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Unformatted text preview: culture in
MMP-sensitive vs. MMP insensitive matrices. Even if diﬀerences
were not statistically signicant, the same trend has been
consistently found between diﬀerent experiments. However, to
better address the eﬀect of MMP-sensitive hydrogels in hMSC
diﬀerentiation, further studies will have to be carried out to
This journal is ª The Royal Society of Chemistry 2013 View Article Online Paper
evaluate the expression of more specic osteogenic markers
using quantitative assays. Moreover, as observed in 2D, hMSC
primarily secreted MMP-2 according to gelatine-zymography
data. Importantly, the study showed that although the amounts
of secreted MMP-2 decreased along the culture in OM (as in 2D),
hMSC in MMP-sensitive PVGLIG/RGD alginate hydrogels
expressed higher amounts of MMP-2 than hMSC in control
matrices. 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 5 Conclusions This study focused on the characterization of MMP-sensitive
alginate hydrogels in terms of their enzymatic, physico-chemical and biological properties. The detailed analysis of the MMP
specicity of PVGLIG peptides, and the prospective screening of
MMP expression in hMSC cultures, were essential to better
elucidate the role of diﬀerent MMPs in the degradation of the
proposed MMP-sensitive hydrogels. In fact, MMP-2 and MMP14 appeared to be key protagonists in that process, at least
in vitro. In 3D-cultures, MMP-sensitive alginate hydrogels
promoted cell–matrix and cell–cell interactions, and stimulated
the secretion of proteases (most likely MMP-2) by hMSC, both in
basal and osteogenic conditions. This feature may be advantageous when using MMP-sensitive alginate hydrogels as vehicles
for hMSC delivery in tissue regeneration applications.
Presumably, these materials will not only provide a more
physiological environment to the transplanted cells, but also
facilitate their outward migration into the surrounding host
tissues, where they will be able to participate more actively in
the regeneration process. Acknowledgements
This work was nanced by FEDER funds through the Programa
Operacional Factores de Competitividade – COMPETE and by
Portuguese funds through FCT – Fundaçao para a Ciˆncia e a
Tecnologia, in the framework of the projects Pest-C/SAU/LA0002/
2011 and BIOMATRIX (PTDC/SAU-BEB/101235/2008 and
FCOMP-01-0124-FEDER-010915). KF, FC and CB acknowledge
FCT for SFRH/BD/30057/2006, INEB/Unidade 174/BII-01/2008
and Ciˆncia 2008 program, respectively. FRM acknowledges INL
for her PhD scholarship. The authors are grateful to Maria J.
Oliveira from INEB for her help with the qRT-PCR analysis and
the manuscript revision, to Daniela Silva from CEMUP (Centro
de Materiais da Universidade do Porto) for the CryoSEM analysis, and to Paula Gameiro and Tivadar Mach (FCUP) for their
support to use of the uorometer. References
1 F. Munarin, P. Petrini, M. C. Tanzi, M. A. Bar...
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