SCAFFOLD CONSIDERATIONS FOR OSTEOCHONDRAL TISSUE ENGINEERING - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 793

different layers. Ideally, an implanted scaffold will degrade in vivo
and be replaced by a functional repair tissue. This needs to be accu-
rately tailored in order to ensure that the rate of degradation does
not exceed the rate of native tissue formation to the detriment of
mechanical stability. A study by Solchaga et al . 69 found that faster-
degrading scaffolds resulted in an increase in bone formation, while
slow-degrading scaffolds prolonged the presence of cartilage tissue,
delayed endochondral bone formation, and sustained a thicker car-
tilage layer. However, if bone formation was delayed, the lack of an
appropriate mechanical support for the developing overlying carti-
lage resulted in cracks and discontinuities at the surface. The engi-
neering of osteochondral tissues requires more attention to achieve
a suitable graft solution to reproducibly provide regenerated, func-
tional in vivo cartilage and bone tissues. It is also clear that the
scaffold characteristics will greatly influence the mechanical envi-
ronmenttowhichcellsareexposedonceimplantedintodefectsand
therefore needs careful consideration during the design process.
38.7 Endochondral Ossification, a More Logical Approach
for Osteochondral Tissue Engineering
The fields of tissue engineering and regenerative medicine (TERM)
have improved noticeably in recent years with new developments
and progression in bone and cartilage repair too numerous to dis-
cusshere(forreviewseeRefs.70-78).Despitethisandtheadvances
discussedearlier,veryfewclinicalstudieshavebeenperformedwith
regard to tissue-engineered bone with varying success 79 with even
fewer studies at the bone-cartilage interface. There is currently a
hugedeficitintheavailableoptionsforthemillionsofboneandjoint
replacementproceduresperformedeveryyearworldwide.However,
there are many factors that determine the success of a TERM-based
approach to this issue, and some of these have yet to be addressed
satisfactorilybeforeaTERMtreatmentoptionbecomesviable.Prob-
ably the most important issue of any TERM approach is that of vas-
cularization. Researchers in every field are now aware that it is vital
that constructs/treatments take vascularization into account. This
is crucial at the bone-cartilage interface as discussed earlier. Ideally,