Biomimetic Polysaccharides and Derivatives for Cartilage Tissue Regeneration - Biomimetics: Advancing Nanobiomaterials and Tissue Engineering - page 17

glutaraldehyde. In vitro investigation showed that the cellulose and cel-
lulose/recombinant type II collagen sponges supported the chondrocytes
growth. These sponges provided a nontoxic environment for these cells
and maintained chondrocyte morphology. Crosslinked type II collagen
promoted a slight increase in scaffold stiffness, however, the constructs
remained soft compared with normal articular cartilage, and is therefore a
potential candidate material for cartilage tissue engineering.

1.5 Conclusions and Remarks on Prospects

Despite extensive research conducted on cartilage tissue engineering over
the past four decades, a procedure for a successful repair of damaged car-
tilage still remains elusive. However, many new repair techniques have
recently emerged which have demonstrated promising results in experi-
mental animal models.
The current practice is the direct injection of autologous chondrocytes,
whereas, the future cartilage therapies will most likely utilize complex tis-
sue engineering strategies. For example, chondrocytes growth on fi brous
or sponge 3D scaffolds with controlled pores, pore sizes and excellent
mechanical properties have been demonstrated. They have been shown
to have enhanced cell-cell communication and biological signaling path-
ways for promoting specifi c cartilage regeneration. The hydrogel-based
system has been shown to have high potential for the delivery of chondro-
cyte to a localized area. However, for this system, the crosslinking density
needs to be optimized prior to the cells encapsulation. To evaluate novel
materials strategies an in vitro model needs to be developed to under-
stand how materials and strategy infl uence the chondrocyte proliferation
and maintain the chondrogenic genes' expression while providing a non-
cytotoxic microenvironment. This will provide valuable information that
will allow for the design of in vivo animal study procedures. Designing an
appropriate animal model is an important factor for monitoring cell fate,
infl ammatory response and long-term functional stability. While design-
ing the experiment, it is also important to take into account the variation
of cartilage thickness and different loading distribution in cartilage across
species.
Over the past decade, there have been a growing number of investi-
gations on the in vivo biocompatibility of these materials, with encour-
aging results in terms of host tissue response. However, there remains a
lack of knowledge on the issue of the long-term in vivo studies as well
as the tracking of biodegradation profi le of these polysaccharide-based
polymers. It is now our hope that with greater understanding of cartilage
tissue engineering with a novel materials approach an effective solution to
repair damaged cartilage will be available in the very near future.