Papers by Keyword: In Vivo Test

Abstract: It is important to develop scaffolds that resemble the extracellular matrix, thereby facilitating tissue regeneration. The objective of this work is to evaluate the biocompatibility of scaffolds of poly (L-lactide) with pure and grafted hydroxyapatite, at various concentrations of reinforcement, in Wistar Rat tissues, to evaluate the potential application on hard tissue regeneration. The biocompatibility tests were carried out in vivo in Wistar rats by implanting the material into the subcutaneous tissue and muscle from 1 to 14 weeks and evaluating the surrounding tissue stained with hematoxylin-eosin. All variants of scaffolds provoked an inflammatory response from mild to moderate, without showing necrosis. These results show that even if there is recognition of the implanted materials by the immune system, it does not provoke a violent response that damages the surrounding tissue, implying that the materials to be implanted for use in hard tissue can cause a mild reaction and tolerable long term effect that does not prevent their later use in hard tissue regeneration.

Abstract: Zirconia-alumina ceramic foam scaffolds with a nanocrystalline HAP coating were used for the preparation of integrated motile orbital implants. This study demonstrated that open-cell ceramic foams with enhanced strength-to-density ratio are quite suitable as biocompatible materials for the manufacture of orbital implants for post-enucleation syndrome treatment. In-vivo studies demonstrated that the application of a nanocrystallyne (not sintered) HAP coating facilitated the formation of dense fibrous capsule around the implant as well as the fast tissue ingrowth into the implant’s internal space. Orbital implants with the optimized pore size and HAP content were implanted to the animal’s eye cavity with their fixation to the extraocular muscles, and their motility was ensured.

Abstract: The aim of this paper was to evaluate the usefulness of coupling digital image analysis with immunohistochemistry and histomorphometry data to the study of tissue response to hydroxyapatite in a model of critical size bone defect in calvaria of rats. A transosseous defect measuring 8 mm in diameter was performed with a surgical trephine in the parietal bone of 40 rats and divided into two experimental groups according to the treatment: group I (blood clot, control), group II (HA) and killed 1, 3, 6 and 9 months after implantation (n=5/group/period). The skullcaps with overlaying skin were collected and processed for paraffin embedding. The specimens were cut in the laterolateral direction into 5-µm thick semi-serial sections and stained with hematoxylin-eosin for identification and counting of polymorphonuclears cells, mastocytes, and multinucleated giant cells, MNG, or immunolabeled with anti- lysozyme, -factor VIII and –PCNA. Digital images were obtained and analyzed with the ImagePro-Plus® software for cell couting (polymorphonuclears cells, mastocytes, macrophages and MNG) and microvessel density. Image segmentation of anti-PCNA immunostaining was used for cell proliferation analysis. The digital images obtained allowed clear identification of cells of interest by through morphological aspects or immunostaining. Data recording and analysis was facilitated by the use of specific software for image processing and graphical and statistical analysis. It can be concluded that the techniques applied were usefull to identify and count cells, structures and process of interest making easier the effectiveness of hydroxyapatite in the critical size defect in rat calvaria model.

Abstract: 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 Thermogravimetric 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.

Abstract: 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 (TCP15), containing crystalline α-TCP and β-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 β-W-doped α-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.

Abstract: We recently developed a new biomimetic calcium phosphate bone cement enriched with gelatin (GEL-CP) which exhibits improved mechanical properties with respect to the control cement (C-CP) and a good response to osteoblast-like cells. In this work, we have extended the investigation to primary culture of osteoblasts derived from normal (N-OB) and osteopenic (O-OB) sheep bones cultured on samples of GEL-CP, and their behavior was compared to that of cells cultured on C-CP as control. Cell morphology, proliferation, and differentiation were evaluated at 3 and 7 days. Preliminary in vivo tests were carried out onto critical size defects in the radius diaphysis of rats.

Abstract: Dense and porous HA and Si-HA discs and granules with varying percentages of silicon substitution have been produced and physically and chemically characterised using scanning electron microscopy, surface area analysis, porosimetry, density measurement, image analysis, Xray diffraction, X-ray fluorescence, FT-infrared spectroscopy and in-vitro and in-vivo testing. Results have shown that cell adhesion in-vitro and bone apposition in-vivo are enhanced by the presence of silicon substitution in the hydroxyapatite structure. The biological response to the materials appears to indicate an optimum outcome for levels of silicon substitution of 0.8wt%.

Abstract: A great number of studies have shown that diamond-like carbon (DLC) coatings could be developed for orthopaedic implants, but few articles have been published about in vivo evaluation. In this study, DLC coatings were deposited on titanium alloy (Ti-13Nb-13Zr) implants using the plasma immersion implantation and deposition (PIII-D), and the in vivo biocompatibility of DLC coatings was evaluated into both muscular tissue and femoral condyles of rats. Results indicate that DLC coatings are biocompatible in vivo, and DLC-coated implants were observed directly bonding to bone without any intervening soft tissue layer.

Abstract: In the present work two different hydroxyapatite nanofilms (50 and 100 nm thick) have been successfully deposited on titanium implants that were previously laser macrostructured in order to assess the influence of the thickness of nanometric calcium phosphate coatings on the osseointegration. Cylindrical implants were tested in a sheep tibia model together with titanium alloy controls achieving very good osseointegration results. Laser macrostructured titanium alloy implants have shown improved bone regeneration when coated with nanometric films of carbonated HA. The pulsed laser deposited nanofilm has promoted bone in-growth deep into the laser ablated craters. There were no significant differences between the two coating thicknesses, neither when assessed with electron microscopy or classical optical methods. This result suggests that the 50 nm coating is as effective as the 100 nm one, therefore implying that the thickness limit for such a bioactive layer to stimulate bone growth may be even further below.

Abstract: Diamond-like carbon (DLC) coatings were deposited on titanium alloy (Ti-13Nb-13Zr) by plasma immersion process. DLC-coated Ti alloy and uncoated Ti were investigated in an animal model using the femoral condyles of rats for intervals of 4 and 12 weeks postoperatively. The interface between the implants and bones of the femoral condyles were analysed using scanning electron microscopy (SEM) by backscattering. The results showed that the DLC coatings were well tolerated in both periods.