Papers by Keyword: Animal Model

Abstract: Prosthetic loosening in absence of infection (aseptic loosening) is the most common reason for revision of Total Hip Replacements (THR) Alumina and/or zirconia-based ceramic materials generally displayed high wear resistance and are considered suitable for load bearing application. To characterize the possible chronic cellular reactions to ceramic debris is then relevant in view of their long-term implantation. Low density ceramic pellets obtained by alumina and zirconia (Y-TZP) medical-grade precursors, were sintered at intermediate density and implanted in the patellar tendon of 24 NZW adult rabbits (group A). In this way the progressive release into the joint space of grains detached from surface of the pellets by the motion of the joint. Other 24 NZW rabbits (group B) received 5mg of powders injected in the articular capsule. Animals were killed at different intervals (1,3,6,12 months). Retrieved knee joints underwent X-Ray, histological and ultrastructural analysis. Peripheral organs (liver, kidney, lung, spleen, brain) were collected at same time. For, histologic analysis of tissue specimens collected in revision surgeries were fixed in 10% formalin, then decalcified ethylendiamintetracetic acid (EDTA), dehydrated and embedded in paraffin, sectioned and stained with hematoxylin-eosin. Histologic reaction was similar for the two ceramics and independent of the physical form (powders or pellets). Ceramic particulate was observed in the periprosthetic tissue membrane, the smaller inside mononuclear histiocyte-like cells in granuloma-like tissue, while the largest were in a synovial-like membrane inside a stroma poor in vessel containing mononuclear cells and rarely giant cells. No toxic nor carcinogenic effects were observed in peripheral organs retrieved at different time intervals. Although the ankyloses of the joints is a limiting factor for the duration of the test, this method may be a useful tool to evaluate the reactions to wear debris, and may result suitable also to evaluate the chronic response to metals or polymers of clinical interest.

Abstract: The testing of novel biomaterials for percutaneous vertebroplasty depends on suitable animal models. The aim of this study was to develop ex vivo a reproducible and feasible model of percutaneous vertebroplasty, for ulterior application in vivo. A large animal model was used (Merino sheep), due to its translational properties. Vertebroplasty was performed under tactile and fluoroscopic control, through a bilateral modified parapedicular access in lumbar vertebrae (n=12). Care was taken in order to avoid disruption of the vertebral foramen. The average defect volume was 1234±240 mm³. This mean volume ensures practical defects to test novel injectable biomaterials. 6 vertebrae were injected with a commercial cement (Cerament®, Bone Support, Sweden). Adequate defect filling was observed in all vertebrae. All vertebrae were assessed by microCT, prior to and post defect creation and after biomaterial injection. All vertebrae were mechanical tested. No mechanical failure was observed under loads higher than the physiological. Ultimately, this model is considered suitable for pre-clinical in vivo studies, mimicking clinical application.

Abstract: Objective: To compare the effectiveness of different proportional nHA / PLA application in alveolar bone preservation. Methods: After extraction, apply extraction socket filling based on the alveolar bone defect model due to absorption in Beagle dog. Implant materials are divided into 3 different groups: nHA / PLAI, nHA / PLAII and the control group. Samples of the alveolar bone were collected at Week 4 and 8, respectively for the bone resorption assessment, bone density measurement, and histological examination. Results: After nHA / PLA implantation, the alveolar bone preservation was significantly improved. There was no difference in the alveolar bone preservation between the nHA / PLAI and nHA / PLAII groups. However, the sample which are 8w from group I, have higher bone density and have complete absorption in their dental material nest .Therefore group I is better than group II. Conclusions: The results can provide a reliable basis for the application of alveolar bone preservation in basic research and selection of clinical materials.

Abstract: This study presents some aspects regarding the evaluation of bone-implant interactions using two animal models (rabbit and rat). The proposed implants are new alumina/zirconia bioceramics designed for hard tissue replacement (oral implantology or arthroplasty). The animal selection was made based on the number and size or design of implants to be tested as these factors influence directly the species of animal chosen for this study. The correct placement and stability of the implants were evaluated by radiographic images. SEM micrographs were recorded on the bone/implant area along with the elemental composition of the sheared implant surfaces at different time intervals after the surgery. Calcium/phosphate ratio was considered as an indicative of the surface implant coverage for a successful osseointegration. Histological examination of the bone and bone marrow in direct contact with the implants was performed to detect any immunological or inflammatory responses. Each of the animal species (rat or rabbit) demonstrated unique advantages and disadvantages as a model for demonstrating the response of bone tissue to an implant material. The size and design of the implants also influenced the bone turnover as demonstrated histologically.

Abstract: The SCID mouse (severe combined immunodeficiency mouse) has been used as a small animal model in the analysis of human pathophysiology and preclinical experiment for many years. As the most difficult challenge faced in the research of AIDS, chronic hepatitis B and chronic hepatitis C is the lack of appropriate small animal model, researchers have always attempted to develop a series of mouse models based on the improvements of the SCID mouse. This review focuses on the developments and applications of such SCID mouse models in three types of the above chronic infectious diseases.

Abstract: Currently, the methods of establishing mammary precancer animal model is various, including hormones-induced precancerous lesions model, chemical carcinogen precancerous lesions model, precancerous lesions model induced by hormones combined with chemical carcinogen, MCF10AT cell lines transplantation model, transgenic model and disease and syndrome animal model. This paper aims to explore the establishing and applied research of animal models of mammary precancerous lesions. Showing it would play a critical role in studying the cause and pathogenesis of mammary precancerous lesions, effective prevention and improving treatment effect by a proper mammary precancerous lesion animal model.

Abstract: The aim of this study was to study bone marrow quality from various location and species for reconstruction of segmental critical size defect in irradiated weigh bearing bone. Sample of bone marrow aspirates from rabbits and Beagle dog were analyzed. Rabbits were implanted with a composite associating resorbable collagen membrane plus micro macroporous biphasic calcium phosphate (MBCP®) and autologous bone marrow (BM) injected after irradiation. Bone marrow samples were found to be significantly less rich in tibia than in humerus and ilium in Dog and less rich in Dog than in Rabbit (p<0,05). Successful osseous colonization bridging of the defect were obtain at 16 weeks in all animals. Identical repartition of bone ingrowth and residual ceramic at the different levels of the implant suggest an osteoinduction role of the bone marrow graft in the center of the defect. This model succeeded in reconstruct a large segmental defect in weight bearing and irradiated bone in rabbit.

Abstract: This paper reports on the research into multiphase bone substitutes carried out by laboratories from the ‘Pays de la Loire’ region in France. This collaborative research was funded by both the French Government and the Regional Council in the period 2000-2007. Calcium phosphate bioceramics, polymers and combinations have been developed as bone substitutes for various maxillofacial and orthopaedic applications. These bone substitutes should support and regenerate bone tissue and resorb after implantation. In the bone tissue engineering area, they have been combined with autologous bone marrow cells or bioactive factors. The bone substitutes were tested in various animal models mimicking clinical situations or under pathological conditions (osteoporosis). In order to complete our research, the multiphase materials were also evaluated in clinical trials.

Abstract: To prevent prolonged air leakage after lung surgery, we developed a biodegradable polyglycolic acid (PGA) sheet and compared it with an expanded polytetrafluoethylene (ePTFE). Eighteen adult mongrel dogs were used in this experiment. The airway pressures at which air first leaked at the stapled resection margins were measured immediately after surgery in group I (N=5), 2 days after surgery in group II (N=5), and 7 days after surgery in group IIII (N=5), Based on the presence of SLR, there were 3 subgroups in each group: there was no SLR in subgroup a; ePTFE in subgroup b; PGA sheet in subgroup c. The histologic examination was performed 2 months after surgery (N=3). In group I, there was a significant difference in air leakage pressures (mm Hg) between no reinforcement and SLR. We observed the same results in group II and III with statistical significance. However, there was no significant difference between the reinforcement groups. The histologic findings demonstrated more severe adhesions and biodegradation in the dogs in which the PGA sheet was used. Our PGA sheet was considered a useful reinforcement material, because it had a similar threshold for air leakage with the ePTFE with excellent biodegradation.

Abstract: The extent of osseous involvement, particularly spinal cord compression, is directly correlated with patient survival. To treat metastatic spine cancer, we have developed novel paclitaxel-loaded hydroxyapatite-alginate gels. In this study, an intraosseous spinal cancer model in rats was used to investigate the efficacy of local treatment. Ten rats were randomized into two groups, a local treatment group and a control group. Disease-free time and survival rate in the local treatment group were significantly longer in this model. (p<0.05)