Hassane Oudadesse

In vitro bioactivity of melt-derived glass 46S6 doped with magnesium

Melt-derived glasses in the system SiO(2)-CaO-Na(2)O-P(2)O(5) were synthesized pure or doped with magnesium from 0.4 to 1.2 wt %, for applications as biomaterials in bony surgery. This chemical element has been chosen because of its high physiological interest. Its introduction for different contents in melt derived glasses has never been studied. The bioactivity of glasses was assessed by immersion of the samples in the simulated body fluid solution. Changes in glass surface morphology and composition after immersion were evaluated by several physico-chemical techniques. The aim of this work was to characterize the formation of the apatite-like layer at the glass surface, after in vitro assays and to evaluate the kinetic reaction between the glass and the surrounding synthetic fluids. Results indicate that magnesium influences the formation and the evolution of the newly formed layers: (1) it promotes the dissolution of the silica network, (2) it increases the thickness of the silica gel layer formed conventionally prior to the apatite-like layer, and (3) it slows down the crystallization of the apatite layer. However, the intensity of these effects depends on the content of magnesium introduced in the glass matrix.

Prospect of Stem Cells in Bone Tissue Engineering: A Review

Mesenchymal stem cells (MSCs) have been the subject of many studies in recent years, ranging from basic science that looks into MSCs properties to studies that aim for developing bioengineered tissues and organs. Adult bone marrow-derived mesenchymal stem cells (BM-MSCs) have been the focus of most studies due to the inherent potential of these cells to differentiate into various cell types. Although, the discovery of induced pluripotent stem cells (iPSCs) represents a paradigm shift in our understanding of cellular differentiation. These cells are another attractive stem cell source because of their ability to be reprogramed, allowing the generation of multiple cell types from a single cell. This paper briefly covers various types of stem cell sources that have been used for tissue engineering applications, with a focus on bone regeneration. Then, an overview of some recent studies making use of MSC-seeded 3D scaffold systems for bone tissue engineering has been presented. The emphasis has been placed on the reported scaffold properties that tend to improve MSCs adhesion, proliferation, and osteogenic differentiation outcomes.

Apatite forming ability and cytocompatibility of pure and Zn-doped bioactive glasses

The use of bone grafts permits the filling of a bone defect without risk of virus transmission. In this work, pure bioactive glass (46S6) and zinc-doped bioactive glass (46S6Zn10) with 0.1 wt% zinc are used to elaborate highly bioactive materials by melting and rapid quenching. Cylinders of both types of glasses were soaked in a simulated body fluid (SBF) solution with the aim of determining the effect of zinc addition as a trace element on the chemical reactivity and bioactivity of glass. Several physico-chemical characterization methods such as x-ray diffraction, Fourier transform infrared spectroscopy and nuclear magnetic resonance methods, with particular focus on the latter, were chosen to investigate the fine structural behaviour of pure and Zn-doped bioactive glasses as a function of the soaking time of immersion in SBF. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to measure the concentrations of Ca and P ions in the SBF solution after different durations of immersion. The effect of the investigated samples on the proliferation rate of human osteoblast cells was assessed by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, and tested on two different sizes of pure and zinc-doped glasses in powder form, with particle sizes that ranged between 40 to 63 µm and 500 to 600 µm. The obtained results showed the delay release of ions by Zn-doped glass (46S6Zn10) and the slower CaP deposition. Cytotoxicity and cell viability were affected by the particle size of the glass. The release rate of ions was found to influence the cell viability.

Aluminosilicates and biphasic HA-TCP composites: studies of properties for bony filling.

Aluminosilicate materials synthesized at room temperature present good mechanical properties. Hydroxyapatite, tricalcium phosphate or both offer a high biocompatibility in the biomedical field. In this work, we focused on the composites resulting from associations of these materials. The best compromise between porosity and biomechanical properties versus different parameters was determined. The in vitro behaviour of compounds in contact with the simulated body fluid (SBF) was studied and in vivo experiments in a rabbits thighbones were carried out. The inductively coupled plasma-optical emission spectroscopy (ICP-OES) method permitted us to study the eventual release of Al from composites to SBF and to evaluate the chemical stability of composites characterized by the succession of SiO(4) and AlO(4) tetrahedra. The kinetic biomineralization, the bioconsolidation and biological studies were made. The results obtained show the chemical stability of composites. In the bone-implant interface, the intimate links reveal the high quality of the biointegration and the bioconsolidation between composites and bony matrix. Histological studies confirm good bony bonding and highlight the total absence of inflammation or fibrous tissues.

Biological therapy of strontium-substituted bioglass for soft tissue wound-healing: responses to oxidative stress in ovariectomised rats.

New synthetic biomaterials are constantly being developed for wound repair and regeneration. Bioactive glasses (BG) containing strontium have shown successful applications in tissue engineering account of their biocompatibility and the positive biological effects after implantation. This study aimed to assess whether BG-Sr was accepted by the host tissue and to characterize oxidative stress biomarker and antioxidant enzyme profiles during muscle and skin healing. Wistar rats were divided into five groups (six animals per group): the group (I) was used as negative control (T), after ovariectomy, groups II, III, IV and V were used respectively as positive control (OVX), implanted tissue with BG (OVX-BG), BG-Sr (OVX-BG-Sr) and presented empty defects (OVX-NI). Soft tissues surrounding biomaterials were used to estimate superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and malondialdehyde (MDA) concentration. Our results show that 60 days after operation, treatment of rats with BG-Sr significantly increased MDA concentration and caused an increase of SOD, CAT and GPx activities in both skin and muscular tissues. BG-Sr revealed maturation of myotubes followed a normal appearance of muscle regenerated with high density and mature capillary vessels. High wound recovery with complete re-epithelialization and regeneration of skin was observed. The results demonstrate that the protective action against reactive oxygen species (ROS) was clearly observed in soft tissue surrounding BG-Sr. Moreover, the potential use of BG-Sr rapidly restores the wound skin and muscle structural and functional properties. The BG advantages such as ion release might make BG-Sr an effective biomaterial choice for antioxidative activity.

Fabrication, Characterization and Drug Release of Ciprofloxacin Loaded Porous Polyvinyl Alcohol/Bioactive Glass Scaffold for Controlled DrugDelivery

Composite scaffolds of Polyvinyl Alcohol (PVA) and/or quaternary bioactive glass (46S6 system) containing 5, 10 and 20 wt % ciprofloxacin were prepared by lyophilisation technique. The porosity of the prepared scaffolds was measured by liquid displacement, Hg-porosimeter and SEM. The structure and the nature of chemical bonds between atoms were examined by XRD and FTIR. They confirmed the incorporation of ciprofloxacin into the scaffolds. Biodegradation rate and drug release behaviour were conducted in Phosphate Buffer Saline (PBS) at pH 7.4. A porous scaffold has been obtained with porosity up to 85%. By increasing the glass contents and drug concentration in the prepared scaffold the porosity and the degradation rate decrease however, the compressive strength was enhanced. A sustained drug release pattern was observed from the optimized scaffold with a quasi-Fickian diffusion mechanism and it was able to deliver the drug in a prolonged release pattern which offers a distinguish treatment for osteomylitis as well as local antibacterial effect.

Development of a three-dimensional model for rapid evaluation of bone substitutes in vitro: effect of the 45S5 bioglass.

The evaluation of innovative bone substitutes requires the development of an optimal model close to physiological conditions. An interesting alternative is the use of an immortalized cell line to construct multicellular spheroids, that is, three-dimensional (3D) cultures. In this study, a modified hanging drops method has resulted in the generation of spheroids with a well-established human fetal osteoblasts line (hFOB 1.19), and tests have been focused on the effect of 45S5 bioglass ionic dissolution products in comparison with two-dimensional (2D) cultures. Depending on cell culture type, quantitative analysis (cell proliferation, viability/cytotoxicity, and cellular cycle) and qualitative analysis (electron microscopy and genes expression) showed a differential effect. Cell proliferation was enhanced in 2D-conditioned cultures in accordance with literature data, but decreased in 3D cultures submitted to the same conditions, without change of gene expression patterns. The decrease of cell proliferation, observed in conditioned spheroids, appears to be in agreement with clinical observations showing the insufficiency of commercially available bioglasses for bone repairing within nonbearing sites, such as periodontal defects or small bone filling, in general. Therefore, we suggest that this model could be adapted to the screening of innovative bioactive materials by laboratory techniques already available and extended monitoring of their bioactivity.

Bioactivity behaviour of biodegradable material comprising bioactive glass

Biocomposite of bioactive glass (BG) with chitosan polymer (CH) is prepared by freeze-drying technique. Obtained material is investigated by using several physico-chemical methods. The XRD and FTIR show the interface bonding interactions between glass and polymer. The specific surface and porosity of biocomposite were determined. In vitro assays were employed to evaluate the effect of chitosan addition on the glass by studying the chemical reactivity and bioactivity of the BG and BG/CH biocomposite after soaking in a simulated body fluid (SBF). The obtained results show the formation of a bioactive hydroxycarbonate apatite (HCA) layer and highlight the bioactivity and the kinetics of chemical reactivity of bioactive glass, particularly after association with chitosan. The BG/CH biocomposite has excellent ability to form an apatite layer. Inductively coupled plasma-optical emission spectrometry (ICP-OES) highlights the negative effect of chitosan on the silicon release toward the SBF of bioactive glass when in vitro assays.

Thermal behaviour of composites aluminosilicate-calcium phosphates

A new type of aluminosilicate matrix calcium phosphate crystallites composites (ACPC) was synthesized and studied for osseous bone applications. The room temperature synthesis of the aluminosilicate matrix and composites was described. Thermal treatments of compounds allowed the adaptability of some parameters (pH, porosity and mechanical properties). Structure of heat treated composites were characterized by XRD and FTIR. The influence of thermal treatment on the mechanical properties, the porosity and the pH was studied for two temperatures (250 and 500°C). Results evidenced the ability to control the pH, the high level of porosity (»70%) and the good mechanical properties, allowing to consider that ACPC are potential biomaterials for osseous bone application.

Physical and biological characteristics of nanohydroxyapatite and bioactive glasses used for bone tissue engineering

Abstract Critical-sized bone defects have, in many cases, posed challenges to the current gold standard treatments. Bioactive glasses are reported to be able to stimulate more bone regeneration than other bioactive ceramics; however, the difficulty in producing porous scaffolds made of bioactive glasses has limited their extensive use in bone regeneration. On the other hand, calcium phosphate ceramics such as synthetic hydroxyapatite and tricalcium phosphate are widely used in the clinic, but they stimulate less bone regeneration. This paper gives an overview of the recent developments in the field of bioactive nanoparticles, with a focus on nanohydroxyapatite and bioactive glasses for bone repair and regeneration. First, a brief overview of the chemical structure and common methods used to produce synthetic nanohydroxyapatite and bioactive glasses has been presented. The main body of the paper covers the physical and biological properties of these biomaterials, as well as their composites with biodegradable polymers used in bone regeneration. A summary of existing challenges and some recommendations for future directions have been brought in the concluding section of this paper.