Conclusion & Future Perspective
Studies have demonstrated that electrospun nanofiber scaffolds, in combination with cell therapy and drug delivery, have great potential in orthopedic tissue repair and regeneration. Topographic cues rendered by electrospun nanofibers have shown significant influences on the regulation of cell behaviors, including adhesion, migration, proliferation and differentiation.[125] Although mechanical properties of nanofibers can be modulated in a number of ways, such mechanical cues presented from electrospun nanofibers have not been thoroughly investigated for regulating cell behaviors. Future efforts may be devoted to the design of nanofiber scaffolds with a wide range of mechanical properties (i.e., elastic modulus) that can both tailor cell response and match the mechanical properties of a variety of orthopedic tissues. Orthopedic tissues usually contain multiple components. Most nanofiber scaffolds that have been designed so far only recapitulate the fiber organization of orthopedic tissues to a certain extent. Multiple components related to orthopedic tissues should be added to nanofiber scaffolds to fully imitate their compositions (i.e., encapsulation, surface modification or combining hydrogel systems). In addition, based on our knowledge of developmental biology, multiple signaling molecules should be incorporated into nanofiber scaffolds to be released sequentially at various times for orthopedic tissue regeneration in vivo. Electrospun nanofiber scaffolds developed for orthopedic tissue engineering have mainly focused on fiber mats or tubes. Novel approaches with a combination of electrospinning and other techniques (i.e., 3D weaving) should be developed for the creation of 3D nanofiber scaffolds with controlled porosity and anisotropic properties.[126]
The ultimate goal for orthopedic tissue repair and regeneration is to restore the function of damaged orthopedic tissues. Nanofiber scaffolds for repairing and regenerating orthopedic tissue should not only be capable of mimicking their key microstructures, compositions and mechanical properties, but also enable the recovery of functional loss. Recent findings have demonstrated the ability to directly form cell-laden nanofibers in relatively large quantities using cell electrospinning. Such an approach could be useful for constructing 3D functional tissues for repairing and regenerating damaged orthopedic tissues.[127,128] Although electrospun nanofiber scaffolds have been widely examined for orthopedic tissue repair and regeneration, most studies are still in their infancy and are limited to in vitro studies. In order to facilitate the translational research of newly designed electrospun nanofiber scaffolds for repairing orthopedic tissue injury, more in vivo and clinical studies will be needed to comprehensively test their performance. Although there are various preclinical efforts in the field of nanofiber scaffold development for orthopedic tissue regeneration, perhaps very few will reach clinical trial. However, it is expected that the clinical trials will be conducted for some nanofiber scaffolds that are currently in development in laboratories over the next 5–10 years.
Nanomedicine. 2013;8(9):1459-1481. © 2013 Future Medicine Ltd.
