Hafed El Feki

Chitosan-based bioglass composite for bone tissue healing : Oxidative stress status and antiosteoporotic performance in a ovariectomized rat model

Tissue engineering has opened up a new therapeutic avenue promising a revolution in regenerative medicine. Considerable attention has been given to chitosan composite materials and their applications in the field of the bone graft substitutes. We evaluated the antioxidative properties of chitosan-doped bioactive glass (BG-CH) with 17 wt% chitosan, and their applications in the guided bone regeneration. BG-CH was produced by a freeze-drying process and implanted in the femoral condyles of ovariectomized rats. Grafted bone tissues were carefully removed to evaluate the oxidative stress analysis, histomorphometric profile and mineral bone distribution by using inductively coupled plasma optical emission spectrometry (ICP-OES). A significant decrease of thiobarbituric acid-reactive substances (TBARs) was observed after BG-CH implantation. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities significantly increased in ovariectomized group implanted with chitosan-doped bioactive glass (OVXBG-CH) as compared to ovariectomized group implanted with bioactive glass (OVX-BG). The histomorphometric analysis showed that bone/tissue volume (BV/TV), osteoblast number (N.Ob) and osteoblast surface/bone surface (Ob.S/BS) were significantly higher in OVX-BG-CH group than in OVX-BG group. On the other hand, a rise in Ca and P ion concentrations in the implanted microenvironment was shown to lead to the formation/deposition of Ca-P phases. Trace elements such as Sr and Fe were detected in the newly formed bone and involved in bone healing. These results suggested that BG-CH composites could become clinically useful as a therapeutic and implantable material.

Biologic response to carbonated hydroxyapatite associated with orthopedic device: experimental study in a rabbit model.

Background Carbonated hydroxyapatite (CHA) and related calcium phosphates have been studied for many years as implant materials due to their similarity with the mineral phase of bone. The main limitation of CHA ceramics as well as other bioactive materials is that they have poor mechanical proprieties. It is thought that the mechanical device can cause an increase in metabolic activity and bone healing. In this study we investigated the reactivity and tissue behaviour of implanted CHA biomaterial reinforced by mini external fixator. Methods The evaluation of biomaterial biocompatibility and osteogenesis was performed on a rabbit model over a period of 6 weeks by radiological, histological and scanning electron microscopy (SEM) coupled with energy dispersive X-ray SEM-energy-dispersive X-ray (EDX) analysis. Results While rabbits treated with CHA exhibited more bone formation, and fibrous tissue was observed when empty bone defects were observed. EDX analysis detected little calcium and phosphorus on the surface of the bone that was not implanted, while high content of calcium (62.7%) and phosphorus (38%) was found on the interface bone cement. Conclusions Bone repairing showed that the mini external fixator stimulated the ossification which was pushed when grafted by CHA. This effect may play an important role in the prevention of implant loosening.

The potential restorative effects of strontium-doped bioactive glass on bone microarchitecture after estrogen-deficieny induced osteoporosis: Physicochemical and histomorphometric analyses

Strontium (Sr) compounds have become increasingly popular in the field of osteoporosis treatment. However, the quality of new bone after implantation of strontium-containing bioceramics has yet to be investigated. In the present study, the newly formed bone tissue around strontium-doped bioactive glass (BG-Sr) implants was characterized. BG-Sr was implanted in the femoral condyl of ovariectomised rats (OVX). The resected bone was prepared for analysis using several physico-chemical and biological assays such as Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, and histomorphometry. BG-Sr biomaterial favored calcium phosphate layer integration on the surface of the glass and offered better bioactivity. Moreover, the histomorphometric analysis demonstrated that BV/TV, N. Ob were significantly higher in BG-Sr treated rats groups than those of BG groups. However, Ob. S/BS, and OV/BV were significantly lower in BG-Sr treated rats groups than those of BG groups. The (Oc.S/BS) was significantly decreased in BG-Sr groups, when compared with that of BG rat groups. On the other hand, the MS/BS had not significantly decreased in the BG-Sr treated rats groups when compared with that of BG groups, however; it was significantly higher when compared with control and OVX groups. These findings suggest that BG-Sr can be used as an inhibitory therapeutic potential of osteoporosis by delivering strontium to stimulate new bone remodeling.

Novel alkali borosilicate glasses: Preparation, structural investigation and thermal study

Bioactive glasses are indicated for use as bone substitutes in orthopedic or dental surgery because of their high reactivity once in contact with the biological medium. Boron is known as a glass network former and an activator of the glasses bioactivity. In this work, bioactive glass was doped by 5, 10 and 20 wt% of B2O3 according to the melting process. Adding boron oxide with high content enhances glass materials’ bioactivity. Likewise, thanks to their solubility, borate-containing bioactive glasses were fluently used as orthopedic implants. The aim of our study was to investigate of boron effect on the thermal characteristics of our bioactive glass to better understand their proprieties in order for use as bone biomaterial. The obtained results proved that the more the boron content in the glass network increases, the more the melting temperature decreases and the more the thermal stability increases.