b2815 Tissue Engineering and Nanotheranostics “9.61x6.69”
42 Tissue Engineering and Nanotheranostics
process, oxygen is metabolized, and lysosomes containing oxidants
like hydrogen peroxide are released. Since a mesh can never be fully
degraded and dispatched from the body, constant activation of
phagocytic cells and production of oxidants can occur, stimulated by
an inflammatory response.^21
Characterization of explanted PP hernia meshes was carried out
by Costello and Bachman, using scanning electron microscopy
(SEM), differential scanning calorimetry (DSC) and thermogravimet-
ric analysis (TGA).^21 The sample population (n = 14) was composed
of PP components from PP/expanded PTFE composite hernia
meshes such as Composix® E/X or Kugel® Composix. PP meshes were
extracted from patients in need of revision surgery due to chronic
pain, recurrence and other complications. Adherent tissue was sepa-
rated from the meshes before testing, by immersion in a sodium
hypochlorite solution for 2 h at 37°C, followed by repeated rinse
cycles in distilled water and overnight drying.^21
SEM was performed on sputter-coated pristine and explanted
mesh samples using a Hitachi S-4700 scanning electron microscope,
by a secondary electron detector at an accelerating voltage of 5 keV.^21
Using a PyrisTM1 DSC was conducted on mesh samples weighing
1–3 mg with an empty aluminum pan acting as the reference.
Samples were heated from 50°C to 400°C at 10°C/min under nitro-
gen flow. For thermogravimetric analysis, a TGAQ50 was pro-
grammed to heat the sample from room temperature to 600°C at
10 °C/min under nitrogen flow, where samples were cut to approxi-
mately 5 mm × 5 mm.^21 Statistical analyses were performed using
GraphPad Prism version 4.0 where significant differences in means of
pristine versus explanted specimens were determined by a one-way
analysis of variance with a 95% confidence interval and Dunnett’s
post-test (n = 3, p < 0.05).
SEM micrographs of explanted PP specimens divulged cracks, fis-
sures and blisters were compared to micrographs of pristine specimens
(Fig. 9), and such surface abnormalities were observed for 85% of the
explanted specimens. The DSC results are shown in Fig. 9, where
subject #2 and subject #9 represent the results for all 14 explants.
A lower melting temperature (Tm) of approximately 163°C was
