Biomedical Engineering Reference
In-Depth Information
8
Chemical Modifications of Hyaluronan
for Therapeutic Applications
Oommen P. Oommen, Shujiang Wang, Jöns Hilborn
and Oommen P. Varghese
8.1 Introduction
Hyaluronic acid (HA) is a naturally occurring polyanionic,
polysaccharide that consists of alternating
N
-acetyl-
d
-glucosamine
and
d
-glucoronic acid with (1→4) interglycosidic linkages. It is the
only non-sulfated glycosaminoglycan present abundantly in the
extracellular matrix (ECM), skin, synovial fluid, lungs and intestine. It
is also present in the intercellular matrix of most vertebrate connective
tissues, especially the skin where it has a protective, hydrating,
stabilising and shock absorbing role. Nearly 15 g of HA is recycled
every day in our body, performing various important biochemical
processes and perform intracellular signalling
via
CD44 receptor that
provides a communication link between the cell and the ECM. It
undergoes fragmentation by catabolic process or metabolism through
the tissues, lymphatics, lymph nodes, blood, liver and kidney [1]
which possess various biochemical roles as discussed below.
8.2 Influence of Molecular Weight on Biological
Function
HA with different molecular weights (MW) (fragmented HA or
the intact macromolecule) in our body play different roles. For
example, high MW HA, which is typically found in loose connective
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