Porous crosslinked poly(ε-caprolactone fumarate)/nanohydroxyapatite composites for bone tissue engineering

Effect of bassorin (derived from gum tragacanth) and halloysite nanotubes on physicochemical properties and the osteoconductivity of methylcellulose-based injectable hydrogels

Injectable hydrogels have been known as promising materials for the regeneration of irregular shape tissue defects. In this study, novel thermosensitive methylcellulose (MC) hydrogels containing bassorin (Ba) and halloysite nanotubes (HNTs) have been developed for application in bone tissue engineering. Bassorin isolated from gum tragacanth (GT) with the concentration of 0.25-1.5 w/v% was blended with MC. The best MC/Ba gel (containing 0.5% bassorin) was chosen based on the results of injectability and rheological tests. HNTs (1-7%) were added to this formulation and tested for the physicochemical, mechanical, rheological, degradation, swelling, and biological properties. In vitro biological evaluations including cell proliferation (by MTT assay), cell attachment (by SEM), osteogenic activity (by Alizarin Red staining and alkaline phosphatase assay), and osteogenic gene expression (by quantitative real-time polymerase chain reaction) were done using MG-63 cells. Results showed that bassorin led to the increased gel-forming ability (at a lower temperature) and mechanical properties of MC hydrogel. The presence of HNTs and bassorin affected the degradation rate and swelling degree of MC-based hydrogel. Results showed significant enhancement in cell proliferation, differentiation, and mineralization, as well as higher bone-specific gene expression of the cell on bassorin and HNTs incorporated MC compared to pure MC hydrogel.

Silk fibroin/hydroxyapatite scaffold: a highly compatible material for bone regeneration

In recent years remarkable efforts have been made to produce artificial bone through tissue engineering techniques. Silk fibroin (SF) and hydroxyapatite (HA) have been used in bone tissue regeneration as biomaterials due to mechanical properties of SF and biocompatibility of HA. There has been growing interest in developing SF/HA composites to reduce bone defects. In this regard, several attempts have been made to study the biocompatibility and osteoconductive properties of this material. This article overviews the recent advance from last few decades in terms of the preparative methods and application of SF/HA in bone regeneration. Its first part is related to SF that presents the most common sources, preparation methods and comparison of SF with other biomaterials. The second part illustrates the importance of HA by providing information about its production and properties. The third part presents comparative studies of SF/HA composites with different concentrations of HA along with methods of preparation of composites and their applications.

Preparation and in vitro evaluation of polycaprolactone/PEG/bioactive glass nanopowders nanocomposite membranes for GTR/GBR applications

In the present study, nanocomposite membranes are investigated using poly-ε-caprolactone (PCL), polyethylene glycol (PEG) and bioactive glass nanopowders (BGs) synthesized via solvent casting method with different reinforcement rates of BGs consisting of 3, 5 and 7 wt% for regenerating the periodontal tissue in vitro. These prepared membranes were evaluated by a vast range of essential tests; including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Transmition-electron microscopy (TEM), tensile testing before and after soaking in PBS solution, degradation and contact angle assessments as well as cell culture assays. In spite of the fact that the percentage of Cu incorporated into BGs was trivial, this negligible amount exerted major cytotoxic impact upon cells during in vitro cell tests. According to the results, the blended-membrane contained 7 wt% copper-free BGs indicated optimum characteristics including satisfactory mechanical and biodegradation features, more wettable surface, higher proliferation rates of adipose-derived stem cells (ADSCs), superior ALP activity and brilliant bone mineralization capacity which was confirmed by Alizarin red assay. As a consequence, it can be used as a desirable candidate for guided tissue/bone regeneration (GTR/GBR) to accelerate bone tissue healing.

Fabrication of porous magnetic nanocomposites for bone tissue engineering

Porous superparamagnetic chitosan/polyethylene glycol/hydroxyapatite–Fe₃O₄ nanocomposites were developed for bone tissue engineering.

Porous crosslinked polycaprolactone hydroxyapatite networks for bone tissue engineering

In this study, porous scaffolds were produced by a thermal crosslinking of polycaprolactone diacrylate in the presence of hydroxyapatite (HA) and particulate leaching technique with sodium chloride as the water soluble porogen for bone tissue engineering applications. The prepared scaffolds were characterized using techniques such as Field Emission Scanning Electron Microscopy, Differential Scanning Calorimetry, and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy. Moreover, dynamic mechanical properties were investigated using Dynamic Mechanical Thermal Analysis. The obtained scaffolds present a porous structure with interconnected pores and porosity around 73%. It was found that the incorporation of HA particles to polycaprolactone (PCL) matrix resulted in an increased crystallinity. Moreover, both the storage modulus (E') and glass transition temperature (T_g) increased, while the loss factor (tan δ) decreased due to the hindrance of the HA particles to the mobility of polymer segments. Cytocompatability of the scaffolds was assessed by MTT assay and cell attachment studies. Osteoconductivity of the scaffolds was investigated with cells alkaline phosphatase extraction. The levels of alkaline phosphatase activity were found to be higher for PCL/HA network scaffold than for PCL network scaffold. In addition, cytocompatibility of the PCL/HA network scaffold indicated no toxicity, and cells were attached and spread to the scaffold walls.

Recent advances in the biomedical applications of fumaric acid and its ester derivatives: The multifaceted alternative therapeutics

Several lines of evidence have demonstrated the potential biomedical applications of fumaric acid (FA) and its ester derivatives against many human disease conditions. Fumaric acid esters (FAEs) have been licensed for the systemic treatment of the immune-mediated disease psoriasis. Biogen Idec Inc. announced about the safety and efficacy of the formulation FAE (BG-12) for treating RRMS (relapsing-remitting multiple sclerosis). Another FAE formulation DMF (dimethyl fumarate) was found to be capable of reduction in inflammatory cardiac conditions, such as autoimmune myocarditis and ischemia and reperfusion. DMF has also been reported to be effective as a potential neuroprotectant against the HIV-associated neurocognitive disorders (HAND). Many in vivo studies carried out on rat and mice models indicated inhibitory effects of fumaric acid on carcinogenesis of different origins. Moreover, FAEs has emerged as an important matrix ingredient in the fabrication of biodegradable scaffolds for tissue engineering applications. Drug delivery vehicles composed of FAEs have shown promising results in delivering some leading drug molecules. Apart from these specific applications and findings, many more studies on FAEs have revealed new therapeutic potentials with the scope of clinical applications. However, until now, this scattered vital information has not been written into a collective account and analyzed for minute details. The aim of this paper is to review the advancement made in the biomedical application of FA and FAEs and to focus on the clinical investigation and molecular interpretation of the beneficial effects of FA and FAEs.

Effect of interface on mechanical properties and biodegradation of PCL HAp supramolecular nano-composites

This research explores the correlation between the structural properties of supramolecular biocomposites and their mechanical strength. Hybrid biocomposites composed of surface-modified hydroxyapatite nano-particles and supramolecular polycaprolactone (SP PCL), were prepared at different compositions, and their mechanical, thermal and viscoelastic properties as well as biodegradability, biocompatibility and cytotoxicity were evaluated in vitro. The results were compared with those for SP PCL/naked hydroxyapatite nano-composites. We show that surface modification of hydroxyapatite nanoparticles resulted in outstanding improvement of tensile strength and modulus up to 3.6 and 2.2-fold, respectively. At above 10 wt% HAp and 20 wt% HApUPy, heterogeneous nano-composites with inferior mechanical properties were obtained. Based on rheological (in steady shear mode) and small/wide angle X-ray scattering measurements, unusual improved mechanical properties were ascribed to the formation of supramolecular clusters around nanoparticles. In-vitro degradation of the supramolecular nano-composites was also studied to investigate the overall product biodegradation as well as toxicity of the degradation product(s).

Bio-hybrid silk fibroin/calcium phosphate/PLGA nanocomposite scaffold to control the delivery of vascular endothelial growth factor

This study investigated the efficacy of bio-hybrid silk fibroin/Calcium phosphate/PLGA nanocomposite scaffold as vascular endothelial growth factor (VEGF) delivery system. The scaffold was fabricated using freeze-drying and electrospinning. Here, we highlight the structural changes of the scaffold using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and differential scanning calorimetry (DSC). The uniform dispersion of calcium phosohate (CaP) powder within silk fibroin (SF) solution was also confirmed using Zeta potential analysis. Moreover, good biocompatibility of osteoblast cells next to the scaffold was approved by cell adhesion, proliferation and alkaline phosphatase production. The release profile of VEGF during 28 days has established the efficacy of the scaffold as a sustained delivery system. The bioactivity of the released VEGF was maintained about 83%. The histology analysis has shown that the new bone tissue formation happened in the defected site after 10 weeks of implantation. Generally, our data showed that the fabricated scaffold could be considered as an effective scaffold for bone tissue engineering applications.