Biological Response to Wollastonite Doped alpha-Tricalcium Phosphate Implants in Hard and Soft Tissues in Rats

The biological response following subcutaneous and bone implantation of beta-wollastonite(beta-W)-doped alpha-tricalcium phosphate bioceramics in rats was evaluated. Tested materials were: tricalciurn phosphate (TCP), consisting of a mixture of alpha- and beta-polymorphs; TCP doped with 5 wt. % of beta-W (TCP5W), composed of alpha-TCP as only crystalline phase; and TCP doped with 15 wt. % of beta-W (TCP15), containing crystalline alpha-TCP and beta-W. Cylinders of 2x1 mm were implanted in tibiae and backs of adult male Rattus norvegicus, Holtzman rats. After 7, 30 and 120 days, animals were sacrificed and the tissue blocks containing the implants were excised, fixed and processed for histological examination. TCP, TCP5W and TCP15W implants were biocompatible but neither bioactive nor biodegradable in rat subcutaneous tissue. They were not osteoinductive in connective tissue either. However, in rat bone tissue beta-W-doped alpha-TCP implants (TCP5W and TCP15W) were bioactive, biodegradable and osteoconductive. The rates of biodegradation and new bone formation observed for TCP5W and TCP15W implants in rat bone tissue were greater than for non-doped TCP.

Desenvolvimento de biocerâmicas porosas de hidroxiapatita para utilização como scaffolds para regeneração óssea

Biocerâmicas porosas tem aplicações biomédicas importantes como preenchimento de defeitos ósseos e scaffolds na engenharia de tecidos. A hidroxiapatita (HA, Ca10(PO4)6(OH)2) que apresenta semelhança química e estrutural com a fase mineral dos ossos e dos dentes, é biocompatível e osteocondutiva, e tem excelente afinidade química e biológica com os tecidos ósseos. Este trabalho teve como objetivo desenvolver biocerâmicas porosas HA para utilização como scaffold para regeneração óssea empregando-se a técnica de réplica da esponja polimérica. A pasta biocerâmica de HA foi obtida por via úmida utilizando hidróxido de cálcio [Ca(OH)2] e ácido fosfórico (H3PO4) e impregnada em esponjas de poliuretano com diferentes densidades. Tratamento térmico a 600°C por 1h foi realizado para eliminação da esponja seguido da sinterização a 1100°C por 2 horas. Os scaffolds apresentaram a HA como fase majoritária, elevada porosidade (> 70%) e poros com tamanhos variando na ordem de macro (>100μm) e microporosidade (1-20μm), sendo estes fatores adequados para a aplicação como scaffolds para regeneração óssea.

Fosfatos de cálcio de interesse biológico: importância como biomateriais, propriedades e métodos de obtenção de recobrimentos

For decades the Hydroxyapatite (HA) was only bioceramic of calcium phosphate system used for bone replacement and regeneration, due to its similarity to the mineral phase of bones and teeth. Because its slow degradation, other calcium phosphate classified as biodegradable started to awaken interest, such as: amorphous calcium phosphate (ACP), octacalcium phosphate (OCP) and tricalcium phosphate (TCP). This work presents the evolution of the use of other calcium phosphates due to their better solubility than the HA, comparing their main physical-chemical and biological properties. Are also presented the main methods used to obtain bioceramic coatings on metal and polymer surfaces.

Hydroxyapatite deposition study through polymeric process on commercially pure Ti surfaces modified by laser beam irradiation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Synthesis of chitosan/hydroxyapatite membranes coated with hydroxycarbonate apatite for guided tissue regeneration purposes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

In vivo biological behavior of calcium phosphate cements with different Ca/P ratio

Bioceramics with different Ca/P ratio were prepared from a mechanical mixture of NaPO3, CaCO3, Ca(OH)2 and phosphate buffer solution and implanted in rats subcutaneous tissues. The cements were characterized by Thermo gravimetric analysis (TG-TDA), X-ray diffraction and 31P-NMR. The implant sites were excised after 1, 4 and 16 weeks, fixed, dehydrated, included in paraffin wax for serial cutting and examined under the light transmitted microscope. They were biocompatible and biodegradable when implanted in rat subcutaneous. None of the materials induced ectopic osteogenesis. According to the results, the studied materials seem to be able for manufacturing reabsorbable bone implants.

Biological response to wollastonite doped α-tricalcium phosphate implants in hard and soft tissues in rats

The biological response following subcutaneous and bone implantation of β-wollastonite(β-W)-doped α-tricalcium phosphate bioceramics in rats was evaluated. Tested materials were: tricalcium phosphate (TCP), consisting of a mixture of α- and β-polymorphs; TCP doped with 5 wt. % of β-W (TCP5W), composed of α-TCP as only crystalline phase; and TCP doped with 15 wt. % of β-W (TCP 15), containing crystalline α-TCP and β-W. Cylinders of 2×1 mm were implanted in tibiae and backs of adult male Rattus norvegicus, Holtzman rats. After 7, 30 and 120 days, animals were sacrificed and the tissue blocks containing the implants were excised, fixed and processed for histological examination. TCP, TCP5W and TCP15W implants were biocompatible but neither bioactive nor biodegradable in rat subcutaneous tissue. They were not osteoinductive in connective tissue either. However, in rat bone tissue β-W-doped α-TCP implants (TCP5W and TCP 15W) were bioactive, biodegradable and osteoconductive. The rates of biodegradation and new bone formation observed for TCP5W and TCP15W implants in rat bone tissue were greater than for non-doped TCP.

Dispersed hydroxyapatite bioglass 45S5 composites: Comparative evaluation of the use of bovine bone and synthetic hydroxyapatite

The bovine bone and sintetic hydroxyapatite (HA) bioceramics are reference materials to employment as a bone substitute, however, their slow rate of degradation and its low rate of bioactivity index (Ib) are presented as limiting factors for application as bone graft. In contrast, the bioglass is a resorbable and osteoinductive material. the present work objective the development of composites of dispersed bovine bone or sintetic HA in silicate-phosphate bioglass, seeking to obtain a biomaterial with properties suitable for application as bone grafts. The composites were prepared by mixing between the powder components followed by sintering for 1h. Were used HA and bioglass (45S5) with particle size <240μm. The tested proportions of HA/45S5 were 20/80, 30/70 and 40/60 (wt%). The composites characterization was made employing scanning electron microscopy, Infra-Red Spectrometry and hydrolytic resistance test. The test results indicate the potential use of the materials developed for applications such as bone graft. © (2012) Trans Tech Publications, Switzerland.

Obtenção de fosfatos de cálcio pelo método biomimético sobre a superfície da liga Ti-6Al-4V modificada pelo laser Nd:YAG

In this work, surface modification of the Ti-6Al-4V alloy by irradiation with a Nd:YAG laser beam was studied. The matrix spacing was varied and the other parameters were kept constant. After theirradiation, the samples were immersed into SBF solution (Simulated Body Fluid) for 7 days at 37 ° C for nucleation and formation of calcium phosphates. After this period, the samples were subjected to a heat treatment at 600 °C. X-ray diffraction results indicated the formation of a mixture of phases containing hydroxyapatite and tricalcium phosphate. Infrared analysis demonstrated the presence of bands related to hydroxyapatite. SEM micrographs showed that different matrix spacing used leads to the formation of different morphologies.The 0.01 cm spacing induced the formation of microspheres, characteristic of the hydroxyapatite phase, while for 0.02 cm spacing, only a non-homogeneous coating was obtained. Therefore, the use of laser in the production of active surfaces for deposition of bioceramics proved to be viable, and the final coating has potential for applications in the field of dental implants.

Estudo da solubilidade de apatitas em meios de interesse biológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Recobrimento de apatitas empregando-se o método biomimético: estudo da influência dos íons K+, Mg2+, SO42- e HCO3- na formação de hidroxiapatita

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento de estruturas porosas de polietileno de ultra alto peso molecular (PEUAPM) recobertas com apatitas para substituição e regeneração óssea

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aplicação do processo sol-gel na produção de recobrimentos de hidroxiapatita sobre ligas a base de Ti empregadas em implantes odontológicos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Hydroxyapatite and a new fibrin sealant derived from snake venom as scaffold to treatment of cranial defects in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytocompatibility of Porous Biphasic Calcium Phosphate Granules With Human Mesenchymal Cells by a Multiparametric Assay

This work aims to evaluate the cytocompatibility of injectable and moldable restorative biomaterials based on granules of dense or porous biphasic calcium phosphates (BCPs) with human primary mesenchymal cells, in order to validate them as tools for stem cell-induced bone regeneration. Porous hydroxyapatite (HA) and HA/beta-tricalcium phosphate (beta-TCP) (60: 40) granules were obtained by the addition of wax spheres and pressing at 20 MPa, while dense materials were compacted by pressing at 100 MPa, followed by thermal treatment (1100 degrees C), grinding, and sieving. Extracts were prepared by 24-h incubation of granules on culture media, with subsequent exposition of human primary mesenchymal cells. Three different cell viability parameters were evaluated on the same samples. Scanning electron microscopy analysis of the granules revealed distinct dense and porous surfaces. After cell exposition to extracts, no significant differences on mitochondrial activity (2,3-bis(2-methoxy-4-nitro-5-sulfophenly)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) or cell density (Crystal Violet Dye Elution) were observed among groups. However, Neutral Red assay revealed that dense materials extracts induced lower levels of total viable cells to porous HA/beta-TCP (P < 0.01). Calcium ion content was also significantly lower on the extracts of dense samples. Porogenic treatments on BCP composites do not affect cytocompatibility, as measured by three different parameters, indicating that these ceramics are well suited for further studies on future bioengineering applications.