Carbon Nanotubes in Acrylic Bone Cement - Biologically Responsive Biomaterials for Tissue Engineering - page 192

Fig. 8.10 Representative image of lung section from the SWCNT inhalation study depicting gran-
uloma formation on day 28 post treatment. Fibrosis is indicated by blue staining in this Masson's
Trichrome stained section of the lung [ 84 ]

While the results seem to be controversial, it is apparent that the presence or
absence of specialised signals determined the recognition and subsequent interac-
tions of CNT with cells. Overall, pristine CNTs carrying no recognisable signals
were poorly taken up whereas CNTs modified chemically (e.g. oxidatively modified
and functionalised) or by adsorbed macromolecules (e.g. proteins, lipids) were
more readily recognised and engulfed by cells [ 85 ]. Several in vitro studies support
the concept that pristine CNTs are not readily taken up by lung cells. Herzog et al.
[ 35 ] reported no uptake of CNT in either A549 cells or BEAS-2B cells (a human
bronchial epithelial cell line). Lastly, no evidence of CNT uptake was reported
after electron microscopic evaluation of exposed RAW 264.7 cells (a mouse peri-
toneal macrophage cell line) [ 83 ]. In contrast, functionalisation of SWCNT with a
phospholipid signal, phosphatidylserine, made CNTs recognisable in vitro by dif-
ferent phagocytic cells, including murine RAW264.7 macrophages, primary mono-
cyte-derived human macrophages and dendritic cells, and microglia from rat brain
(Fig. 8.10 ) [ 85 ] .

8.5 Summary

The number of primary TJRs continues to increase each year and, even with the
reported decrease in the proportion of cemented TJRs performed, PMMA bone
cement is still required for the majority of TJR procedures. At present, with longer
life expectancy and younger patient populations requiring TJR, an increase in
cemented revisions seems inevitable. Aseptic loosening is continually cited as
being the most common indication for revision. It is well established that for
cemented implants a number of factors contribute to aseptic loosening, of which
fatigue damage of the cement mantle has been observed in vivo. Fibre-reinforced