Hyaluronic Acid Incorporation into Scaffolds for Bone and Cartilage Regeneration - Hyaluronic Acid for Biomedical and Pharmaceutical Applications - page 32

Figure 2.3 Histological sections, with immunohistochemical
staining for CS to display the matrix produced, of in vitro cultures
at day 14 of encapsulated human MSC in a two-component
scaffold of methacrylated HA and a methacrylated lactic acid-
HA copolymer, where the degradation rate was controlled by the
percentage of the lactic acid-HA copolymer. (a) 0% lactic acid-HA
copolymer, slowest degrading; (b) 25% lactic acid-HA copolymer,
slow degrading; (c) 50% lactic acid-HA copolymer, intermediate
degrading; (d) 75% lactic acid-HA copolymer, fast degrading.
Scale bar = 100 µm. Reproduced with permission from S. Sahoo,
C. Chung, S. Khetan and J.A. Burdick, Biomacromolecules , 2008,
9 , 4, 1088. ©2008, American Chemical Society [65]
2.6.3 Delivery of Growth Factors
Hybrid scaffolds have also been tested as growth factor delivery
vehicles, especially for the TGF-β superfamily. TGF-β1 was
immobilised, via EDC crosslinking, on the surface of a gelatin scaffold
copolymerised with HA and CS. These TGF-β1 immobilised sponges
led to the suppression of osteogenic gene expression of seeded porcine
chondrocytes and enhanced chondrogenic gene expression, when
compared to sponges without TGF-β1 [75]. More recently, TGF-β3
was immobilised by EDC crosslinking onto a PLGA hybrid scaffold
composed of HA, CS, and collagen and seeded with rabbit bone
marrow MSC. The constructs not only produced abundant cartilage
ECM in vitro but also led to in vivo chondrogenic differentiation of
autologous MSC in rabbit chondral defects [76].