Avaliação pré-clínica dos efeitos do osso bovino desproteinizado revestido com estrôncio sobre o reparo ósseo
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2019-09-09
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Universidade Estadual Paulista (Unesp)
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O objetivo deste estudo foi avaliar o efeito do uso de diferentes substitutos sobre o reparo ósseo de defeitos críticos de calvárias de ratos com ou sem osteoporose. Para tanto, foram divididos em três estudos. O estudo 1 avaliou o efeito de diferentes biomateriais sobre o reparo de defeitos críticos de calota (DCC) de 40 ratos saudáveis que foram aleatoriamente divididos em 5 grupos com 8 animais, de acordo com o tipo de biomaterial utilizado para preencher os DCC: Grupo COA (coágulo); Grupo AUT (osso autógeno); Grupo OBD (osso bovino desproteinizado); Grupo HA/ TCP (cerâmica bifásica composta de hidroxiapatita e β-fosfato tricálcio); Grupo TCP (β-fosfato tricálcio). Foram executadas análise microtomográfica para avaliação do comprimento linear remanescente (DLL) do DCC e o volume dos tecidos mineralizados (MT) dentro do defeito nos períodos de 3, 7, 15 e 30 dias após cirurgia. Adicionalmente, foi executado análise histométrica para avaliar a composição do tecido ósseo reparado (% Osso e % Biomaterial) no período de 30 dias. O grupo COA apresentou o menor DLL e MT dentro do DCC e maior % osso do que os outros grupos. O grupo OBD apresentou maior volume de tecidos mineralizados e maior % biomaterial do que o grupo os grupos AUT e TCP. Os grupos OBD e AUT apresentaram maior % osso que o grupo TCP. O estudo 2 avaliou o efeito do enxerto com OBD carregado de estrôncio (Sr) na cicatrização óssea em DCC em 42 ratos saudáveis. Foram feitos 2 defeitos/rato, e um destes aleatoriamente foi enxertado com (a) OBD, (b) OBD carregado com 19,6 μg/g de Sr (OBD / Sr1), ou (c) OBD carregado com 98,1 μg/g de Sr (OBD / Sr2), e outro defeito foi deixado vazio como controle negativo. Grupos de sete animais de cada um dos grupos foram eutanasiados 15 e 60 dias pós-operatórios. A cicatrização óssea no DCC foi avaliada por micro-CT e histologia / histomorfometria e imuno-histoquímica. Os sítios enxertados com OBD Sr2 mostraram um comprimento de defeito residual radiográfico significativamente menor comparado com OBD Sr1, OBD e com controles vazios aos 60 dias. Além disso, a quantidade de formação óssea nova no OBD/Sr1 e OBD/Sr2 foram significativamente maiores em comparação com os sítios enxertados com OBD aos 60 dias. Os grupos OBD/Sr1 e OBD/Sr2 apresentaram ligeira ausência de inflamação em comparação com os defeitos enxertados com OBD, especialmente aos 60 dias. Maior expressão de osteocalcina foi observada em sítios enxertados com OBD/Sr1 e OBD/Sr2 em comparação com OBD. O estudo 3 avaliou o efeito do OBD carregado de estrôncio sobre o reparo ósseo em DCC de ratas ovariectomizadas. Cinqüenta e seis ratas adultas foram alocadas aleatoriamente em quatro grupos com 14 animais cada, de acordo com o tipo de biomaterial utilizado para preencher os defeitos de 5mmØ: OBD /controle: O DCC foi preenchido com OBD em animais submetidos à simulação da ovariectomia; OBD / Ovx: O DCC foi preenchido com OBD em animais submetidos à ovariectomia; OBD-Sr1 / Ovx: o DCC foi preenchido com OBD revestido com estrôncio em baixa concentração (140 µM) em animais submetidos à ovariectomia; OBD-Sr2 / Ovx: O DCC foi preenchido com OBD revestido com estrôncio em alta concentração (700 µM) submetido à ovariectomia. As análises de comprimento radiográfico remanescente do defeito (R-RDL) e preenchimento com tecido mineralizado (R-MTF) foi avaliado pela Micro CT, e a composição do tecido reparado (osso e biomaterial) foi avaliada pela análise histométrica após 15 e 60 dias do sacrífio. Os animais do OBD-Sr1/Ovx e OBD-Sr2/Ovx apresentaram maior R-MTF que os animais do OBD/controle e OBD/Ovx. Além disso, o grupo OBD-Sr2/Ovx apresentou maior R-MTF que o OBD-Sr1/Ovx. O OBD/controle, OBD-Sr/Ovx e OBD-Sr2/Ovx apresentaram mais osso que o grupo OBD/Ovx. De acordo com esses estudos, pode-se concluir que o OBD possui melhor qualidade de reparo ósseo quando comparado com outros biomaterias, como TCP e HA/TCP, porém é inferior ao enxerto autógeno. Quando o OBD está associado ao Sr, suas propriedades biológicas são melhoradas, de modo a aumentar a formação óssea, além disso, em altas concentrações de Sr produz maior volume de tecido ósseo reparado em ratas com indução de osteoporose.
The objective of this study was to evaluate the effect of the use of different substitutes on bone repair of critical calvarial defects (CCD) of rats with or without osteoporosis.. Study 1 evaluated the effect of different biomaterials on the repair of CCD of 40 healthy rats that were randomly divided into 5 groups with 8 animals, according to the type of biomaterial used to fill the CCDs: Group COA (clot); AUT group (autogenous bone); DBB group (deproteinized bovine bone); HA / TCP group (biphasic ceramic composed of hydroxyapatite and β-phosphate tricalcium); TCP group (β-tricalcium phosphate). Microtomographic analysis was performed to evaluate the remaining linear length (DLL) of the CCD and the volume of the mineralized tissues (TM) within the CCD at 3, 7, 15 and 30 days after surgery. In addition, histometric analysis was performed to evaluate the composition of the bone tissue repaired (% Bone and% Biomaterial) in the period of 30 days. The COA group presented the lowest DLL and MT within the CCD and higher bone% than the other groups. The DBB group had a higher volume of mineralized tissues and a higher biomaterial percentage than the AUT and TCP groups. The DBB and AUT groups had a higher percentage of bone than the TCP group. Study 2 evaluated the effect of strontium-loaded DBB (Sr) graft on bone healing in CCD in 42 healthy rats. Two defects / mouse were made, and one of these was randomly grafted with (a) DBB, (b) DBB loaded with 19.6 μg / g Sr (DBB / Sr1), or (c) DBB loaded with 98.1 μg / g of Sr (DBB / Sr2), and another defect was left empty as a negative control. Groups of seven animals from each of the groups were euthanized 15 and 60 postoperative days. Bone healing in DSC was assessed by micro-CT and histology / histomorphometry and immunohistochemistry. The sites grafted with DBB / Sr2 showed a significantly lower radiographic residual defect length compared to DBB / Sr1, DBB and with empty controls at 60 days. In addition, the amount of new bone formation in DBB / Sr1 and DBB / Sr2 were significantly higher in comparison to sites grafted with DBB at 60 days. A higher number of DBB / Sr1 and DBB / Sr2 showed slight absence of inflammation compared to DBB grafted sites, especially at 60 days. Higher osteocalcin expression was observed at sites grafted with DBB / Sr1 and DBB / Sr2 compared to DBB. Study 3 evaluated the effect of strontium loaded DBB on bone repair in CCD of ovariectomized rats. Fifty-six adult rats were randomly assigned to four groups with 14 animals each, according to the type of biomaterial used to fill the 5mmØ CCD: DBB / control: The CCD was filled with OBP in animals submitted to ovariectomy simulation; OBP / Ovx: The CCD was filled with OBP in animals submitted to ovariectomy; DBB-Sr1 / Ovx: CCD was filled with DBB coated with low strontium (140 μM) in animals submitted to ovariectomy; DBB-Sr2 / Ovx: CCD was filled with DBB coated with high concentration strontium (700 μM) subjected to ovariectomy. Remaining defect radiographic length (R-RDL) and mineralized tissue filling (R-MTF) analyzes were evaluated by Micro CT, and the composition of the repaired tissue (bone and biomaterial) was assessed by histometric analysis after 15 and 60 days of the sacrifice. The DBB-Sr1 / Ovx and DBB-Sr2 / Ovx animals presented higher R-MTF than the DBB / control and DBB / Ovx animals. In addition, the DBB-Sr2 / Ovx group had higher R-MTF than DBB-Sr1 / Ovx. The DBB / control, DBB-Sr / Ovx and DBB-Sr2 / Ovx had more bone than the DBB / Ovx group. According to these studies, it can be concluded that DBB has a better amount of bone repair when compared to other biomaterials, such as TCP and HA / TCP, but it is inferior to the autogenous graft. When DBB is associated with Sr its biological properties are improved in order to increase bone formation, moreover when in high Sr concentrations it produces a larger volume of bone tissue repaired in osteoporotic induction rats.
The objective of this study was to evaluate the effect of the use of different substitutes on bone repair of critical calvarial defects (CCD) of rats with or without osteoporosis.. Study 1 evaluated the effect of different biomaterials on the repair of CCD of 40 healthy rats that were randomly divided into 5 groups with 8 animals, according to the type of biomaterial used to fill the CCDs: Group COA (clot); AUT group (autogenous bone); DBB group (deproteinized bovine bone); HA / TCP group (biphasic ceramic composed of hydroxyapatite and β-phosphate tricalcium); TCP group (β-tricalcium phosphate). Microtomographic analysis was performed to evaluate the remaining linear length (DLL) of the CCD and the volume of the mineralized tissues (TM) within the CCD at 3, 7, 15 and 30 days after surgery. In addition, histometric analysis was performed to evaluate the composition of the bone tissue repaired (% Bone and% Biomaterial) in the period of 30 days. The COA group presented the lowest DLL and MT within the CCD and higher bone% than the other groups. The DBB group had a higher volume of mineralized tissues and a higher biomaterial percentage than the AUT and TCP groups. The DBB and AUT groups had a higher percentage of bone than the TCP group. Study 2 evaluated the effect of strontium-loaded DBB (Sr) graft on bone healing in CCD in 42 healthy rats. Two defects / mouse were made, and one of these was randomly grafted with (a) DBB, (b) DBB loaded with 19.6 μg / g Sr (DBB / Sr1), or (c) DBB loaded with 98.1 μg / g of Sr (DBB / Sr2), and another defect was left empty as a negative control. Groups of seven animals from each of the groups were euthanized 15 and 60 postoperative days. Bone healing in DSC was assessed by micro-CT and histology / histomorphometry and immunohistochemistry. The sites grafted with DBB / Sr2 showed a significantly lower radiographic residual defect length compared to DBB / Sr1, DBB and with empty controls at 60 days. In addition, the amount of new bone formation in DBB / Sr1 and DBB / Sr2 were significantly higher in comparison to sites grafted with DBB at 60 days. A higher number of DBB / Sr1 and DBB / Sr2 showed slight absence of inflammation compared to DBB grafted sites, especially at 60 days. Higher osteocalcin expression was observed at sites grafted with DBB / Sr1 and DBB / Sr2 compared to DBB. Study 3 evaluated the effect of strontium loaded DBB on bone repair in CCD of ovariectomized rats. Fifty-six adult rats were randomly assigned to four groups with 14 animals each, according to the type of biomaterial used to fill the 5mmØ CCD: DBB / control: The CCD was filled with OBP in animals submitted to ovariectomy simulation; OBP / Ovx: The CCD was filled with OBP in animals submitted to ovariectomy; DBB-Sr1 / Ovx: CCD was filled with DBB coated with low strontium (140 μM) in animals submitted to ovariectomy; DBB-Sr2 / Ovx: CCD was filled with DBB coated with high concentration strontium (700 μM) subjected to ovariectomy. Remaining defect radiographic length (R-RDL) and mineralized tissue filling (R-MTF) analyzes were evaluated by Micro CT, and the composition of the repaired tissue (bone and biomaterial) was assessed by histometric analysis after 15 and 60 days of the sacrifice. The DBB-Sr1 / Ovx and DBB-Sr2 / Ovx animals presented higher R-MTF than the DBB / control and DBB / Ovx animals. In addition, the DBB-Sr2 / Ovx group had higher R-MTF than DBB-Sr1 / Ovx. The DBB / control, DBB-Sr / Ovx and DBB-Sr2 / Ovx had more bone than the DBB / Ovx group. According to these studies, it can be concluded that DBB has a better amount of bone repair when compared to other biomaterials, such as TCP and HA / TCP, but it is inferior to the autogenous graft. When DBB is associated with Sr its biological properties are improved in order to increase bone formation, moreover when in high Sr concentrations it produces a larger volume of bone tissue repaired in osteoporotic induction rats.
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Palavras-chave
Estrôncio, Renegeração óssea, Substitutos ósseos, Strontium, Bone regeneration, Bone substitutes