Hyaluronic Acid Incorporation into Scaffolds for Bone and Cartilage Regeneration - Hyaluronic Acid for Biomedical and Pharmaceutical Applications - page 40

calvarial defect model, compared to scaffolds with Bio-Oss or other
HA-only formulations [108].
2.8 Surface Treatments with Hyaluronic Acid for Bone
Regeneration
HA can further be used to improve the bioactivity of other 3D
scaffolds for bone regeneration by impregnating or coating porous
scaffolds or as a surface modification.
2.8.1 Hyaluronic Acid Coating on Three-dimensional
Porous Scaffolds
An early study used high MW HA as a carrier of BMP-2 to coat
titanium fibre mesh implants [109]. The scaffolds with HA, BMP-2,
or the combination of both all led to increases in the area fraction
of new bone formed in a rat calvarial model when compared to the
untreated titanium implants, suggesting that HA itself may have a
positive effect on bone generation in vivo [109]. More recently, a
combined HA and fibrin surface coating was used to incorporate
BMP-2 onto poly(e-caprolactone) (PCL)/PLGA scaffolds made via
solid free-form fabrication ( Figure 2.6 ) [110]. This coating released
BMP-2 in a sustained manner and supported the in vitro attachment
and alkaline phosphatase activity of adipose-derived stromal cells
(ASC) [110]. In vivo , undifferentiated ASC combined with the BMP-
2-loaded and fibrin/HA-coated scaffolds resulted in greater bone
formation and mineralisation when compared to uncoated scaffolds
or scaffolds without BMP-2 [110].
Without growth factors, a mixture of HA, methylated collagen, and
terpolymer was used to coat porous PCL meshes by polyelectrolyte
complex coacervation [111]. The coated scaffolds supported
better cell seeding efficiency and distribution as well as led to an
upregulation of osteogenic gene expression (alkaline phosphatase,
osteocalcin, and bone sialoprotein I and II) by MSC in vitro [111].