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Unformatted text preview: nce of CM from
hMSC cultures within PVGLIG/RGD–alginate, as compared to
RGD–alginate. Upon induction, hMSC were able to diﬀerentiate
along the osteoblastic lineage in both types of matrices. As
depicted in Fig. 7A and B (cytostaining and colorimetric assays, 3288 | Soft Matter, 2013, 9, 3283–3292 Fig. 5 Physico-chemical properties of binary alginate hydrogels composed of
50% LMW alginate (grafted or not with PVGLIG) and 50% HMW alginate (grafted
or not with RGD) analyzed by DMA (viscoelastic properties) and cryoSEM
(microstructure): (A) E0 and tan d as a function of the amount of PVGLIG grafted to
the LMW fraction (L0 to L200). (B) E0 and tan d values of the hydrogel formulations
used in the cell culture studies, loaded or not with MSC, 24 h after crosslinking.
Results are presented as mean Æ SD (n ¼ 5) and are representative of at least 3
independent experiments. No statistical diﬀerences were found between the
tested groups. (C) Microstructure of MSC-laden hydrogels at 24 h post-entrapment illustrates the similarities between the samples. respectively), ALP activity was greatly increased aer 21 days in
OM vs. BM, and was slightly higher in MMP-sensitive matrices.
As expected, hMSC remained metabolically active aer 3
weeks of culture (Fig. 7C) under all the tested conditions.
Zymography analysis of CM showed that under all tested
conditions the secretion of MMP-2 decreased from day 7 to day
21 (Fig. 7D). Only a slight decrease of MMP-2 activity in OM
compared to BM was observed. However, and most importantly,
the amounts of both latent and active MMP-2 forms were mainly
up-regulated in PVGLIG/RGD–alginate matrices, compared to
RGD-matrices at these time points. This journal is ª The Royal Society of Chemistry 2013 View Article Online Downloaded by State University of New York at Buffalo on 16/04/2013 03:56:51.
Published on 08 February 2013 on http://pubs.rsc.org | doi:10.1039/C3SM27560D Paper Soft Matter Fig. 7 3D-culture of MSC within MMP-sensitive (PVGLIG/RGD–alginate) and
MMP-insensitive (RGD–alginate) hydrogels under osteogenic (OM) vs. basal (BM)
conditions: (A) ALP activity, showing the positive staining for both hydrogels
(representative picture of BM for both hydrogels is presented, original magniﬁcation 63Â) and (B) ALP activity quantiﬁcation at day 21 is signiﬁcantly higher for
both samples in OM compared to BM; (C) cell metabolic activity at day 21 in
relation to day 1 (resazurin assay). (D) MMP-2 activity in 3D-culture supernatants
from days 7 and 21 (gelatine-zymography). Data are representative of at least 2
independent experiments. Quantitative results are presented as mean Æ SD
(n ¼ 3). * denotes statistically signiﬁcant diﬀerences (p < 0.05), as determined by
the non-parametric Kruskal–Wallis test, followed by Dunn's post-test of the
selected groups. Fig. 6 Behaviour of MSC after 1 week of 3D-culture within MMP-sensitive
(PVGLIG/RGD–alginate) (B, D, and F) and MMP-insensitive (RGD–alginate)...
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