Papers by Keyword: Bone Repair

Abstract: Hydroxyapatite (HA), widely used as bone graft, can be modified by the incorporation of bivalent cations (Mg2+ and Zn2+) and its gradual release could favor the bone repair. The purpose of this research was to evaluate the effect of the HA and zinc-containing hydroxyapatite (Zn-HA) in the bone repair in rat calvaria in comparison to autogenous bone. Critical size defect in the calvaria was filled with the graft material and the samples were harvested at the 30, 90 and 180 days. The light microcopy observations showed the biocompatibility of the graft materials. In the Zn-HA group the area of neoformed bone was larger than in the HA group, but smaller than in the autograft. A fibrous connective tissue was more evident around HA granules. It could be conclude that the presence of zinc ions in HA crystal accelerated the osteogenesis and increased the area of newly formed bone in relation to HA.

Abstract: The study was carried out aiming the evaluation of the effect of hydroxyapatite (HA) and zinc-substituted hydroxyapatite (ZnHA) on osseous repair of rabbit’s tibia. For the study, 15 adult animals, weighing around 2.5 and 3.0 Kg, sourced by the Fluminense Federal University Animal Lab were acquired. Two perforations were created in each tibia and filled with cylinders (2x6 mm) of HA (group 1, right) or ZnHA (group 2, left). The animals were killed after 7, 14, and 28 days for evaluating the histological aspects of the interface site and bone repair. No sign of inflammatory reaction surrounding the cylinders area were observed, neither giant cells. Osteogenesis was evidently accelerated in all healing periods for the ZnHA group in regards to the HA group. Randomly dispersed areas of neoformed bone among wide areas of fibrous connective tissue was observed in the HA group. We conclude that both biomaterials are biocompatible, but zinc-containg HA enhanced and accelerated the osteogenesis in relation to HA.

Abstract: An appropriate scaffold, which provides structural support for transplanted cells and acts as a vehicle for the delivery of biologically active molecules, is critical for tissue engineering. We developed a fully interconnected globular porous biphasic calcium phosphate ceramic scaffold by adopting a foaming method, and evaluated its efficiency as a bone substitute and a scaffold for bone tissue engineering by in vitro and in vivo biocompatible analysis and its osteogenic healing capacity in rat tibial bone defects. They have spherical pores averaging 400um in diameter and interconnecting interpores averaging 70um in diameter with average 85% porosity. They elicited no cytotoxicity and noxious effect on cellular proliferation and osteoblastic differentiation during the cell-scaffold construct formation. Also the bone defects grafted with fully interconnected globular porous biphasic calcium phosphate ceramic blocks revealed excellent bone healing within 3 weeks. These findings suggest that the fully interconnected porous biphasic calcium phosphate scaffold formed by the foaming method can be a promising bone substitute and a scaffold for bone tissue engineering.

Abstract: Hydroxyapatite (HAP)-forming calcium phosphate cement (CPC), due to the high biocompatibility, easy-to-shape characteristic, and the capacity to self-setting under ambient conditions, has been widely used for the repair of hard tissue defects. To satisfy the different clinical need, some modified CPC, including porous CPC, fast-biodegradable CPC, injectable CPC, water-resistant CPC, and rhBMP-2/CPC, have been designed and fabricated in recent years. This paper attempts to give an overview of different types of CPC that have being developed at the present time. Meanwhile, the application perspective of these modified CPC is also explored.

Abstract: In the last few years, clinical procedures undergone huge modifications. Among them, mini-invasive surgery has modified the clinical practice and the quality of life of patients. Shape Memory Polymers (SMPs), a class of stimuli-responsive materials, can be considered ideal candidates for the design of devices for mini-invasive surgical procedures. Such a device can be inserted in a packed in, temporary shape and later can expand at body temperature. A bone defect could be filled by a SMP porous structure, that improves the tissue integration and healing. In this work, two different processing techniques to obtain porous shape memory polymer scaffolds from Calo MER™ and MM-4520, two SMPs, are presented. Porous structures were obtained by micro-extrusion with different chemical foaming agents or with sodium chloride, or by solvent casting/particulate leaching. The morphology, the thermo-mechanical and the shape recovery properties of the SMP porous samples were investigated. Tridimensional porous structures showed a well interconnected morphology, with a pore size in the range aimed for bone interaction applications. The shape memory properties were not significantly affected by the transformation processes: a good ability of recovering the original shape was verified. Therefore, the porous structures, obtained from these SMP materials, appear adequate for an use as bone filler.

Abstract: The use of 3D osteoconductive scaffolds provides an informative substrate serving as a physical support matrix for in vivo tissue regeneration. In the last few years the use of bioengineered 3D scaffolds has been becoming the most promising experimental approach for the regeneration of living tissues. Stem cells are typically used, in combination with 3D substrates, to promote in vivo bone regeneration and repair. For tissue engineering applications, biomaterials should therefore be able to support the functional properties of osteo-progenitor cells, giving them the optimal microenvironment to perform their physiological activity. Inorganic biomaterials are particularly relevant for bone regeneration; calcium phosphate ceramics have in fact been shown to strongly interact with bone tissue. The aim of the present work was to evaluate two different scaffolds with a defined design and different composition developed to guide/promote tissue repair.

Abstract: Composite biomaterials, like calciumphosphate/bioresorbable polymer, offer excellent potential for reconstruction and reparation of bone tissue defects induced by different sources. In this paper synthesis of calciumphosphate/poly-DL-lactide-co-glycolide (BCP/DLPLG) composite biomaterial formed as filler and blocks was studied. BCP/DLPLG composite biomaterial was produced in the form of spherical granules of BCP covered by a DLPLG layer, average diameter of 150-250 µm. By cold and hot pressing of granules at up to 10000 kg/cm2, blocks with fine distribution of phases and porosity up to 3% were obtained. Characterization was performed by wide-angle X-ray structural analysis (WAXS), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), infrared spectroscopy (IR), and mechanical properties by defining the compressive strength. In vitro citotoxicity research was carried out on cellular cultures of fibroblasts of human (MRC5) and mouse (L929). In vivo research was performed in two steps. Reparatory ability of BCP/DLPLG in mice was examined in the first step, and then bone tissue reconstruction possibilities on 10 patients in the next step. In vitro tests showed very good fibroblast adhesion and non-citotoxicity of the composite. A material is considered non-cytotoxic if the cell survival is above 50 %, and in our case it was 90%. In vivo research on mice indicated high level of reparatory ability of this composite with formation of new bone and vascular tissue six weeks after reparation. Application of this composite for healing infrabone defects of patients showed a high level of osseous regeneration.

Abstract: This paper demonstrated a simple technique to seed the hydroxyapatite (HA) ceramic with 2-D cultured cells to establish an advanced mode of HA grafting. The HA beads with a through-hole were fabricated to have an oblate shape to keep an opening of the through-hole contact with 2-D cultured cells layer. The seeding was performed by leaving the HA beads in a culture dish with MG63 cells in culture. The through-hole trapped MG63 cells in a sheet form by 1-day seeding. After 5 days, the number of trapped cells increased about nine fold, forming cell clumps in the through-hole. The seeding of the HA beads was considered an easy and practical method to provide HA/Cell hybrids that would realize active bone forming orthopedic treatment.

Abstract: Bone invasion is common in case of Squamous Cell Carcinomas (SCC) of the upper aero-digestive tract. Radiotherapy is required in addition to large surgical tumor removal. This treatment usually generates irreversible injuries on the reparation properties of the tissues, especially on bone. The quality of life of patients undergoing major surgery and radiotherapy in maxillary and mandible areas is reduced, but could be improved by bone reconstruction. The aim of this study was to evaluate the bone reconstruction possibilities by Macroporous Biphasic Calcium-Phosphate (MBCPÔ). The MBCP substitute was evaluated as granules and associated to autologous bone marrow (BM) graft in irradiated areas, in an inbreeding rodent model. Radiation sequels were created on inferior members of half of the rats. 3 weeks later, 3-mm osseous defects were created on each animal. The inbreeding model allows BM to be grafted without graft-versus-host reaction. Defects were filled either with MBCP alone, BM alone or a mixture of MBCP and BM. Six weeks after implantation, animals were sacrificed: bone repair and ceramic degradation were evaluated by qualitative and quantitative study. Results showed that bioceramics were well osteointegrated. Filling the defects with BM alone showed a significant increased of newly-formed bone formation but only after irradiation, whereas filling defects with MBCP alone increased new-bone formation only without previous irradiation. Associating MBCP to BM provided the best new-bone formation rates after irradiation. Degradation of the ceramic was the most important in case of BM grafting. This study demonstrated that BM added to MBCP constitute an appropriate material to be considered in case of bone defect occurring in irradiated tissue, and could be foreseen for use after bone removal for oncologic obligations.