Abstract Objectives This study aimed to evaluate the potential of adipose-derived stem cells (ASCs) combined with a modified α-tricalcium phosphate (α-TCP) or gelatin sponge (GS) scaffolds for bone healing in a rat model. Material and Methods Bone defects were surgically created in the femur of adult SHR rats and filled with the scaffolds, empty or combined with ASCs. The results were analyzed by histology and histomorphometry on days seven, 14, 30, and 60. Results Significantly increased bone repair was observed on days seven and 60 in animals treated with α-TCP/ASCs, and on day 14 in the group treated with GS/ASCs, when compared with the groups treated with the biomaterials alone. Intense fibroplasia was observed in the group treated with GS alone, on days 14 and 30. Conclusions Our results showed that the use of ASCs combined with α-TCP or GS scaffolds resulted in increased bone repair. The higher efficacy of the α-TCP scaffold suggests osteoconductive property that results in a biological support to the cells, whereas the GS scaffold functions just as a carrier. These results confirm the potential of ASCs in accelerating bone repair in in vivo experimental rat models. These results suggest a new alternative for treating bone defects.

Current treatments of craniosynostosis rely on the application of metal springs for cranial bone deviation. However, those metal springs demand a second surgical procedure for their removal. An attractive alternative would be the substitution of metal for bioresorbable polymers in the composition of the springs. The addition of poly(isoprene), PI, to poly(lactic-co-glycolic acid), PLGA, produces a polymeric blend with partial miscibility and distinct mechanical behavior that may benefit the patient recover. It is necessary to compare the histotoxicity of PLGA/PI to that presented by PLGA. In order to verify the histological behavior of the blend, 46 male Wistar rats (Rattus norvegicus, albino strain) underwent implantation of PLGA or PLGA/PI in the skull and were allocated into subgroups by timing of euthanasia (15, 30, 60, or 90 days). After euthanasia, the skull was removed and the histotoxicity was assessed histopathologically. The PLGA/PI blend showed greater histotoxicity in animals euthanized at 60 days, although in this period the histotoxicity of the PLGA/PI blend was similar to that of the PLGA copolymer at 15 days. Despite the instability of histological response, presented in different periods of observation, the results obtained in long-term show that the material has high potential for studies in craniosynostosis treatment.

The application of renewable raw materials encourages research in the biopolymers area. The Poly(Lactic-co-Glycolic Acid)/Poly(Isoprene) (PLGA/IR) blend combines biocompatibility for application in the health field with excellent mechanical properties. The blend was obtained by solubilization of polymers in organic solvents. To investigate the polymer thermochemical properties, FTIR and DSC were applied. To investigate the composition's influence over polymer mechanical properties, tensile and hardness test were applied. To analyze the blends response in the cell environment, a stent was produced by injection molding process, and Cell Viability Test and Previous Implantability were used. The Infrared spectra show that chemical composition is related only with polymers proportion in the blend. The calorimetry shows a partial miscibility in the blend. The tensile test shows that adding Poly(Isoprene) to Poly(Lactic-co-Glycolic Acid) induced a relevant reduction in the Young modulus, tensile stress and tenacity of the material, which was altered from the fragile raw PLGA to a ductile material. The composition did not affect the blend hardness. The cell viability test shows that the blend has potential application as biomaterial, while the first results of implantability indicate that the polymeric stent kept its original position and caused low fibrosis.

The addition of tricalcium silicate (C3S) to apatite cements results in an increase of bioactivity and improvement in the mechanical properties. However, adding large amounts raises the local pH at early stages, which retards the precipitation of hydroxyapatite and produces a loss of mechanical strength. The introduction of Pozzolanic materials in cement pastes could be an effective way to reduces basicity and enhance their mechanical resistance; thus, the effect of adding silica on the chemical, mechanical and biological properties of α-tricalcium phosphate/C3S cement was studied. Adding silica produces a reduction in the early pH and a decrease in setting times; nevertheless, the presence of more calcium silicate hydrate (C-S-H) delays the growth of hydroxyapatite crystals and consequently, reduces early compressive strength. The new formulations show a good bioactivity, but higher cytotoxicity than traditional cements and additions higher than 2.5% of SiO2 cause a lack of mechanical strength and an elevated degradability.

OBJETIVO: Avaliar a capacidade da mistura de α-TCP e osso autógeno (OA) Vs somente α-TCP e somente OA em promover a neoformação óssea e reparo tecidual em defeitos ósseos. MÉTODOS: Foram criados cirurgicamente defeitos ósseos em 15 ratos Wistar machos, distribuídos em quatro grupos: Grupo I (OA), Grupo II (α-TCP), Grupo III (α-TCP + OA avaliado por microscopia de luz) e Grupo IV (α-TCP + OA avaliado por microscopia eletrônica de varredura). Os resultados da reparação óssea foram avaliados em 30, 60 e 120 dias. RESULTADOS:os achados histológicos obtidos nos grupos I (p = 0,459), II (p = 0,368) e III (p = 0,459) e aos 30 dias (p = 0,717), 60 dias (p = 0,717), e 120 dias (p = 0,779) não apresentaram diferenças estatisticamente significativas. A análise por microscopia eletrônica de varredura revelou contacto direto entre o implante de α-TCP + AO e o tecido ósseo aos 120 dias. CONCLUSÃO: O implante de α-TCP é alternativa eficaz como substitutos ósseos para o tratamento de defeitos ósseos de tamanho crítico.

PURPOSE: To evaluate the ability of a mixture of α-TCP and autogenous bone (AB) vs. α-TCP alone and AB alone to promote new bone formation and tissue repair in bone defects. METHODS: Bone defects surgically created in 15 male Wistar rats were divided into four groups: Group I (AB), Group II (α-TCP), Group III (α-TCP+AB assessed by light microscopy), and Group IV (α-TCP+AB assessed by scanning electron microscopy). Bone repair findings were assessed at 30, 60, and 120 days postoperatively. RESULTS: The histological findings obtained in Groups I (p=0.459), II (p=0.368), and III (p=0.459) and at 30 days (p=0.717), 60 days (p=0.717), and 120 days (p=0.779) did not show statistically significant differences. Scanning electron microscopy revealed direct contact between the α-TCP+AB implant and the bone tissue at 120 days. CONCLUSION: The α-TCP implant is effective alternative bone substitutes for the treatment of critical size bone defects.

Os cimentos de fosfatos de cálcio são biomateriais formados pela mistura de um pó de fosfato de cálcio com água ou com solução aquosa de sais orgânicos ou inorgânicos formando uma pasta que reage à temperatura ambiente ou corpórea, endurecendo como resultado da reação de precipitação. Cimentos de fosfato de cálcio são usados comumente em cirurgias de preenchimento ósseo na odontologia e ortopedia, que requerem procedimentos extremamente invasivos. A inovação consiste em formular uma pasta injetável pela incorporação de aditivos. Neste estudo, três aditivos (carboxi-metil-celulose, polímero de agar e alginato de sódio) foram incorporados a fosfato tricálcico-alfa, nas concentrações de 0,4%; 0,8%; 1,6%; 3,2%; 6,4% em massa. Os resultados demonstraram que foi possível obter composições de cimento de fosfato tricálcico injetáveis. Verificou-se que a injetabilidade, medida por um método inédito proposto, depende do comportamento reológico das pastas. Neste estudo, as formulações com 1,6% de carboxi-metil-celulose, 1,6% de agar e 0,8% de alginato de sódio, permitiram a obtenção de uma viscosidade suficiente para uma boa homogeneização e injeção do cimento.

Calcium phosphate cements are biomaterials made of a mixture of calcium phosphate powder with water or with aqueous solutions of inorganic or organic salts, forming a paste that reacts at room or body temperature and hardens as a result of precipitation reactions. Calcium phosphate cements are commonly used in both dentistry and orthopedic bone filling surgeries, which require extremely invasive procedures. The innovation consists in formulate an injectable paste by incorporation of additives. In this work, three different additives (carboxymethylcellulose, agar polymer and calcium alginate) were incorporated in alpha-tricalcium phosphate (alpha-TCP), in concentrations of 0.4%; 0.8%; 1.6%; 3.2% and 6.4% wt%. Results showed that it was possible to obtain injectable compositions of tricalcium phosphate cement. It was verified that the injectability, measured by a novel method, depends on the rheological behavior of the pastes and injection time. In this study, pastes with sufficient viscosity for good homogenization and injection were obtained. In this study, pastes with 1.6% carboxymethylcellulose, 1.6% agar and 0.8% sodium alginate present sufficient viscosity for good homogenization for cement injection.

OBJETIVO: Avaliar a biocompatibilidade do cimento de fosfato de cálcio, para verificar sua eficácia como possível substituto ósseo. MÉTODOS: No presente trabalho, foi utilizado cimento de fosfato de cálcio em rádio de 8 coelhos, separados em dois grupos (GI e GII), referentes aos tempos de observação de 12 e 26 semanas pós-operatórias, a fim de se observar as reações entre este biomaterial e o tecido ósseo do animal. Foram feitas análises radiográficas e de densitometria óptica, além de microscopia óptica e eletrônica de varredura. RESULTADOS: Observou-se, ao final do experimento, que o cimento à base de fosfato de cálcio foi parcialmente reabsorvido durante o tempo de observação de 26 semanas, apresentando biocompatibilidade, com ausência de reações indesejáveis que pudessem ser atribuídas aos implantes. CONCLUSÕES: O cimento à base de fosfato de cálcio foi biocompatível e parcialmente reabsorvido no período de 26 semanas de observação. Tempos maiores de observação são necessários para a avaliação da reabsorção.

PURPOSE: The objective of this paper was to evaluate the biocompatibility of calcium phosphate cement in radius of rabbits. METHODS: For this experiment, calcium phosphate were implanted in the radius of 16 rabbits, divided in two groups (GI and GII), according to postoperative follow-up of 12 and 26 weeks, respectively. Reactions of these biomaterials on animal bone tissue were observed. X-ray, optical densitometry, optical microscopy and scanning electron microscopy analyses were performed. RESULTS: It was observed that calcium phosphate cement were partially resorbed during the 26-week follow-up, showing biocompatibility, with absence of inflammatory or other undesirable reactions due to the implants. CONCLUSIONS: Calcium phosphate-based cements did not cause inflammatory reactions when in contact with the osseous tissue, and were therefore biocompatible. Follow-up periods longer than 26 weeks are necessary to better evaluate the behavior of calcium phosphate-based cement.