Ossäre Regeneration eines experimentellen critical-size Defektes ...

1.2 Summary
1.2.1 Objective
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The limited ability for regeneration of a critical‐size defect causes special standards
to an alloplasts. For this reason a biphasic bone substitute with tricalciumphosphate,
hydroxylapatite and polyethylenglycol‐(PEG) was used in this study, to arrange con‐
temporary defect regeneration by osteoinductive substances.
1.2.2 Methods
By an animal experiment the effect of the new PEG‐hydrogel membrane according to
bone regeneration was shown in critical size defects of domestic pigs. The influence
of the biodegradable hydrogel was tested for a temporary wound closure between
bone defect and proximated periost, for using as a cellular growing medium and for
guided bone regeneration. Recombinant PDGF and BMP‐2 transfected osteoblasts
were inserted into the defects by the biodegradable PEG‐hydrogel and the respective
osteoinductivity was determined. The bone regeneration was evaluated after one,
two, four and twelve weeks. Bone resections, embedded in plastic were analysed by
microradiography and histological Toluidinblue‐O coloration. Afterwards the sam‐
ples were prepared with immunhistochemical methods, detecting BMP‐2, SOX‐9,
and a vectorial V5‐tag on the osteoblasts DNA.
1.2.3 Results
Hereby the osteoinductive potency of PDGF and BMP‐2 could be shown: This
caused higher bone regeneration in the critical‐size defects than could be achieved
without any growth‐ and differential factors in comparison groups. In combination
with the mitogen PDGF an immigration resistance by the biodegradable PEG‐gel
benefits the osteoinductive defect regeneration. By using BMP‐2 transfected os‐
teoblasts a disutility of the subperiostal PEG‐membran coud be verified, whereas the
BMP‐2 transfected cells of the alloplast could be detected until two weeks after op‐
eration.