Biological evaluations of novel 2,3,3-Trisphosphonate in osteoclastic and osteoblastic activities

Bisphosphonates (BPs) are the first line treatment for many bone diseases including hypercalcimia associated with bone malignancies. In this paper, we introduce a new analogue of bisphosphonate called the 2,3,3-Trisphosphonate (2,3,3-TriPP) that was synthesised in a two steps reaction. In vitro investigations using a medically known bisphosphonate (Etidronate) and the 2,3,3-TrisPP were performed with an aim to evaluate biological effect of this novel compound in major bone cells. 2,3,3-TrisPP showed to have potential to supress the bone resorption process, as our data found that this novel compound exhibited cytotoxic effect in osteoclastic cells at a low concentration of 0.172 mg/mL (LC50). A molecular docking computational simulation calculated a high level of binding affinity between the human farnesyl pyrophosphate synthase (hFPPS) and 2,3,3-TrisPP. This calculation suggested 2,3,3TrisPP may have undergone the mevalonate pathway to prevent the prenylation step during biosynthesis and subsequently resulted in the deactivation of osteoclastic cells. Finally, high levels of osteoblast mineralisation potentials were recorded upon treatments with 2,3,3-TrisPP (0.01-0.1 mg/ml), which implied 2,3,3-TrsiPP may also facilitate bone regeneration.Peer reviewe

Biofabrication of 3D hard-soft and composite constructs for bone regeneration

Biofabrication encompasses the use of additive manufacturing techniques for fabricating complex constructs from a wide range of biomaterials, cells and bioactive substances as well as their maturation for the formation of tissue. The fabricated constructs should provide mechanical stability, porosity, and accurate positioning of cells. The aim of this work was the creation of hybrid constructs consisting of a combination of a thermoplastic hard polymer with and without addition of bioactive glass particles and a soft hydrogel matrix with immobilised cells. The hard phase should enhance the limited mechanical performance of the soft hydrogel phase. Moreover the addition of bioactive glass will enhance the local bioactivity of the scaffolds, of relevance for bone tissue engineering [1]. The hydrogel composition, based on alginate, was tailored to enable the proliferation, migration and differentiation of cells. The mechanical properties and the degradation kinetic of the constructs were investigated. Alginate-dialdehyde (ADA) gelatine (GEL) hydrogel (= ADA-GEL) containing murine bone marrow derived stroma cells (ST2) and polycaprolactone (PCL), polyethylene glycol (PEG) blends were used. Processing was done by additive manufacturing using a dispense plotter equipped with multiple cartridges. Process parameters like plotting speed, pressure and temperature were optimized for the two material systems. Porosity, degradation behaviour and mechanical stability of the PCL-PEG frame structure scaffolds were tested as well as the response of ST2 cells. The presence of bioactive glass leading to enhance local formation of hydroxyapatite was investigated. The cell behaviour and cell development were characterized by assessing the morphology and by measuring the viability of the immobilized cells in the ADA-GEL over an incubation period of 28 days. Both materials could be processed in a defined manner with optimized process parameters. The PEG phase could be dissolved and porous (bioactive) struts forming a framework structure were created. The viability of immobilized ST2 cells after hydrogel plotting was proven as well as their attachment, migration and proliferation by SEM and fluorescence microscopy images. Thus, two promising material systems for creating hybrid constructs were successfully evaluated. The two phase plotting approach enables the fabrication of hydrogel constructs with improved mechanical properties and bioactivity, which exhibit high potential for applications in bone regeneration. [1] A. J. Leite, et al., Bioplotting of a bioactive alginate dialdehyde-gelatin composite hydrogel containing bioactive glass nanoparticles, Biofabrication, 8, pp. 035005 (2016

Engineering of Metabolic Pathways by Artificial Enzyme Channels.

Application of industrial enzymes for production of valuable chemical compounds has greatly benefited from recent developments in Systems and Synthetic Biology. Both, in vivo and in vitro systems have been established, allowing conversion of simple into complex compounds. Metabolic engineering in living cells needs to be balanced which is achieved by controlling gene expression levels, translation, scaffolding, compartmentation, and flux control. In vitro applications are often hampered by limited protein stability/half-life and insufficient rates of substrate conversion. To improve stability and catalytic activity, proteins are post-translationally modified and arranged in artificial metabolic channels. Within the review article, we will first discuss the supramolecular organization of enzymes in living systems and second summarize current and future approaches to design artificial metabolic channels by additive manufacturing for the efficient production of desired products

Fabrication and characterization of alginate-keratin based composite microspheres containing bioactive glass for tissue engineering applications

3D cell encapsulation within hydrogels has attracted more and more attention in tissue engineering applications because hydrogels provide a hydrated environment closely mimicking the in vivo environment for cell and tissue growth1. This present study considers the fabrication of alginate-keratin based composite microspheres containing bioactive glass (BG) of 45S5 composition for cell encapsulation. We propose the use of alginate di-aldehyde (ADA) synthesized via periodate oxidation of alginate to enhance the biodegradability of alginate, and the incorporation of keratin into the alginate based hydrogel to improve cellular interaction of the hydrogel. Keratins extracted from wool contain cell adhesive peptide sequences including RGD (arginine-glycine-aspartic acid), and LDV (leucine-aspartic acid-valine)2. BG particles, well known for promoting calcium phosphate deposition, were incorporated into the microspheres to enhance osseointegration3. The microspheres were prepared via a pressure-driven extrusion technique. Weight loss, protein release measurements, and FTIR spectroscopy of the fabricated microspheres were carried out. The morphology and microstructure of the microspheres were investigated by light microscopy and scanning electron microscopy (SEM), respectively. The results demonstrated that the composition of the hydrogels had a significant effect on their physical properties. Biological properties of ADA-keratin based microspheres were evaluated by encapsulating MG-63 osteosarcoma cells into the microspheres. Cell viability of MG-63 cells in ADA-keratin-1%BG hydrogels was found to be comparable to that of alginate-keratin and ADA-keratin after culturing for 21 days. The results proved that such novel composite hydrogel might be a promising material for biofabrication in bone healing approaches. Please click Additional Files below to see the full abstract

Magnetic Glass Ceramics by Sintering of Borosilicate Glass and Inorganic Waste

Ceramics and glass ceramics based on industrial waste have been widely recognized as competitive products for building applications; however, there is a great potential for such materials with novel functionalities. In this paper, we discuss the development of magnetic sintered glass ceramics based on two iron-rich slags, coming from non-ferrous metallurgy and recycled borosilicate glass. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low temperatures (900–1000 °C), whereas glass/slag interactions resulted in the formation of magnetite crystals, providing ferrimagnetism. Such behavior could be exploited for applying the obtained glass ceramics as induction heating plates, according to preliminary tests (showing the rapid heating of selected samples, even above 200 °C). The chemical durability and safety of the obtained glass ceramics were assessed by both leaching tests and cytotoxicity tests

Cell adhesion evaluation of laser-sintered HAp and 45S5 bioactive glass coatings on micro-textured zirconia surfaces using MC3T3-E1 osteoblast-like cells

Laser texturing is a technique that has been increasingly explored for the surface modification of several materials on different applications. Laser texturing can be combined with conventional coating techniques to functionalize surfaces with bioactive properties, stimulating cell differentiation and adhesion. This study focuses on the cell adhesion of laser-sintered coatings of hydroxyapatite (HAp) and 45S5 bioactive glass (45S5 BG) on zirconia textured surfaces using MC3T3-E1 cells. For this purpose, zirconia surfaces were micro-textured via laser and then coated with HAp and 45S5 BG glass via dip coating. Afterwards, the bioactive coatings were laser sintered, and a reference group of samples was conventionally sintering. The cell adhesion characterisation was achieved by cell viability performing live/dead analysis using fluorescence stains and by SEM observations for a qualitative analysis of cell adhesion. The in vitro results showed that a squared textured pattern with 100μm width grooves functionalized with a bioactive coating presented an increase of 90% of cell viability compared to flat surfaces after 48h of incubation. The functionalized laser sintered coatings do not present significant differences in cell viability when compared to conventionally sintered coatings. Therefore, the results reveal that laser sintering of HAp and 45S5 BG coatings is a fast and attractive coating technique.publishe

3D Printing of Piezoelectric Barium Titanate-Hydroxyapatite Scaffolds with Interconnected Porosity for Bone Tissue Engineering

The prevalence of large bone defects is still a major problem in surgical clinics. It is, thus, not a surprise that bone-related research, especially in the field of bone tissue engineering, is a major issue in medical research. Researchers worldwide are searching for the missing link in engineering bone graft materials that mimic bones, and foster osteogenesis and bone remodeling. One approach is the combination of additive manufacturing technology with smart and additionally electrically active biomaterials. In this study, we performed a three-dimensional (3D) printing process to fabricate piezoelectric, porous barium titanate (BaTiO3) and hydroxyapatite (HA) composite scaffolds. The printed scaffolds indicate good cytocompatibility and cell attachment as well as bone mimicking piezoelectric properties with a piezoelectric constant of 3 pC/N. This work represents a promising first approach to creating an implant material with improved bone regenerating potential, in combination with an interconnected porous network and a microporosity, known to enhance bone growth and vascularization

Highly Porous Polymer-Derived Bioceramics Based on a Complex Hardystonite Solid Solution

Highly porous bioceramics, based on a complex hardystonite solid solution, were developed from silicone resins and micro-sized oxide fillers fired in air at 950 °C. Besides CaO, SrO, MgO, and ZnO precursors, and the commercial embedded silicone resins, calcium borate was essential in providing the liquid phase upon firing and favouring the formation of an unprecedented hardystonite solid solution, corresponding to the formula (Ca0.70Sr0.30)2(Zn0.72Mg0.15Si0.13) (Si0.85B0.15)2O7. Silicone-filler mixtures could be used in the form of thick pastes for direct ink writing of reticulated scaffolds or for direct foaming. The latter shaping option benefited from the use of hydrated calcium borate, which underwent dehydration, with water vapour release, at a low temperature (420 °C). Both scaffolds and foams confirmed the already-obtained phase assemblage, after firing, and exhibited remarkable strength-to-density ratios. Finally, preliminary cell tests excluded any cytotoxicity that could be derived from the formation of a boro-silicate glassy phase

Structure optimisation and biological evaluation of bone scaffolds prepared by co-sintering of silicate and phosphate glasses

A degradable phosphate glass (ICEL) and a bioactive silicate glass (CEL2) were mixed in different ratios (wt-%: 100%ICEL, 70%ICEL-30%CEL2, 30%ICEL-70%CEL2, 100%CEL2; codes 100-0, 70-30, 30-70, 0-100) and then co-sintered to obtain three-dimensional porous scaffolds by gel casting foaming. Thermal analyses were carried out on the glass mixtures and were used as a starting point for the optimisation of the scaffold sintering treatment. The microcomputed tomography and field emission scanning electron microscope analyses allowed the selection of the optimal sintering temperature to obtain an adequate structure in terms of total and open porosity. The scaffolds showed an increasing solubility with increasing ICEL glass content, and for 30-70 and 0-100, the precipitation of hydroxyapatite in simulated body fluid was observed. In vitro tests indicated that all the scaffolds showed no cytotoxic effect. The co-sintering of silicate and phosphate glasses showed to be a promising strategy to tailor the scaffold osteoconductivity, degradation and bioactivit