Angiogeneza je proces koji prostorno i vremenski prethodi osteogenezi i neophodna je za
odvijanje kako intramembranozne tako i enhondralne osifikacije. Shodno tome, regeneracija
kosti ne može biti postignuta bez adekvatne revaskularizacije. Pored morfologije i strukture
koštanog defekta, zarastanje kosti i revaskularizacija koštanog defekta zavise i od izbora
koštanog zamenika.Za uspešno zarastanje i integraciju grafta neophodno je ispuniti dva
preduslova: prorastanje krvnih sudova iz zidova koštanog defekta, i blizak kontakt između
površine koštanog zamenika i vaskularizovanog tkiva.
Cilj doktorske disertacije bio je ispitati da li različita veličina i struktura granula koštanih
zamenika ima uticaj na neoangiogenezu a samim tim i na stvaranje nove kosti.
Kontrolisano eksperimentalno istraživanje sprovedeno je na animalnom modelu kunića.
Istraživanje je obuhvatilo deset novozelandskih belih kunića. S obe strane svoda lobanje
formirana su po dva defekta kritične veličine promera 8mm koj...i su bili ispunjeni granulama
koštanog zamenika. Ispitivani materijali su komercijalno dostupni u dve veličine i obuhvatali su
sledeće: deproteinizovani goveđi mineral u formi sitnih granula (Bio-Oss 250-1000μm,
Geistlich AG,Switzerland), deproteinizovani goveđi mineral u formi krupnih granula (Bio-Oss
1000-2000μm, Geistlich AG,Switzerland), deantigenizovanu kost konjskog porekla u formi
sitnih granula (Osteoxenon 500-1000μm, Bioteck, Italy) i deantigenizovanu kost konjskog
porekla u formi krupnih granula (Osteoxenon 2000-3000μm, Bioteck, Italy). Životinje su bile
žrtvovane nakon 4 i nakon 8 nedelja, a uzorci tkiva su obrađeni za patohistološku analizu.
Karakteristike neoangiogeneze analizirane su histološkim, histohemijskim i
imunohistohemijskim metodama. Pored toga, mikroCT analiza korišćena je za procenu
morfoloških karakteristika i razlika između ispitivanih koštanih zamenika.
Rezultati istraživanja pokazali su morfološku osnovu intenzivnije neoangiogeneze u slučaju
primene krupnih granula, bez obzira na poreklo ispitivanog ksenografta. Kada su u pitanju
krupne granule, gustina vaskularne mreže nakon 8 nedelja zarastanja bila je veća u defektima
ispunjenim Osteoxenonom u odnosu na Bio-Oss. Međutim, kada je reč o sitnim granulama,
nakon 8 nedelja zarastanja gustina vaskularne mreže bila je veća u defektima ispunjenim
partikulama Bio-Ossa u odnosu na defekte ispunjene Osteoxenonom. Veću gustinu vaskularne
mreže pratila je intenzivnija produkcija koštanog tkiva. Pored toga, rezultati istraživanja
pokazuju da i Bio-Oss i Osteoxenon imaju sposobnost da indukuju stvaranje džinovskih ćelija
tipa oko stranog tela, bez obzira na veličinu granula. Najveći broj džinovskih ćelija tipa oko
stranog tela zabeležen je u defektima ispunjenim sitnim granulama Osteoxenona. Postojala je
tendencija smanjenja broja ovih ćelija između 4. i 8. nedelje zarastanja.
Istraživanje je pokazalo da krupne granule obezbeđuju više prostora za prorastanje novih krvnih
sudova a samim tim i za fomiranje nove kosti. Tendencija smanjenja broja džinovskih ćelija tipa
oko stranog tela ili njihovo sporadično prisustvo mogu ukazivati na postignut „imunološki
ekvilibrijum” i uspešnu integraciju oba ispitivana biomaterijala. U skladu sa dobijenim
rezultatima, čini se da kolagen unutar mineralne strukture Osteoxenona ne utiče na angiogenezu
i osteogenezu.
Angiogenesis spatially and temporally precedes osteogenesis and it is required for both
ossification processes, intramembranous and enchondral. Consequently, bone regeneration
could not be achieved without adequate bone defect revascularisation. In addition to
morphology and bone defect structure, bone healing and revascularisation are also influenced by
choice of bone substitute. It is necessery to complete two preconditions for successful graft
healing and integration and they are: blood vessels ingrowth from surrounding bone walls into
defect and close contact between bone substitute surface and vascularized tissue.
The main objective of the doctoral dissertation was to evaluate whether size and structure of the
bone substitute particles have an effect on neoangiogenesis and therefore on a new bone
formation.
The control experimental study was carried out on rabbit animal model. The study included ten
New Zealand rabbits. On both sides of cranial vault two 8mm-diameter defects were ...formed and
filled with bone substitute particles. The tested materials are commercially available in two
dimensions and contained the following deproteinized bovine bone minerals in the form of
small particles (Bio-Oss 250-1000μm, Geistlich AG,Switzerland), deproteinized bovine bone
minerals in the form of large particles (Bio-Oss 1000-2000μm, Geistlich AG,Switzerland),
deantigenated equine-derived bone in the form of small particles (Osteoxenon 500-1000μm,
Bioteck, Italy) and deantigenated equine-derived bone in the form of large particles
(Osteoxenon 2000-3000μm, Bioteck, Italy). After 4 and 8 weeks the animals were sacrifised
and tissue samples were prepared for pathohistological analysis. The neoangiogenesis
characteristics were analized using histological, histochemical and immunochistochemical
methods. Besides, microCT analise was used to reckon morphological features as well as
differences among all examined bone substitutes.
The research results showed morphological basis for more intense neoangiogenesis in case of
large particles used, regardless the type of xenograft origin. When the word is about large
particles, the value of microvessel density after 8 weeks of healing was higher in defects filled
with Osteoxenon particles than Bio-Oss ones. Regarding to small particles the opposite results
were found. After 8 weeks of healing more intense neoagiogenesis was found in defect filled
with Bio-Oss small particles. The rate of defect revascularisation was followed by appropriate
new bone formation. Furthermore, results indicated that Bio-Oss and Osteoxenon have potential
to induce foreign body giant cells formation regardless the particles’ size. The greatest number
of foreign body giant cells was found in defect filled with Osteoxenon small particles. There
was decreasing tendency in number of foreign body giant cells of between 4 and 8 weeks.
The research has shown that large particles provide more space for vascular ingrowth and
therefore more new bone formation. Decreasing tendency of foreign body giant cells number or
their scattered presence could point to achieve immunological equilibrium and successful
osseointegration in both examined biomaterials. In accordance with our results it does not seem
that collagen inside the mineral structure of Osteoxenon particles have an effect on angiogenesis
and osteogenesis as well.
