Development and Application of Naturally Renewable Scaffold Materials for Bone Tissue Engineering - The Nanoscience and Technology of Renewable Biomaterials - page 306

11.4 Conclusions and Future Directions

Though much innovation continues to drive the development of naturally renewable
materials for bone tissue engineering, much controversy exists as to which materials
exhibit paramount in vivo evidence for direct clinical significance. One of the principle
issues remaining to be addressed is the understanding why some systems allow and/or
promote calcification and skeletal integration while others do not. The combination of
MSCs and growth factors, notably BMP-2, seem to be the current status quo for promot-
ing bone formation in vivo . Work has largely focused on varying the material or carrier
in use. Overall, when choosing which natural material should be used for bone tissue
engineering, one must keep in mind the anatomical location of the defect, i.e. whether
it is a loadbearing or nonloadbearing site, as this will greatly limit the application of
most gelatinous systems that are unable to withstand physiological loading forces for
that defect site. Composite systems of inorganic and organic components have become
popular and a recent review discusses some in use (139). In Vivo work has focused
on examining implanted materials via histology and quantifying radio-opacity compared
to bone controls. These techniques offer merely a glance at what has been achieved
and require more detailed investigatory work before worldwide clinical acceptance. For
instance, few implanted tissue constructs have been examined for the osteogenic proper-
ties of bone such as the organization of osteons or formation of haversian canal systems.
Though much progress has been made, bone tissue engineering is still in its infancy, as
specialized materials are being developed and analyzed for skeletal regeneration.

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