ENGINEERING PEPTIDES IN HYDROGELS FOR CARTILAGE TISSUE REGENERATION - Biologically-Responsive Hybrid Biomaterials - page 321

A
B
C
Fig. 3. Chemical structures for PEGDA (A), a bifunctional peptide containing RGD and MMP-
sensitive motifs, CPENFFGRGDSG (B) and a RGD peptide, CRGDSG (C). (Reprinted with
permission from Salinas CN, Anseth KS (2008) Biomaterials 29(15): 2370 and with permission
from Elsevier Ltd, Copyright © 2008).
found to be lower than that in RGE (a non-adhesion peptide)-modified alginate,
even though increased proliferation in RGD-modified alginate was observed
[264]. The introduction of MMP-13 cleavage motif (PENFF) to the RGD peptide
sequence could enable cellular responsive release of RGD peptides from the
hydrogels along with the differentiation process of MSCs [273]. In this study, the
bifunctional peptide (CPENFFGGRGDSG) was incorporated in PEG hydrogels
via photoinitiated mixed-mode thiol-acrylate addition with PEG dimethacrylate
( Figure 3 ). Therefore, the peptide was only pendantly attached since only one
cysteine in the sequence. hMSCs encapsulated in hydrogels with cleavable RGD
peptides produced 10 times as much GAG as those in hydrogels with uncleavable
RGD peptides by day 21 of culture. However, the cell viability was observed
to be decreasing dramatically after day 11 culture in chondrogenic medium