Artificial Scaffolds and Mesenchymal Stem Cells for Hard Tissues - Tissue Engineering: Cell-Surface Interactions for Tissue Culture - page 171

systems are immobilized on nanofiber composites; invitro release kinetics of
rhBMP-7 from nanosphere-immobilized nanofibrous scaffolds were studied. Three
distinct release profiles were achieved from three different co-polymers (different
co-monomer ratios, or different molecular weights). New bone formation in
rhBMP-7 incorporated PLA nanofibrous scaffolds retrieved six weeks after sub-
cutaneous implantation in rats [ 117 ].
So-called ''integrated biomimetic systems'' combine conventional materials
and fabrication methods, respectively, with nanomaterials and nanotechnologies:
e.g., chitosan/hyaluronic acid composites [ 138 ], PLA/hyaluronic acid [ 102 ], and
calcium phosphate/polymer composites (Wagoner et al. 2009).
Biomimetic composite coating is performed to improve the functional perfor-
mance of rapid prototyped scaffolds for bone tissue engineering. Thus, rapid
prototyped poly(e-caprolactone)/tri-calcium phosphate (PCL/TCP) scaffolds were
fabricated using the screw extrusion system (SES). The fabricated PCL/TCP
scaffolds were coated with a carbonated hydroxyapatite-gelatin composite via
biomimetic co-precipitation. The cell-scaffold interaction was studied by culturing
porcine BMSCs on the scaffolds and assessing the proliferation and bone-related
gene and protein expression capabilities of the cells. Confocal laser microscopy
and scanning electron microscopy (SEM) images of the cell-scaffold constructs
showed a uniformly distributed cell sheet and accumulation of ECM in the interior
of carbonated hydroxyapatite-gelatin composite-coated PCL/TCP scaffolds. The
proliferation rate of BMSCs on gelatin composite-coated PCL/TCP scaffolds was
about 2.3 and 1.7 times higher than that on PCL/TCP scaffolds and gelatin-coated
PCL/TCP scaffolds, respectively, by day ten. Furthermore, reverse transcription
polymerase chain reaction and Western blot analysis revealed that gelatin

composite-coated PCL/TCP scaffolds stimulated osteogenic differentiation of

BMSCs [ 141 ].
The effect of surface-modified collagen on the adhesion, biocompatibility, and
differentiation of BMSCs has been studied in poly(lactides-co-glycolide)/chitosan
scaffolds. The scaffold containing type I collagen (640 lg/ml) had about 1.2 times
the cell adhesion efficiency of the corresponding unmodified scaffold. In addition,
the modification of type I collagen increased the cell viability about 1.3-fold and
the biodegradation 1.2-fold. The differentiation of BMSCs in PLGA/chitosan
scaffolds produced osteoblasts with mineral deposition on the substrate. Moreover,
the surface collagen promoted the formation of mineralized tissue and reduced the
amount of phenotypic BMSCs in the constructs [ 142 ].
Nanoscaled drug release systems incorporated into nanostructured biomaterials
represent a novel and promising strategy for tissue regeneration [ 104 ]. Biomaterials
used as matrices for controlled drug release include hyaluronic acid, acrylic acid,
dextran methacrylic acid, polyethylene glycol acrylate/methacrylate, and polyeth-
ylene glycol diacrylate/dimethacrylate [ 143 ]. BMP-2 loading to enhance bone
regeneration was studied using solid-freeform-based polymer scaffolds with fibrin
hyaluronic acid hydrogel-modified surfaces [ 134 ]. Novel dendron-like nanoparticles
have been investigated by Oliveira and colleagues, including in vivo studies of SC
differentiation into osteoblasts. Biodegradable dexamethasone-loaded dendron-like