Bioactive Inorganic and Organic Composite Materials for Bone Regeneration and Gene Delivery - Advanced Bioactive Inorganic Materials for Bone Regeneration and Drug Delivery - page 191

biocompatibility of the PCL/BGNF composite compared with the PCL/BGP
composite. Furthermore, the PCL/BGNF composite showed a significantly
higher level of bioactivity compared with the PCL/BGP composite. In addi-
tion, the results of the in vivo animal experiments using Sprague-Dawley
albino rats revealed the good bone regeneration capability of the PCL/BGNF
composite when implanted in a calvarial bone defect. In the result of the ten-
sile test, the stiffness of the PCL/BG composite was further increased when
the BGNFs were incorporated. These results indicate that the PCL/BGNF
composite has greater bioactivity and mechanical stability when compared
with the PCL/BG composite and great potential as a bone regenerative mate-
rial (Jo et al. 2009).
Mohammadi et al. (2011) investigated the effect of Si and Fe on the surface
properties of calcium-containing phosphate based glasses (PGs) in the sys-
tem (50P(2)O(5)-40CaO-(10-x)SiO(2)-xFe(2)O(3), where x = 0, 5 and 10 mol%).
Two PG formulations, 50P(2)O(5)-40CaO-10Fe(2)O(3) (Fe10) and 50P(2)O(5)-
40CaO-5Fe(2)O(3)-5SiO(2) (Fe5Si5), were melt drawn into fibers and ran-
domly incorporated into poly(lactic acid) (PLA) produced by melt processing.
In deionized water (DW), the dissolution rate of PLA-Fe5Si5 was signifi-
cantly higher than that of PLA-Fe10. Dissolution of the glass fibers resulted
in the formation of channels within the matrix. After phosphate buffered
saline (PBS) aging, the reduction in mechanical properties was greater for
PLA-Fe5Si5 compared to PLA-Fe10. MC3T3-E1 preosteoblasts seeded onto
PG discs, PLA, and PLA-PGF composites were evaluated for up to 7 days
indicating that the materials were generally cytocompatible. In addition, cell
alignment along the PGF orientation was observed showing cell preference
toward PGF (Mohammadi et al. 2011).
The in vitro osteogenic development of rat bone marrow mesenchymal
stem cells (rBMSCs) upon different membrane substrates (pure PLA control,
PLA-BG, and PLA-ZnBG) was investigated in terms of bone cell phenotype
syntheses and mineralization. Oh et al. (2011) showed significantly stimu-
lated production of ALP and osteocalcin at days 14 and 21 in the membranes
containing BG and bioactive inorganic zinc-containing bioactive glass
(ZnBG), with more in the samples containing ZnBG. The addition of ZnBG
in poly(lactic acid) (PLA) allowed the rBMSCs to express a high level of bone
sialoprotein as confirmed by immunostaining. Cellular mineralization of the
secreted extracellular matrix showed a significantly higher Ca level on the
BG- and ZnBG-added membrane than on the PLA, and more so in the ZnBG-
added one (Oh et al. 2011).
As the amount of bioactive nanofiber increased (from 5% to 25%), the
in vitro bioactivity of the nanocomposite was improved. The osteoblast
responses to the nanocomposites (compositions with 5% and 25% nanofi-
ber) were assessed in terms of cell proliferation, differentiation, and miner-
alization. Osteoblasts attached and grew well on the nanocomposites and
secreted collagen protein at initial culturing periods. The differentiation of
cells, as assessed by the expression of ALP, was significantly improved on