NANOTECHNOLOGY AND 3D BIOPRINTING FOR NEURAL TISSUE REGENERATION - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 312

FIGURE 14.8
SEM images of (A) an aligned electrospun neural scaffold fabricated in our lab; (B) random nanopores created
on the surface of the electrospun fibers via solvent evaporation; and (C) electrosprayed core-sheel nanospheres
incorporated aligned scaffold. (D) Confocal images of axons extension along the direction of aligned fibers (red
represents the cell skeleton and axons). A color version of this figure can be viewed online.
in our lab investigated the effects of a highly aligned fibrous neural scaffold using electrospinning in
conjunction with electrosprayed growth factor encapsulated nanospheres ( Figure 14.8 ). Results dem-
onstrated that aligned scaffolds with sustained growth factor release can improve PC-12 cell growth
and effectively guide neural axon extension along the orientation of fiber(s). Another intriguing feature
that can improve neural generation is a scaffold's electrical conductivity. Recent studies have shown
that electrical stimulation can also improve the communication between nerve and muscle cells, and
further promote neural network formation and functional recovery ( Ghasemi-Mobarakeh et al., 2009;
Huang et al., 2012; Zhang et al., 2013 ). With regards to this aspect, electrically conductive polymers
have offered an attractive option in neural tissue engineering ( Chronakis et al., 2006 ). Two approaches
currently employed in the fabrication of conductive electrospun nanofibrous scaffolds rely on the use
of inherently electrically conductive polymeric biomaterials such as polypyrrole (PPy) and polyani-
line (PANI): either directly dope conductive polymer into electrospun solution or coat nonconductive
fibers with a conductive polymer ( Ghasemi-Mobarakeh et al., 2009; Jin et al., 2012; Lee et al., 2009 ).
PPy is one of the most widely studied neural biomaterials due to its ease of synthesis, excellent cy-
tocompatibilty, and excellent conductivity ( Lee et al., 2009 ). Both, in vitro and in vivo, studies have
shown PPy-doped or coated neural substitutes are suitable for implantation ( Brett Runge et al., 2010;
George et al., 2005; Xu et al., 2014 ). It was also revealed that nanofibrous scaffolds fabricated through
electrospinning PCL/gelatin doped with conductive PANI could significantly improve nerve stem cell
proliferation and neurite outgrowth under electrical stimulation when compared with the absence of
electrical stimulation group ( Ghasemi-Mobarakeh et al., 2009 ).