Biomedical Engineering Reference
In-Depth Information
The use of cells, from differentiated chondrocytes to expanded cells and various adult and
embryonic stem cells, for
in vitro
cartilage tissue engineering seeks to improve upon or replace
the function of injured cartilage tissue.
Desirable characteristics for cartilage repair scaffolds include biocompatibility, the capacity to
bear load, cell attachment, proliferation, and metabolism, and a degradation rate that matches
tissue formation.
Scaffolds can come in several natural or synthetic forms.
Natural scaffolds that have been studied for cartilage engineering include collagen, alginate,
agarose, chitosan, fibrin glue, hyaluronic acid-based materials, and reconstituted tissue matri-
ces.
Synthetic materials include poly-glycolides, poly-lactides, poly-caprolactone, poly-ethylene
glycol, and many others.
Natural and synthetic materials can be combined to form composite scaffolds, such as infil-
trating a fibrous mesh with a hydrogel to form one construct.
Cartilage tissue engineering has also been attempted without the use of scaffolds in combina-
tion with biochemical and biomechanical stimuli.
Self-assembly, a scaffoldless tissue engineering approach, has recently been demonstrated to
result in neocartilage of clinically relevant dimensions and with functional properties approach-
ing those of native tissue.
Bioactive molecules can be soluble or tethered, with intended effects being anabolic or catabolic,
or even structural, in improving the functional properties of engineered cartilage.
TGF-
β
, BMP, IGF, bFGF, and many other growth factors in their soluble forms have been
applied in different concentrations, dosage frequencies, and combinations to engineer cartilage.
Proteins and peptide coatings and modifications have been used to improve chondrocyte
response to biomaterials. These include collagen, vitronectin, CMP, and many amino acid
sequences such as RGD.
Micropatterning can apply proteins and peptides to effect phenotypical and morphological
changes in chondrocytes and other cells.
