Osteoblast Cell Viability Research Articles

Porous titanium scaffold surfaces modified with silver loaded gelatin microspheres and their antibacterial behavior

Abstract Recent years, porous titanium (PT) attracts much attention because of its growing application as medical implants. However, bacterial infections related to implants remain one of the most common and serious complications. In this study, silver loaded gelatin microspheres (Ag/GMSs) were fabricated and incorporated into porous titanium to get antibacterial implants. Prior to incorporating microspheres, oxide film and micro/nanostructures were formed on porous titanium by micro-arc oxidation (MAO) to improve its activity, and the resulted sample is named MPT. Samples were characterized with scanning electron microscope, energy dispersive X-ray spectroscope, transmission electron microscope, X-ray diffractometer, laser scattering particle analyzer and atomic absorption spectrometer. The results showed that Ag0 particles were loaded to the gelatin microspheres with average diameter of 4.46 μm and Ag/GMSs distributed uniformly on the pore walls of PT and MPT. Ag0 particles were demonstrated not only formed on the surface of gelatin microspheres but also inside them. The silver loaded samples exhibited a high antibacterial ability against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The MPT sample was not only better in supporting osteoblast cell viability and good cell proliferation, but also was beneficial to immobilize the silver loaded microspheres to achieve a stronger antibacterial effect than PT. The MPT sample with silver loaded gelatin microspheres increased the cumulative release period of Ag and reached to more than ten days. The main idea of this study also elicited a new surface functionalization strategy for improving antibacterial ability of porous titanium.

Antimicrobial and cell viability measurement of bovine serum albumin capped silver nanoparticles (Ag/BSA) loaded collagen immobilized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) film

Bacterial infection of orthopedic devices has been a major concern in joint replacement procedures. Therefore, this study is aimed at formulating collagen immobilized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) film loaded with bovine serum albumin capped silver nanoparticles (Ag/BSA NPs) to inhibit bacterial growth while retaining/promoting osteoblast cells viability. The nanoparticles loaded collagen immobilized PHBV film was characterized for its composition by X-ray Photoelectron Spectroscopy and Anodic Stripping Voltammetry. The extent of loading of Ag/BSA NPs on collagen immobilized PHBV film was found to depend on the chemistry of the functionalized PHBV film and the concentration of Ag/BSA NPs solution used for loading nanoparticles. Our results showed that more Ag/BSA NPs were loaded on higher molecular weight collagen immobilized PHEMA-g-PHBV film. Maximum loading of Ag/BSA NPs on collagen immobilized PHBV film was observed when 16ppm solution was used for adsorption studies. Colony forming unit and optical density measurements showed broad antimicrobial activity towards Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa at significantly lower concentration i.e., 0.19 and 0.31μg/disc, compared to gentamicin and sulfamethoxazole trimethoprim while MTT assay showed that released nanoparticles from Ag/BSA NPs loaded collagen immobilized PHBV film has no impact on MCTC3-E1 cells viability.

A novel silica nanotube reinforced ionic incorporated hydroxyapatite composite coating on polypyrrole coated 316L SS for implant application

An attempt has been made to deposit a novel smart ion (Sr, Zn, Mg) substituted hydroxyapatite (I-HAp) and silica nanotube (SiNTs) composite coatings on polypyrrole (PPy) coated surgical grade 316L stainless steel (316L SS) to improve its biocompatibility and corrosion resistance. The I-HAp/SiNTS/PPy bilayer coating on 316L SS was prepared by electrophoretic deposition technique. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies were carried out. These results confirmed the significant improvement of the corrosion resistance of the 316L SS alloy by the I-HAp/SiNTs/PPy bilayer composite coating. The adhesion strength and hardness test confirmed the anticipated mechanical properties of the composite. A low contact angle value revealed the hydrophilic nature. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) was used for the leach out analysis of the samples. Added to this, the bioactivity of the composite was analyzed by observing the apatite formation in the SBF solution for 7, 14, 21 and 28days of incubation. An enhancement of in vitro osteoblast attachment and cell viability was observed, which could lead to the optimistic orthopedic and dental applications.

Synthesis of PEO-based di-block glycopolymers at various pendant spacer lengths of glucose moiety and their in-vitro biocompatibility with MC3T3 osteoblast cells

Di-block copolymers of poly(ethylene oxide) (PEO) and glycopolymers at three different pendant spacer lengths of glucose moiety were synthesized by deacetylation of pendant moieties of 2,3,4,6-tetra-O-acetyl-d-glucopyranosides which were prepared by reversible addition-fragmentation chain-transfer (RAFT) process. The water soluble deacetylated copolymers, PEO-b-poly(acryl-d-glucopyranoside) (PEO-b-PAG, 2a), PEO-b-poly[4′-(acryloxy)butyl-d-glucopyranoside] (PEO-b-PABG, 2b), and PEO-b-poly[6′-(acryloxy)hexyl-d-glucopyranoside] (PEO-b-PAHG, 2c) were characterized in comparison with acetylated copolymers by spectroscopic and gel permeation chromatography methods. In order to assess the biocompatibility of these three di-block copolymers, the adhesion (%), viability (%), and proliferation assays were carried out in MC3T3 cells in-vitro at different concentrations from 10 nM to 1000 μM. Qualitative analysis of cell cytoskeletal organization was obtained by immunostaining with talin and integrin α5. It was clearly indicative of well spreading of cells in the presence of all glycopolymers at lower concentrations but with an increase in the concentration (10 and 100 μM) showed significant change in the cell surface morphologies, despite having good cell adhesion and viability as compared to the control conditions. The use of di-block glycolpolymers at ≤ 100 μM of the concentration showed very good osteoblast cells adhesion and viability response; however at higher concentrations (1000 μM) of glycopolymers > 80% of cells lost their viability.

Concentration-dependent effects of alendronate and pamidronate functionalized gold nanoparticles on osteoclast and osteoblast viability.

Severe osteoporotic diseases, such as Paget's disease, Osteogenesis Imperfecta, and Legg Calve Perthes disease, lack treatments that address the pathobiology of the diseases, as well as, long-term and prospective studies. Bisphosphonates, which are known to dramatically hinder the viability of osteoclast cells, along with gold nanoparticles (GNP) are a potential theranostic for osteoporotic diseases. We evaluated GNP functionalized with two different bisphosphonates, namely, alendronate and pamidronate. RANKL differentiated murine pre-osteoclasts (Raw 264.7) and murine osteoblasts (7F2) were treated with varying concentrations ranging from 0.1-5 µM of free and GNP bound bisphosphonates. GNPs with an average size of ∼15 nm were functionalized with alendronate and pamidronate through surface modification by self-assembly. MTT viability assay results show no changes in viability of the osteoclasts when treated with free bisphosphonates in the range of 1-5 µM, but significant decrease on treatment with functionalized GNP at concentrations above the range of 0.1-1 µM depending on the bisphosphonate. Osteoblast cell viability is maintained at all but the highest concentrations used. Qualitative and quantitative characterization by Western Blot for RANKL expression in the osteoblast cell line shows that expression is largely maintained. These results provide a basis for methods that use bisphosphonate functionalized GNP in the treatment of osteoporotic bone diseases. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 21-29, 2017.

PTHrP attenuates osteoblast cell death and apoptosis induced by a novel class of anti-cancer agents.

The effectiveness of chemotherapeutic agents often limits their use due to their negative effects on normal cells. Apoptosis regulatory protein (CARP)-1 functional mimetics (CFMs) belong to a novel class of compounds that possess anti-cancer properties with potential utility in breast and other cancers. In this study, we investigated the growth inhibitory action of CFM-4 and -5 in bone-forming osteoblasts and role of a skeletal regulator, parathyroid hormone (PTH)-related peptide (PTHrP), which is frequently associated with oncologic pathologies. MC3T3E1-clone4 (MC-4) or primary osteoblasts were treated with CFMs. Western blots were performed to determine specific protein expressions. MTT, TUNEL assay, ethidium bromide/acridine orange staining, and ApoAlert caspase profiling were used to investigate cell viability and apoptosis of osteoblasts. Immunofluorescence staining was performed to observe intracellular localization of CARP-1. Our studies revealed that CFM-4 and -5 suppressed growths of mature differentiated, but not proliferating, MC-4 cells and PTHrP attenuated this effect. Mechanistically, induction of CARP-1 protein by CFM-4 and -5 was partially decreased by PTHrP. While CARP-1 increased by CFM-4 or -5 correlated with activated caspase-3, PTHrP remarkably blocked caspase-3 activation. PTHrP also influenced translocation of CFM-induced CARP-1 from the nucleus to the cytoplasm. Our data identify a new function of PTHrP in maintaining osteoblast homeostasis in chemotherapy and define a role of CARP-1 in this process. The crosstalk of PTHrP and CFM-4 and -5 signaling highlights the importance of CFMs as potential anti-cancer therapeutics in breast and other cancers which adversely affect bone.

Detection and qualification of optimum antibacterial and cytotoxic activities of silver‐doped bioactive glasses

This study aims to detect the optimum antibacterial activity of silver-doped bioactive glasses (Ag-BGs) for prevention of post-transplant infections in tissue engineering. The results have shown that the Ag-BG samples had broad-spectrum antibacterial efficacy in an Ag concentration-dependent manner. The 2% Ag-BG had the highest effect during the first 10 min to 72 h. The minimum inhibitory concentration of 2% Ag-BG was estimated to be 2 mg/ml for Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) and 2.66 mg/ml for Staphylococcus aureus (S. aureus). A concentration of 0.5% Ag-BG repressed growth of E. coli after 1 h, but did not have any detectable antibacterial effect for longer periods. Evaluation of the effects of prepared Ag-BG on human osteoblast cells viability showed that 1 and 2% samples changed the cell proliferation rate in masses of more than 3.33 and 2 mg/ml, respectively. Moreover, in a typical manner, the release of Ag ions from the glass structure started immediately, continued steadily and affected bacterial growth when it reached its critical concentration in the medium. This systematic study can illustrate the optimum antibacterial property of the Ag-BG samples in masses of 3.33 and 2 mg/ml for 1 and 2% Ag, respectively, for prevention of post-transplant infections.

Anti-Resorptive Functions of Poly(ethylene sodium phosphate) on Human Osteoclasts.

Osteoporosis involves hyperactive osteoclasts. A large number of current drugs result in side effects affecting their efficacy in the clinic. Polyphosphoesters are unique polymeric biomaterials because of their biocompatibility, biodegradability, and bone affinity. We studied the viability and ability of human osteoclasts to resorb bone when dosed with poly(ethylene sodium phosphate) (PEP·Na). This did not trigger any change in osteoblast cell viability, however the polymer diminished human osteoclasts and their ability to resorb bone at concentrations as low as 10(-4) m · mL(-1). This is the first report to validate the possibility of using polyphosphoesters for selective inhibition of human osteoclast functions, indicating its potential to be used as an effective polymer prodrug for treatment of osteoporosis.

Bio-inspired mineralization of hydroxyapatite in 3D silk fibroin hydrogel for bone tissue engineering

To fabricate hard tissue implants with bone-like structure using a biomimetic mineralization method is drawing much more attentions in bone tissue engineering. The present work focuses in designing 3D silk fibroin hydrogel to modulate the nucleation and growth of hydroxyapatite crystals via a simple ion diffusion method. The study indicates that Ca2+ incorporation within the hydrogel provides the nucleation sites for hydroxyapatite crystals and subsequently regulates their oriented growth. The mineralization process is regulated in a Ca2+ concentration- and minerlization time-dependent way. Further, the compressive strength of the mineralized hydrogels is directly proportional with the mineral content in hydrogel. The orchestrated organic/inorganic composite supports well the viability and proliferation of human osteoblast cells; improved cyto-compatibility with increased mineral content. Together, the present investigation reports a simple and biomimetic process to fabricate 3D bone-like biomaterial with desired efficacy to repair bone defects.

Effect of silver nanoparticle geometry on methicillin susceptible and resistant Staphylococcus aureus, and osteoblast viability.

Orthopedic implant failure as a result of bacterial infection affects approximately 0.5-5% of patients. These infections are often caused by Staphylococcus aureus which is capable of attaching and subsequently forming a biofilm on the implant surface, making it difficult to eradicate with systemic antibiotics. Further, with the emergence of antibiotic-resistant bacteria, alternative treatments are necessary. Silver nanoparticles have received much attention for their broad spectrum antibacterial activity which has been reported to be both size and shape dependent. The purpose of this study was therefore to evaluate the effect of three different geometries on their effect on microbial susceptibility as well as evaluate their effect on bone cell viability. Silver nanoparticles of spherical, triangular and cuboid shapes were synthesized by chemical reduction methods. The susceptibility of S. aureus and methicillin-resistant S. aureus was evaluated a 24 h period and determined using a colorimetric assay. Further, the viability of human fetal osteoblast (hFOB) cells in the presence of the silver nanoparticles was evaluated over a period of 7 days by AlmarBlue fluorescence assay. hFOB morphology was also evaluated by light microscopy imaging. Results indicated that silver nanoparticle geometry did not have an effect on microbiota susceptibility or hFOB viability. However, high concentrations of silver nanoparticles (0.5 nM) conferred significant susceptibility towards the bacteria and significantly reduced hFOB viability. It was also found that the hFOBs exhibited an increasingly reduced viability to lower silver nanoparticle concentrations with an increase in exposure time.

Cytotoxicity Evaluation of Bioresorbable Fixation Screws on Human Gingival Fibroblasts and Mouse Osteoblasts by Real-Time Cell Analysis

To evaluate the effects of bioresorbable fixation screws (BFSs) on human gingival fibroblast (HGF) and mouse osteoblast (MC3T3-E1) cell viability. The KLS Martin SonicPins Rx, Synthes RapidSorb Cortex Screws, and Inion CPS Bioabsorbable Fixation System each were incubated in Dulbecco's Modified Eagle Medium for 72 hours according to ISO 10993-5 standards. A real-time cell analyzer was used to evaluate cell survival. After seeding 200-μL cell suspensions in the wells of an E-plate View 96, HGF and MC3T3-E1 cells were treated with the bioactive components released by the bioresorbable materials and monitored every 15 minutes for 96 hours. Statistical significance was determined using 1-way analysis of variance and Tukey-Kramer tests. There were significant differences in the HGF responses to the untreated control conditions and the Synthes (P < .01), Inion (P < .05), and KLS Martin (P < .05) treatments over 48 hours. The Synthes (P < .01) and Inion (P < .01) treatments produced lower HGF cell index values than the untreated control at 72 hours, whereas the KLS Martin treatment did not. When left to elute for 96 hours, there were no significant differences in values among the control and study groups for HGFs (P > .05). All tested BFSs decreased cell survival rates of M3T3C1 cells for 48 hours (P < .01), 72 hours (P < .001), and 96 hours (P < .001). Differences in the sensitivities of the 2 tested cell lines to the different BFSs might be the result of the different materials used to manufacture the screws. These results provide fundamental knowledge and new insights for the future design and development of new biocompatible BFSs for oral and maxillofacial surgery.

In Vitro Effects of FBS and Ovarian Steroids on Osteoblast Viability

We evaluated the effects of different concentrations (0, 10‐8 M and 10‐7M) of progesterone (P4), testosterone (T) and estradiol (E2) on the osteoblast viability in vitro. Osteoblast lineages (OSTEO‐1) were cultured in 96‐well plates in DMEM medium a density of 5 x 103 cells/100 μL medium, with or without 10% fetal bovine serum (FBS). Cells were maintained at 37 ºC, with 5% CO2, for up to 48 hours. Cell viability was analyzed by MTT tetrazolium assay. The cells cultured with 10% FBS were more viable than those cultured without FBS. When all hormones were put together, the cell viability was reduced at the 10‐7M concentrations compared with the control and 10‐8 M. The viability of cells cultured without FBS was a) stimulated by E2 (10‐7 M and 10‐8 M (0.1048 ± 0.0227 and 0.1069 ± 0.0124, respectively)) compared with the control group (0.0566 ± 0.008); b) stimulated by P4 (10‐7 M (0.1088 ± 0.0124)) compared with the control group (0.0566 ± 0.008) and 10‐8 M (0.0924 ± 0.022); and c) stimulated by both concentrations of T (10‐7 M (0.0908 ± 0.0153) and 10‐8 M (0.0924 ± 0.0022)) compared with the control group (0.0566 ± 0.008). Our results demonstrated that FBS stimulated osteoblast viability, and P4 (10‐7 M), and both concentrations of T and E2 stimulated the viability of the cells cultured without FBS, suggesting that these steroid hormones may be important at the onset of osteoblast cells viability in vitro for up to 48 hours.

Biomimetic scaffolds based on hydroxyapatite nanorod/poly(d,l) lactic acid with their corresponding apatite-forming capability and biocompatibility for bone-tissue engineering

This study presents a facile synthesis of biomimetic hydroxyapatite nanorod/poly(d,l) lactic acid (HAp/PDLLA) scaffolds with the use of solvent casting combined with a salt-leaching technique for bone-tissue engineering. Field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy were used to observe the morphologies, pore structures of synthesized scaffolds, interactions between hydroxyapatite nanorods and poly(d,l) lactic acid, as well as the compositions of the scaffolds, respectively. Porosity of the scaffolds was determined using the liquid substitution method. Moreover, the apatite-forming capability of the scaffolds was evaluated through simulated body fluid (SBF) incubation tests, whereas the viability, attachment, and distribution of human osteoblast cells (MG 63 cell line) on the scaffolds were determined through alamarBlue assay and confocal laser microscopy after nuclear staining with 4′,6-diamidino-2-phenylindole and actin filaments of a cytoskeleton with Oregon Green 488 phalloidin. Results showed that hydroxyapatite nanorod/poly(d,l) lactic acid scaffolds that mimic the structure of natural bone were successfully produced. These scaffolds possessed macropore networks with high porosity (80–84%) and mean pore sizes ranging 117–183μm. These scaffolds demonstrated excellent apatite-forming capabilities. The rapid formation of bone-like apatites with flower-like morphology was observed after 7 days of incubation in SBFs. The scaffolds that had a high percentage (30wt.%) of hydroxyapatite demonstrated better cell adhesion, proliferation, and distribution than those with low percentages of hydroxyapatite as the days of culture increased. This work presented an efficient route for developing biomimetic composite scaffolds, which have potential applications in bone-tissue engineering.

Hypoxia-inducible factor-1α antagonizes the hypoxia-mediated osteoblast cell viability reduction by inhibiting apoptosis.

Bone fracture is accompanied with poor oxygen supply and nutrient deficiency in the local fracture site, and oxygen supply is an important factor that can affect fracture healing. Hypoxia-inducible factor-1 (HIF-1) plays a key role in the regulation of oxygen homeostasis. HIF-1α is rapidly upregulated in response to hypoxia and antagonizes hypoxia-induced apoptosis. In the present study, the viability of an osteoblast cell line, MC3T3-E1, and the expression of HIF-1α protein in the MC3T3-E1 cells was examined under hypoxic conditions. The HIF-1α level was then manipulated and the reduction in the viability of the MC3T3-E1 cells in response to the hypoxia was re-evaluated. In addition, the regulation of HIF-1α in the adaptation of MC3T3-E1 cells to hypoxia was explored. The results showed that the viability of MC3T3-E1 cells decreased and the expression of HIF-1α protein increased under hypoxic conditions. Furthermore, the reduction in the viability of MC3T3-E1 cells post-hypoxia was attenuated by HIF-1α overexpression, while HIF-1α-knockdown by small interfering RNA enhanced the hypoxia-induced decrease in cell viability. It was additionally found that the forced expression of HIF-1α inhibited the hypoxia-induced cell apoptosis. These findings indicate that the forced expression of HIF-1α inhibits hypoxia-induced apoptosis and thus attenuates the hypoxia-induced decrease in cell viability.

Study of the viability and adhesion of osteoblast cells to bone cements mixed with hydroxyapatite at different concentrations to use in vertebral augmentation techniques

ObjectiveThe purpose of this study is to compare the biocompatibility and the effect in osteoblasts of polymethyl methacrylate alone, and mixed with hydroxyapatite in different concentrations of 5, 10, 15 and 20%, without exceeding 20%, as it can alter mechanical properties of the composite. Materials and methodsExperimental study comparing osteoblast response to polymethyl methacrylate alone and with hydroxyapatite in different concentrations. ResultsComposites at 15 and 20% obtained better osteoblast response, with higher osteoblastic activity markers, and lower apoptosis markers. Electron microscopy images show improved adhesion of osteoblasts.

The influence of laser radiation on human osteoblasts cultured on nanostructured composite substrates.

Background and aimsCarbon-based nanomaterials such as carbon nanotubes, graphene oxide and graphene have been explored by researchers as well as the industry. Graphene is a new nanomaterial which has commercial and scientific advantages. Laser therapy has proven highly useful in biomedicine, with the use of different laser types and energies for distinct purposes. The low level laser therapy (LLLT) can have anti-inflammatory, analgesic and biostimulant effects. Recent research has shown that laser radiation has different effects on osteoblasts. The aim of this study was to identify the influence of laser radiation on human osteoblastic cells cultured on nanostructured composite substrates.Materials and methodsFour types of substrates were created using colloidal suspensions of nanostructured composites in PBS at a concentration of 30 μg/ml. We used human osteoblasts isolated from patella bone pieces harvested during arthroplasty. Irradiation of osteoblasts cultured on nanostructured composite substrates was made with a semiconductor laser model BTL-10 having a wavelength of 830 nm. The proliferation activity of osteoblast cells was assessed using the MTT assay. After laser irradiation procedure the viability and proliferation of osteoblast cells were analyzed using fluorescein diacetate (FDA) staining.Results The osteoblast cells viability and proliferation were evaluated with MTT assay at 30 minutes, 24 hours, 5 days and 10 days after laser irradiation. In the first 30 minutes there were no significant differences between the irradiated and non-irradiated cells. At 24 hours after laser irradiation procedure a significant increase of MTT values in case of irradiated osteoblasts cultivated on nanostructured hydroxyapatite, nanostructured hydroxyapatite with gold nanoparticles and 1.6% and 3.15% graphenes composites substrates was observed. A more marked proliferation rate was observed after 10 days of irradiation for irradiated osteoblasts seeded on nanostructured hydroxyapatite with gold nanoparticles and graphenes containing substrate. Using FDA staining we obtained very similar results with MTT test.Conclusions The association between the 830 nm laser irradiation of osteoblasts and their long-term cultivation of the nanostructured composite substrates induces the cell proliferation and differentiation and therefore it will be a useful alternative for bone regeneration therapy.

Effects of Remifentanil Preconditioning on Osteoblasts under Hypoxia-Reoxygenation Condition.

Background: Ischemia-reperfusion of bone occurs in a variety of clinical conditions, such as orthopedic arthroplasty, plastic gnathoplasty, spinal surgery, and amputation. Usually, cellular models of hypoxia-reoxygenation reflect in vivo models of ischemia-reperfusion. With respect to hypoxia-reoxygenation conditions, the effects of remifentanil on osteogenesis have received little attention. Therefore, we investigated the effects of remifentanil on the proliferation and differentiation of osteoblasts during hypoxic-reoxygenation.Methods: After remifentanil (0.1, 1 ng/mL) preconditioning for 2 hours, human osteoblasts were cultured under 1% oxygen tension for 24 hours. Thereafter, the cells were reoxygenated for 12 hours at 37 °C. The naloxone groups were treated with naloxone for 30 minutes before remifentanil treatment. We measured cell viability via MTT assay. Osteoblast maturation was determined by assay of bone nodular mineralization. Quantitative PCR and western blot methods were used to determine BMP-2, osteocalcin, Akt, type I collagen, osterix, TGF-β1, HIF-1α, and RUNX2 expression levels.Results: Osteoblast viability and bone nodular mineralization by osteoblasts is recovered by remifentanil preconditioning from hypoxia-reoxygenation insult. During hypoxic-reoxygenation condition, remifentanil preconditioning induced the expression of BMP-2, osteocalcin, Akt, type I collagen, osterix, TGF-β1, HIF-1α, and RUNX2 in osteoblasts.Conclusions: Under hypoxia-reoxygenation conditions, remifentanil preconditioning enhanced the cell viability and maturation of osteoblasts, and stimulated the expression of proteins associated with osteoblast proliferation and differentiation of the osteoblast. Our results suggest that remifentanil may help in the treatment of bone stress injuries.

Adhesion and Cell Viability of Normal Human Osteoblasts (NHOst) on Scaffolds of Poly (3-hydroxybutyrate)

ABSTRACTBiodegradable Normal Human Osteoblast (NHOst) cells were inoculated into the polymer scaffolds of poly(β-hydroxybutyrate) (PHB) obtained from a specially developed strain of Azotobacter vinelandii. Cell adhesion is essential to promote growth on scaffolds for tissue engineering. Thus, in this research we focused on the adhesion of osteoblast cells to PHB scaffolds produced by solution casting and electrospinning. Cell viability was also investigated up to 168 hrs. Water contact angle on the PHB scaffolds was determined prior to the cells inoculation. The contact angle is usually related to the ability of different cell strains to adhere to a given material. The as cast film exhibited a contact angle α=72° whereas for the electrospun membrane α=102°, thus in theory cell adhesion would be greater for the cast film. Biological testing was carried out on plates of 24 wells; cell viability was determined by Trypan Blue, cell morphology by optical microscopy, and cell nuclei integrity by staining with Acridine orange. Parallel studies were carried out on control (empty) wells. Microscopy observations 168 hrs after cell inoculation showed larger quantities of osteoblast cells in the wells containing PHB scaffolds and the cell nuclei were still active. Moreover, it was found that the cells grew inside the PHB scaffolds and the cell viability was slightly greater for the electrospun scaffold. Interestingly, the time to remove the cells from the scaffolds (film and membranes) was increasing function of the cell culture time, therefore suggesting that PHB promotes adhesion of Normal Human Osteoblast cells to its surface.

Evaluation of Synthesized Nanohydroxyapatite‐Nanocellulose Composites as Biocompatible Scaffolds for Applications in Bone Tissue Engineering

Basic calcium phosphate (BCP) crystals have been associated with many diseases due to their activation of signaling pathways that lead to their mineralization and deposition in intra‐articular and periarticular locations in the bones. In this study, hydroxyapatite (HAp) has been placed in a polysaccharide network as a strategy to minimize this deposition. This research consisted of the evaluation of varying proportions of the polysaccharide network, cellulose nanocrystals (CNCs), and HAp synthesized via a simple sol‐gel method. The resulting biocompatible composites were extensively characterized by means of thermogravimetric analysis (TGA), powder X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), dynamic light scattering (DLS), zeta potential, and scanning electron microscopy (SEM). It was found that an nHAp = CNC ratio presented greater homogeneity in the size and distribution of the nanoparticles without compromising the crystalline structure. Also, incorporation of bone morphogenetic protein 2 (BMP‐2) was performed to evaluate the effects that this interaction would have in the constructs. Finally, the osteoblast cell (hFOB 1.19) viability assay was executed and it showed that all of the materials promoted greater cell proliferation while the nHAp &gt; CNC proportion with the inclusion of the BMP‐2 protein was the best composite for the purpose of this study.

Synthesis and characterization of poly(ethylene oxide)-based glycopolymers and their biocompatibility with osteoblast cells

Poly(ethylene oxide)-block-poly(methacryl-d-glucopyranoside) (PEO-GP) and poly(methacryl-d-glucopyranoside) (H-GP) glycopolymers were synthesized by deacetylation of acetylated polymers which were synthesized via atom transfer radical polymerization. The synthesized glycopolymers were characterized using 1H NMR, 13C NMR and Fourier transform infrared (FTIR) spectroscopies, gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The deacetylated polymers exhibited onset decomposition temperatures about 60 °C lower compared to the polymers having acetyl pendants. The glass transition temperature (Tg) of the acetylated homopolymer was 133 °C and that of the PEO-based block copolymer was 124 °C. The deacetylated polymers H-GP and PEO-GP exhibited Tg values of about −30 °C. Biocompatibility of the H-GP and PEO-GP glycopolymers was obtained by studying osteoblast cell adhesion, viability and proliferation in vitro. The cell viability showed an increase with increasing concentration of H-GP from 0.1 to 1 µmol L−1 and then decreased with further increase in its concentration (10–1000 µmol L−1). PEO-GP did not show a significant variation in cell viability on variation of its concentration from 0.1 to 1000 µmol L−1. The significant improvement in biocompatibility with osteoblast cells in the presence of PEO-GP was considered as due to the covalently bonded PEO segment of the methacrylate glycopolymer block. © 2014 Society of Chemical Industry