Bone regeneration applications

Though few cell studies on aligned nanofibrous scaffolds have been specifically conducted for bone regeneration applications, preliminary data in other areas... 

The last method to be discussed, which is used to form polymer/ceramic composites by electrospinning, is extremely different to the methods previously described, but worth mentioning. Zuo et al. [129] used a method to create a composite scaffold that is actually the reverse of what most people are doing. Instead of mineralizing the nanofibers, Zuo et al. actually incorporated electrospun polymer nanofibers into a ceramic bone cement in order to form a composite scaffold. It was found that by incorporating electrospun nanofibers into the cement, the scaffold became less brittle and actually behaved similarly to that of a ductile material because of the fibers. Composite scaffolds with different polymers and fiber diameters were then tested in order to determine which scaffold demonstrated the most ideal mechanical properties. However, no cell studies were conducted and this method would most likely be used for a bone substitute instead of for bone regeneration applications. 

Use of 3D foams is also a popular method for bone regeneration applications, although they are most often employed for trabecular bone regeneration [152,154]. There are a few methods utilized to create foams for this application, one of the most popular being a polymer foam replication technique, in which a polymer foam is either electrosprayed or immersed into a HAp/bioactive glass particle slurry in order to fully coat the foam and create a trabecular bone-like aichitecture. However, other methods are also utilized, including creating composite foam solutions that are injectable and form once inside the body [153]. Results of Fu et al. [152] have indicated mechanical properties similar to those of natural trabecular bone. 

The cell adhesion process is critical to most bone regeneration applications [27,28]. In general, cell adhesion to synthetic substrates is a protein-mediated process. Thus, the amount, type, and activity of the adsorbed pro-... 

M. Sadat-Shojai, M.-T. Khorasani, A. Jamshidi, 3-Dimensional cell-laden nano-hydroxyapatite/protein hydrogels for bone regeneration applications. Mater. Sci. Eng. C 49 (2015) 835-843. 

Bio-nanocomposites based on calcium phosphates can perform other innovative fundions such as acting as a reservoir for the controlled release of bioadive compounds once the material is implanted in the bone defect. For instance, the incorporation of a morphogenetic protein that promotes bone regeneration in an HAP-alginate-collagen system [110] or a vitamin in a Ca-deficient HAP-chitosan nanocomposite [111] are recent examples of this kind of application. 

Nodax has superior biocompatibility compared to other bioresorbable plastics, which makes the material suitable for some medical applications such as drug release, bone regeneration, and nerve guidance. 

Kikuchi, M., Koyama, Y, Takakuda, K., Miyairi, H., Shirahama, N., and Tanaka, J., In vitro change in mechanical strength of 3-tricalcinm phosphate/copolymer-ized poly-L-lactide composites and their application forgnided bone regeneration, J. Biomed. Mater. Res., 62, 265, 2002. 

Laurencin CT, Attawia MA, Elgendy HE, Herbert KM (1996) Tissue engineered bone-regeneration using degradable polymers The formation of mineralized matrices. Bone 19 S93-S99 Laurencin CT, Ambrosio AMA, Borden MD, Cooper JA (1999) Tissue engineering Orthopaedic applications. Ann Rev Biomed Eng 1 19-46... 

Chitosan rods are of great importance as they are promising biomaterials for bone fixation applications. However, processing chitosan into a rod is not an easy job due to its low decomposition temperature. So far, many efforts have been made to obtain chitosan rods with high-enough mechanical strength for bone repair and regeneration. 

Polyesters have also been processed into tubular form for orthopedic and cardiovascular tissue engineering applications. Meinig and co-workers evaluated bone regeneration using tubular PLLA membranes in mid-diaphyseal defects in rabbit radii. The membrane prevented soft tissue formation in the defect area, and it allowed woven bone to fill the defect. Local inflammation or systemic intolerance was not observed, and the membranes remained intact for the entire 64-week study. 

Biomaterials for bone regeneration Novel techniques and applications... 

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