The
cells produce high amounts of extracellular matrix such as collagen,
proteoglycans and hyaluronic acid. This new matrix is laid down as new
connective tissue. If matrix metalloproteases digest (destroy) new
connective tissue once it is produced from the cells wound healing
cannot progress.
There
will be no new granulation tissue. Keratinocytes are very sensitive to
proteases as they migrate on a provisional matrix composed of
fibronectin and other protease sensitive components. If these are
digested, the cells cannot migrate, epithelialization stalls.
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Click on image to enlarge
MMPs degrade newly formed connective tissue
Keratinocyte migration is crucial for wound closure.
Keratinocytes migrate on a provisional fibronectin matrix. If MMPs
degrade this fibronectin layer (and only fragments persist)
keratinocyte migration stops. Clinically these wounds may have a nice
granulation tissue but epithelialization is slow or missing.
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