MMP-12 activity during vascular remodelling
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Date
08/07/2017Author
Stott, Holly Rosannah
Metadata
Abstract
Matrix metalloproteinases (MMPs) are required for tissue remodelling processes, including
angiogenesis. MMP activity is generally proangiogenic but MMP-12 is suggested to be
antiangiogenic and its precise role is still unclear. The work in this thesis describes the
synthesis of an MMP-12 inhibitor and activity probe to address the hypothesis that MMP-12
inhibits angiogenesis.
An inhibitor, synthesised in-house, selectively inhibited MMP-12 in in vitro recombinant
enzyme assays. An activity probe, also synthesised in-house, was selective for MMP-12 in in
vitro recombinant enzyme assays.
The function of MMP-12 during angiogenesis was assessed using murine models of
angiogenesis; the in vivo sponge implantation, and the ex vivo aortic ring assays. Angiogenesis
and MMP activity were imaged in vivo in sponges in C57Bl6/J mice over 7 − 21 days (D)
using commercial probes (MMPSense™ and AngioSense™). MMP-12 protein concentration
and activity were higher in sponges during early angiogenesis (D 3 − 7) when gene expression
of vascular endothelial growth factor (a proangiogenic marker) was also high. Gene expression
for MMP-12 and platelet-derived growth factor receptor (a marker of vascular maturation)
were both higher on D 21 as angiogenesis started to stabilise. The MMP-12 activity probe was
unsuccessful in selectively detecting MMP-12 activity in sponge lysate mixtures from D 7 −
21.
Administration of an MMP-12 inhibitor did not increase angiogenesis in the sponges in vivo.
Additionally, sponges implanted in MMP-12-/- mice did not exhibit significant changes in
angiogenesis or MMP activity when imaged in vivo using commercial probes (MMPSense™
and AngioSense™) on D 7. Supporting this, histological analysis of the sponges (removed on
D 21) showed that deletion of MMP-12 also did not increase angiogenesis within the sponges.