmodified alginate (type II collagen, red; vimentin, green)(bar:20lm) (reprinted by permission
from [ 81 ])
cardiac tissue regeneration, as judged by expression of cardiac cell markers, the
arrangement of well-developed myocardial fibers and the formation of contractile
tissue [ 137 ].
Other adhesive peptide fragments were identified and shown to have inductive
properties. For instance, Martino et al. [ 55 ] were able to isolate peptide fragments
from fibronectin that presented different specificities for the integrin a5b1. Few of
them were found to have an increased specificity for a5b1 in contrast to the
relatively promiscuous integrin binding of fibronectin. Interestingly, the presence
of those peptides enhanced osteogenic differentiation of hMSCs in 2D and 3D
fibrin matrix system, compared with the full-length protein, which provides both
pro- and anti-differentiative cues in the natural MSC niche. In contrast, the
attachment, spreading and proliferation were comparable with that on full-length
fibronectin [ 55 ].