Immunohistochemical, tomographic and histological study on onlay iliac grafts remodeling

Abstract

The information concerning the molecular events taking place in onlay bone grafts are still incipient. The objective of the present study is to correlate the effects of perforation of resident bone bed on (1) the timing of onlay autogenous graft revascularization; (2) the maintenance of volume/density of the graft (assessed through tomography); and (3) the occurrence of bone remodeling proteins (using immunohistochemistry technique) delivered in the graft. Thirty-six New Zealand White rabbits were subjected to iliac crest onlay bone grafting on both sides of the mandible. The bone bed was drill-perforated on one side aiming at accelerating revascularization, whereas on the other side it was kept intact. After grafts fixation and flaps suture all animals were submitted to tomography on both mandible sites. Six animals were sacrificed, respectively, at 3, 5, 7, 10, 20 and 60 days after surgery. A second tomography was taken just before sacrifice. Histological slides were prepared from each grafted site for both immunohistochemistry analysis [osteopontin, osteocalcin, type I collagen and vascular endothelial growth factor (VEGF) anti-bodies] and histometric analysis. The values on bone volume measured on tomography showed no statistic significance (P>or=0.05) between perforated and intact sites. Grafts placed on perforated beds showed higher bone density values compared with non-perforated ones at 3 days (P<or=0.05). This correlation was inverted at 60 days postoperatively. The findings from VEGF labeling revealed a tendency for earlier revascularization in the perforated group. The early revascularization of bone grafts accelerated the bone remodeling process (osteocalcin, type I collagen and osteopontin) that led to an increased bone deposition at 10 days. The extended osteoblast differentiation process at intermediate stages in the perforated group cooperated for a denser bone at 60 days.

Autogenous bone block in the treatment of teeth with hopeless prognosis

“…In addition, as the graft material necroses, it releases substances that may stimulate further bone formation and the non-viable cellular elements within the graft may act as a scaffold for ingrowth of vessels and accumulation of osteoblasts. [47] Revascularization of a bone block is critical for cell survival and graft incorporation[348–50] and can vary depending upon the receptor site, type of fixation, orientation of grafted bone or even presence or absence of the periosteum, and patient's age, as well. [5152] Perforation of cortical bone at donor site has been suggested to improve vascularity but the results are yet to be substantiated (about cortical perforation).…”

“…[5152] Perforation of cortical bone at donor site has been suggested to improve vascularity but the results are yet to be substantiated (about cortical perforation). [34750] In the following month, calcification progresses and within a year the newly formed bone develops the normal physical strength. [46]…”

Interactions between osteopontin and vascular endothelial growth factor: Implications for skeletal disorders

“…OPN is continuously expressed postoperatively in both perforated and non-perforated settings, whereas VEGF is initially expressed only in a perforated micro-environment but peaks at day 60 in both settings. This early VEGF expression and hence re-vascularization, accelerates the remodeling process and leads to a higher bone deposition [48,49]. In bone tissue engineering, perfusion culture of osteo-progenitor cells within porous scaffolds elevates the deposition of extracellular matrix via mechano-transductive autocrine signaling pathways that are responsible for higher levels of ERK, P38, prostaglandin E 2 , cytosolic calcium and cyclooxygenase 2.…”

Efeito da desmineralização óssea superficial na consolidação de enxertos ósseos autógenos: estudo histomorfométrico e imunohistoquímico em calvária de ratos

“…Perfurações ou desgastes na cortical óssea do leito receptor com o objetivo de promover a revascularização e melhorar o processo de incorporação (BUSER et al, 1993;GORDH et al, 1997;ALBERIUS;GORDH, 1998;CARVALHO;VASCONCELOS;PI, 2000;FARIA et al, 2008;MAZZONETTO, 2008;BARBOSA et al, 2009;PEDROSA et al, 2009;DAYANGAC et al, 2016), além de constituírem-se trauma cirúrgico adicional, podem resultar em reabsorção excessiva do leito, no qual o enxerto pode submergir, diminuindo seu volume e espessura final (DAYANGAC et al, 2016;FARIA et al, 2008;BARBOSA et al, 2009). Para contornar esse inconveniente, outras propostas como a interposição de plasma rico em plaquetas (PRP) na interface (MIRANDA et al, 2006), de BMPs (GORDH et al, 1999KRISHNAN et al, 2015) MIRANDA et al, 2006;BARBOSA et al, 2009;DOMINGUES, 2013;REZENDE et al, 2014;ROJAS-PAULUS, 2016;DAYANGAC et al, 2016).…”

“…Contudo, além da imobilização, outros tratamentos de superfície estão sendo empregados com a finalidade de promover a revascularização do enxerto e melhora do processo de incorporação, como a realização de perfurações e desgastes na cortical óssea do leito receptor (BUSER et al, 1993;MAZZONETTO, 2008;GORDH et al, 1997;ALBERIUS;GORDH, 1998;CARVALHO;VASCONCELOS;PI, 2000;FARIA et al, 2008), aplicação de plasma rico em plaquetas (PRP) entre o enxerto e o leito (MIRANDA et al, 2006), aplicação de BMPs (GORDH et al, 1999;KRISHNAN et al, 2015), laser de baixa potência OBRADOVIC;KESIC;PESEVSKA, 2009;VALIATI et al, 2012) e desmineralização óssea artificial das superfícies de contato do enxerto e do leito receptor (REZENDE et al, 2014;REZENDE et al, 2015;RODRIGUES et al, 2012 …”