Nanotechnology and Cardiovascular Tissue Engineering - Stem-Cell Nanoengineering - page 274

size scale of extracellular matrix (ECM) fibers, allowing them to be used as biomimetic
scaffolds [34-36]. Compared to macroscale surfaces, nanofibers have shown higher rates of
protein adsorption, a key mediator in cell attachment to a biomaterial surface. For example,
poly( l -lactic acid) (PLLA) fibers with diameters ranging from 50 to 500 nm have been shown
to have four times higher rates of protein adsorption than porous PLLA constructs with
macroscale features. These scaffolds are known to interact with the seeded cells more closely
and also selectively enhance the adsorption of specific proteins, such as fibronectin and
vitronectin, which is significant as fibronectin is a protein known to mediate cell adhesion
and to bind many growth factors (Figure 16.1) [37, 38]. Furthermore, polymeric nanofibers
have been shown to display unique mechanical properties [39].
There are three methods that are commonly used for the production of nanofibers: elec-
trospinning, phase separation, and self-assembly. Electrospinning relies on the electrostatic
repulsion of a polymer solution to form polymer fibers. Electrospinning is a time- and
cost-efficient technique to produce polymer fibers and is the most commonly used method
to produce fiber meshes in tissue engineering. A variety of natural and synthetic polymers
have been electrospun into nanofibers. Natural polymers are often blended with synthetic
polymers or salts to increase the solution viscosity and consistency in electrospinning [40].
Phase separation is a method that has long been used to create porous polymer membranes
and scaffolds by inducing the separation of a polymer solution into a polymer-poor phase
and a polymer-rich phase [41, 42]. More recently, the method has been used to produce poly-
meric nanofibrous constructs from aliphatic polyesters. Self-assembly is a bottom-up

Cardiovascular cells

Nanofibers

Cellular construct Cell-fiber interaction

Figure 16.1 A general schema of seeding cardiovascular cells onto nanofibrous scaffolds. The cells
closely interact with the nanofibers and form an active cellular construct. The nanofibers provide
appropriate in vivo -like cues and mechanical support for the proliferation, growth, and differentiation
of cells.