ABSTRACT
Abstract The aim of this study is to evaluate the biocompatibility and osteoconductivity in surgical defects of sheep tibias filled with 1% strontium-containing nanostructured hydroxyapatite microspheres (SrHA), stoichiometric hydroxyapatite without strontium microspheres (HA), or blood clots. Santa Ines sheep were subjected to three perforations on the medial side of the left tibia. The biomaterials were characterized by X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) before implantation and by X-Ray Microfluorescence (µFRX) and Scanning Electron Microscopy (SEM) after sheep tibias implantation. Surgical defects were filled with blood clots (control), SrHA (Group 1) or HA (Group 2). After 30 days, 5-µm bone blocks were obtained for histological evaluation, and the blocks obtained from 1 animal were embedded in methylmethacrylate for undecalcified sections. Mononuclear inflammatory infiltrate remained mild in all experimental groups. Giant cells were observed surrounding biomaterials particles of both groups and areas of bone formation were detected in close contact with biomaterials. All groups showed newly formed bone from the periphery to the center of the defects, which the control, HA and SrHA presented 36.4% (± 21.8), 31.2% (± 14.7) and 26.2% (± 12.9) of newly formed bone density, respectively, not presenting statistical differences. In addition, the connective tissue density did not show any significant between groups. The SrHA showing a higher volume density of biomaterial (51.2 ± 14.1) present in the defect compared to HA (32.6 ± 8.5) after 30 days (p = 0.03). Microspheres containing 1% SrHA or HA can be considered biocompatible, have osteoconductive properties and may be useful biomaterials for clinical applications.
Subject(s)
Animals , Female , Strontium/pharmacology , Wound Healing/drug effects , Bone Regeneration/drug effects , Bone Substitutes/pharmacology , Nanostructures/chemistry , Hydroxyapatites/pharmacology , Tibia/drug effects , Time Factors , X-Ray Diffraction , Materials Testing , Sheep , Microscopy, Electron, Scanning , Reproducibility of Results , Spectroscopy, Fourier Transform Infrared , Models, Animal , X-Ray MicrotomographyABSTRACT
Objective The aim of this study was to evaluate in vivo the biological response after implantation of a novel alginate-capsule membrane. Methods The material was implanted into subcutaneous tissue of mice (n=15) and after 1, 3 and 9 weeks, the animals were sacrificed and biopsies analyzed with light microscopy, using the stains hematoxylin-eosin, picrosirius and alcian blue pH 2.5. The parameters evaluated were: intensity and kind of inflammatory infiltrate, presence of connective tissue, foreign body reaction, vascularization and biodegradation. Results 1 week after implantation, the following was observed: mixed inflammatory infiltrate, absence of necrosis and beginnings of membrane fragmentation; after 3 weeks, discrete presence of multinuclear giant cells and beginnings of neovascularization; and after 9 weeks there was minor biodegradation associated with the presence of new connective tissue, and persistence of moderate inflammatory reaction observed from beginning to end of the experiment. Conclusion Considering the results obtained, it is possible to conclude that the novel alginate-capsule membrane is partially reabsorbable but with low biocompatibility, requiring more tests to validate its clinical use.
Objetivo Avaliar in vivo a resposta tecidual após a implantação de uma nova membrana de alginato-capsul. Métodos O material foi implantado no tecido subcutâneo de camundongos (n=15) e após 1, 3 e 9 semanas, os animais foram mortos e as biópsias analisadas à microscopia de luz, através de coloração com hematoxilina-eosina, picrosirius e azul de alcian pH 2,5. Os parâmetros avaliados foram: intensidade e tipo de infiltrado inflamatório, presença de tecido conjuntivo, reação de corpo estranho, vascularização e biodegradação. Resultados Após 1 semana da implantação, notou-se infiltrado inflamatório misto, ausência de necrose e início de fragmentação da membrana, em 3 semanas, observou-se presença discreta de células gigantes multinucleadas e início de neovascularização, e em 9 semanas houve pequena biodegradação associada com a presença de novo tecido conjuntivo e persistência de reação inflamatória moderada observada desde o início do experimento. Conclusão Considerando os resultados obtidos concluiu-se que a nova membrana de alginato-capsul é parcialmente reabsorvível, mas com baixa biocompatibilidade, necessitando de mais testes para validar seu uso clínico.
Subject(s)
Seaweed , Tissue Engineering , Materials TestingABSTRACT
Com o avanço das pesquisas em biomateriais, tem sido sugerido que a melhor osteocondutividade da hidroxiapatita seria alcançada se o seu cristal estivesse mais próximo da estrutura, tamanho e morfologia da apatita biológica, por isso a nano-hidroxiapatita (nano-HA) é de grande interesse atual. Os íons estrôncio são conhecidos por reduzir a reabsorção óssea, induzir a atividade osteoblástica e estimular a formação óssea. O objetivo deste estudo foi avaliar a biocompatibilidade e a osteocondução em defeitos cirúrgicos preenchidos com microesferas de nano-hidroxiapatita contendo estrôncio a 1% (nano-SrHA), microesferas de nano-HA estequiométrica (nano-HA) em comparação ao coágulo (controle). Quatro ovelhas Santa Inês, pesando em média 32 kg, foram anestesiadas e submetidas a três perfurações de 2 mm de diâmetro na face medial da tíbia. Os defeitos cirúrgicos foram preenchidos com coágulo sanguíneo, microesferas de Sr-HA 1% e microesferas de HA. Após 30 dias as amostras foram trefinadas (6 mm), descalcificadas, processadas para inclusão em parafina e coradas com hematoxilina e eosina (HE) para avaliação histológica com microscopia de luz. Todos os grupos revelaram neoformação óssea da periferia para o centro do defeito, sendo o grupo nano-SrHA com menor intensidade dentre os estudados. Presença de discreto infiltrado inflamatório mononuclear em todos os grupos experimentais. Células gigantes do tipo corpo estranho só foram observadas no grupo da HA. Áreas de neoformação óssea foram observadas em íntimo contato com ambos os biomateriais. De acordo com os resultados obtidos, microesferas de HA e SrHA 1% são biocompatíveis e apresentam propriedade de osteocondução.
With the advances on biomaterials research have suggested that the best osteoconductivity of hydroxyapatite could be achieved if the crystal was closer to the structure, size and morphology of biological apatite, so the nano-hydroxyapatite (nano-HA) is of current interest. Strontium ions are known to reduce bone resorption, induce osteoblastic activity and thus stimulate bone formation. The aim of this study was to evaluate the biocompatibility and osteoconductive in surgical defects filled with spheres of nano-hydroxyapatite containing strontium 1% (nano-SrHA), nano-hydroxyapatite stoichiometric (nano-HA) when compared to the blood clot (control). Four Santa Inês sheeps, weighing on average 32 kg were anesthetized and subjected to three perforation 2 mm in diameter on the medial site of tibia. The surgical defects were filled with blood clot, Sr-HA 1% microspheres and HA microspheres. After 30 days the samples were trephyned (6 mm), decalcifi ed, processed for embedding in paraffi n and stained with hematoxilin and eosin (HE) for histological evaluation with light microscopy. All groups showed new bone formation from the periphery to the center of the defects, and the group nano-Sr with a lesser extent among those studied. The mononuclear inflammatory infiltrate remained mild in all experimental groups. The presence of giant cells type foreign body was detected only in the HA group. Areas of bone formation were detected in close contact with biomaterials. According to the results spheres containing nano-SrHA 1% and nano-HA can be considered as biocompatible and with osteoconductive properties.