Hyaluronic Acid Incorporation into Scaffolds for Bone and Cartilage Regeneration - Hyaluronic Acid for Biomedical and Pharmaceutical Applications - page 41

Cartilage Regeneration

Similarly, a combined collagen and sulfated HA coating on PCL-
co -lactide scaffolds increased alkaline phosphatase activity and
gene expression for Runx-2, alkaline phosphatase, and osteopontin
by MSC, again in vitro [112]. HA has also been used to improve
naturally-derived scaffolds. For example, soaking of an absorbable
collagen sponge in a solution of 1% HA led to improved healing in
a rat calvarial critical size defect model [113].

2.8.2 Surface Treatment with Hyaluronic Acid

A number of implant materials, such as ceramics and titanium,
have been developed for bone repair because of their mechanical
properties; however, their integration into bone tissue or interactions
with bone cells could be improved. Therefore, the modification of
these materials by surface treatment with HA has been explored.
For example, a photopolymerised HA hydrogel, incorporating either
GDF-5 or BMP-2, was used as a surface treatment for zirconium
oxide and led to improved cell proliferation and differentiation of
MG63 cells, a cell line derived from human osteosarcoma, in vitro
[114]. Interestingly, titanium-adhesive nanoparticles, composed of
a self-assembling PLGA- g -HA copolymer and functionalised with
catechol groups on the surface, were prepared to entrap insulin-like
growth factor-1 and BMP-2 through interactions with the negatively-
charged HA [115]. These particles led to increased attachment,
spreading, proliferation, and alkaline phosphatase activity of human
adipose-derived stem cells cultured on treated titanium surfaces [115].
Similarly, a catechol-modified HA was used to bind to titanium
substrates; the HA was further covalently functionalised with
VEGF via EDC chemistry [116]. These functionalised surfaces led
to increased attachment, alkaline phosphatase activity, and calcium
deposition by MC3T3-E1 cells in vitro [116].