Artificial Scaffolds and Mesenchymal Stem Cells for Hard Tissues - Tissue Engineering: Cell-Surface Interactions for Tissue Culture - page 168

or self-assembling techniques. Biodegradable polymer nanofibers mimic the
nanofibrillar structure of ECM. The nanoscaled collagen fibrillar structure (50-500
nm in diameter) has been found to enhance cell-matrix interactions [ 117 ]. The
most promising approaches are represented by nanocomposites, reviewed by
Zhang [ 110 ]. It could be shown that the early osteogenic signal expression of rat
BMSCs is influenced by both HA nanoparticle content and initial cell seeding
density in biodegradable nanocomposites scaffolds [ 109 ]. Sitharaman and
co-workers introduced a novel nanoparticle-enhanced biophysical stimulus based
on the photoacoustic effect. Results showed that the photoacoustic effect influences
differentiation of bone marrow-derived marrow stromal cells grown on poly(lactic-
co-glycolic acid) polymer films into osteoblasts. Osteodifferentiation of MSCs due
to photoacoustic stimulation is significantly enhanced by the presence of single-
walled carbon nanotubes in the polymer [ 115 ]. Nanostructured mesoporous silicon
can be used for discriminating in vitro calcification of electrospun scaffold com-
posites [ 118 ]. Carbon nanotubes possess exceptional mechanical, thermal, and
electrical properties, facilitating their use as reinforcements or additives in various
biomaterials to improve their mechanical behavior in particular. Carbon nanotubes
are synthesized and added to conventional polymer scaffolds to promote and guide
bone tissue growth and regeneration [ 113 ]. Another approach recently reported
combines controlled synthesis of colloidal nanoparticles with freeze-drying tech-
nique for bone tissue engineering applications. Porous nanocomposite scaffolds
based on poly(vinylalcohol) and colloidal HA nanoparticles were prepared. In
vitro experiments with osteoblast cells indicated an appropriate penetration of the
cells into the scaffold's pores and cell growth support [ 119 ].
Novel Scaffold Fabrication Technologies have been developed in the past
decade that open new opportunities for 3D scaffold design [ 117 , 120 , 121 ].
In particular, electrospinning and different rapid prototyping techniques including
3D printing, fused deposition modelling (FDM), stereolithography, selective laser
ablation (SLA), and selective laser sintering (SLS) are considered to be the most
promising techniques for smart scaffold fabrication [ 101 , 122 ], resulting in new
materials, nanostructured surfaces, and novel 3D architectures. Rapid prototyping
technologies thus enable the production of scaffolds with a controllable inter-
connected pore network, allowing improved cell migration and nutrient exchange.
Electrospinning provides fibrous scaffolds mimicking the dimensions and topology
of ECM fibers. Filaments can be formed on the nanometer scale and used as
medical membranes and scaffolds for tissue engineering.
A broad variety of materials was tested including natural compounds such as
collagen and synthetic polymers, e.g., PLA, PGA, PCL, and corresponding
co-polymers. The preparation and characterization of a 3D printed scaffold based
on a functionalized polyester for bone tissue engineering applications was reported
by Seyednejad and co-workers. Porous scaffolds were prepared based on a
hydroxyl functionalized polymer, poly(hydroxymethylglycolide-co-e-caprolactone)
(PHMGCL). Scaffolds consisting of PHMGCL or PCL were produced via 3D
plotting resulting in a high porosity and an interconnected pore structure. Human
MSCs were seeded onto the scaffolds to evaluate the cell attachment properties and