Synovial mast cells from knee and hip osteoarthritis: histological study and clinical correlations

PURPOSE

The aim of this study was to investigate the presence of synovial mast cells (MCs) in hip and knee tissue from osteoarthritis (OA) patients and to correlate them with clinical and radiological data.

METHODS

Synovial tissue was obtained during arthroplasty from 60 patients, 30 with knee OA and 30 with hip OA. Control synovial tissue was obtained from 30 patients without OA, 15 undergoing above-knee amputation and 15 receiving a hip replacement for fracture. Before surgery, the radiographic findings were graded according to the Kellgren-Lawrence system and clinical data including pain (VAS) and functional information (KOOS and HOOS) was collected. The tissue was stained with hematoxylin-eosin and toluidine blue for histochemistry and incubated with CD117 and CD31 antibodies for immunohistochemistry. MC and vessel number and synovitis score were determined in all samples.

RESULTS

Mean MC number, synovitis score and vessel number were significantly higher in the OA samples (p < 0.05) than in control tissue. MC number correlated with the synovitis score and disease severity in both patient groups.

CONCLUSIONS

The prevalence of MCs in synovium from OA patients and their association with synovial inflammation and pain suggest a role for them in OA pathophysiology.

Skeletal muscle repair in a rat muscle injury model: the role of growth hormone (GH) injection

OBJECTIVE

Muscle injury tends to heal with incomplete functional recovery. Among the growth factors released in the physio-pathological response of muscle lesion, the Insulin-like Growth-Factor-1 (IGF-1) results in an engine factor of the reparation program. The therapeutic use of growth factors has been exploited to improve healing. As IGF-1 is a primary mediator of the effects of growth hormone (GH), we exploited its systemic administration to muscle recovery in a rat model of muscle injury.

MATERIALS AND METHODS

Monolateral lesion of the longissimus dorsi muscle of rats was performed. Animals were divided into 5 groups: four groups for histological studies and serum hormone dosage, whilst the fifth group represented the uninjured control. Rat GH was intraperitoneally administered after 24h from the surgical lesion at three different concentrations (0.1, 0.2, 0.4 mg/kg). At 3 days from surgery, immunohistochemical and histological analyses evaluated the expression of MyoD and Myogenin, and the presence of neovascularization and inflammation, respectively. After 2 months, we analyzed the presence of muscle regeneration and fibrosis.

RESULTS

The treatment with GH resulted in a significant increase in neovascularization and Myogenin expression at 24h from injury in comparison with the control. This suggested speed up biological recovery times. After two-months, a dose-dependent increase of the connective component was observed.

CONCLUSIONS

The potential effect of GH on muscle repair and regeneration, through the activation of satellite cells already demonstrated in vitro, was confirmed in this in vivo experimental approach. This study sheds light on the role of growth factors in damage repair mechanisms to find an appropriate biological treatment for muscle injury.

The effects of ageing on dental pulp stem cells, the tooth longevity elixir

Stem cells are essential for tissue homeostasis and regeneration throughout the lifespan of multicellular organisms. The decline in stem cell function during advanced age is associated with a reduced regenerative potential of tissues that leads to an increased frequency of diseases. Age-related changes also occur in the dental pulp that represents a reliable model tissue, with high regenerative capability, for studying senescence mechanisms. However, little information is available concerning the effects of ageing on dental stem-cell function. In this mini-review, recent data on how the molecular and functional alterations that accumulate in stem cell populations during ageing result in modifications of dental pulp physiology are discussed. Changes that accumulate during ageing such as how reduction of pulp chamber volume, decreased vascular supply and modifications to the stem cell niches affect stem cell functions and, therefore, dental pulp regenerative potential in response to various stressful agents. Dental pulp cells from aged individuals are still metabolically active and secrete pro-inflammatory and matrix-degrading molecules. Furthermore, miRNAs and exosomes derived from dental pulp stem cells constitute an attractive source of nanovesicles for the treatment of age-related dental pathologies. Further investigation of the epigenetic alterations in dental pulp stem cells, accumulating during ageing, might reveal crucial information for potential stem cell-based therapeutic approaches in the elderly.

In Vitro and in Vivo Assessment of Bone-Implant Interface: A Comparative Study

The present in vitro and in vivo comparison of three bioactive (HA, AP40, RKKP) and three bioinert (Ti6-Al4-V, Al2O3, ZrO2) materials was undertaken to identify which of them provide(s) the most suitable coating for prostheses implanted in patients with altered metabolic status.

The experimental design included in vitro tests with human osteoblasts and morphological observations by scanning electron microscopy. For the in vivo evaluation, the materials were implanted in the femoral condyle of ovariectomised and intact female rats, and two months after surgery an X-ray microanalytical study was performed.

The in vitro study showed good biocompatibility with all materials. Microanalysis evidenced a similar behaviour with all materials except the two biological glasses. The differences in Ca and P content observed between intact and ovariectomised rats can be explained by the intrinsic capability of biological glasses to undergo surface modifications in the presence of alterations of the bone metabolism. Thus, their use seems to be indicated in recipients with osteoporotic pathologies.

Tailoring Biomaterial Compatibility: In Vivo Tissue Response versus in Vitro Cell Behavior

Biocompatibility relies essentially on surface phenomena, represented by cell-cell, cell-material and material (polymer)-protein interactions. An in vivo and in vitro experimental investigation was carried out on the biomaterials of two different classes with a good potential for in situ utilisation. Non-resorbable (Polypyrrole, Polyaniline, Polyimide) and resorbable (PLLA-PDXO-PLLA) materials for tissue engineering were studied for their overall tissue tolerance and cellular interactions. These non-resorbable polymers conceived for biosensor applications and implantable drug-delivery systems are intrinsically conductive. The PLLA-PDXO-PLLA triblock copolymer showed interesting tensile properties for bone and cartilage tissue engineering due to the presence of 1,5-dioxepan-2-one. In vitro and in vivo parallel studies showed an interesting correspondence: a) the cells in contact with the resorbable material that appeared to be capable of migratory-regenerative aspects in vitro exhibited good compatibility in vivo; whereas b) the non-resorbable materials, which are designed to remain in situ in vivo, were seen to have the potential to represent an adverse factor (inflammation, fibrotic reactions) that correlated with some aspects of cell behaviour in vitro.

Cell Dynamics in the Correct Control of Bone Metabolism Using Natural Treatments

The present study was undertaken in order to assess the efficacy of a commercial product containing calcium and silicon (Osteosil-Calcium®) on cell metabolism. MG-63 osteblast-like cells were cultured in the presence of three different drug concentrations (10, 5 and 2.5 μg/mL). Either serum-free culture and standard culture with serum were investigated. Morpho-functional tests (MTT and ALP), scanning electron microscopy (SEM), microanalysis (EDAX) and time-lapse video microscopy were performed. Cell actin cytoskeletal modification with fluorescence phalloidin staining was also tested. Our data show the in vitro functional efficacy of Osteosil-Calcium® on MG63 cell viability and ALP production. This study demonstrates its positive effect on the metabolism of the single cell and suggests wider uses of this drug in health protection and or in Regenerative Medicine therapies which are currently applied to the elderly

In Vitro Evaluation of Bio-Functional Performances of Ghimas Titanium Implants

Titanium is the most widely used material for dental implants. The natural formation, in presence of oxygen, of different oxide films (passivation films) is correlated to titanium implant biocompatibility, resistance to corrosion and is responsible for implant bacteriostatic action. Surface roughness is another surface property of Ti-implants that, affecting implant-to-bone contact, improves integration. In the present study data concerning composition, surface roughness and biocompatibility of Ghimas implants and mini-implants undergoing sandblasting with Calcium Magnesium Carbonate (CaMg(CO3)2) are reported. AFM, SEM/EDX, XRD analyses and morphofunctional tests (MTT and ALP) were performed. Cell actin cytoskeletal modification (fluorescence phalloidin staining) was also observed with confocal laser microscopy (CLSM). Data related to surface geometry and chemical properties, associated with evidence of high purity of all the tested materials (XRD and EDX), highlighted the elevated biocompatibility of tested implants and mini-implants. CLSM investigation confirmed osteoblast features of an active cell behavior able to fit cell to chemico-mechanical stimuli present at the bone/implant interface and suggests an effective implant/alveolar bone integration in vivo.

Mesenchymal Stem Cells on Plasma-Deposited Acrylic Acid Coatings: An In Vitro Investigation to Improve Biomaterial Performance in Bone Reconstruction

In this in vitro investigation of a heterogeneous range of bio-functional and modulatory performances of mesenchymal stem cells (MSCs) grown on two plasma-deposited acrylic acid (pdAA) coatings, which differed in chemical characteristics, a view of their potential utility as hybrid scaffolds for bone tissue engineering was obtained. The in vitro behavior of MSCs was compared to that of MG-63 cells, an osteoblast-like cell line that is commonly used to test biocompatibility of materials intended for bone-tissue interface. The coatings exerted a greater stimulus on MSCs and on MG-63 cells in comparison with control cultures. Both studied coatings exhibited satisfactory compatibility and modulatory effects on MSCs, thus they may be suitable for use in 2D or 3D scaffolds for bone tissue reconstruction.

Morpho-Structural Investigations of Biomaterials for Biocidal Activity

A new wound dressing made of gelatin and Ag, was evaluated for the management of tissue reconstitution in rats. The gelatin–based dressing, with metabolic stimulation properties that favored the recovery of the skin was made of stiff sheets to supply the repairingtissue with mechanical support. The gelatin sheets enhanced the development of collagen fibers and subsequently cell proliferation at the level of stromal and vascular elements. A protocol based on the utilization of natural biomaterials in the presence of low concentrations of a biocidal was proposed which could control microbiocidal activities principally in burned and debilitated patients.

Biological Effects of Tissue Modulations in Wound Healing

The reactive and reparative capacity of injured tissue when treated with either Pulsed Electromagnetic Fields (PEMFs) or with immunomodulator drugs (Prostaglandin E2 and Thymopentin) was evaluated. A morphological and quantitative evaluation was made of the interactions and the interferences on the structural stages of tissue repair processes. When PEMFs were used the time required for new tissue to completely cover the wound was 26 days after surgery, instead of 30 days for control conditions or for treatment with PGE2 or Thymopentin. PEMFs showed accelerated healing process. Both PGE2 and Thymopentin should be considered, in association with other drugs, in an attempt to strengthen the various immunomodulative phases of the reconstitution of injured tissue.

Chitin Nanofibrils Linked to Chitosan Glycolate as Spray, Gel, and Gauze Preparations for Wound Repair

Recent advances in process chemistry have made it possible to make chitosan and chitin nanofibril materials more flexible and useful for the development of new biorelated products. In this study, the effectiveness of three chitin nanofibril/chitosan glycolate-based preparations, a spray (Chit-A), a gel (Chit-B), and a gauze (Chit-C), in healing cutaneous lesions are assessed macroscopically and by light microscopy immunohistochemistry. These evaluations are compared to the results obtained using a laser co-treatment. The wound repair provided by the three preparations is clearly evident even without the synergistic effect of the laser co-treatment. These results confirm the effectiveness of chitin nanofibril/chitosan glycolate-based products in restoring subcutaneous architecture. The spray seems to be most effective in healing superficial lesions, including extensive ones; the gel is more effective in repairing shallow lesions as well as an aesthetic factor while the gauze is effective in slow-healing dermo-epidermal wounds.

Osteoinduction in the Presence of Chitosan-Coated Porous Hydroxyapatite

Hydroxyapatite nails, prepared according to a novel method and endowed with better mechanical resistance, were coated with chitosan to impart enhanced biocompatibility and were introduced in the femurs of rabbits. Chitosan was found to be a favorable interface between bone and hydroxyapatite because it promoted an osteoconductive reaction.

Data on glycerol/tartaric acid-based copolymer containing ciprofloxacin for wound healing applications

This data article is related to our recently published research paper “Exploiting a new glycerol-based copolymer as a route to wound healing: synthesis, characterization and biocompatibility assessment", De Giglio et al. (Colloids and Surfaces B: Biointerfaces 136 (2015) 600–611) [1]. The latter described a new copolymer derived from glycerol and tartaric acid (PGT). Herein, an investigation about the PGT-ciprofloxacin (CIP) interactions by means of Fourier Transform Infrared Spectroscopy (FT-IR) acquired in Attenuated Total Reflectance (ATR) mode and Differential Scanning Calorimetry (DSC) was reported. Moreover, CIP release experiments on CIP-PGT patches were performed by High Performance Liquid Chromatography (HPLC) at different pH values.

Exploiting a new glycerol-based copolymer as a route to wound healing: Synthesis, characterization and biocompatibility assessment

The use of biocompatible materials based on naturally derived monomers plays a key role in pharmaceutical and cosmetic industries. In this paper we describe the synthesis of a new low molecular weight copolymer, based on glycerol and l-tartaric acid, useful to develop biocompatible dermal patches with drug delivery properties. The copolymer's chemical composition was assessed by FT-IR (Fourier transform infrared spectroscopy), (1)H NMR ((1)H Nuclear Magnetic Resonance) and XPS (X-ray photoelectron spectroscopy), while its molecular weight distribution was estimated by SEC (size exclusion chromatography). Copolymer thermal properties were studied by TGA (thermogravimetric analysis). Biological evaluations by MTT assay and SEM (scanning electron microscopy) observations performed with murine fibroblasts and human keratinocytes (HaCaT) revealed a good compatibility of the proposed copolymer. Ciprofloxacin was selected as model drug and its release was evaluated by HPLC (high performance liquid chromatography), showing that the new copolymer supplied promising results as drug delivery system for wound healing applications. Furthermore, investigations on Skin-Mesenchymal stem cells (S-MSCs) behaviour and gene expression showed that the copolymer and its combination with ciprofloxacin did not affect their stemness. In this regard, the fabrication of dermal patches with new, low cost materials for local treatment of skin infections represents an attractive strategy in order to bypass the worrying side effects of systemic antibiotic therapy. Overall, the performed physico-chemical characterization, drug release test and biological evaluations showed that this new copolymer could be a promising tool for the in situ delivery of bioactive molecules during skin lesions treatment.

Pressure-activated microsyringe (PAM) fabrication of bioactive glass-poly(lactic-co-glycolic acid) composite scaffolds for bone tissue regeneration

The aim of this work was the fabrication and characterization of bioactive glass-poly(lactic-co-glycolic acid) (PLGA) composite scaffolds mimicking the topological features of cancellous bone. Porous multilayer PLGA-CEL2 composite scaffolds were innovatively produced by a pressure-activated microsyringe (PAM) method, a CAD/CAM processing technique originally developed at the University of Pisa. In order to select the optimal formulations to be extruded by PAM, CEL2-PLGA composite films (CEL2 is an experimental bioactive SiO₂ -P₂ O₅ -CaO-MgO-Na₂ O-K₂ O glass developed at Politecnico di Torino) were produced and mechanically tested. The elastic modulus of the films increased from 30 to > 400 MPa, increasing the CEL2 amount (10-50 wt%) in the composite. The mixture containing 20 wt% CEL2 was used to fabricate 2D and 3D bone-like scaffolds composed by layers with different topologies (square, hexagonal and octagonal pores). It was observed that the increase of complexity of 2D topological structures led to an increment of the elastic modulus from 3 to 9 MPa in the composite porous monolayer. The elastic modulus of 3D multilayer scaffolds was intermediate (about 6.5 MPa) between the values of the monolayers with square and octagonal pores (corresponding to the lowest and highest complexity, respectively). MG63 osteoblast-like cells and periosteal-derived precursor cells (PDPCs) were used to assess the biocompatibility of the 3D bone-like scaffolds. A significant increase in cell proliferation between 48 h and 7 days of culture was observed for both cell phenotypes. Moreover, qRT-PCR analysis evidenced an induction of early genes of osteogenesis in PDPCs. Copyright © 2015 John Wiley & Sons, Ltd.

EFFECT OF PLATELET RICH PLASMA CONCENTRATION ON SKELETAL MUSCLE REGENERATION: AN EXPERIMENTAL STUDY

Skeletal muscle injuries are common causes of severe long-term pain and physical disability, accounting for up to 55% of all sports injuries. The phases of the healing processes after direct or indirect muscle injury are complex but clearly defined and include well-coordinated steps: degeneration, inflammation, regeneration, and fibrosis. Despite this frequent occurrence and the presence of a body of data on the pathophysiology of muscle injuries, none of the current treatment strategies have shown to be really effective in strictly controlled trials. Platelet-rich plasma (PRP) is a promising alternative approach based on the ability of autologous growth factors (GFs) to accelerate tissue healing, improve muscular regeneration, increase neovascularization and reduce fibrosis. The present study is focused on the use of different concentrations of PRP as a source of GFs. Unilateral muscle lesions were created on the longissimus dorsi muscle of Wistar rats. Twenty-four h after surgical trauma, the lesion was filled with an intramuscular injection of PRP at 2 different concentrations. A group of rats were left untreated (controls). Animals were sacrificed at 3, 15 and 60 days from surgery. Histological, immunohistochemical and histomorphometric analyses were performed to evaluate muscle regeneration, neovascularization, fibrosis and inflammation. The PRP-treated muscles showed better muscle regeneration, more neovascularization and a slight reduction of fibrosis compared with the control muscles in a dose dependent manner. However, further studies also assessing pain and functional recovery are scheduled.

MG63 and MC3T3-E1 Osteoblastic Cell Lines Response to Raloxifene

Bone resorption in edentulous regions often results in inadequate ridge for implant osseointegration. In order to overcome this problem, the use of osteoconductive biomaterials has been proposed as a carrier for different types of pharmacological molecules. Since raloxifene, a drug used in osteoporosis therapy, inhibits the osteoclast, but not osteoblast functions, it has been suggested to improve recovery during implant surgery. The present work evaluated in vitro the effect of raloxifene on two different cell populations: the human osteoblast-like cells (MG63) and osteoblasts derived from rat calvaria (MC3T3-E1). The morpho-functional investigations carried out showed a different behavior of the two cell lines. Raloxifene showed a stimulatory effect towards MG63 cell proliferation with a significant increase in cell viability after 7 days of culture. On the contrary, MC3T3-E1 cells showed a significant reduction in cell viability, when compared with the same cells at 72 h, or with the control cell population. The predominantly proliferative effect of raloxifene on MG63 cells is partly confirmed by the reduction of alkaline phosphatase activity, an early marker of osteoblast differentiation. The different effect of raloxifene on osteoblastic population in relationship to the type and age of the cell is an issue that needs further investigation.

Human periosteum-derived stem cells for tissue engineering applications: the role of VEGF

Mesenchymal stem cells (MSCs) are promising tools for studying the mechanisms of development and for the regeneration of injured tissues. Correct selection of the MSCs source is crucial in order to obtain a more efficient treatment and, in this respect Periosteum-Derived Cells (PDPCs) may represent an interesting alternative to bone marrow MSCs for osteochondral tissue regeneration. In the present study we have isolated and characterized a MSCs population from the periosteum of human adult donors. PDPCs were expanded under specific culture conditions that prevent fibroblast contamination and support the maintenance of their undifferentiated phenotype. We show, for the first time, that PDPCs expresses VEGF receptor (Flt1 and KDR/Flk1) proteins and that they were similar to bone marrow Multipotent Adult Progenitor Cells (MAPCs). Since the latter are able to differentiate into endothelial cells, we tested the possible PDPCs commitment toward an endothelial phenotype in view of bone tissue engineering approaches that takes into account not only bone formation but also vascularization. PDPCs were treated with two different VEGF concentrations for 7 and 15 days and, alternatively, with the supernatant of human primary osteoblasts. Differently from MAPCs our PDPCs were unable to differentiate into endothelial cells after their in vitro VEGF treatment. On the contrary, growth factor stimulation induces PDPCs differentiation toward osteoblasts. We concluded that in PDPCs the presence of VEGF receptors is related to different cross-talk between osteogenesis and angiogenesis that could involve in situ PDPCs recruitment.

Platelet rich fibrin matrix effects on skeletal muscle lesions: an experimental study

Even though muscle injuries are very common, few scientific data on their effective treatment exist. Growth Factors (GFs) may have a role in accelerating muscle repair processes and a currently available strategy for their delivery into the lesion site is the use of autologous platelet-rich plasma (PRP). The present study is focused on the use of Platelet Rich Fibrin Matrix (PRFM), as a source of GFs. Bilateral muscular lesions were created on the longissimus dorsi muscle of Wistar rats. One side of the lesion was filled with a PRFM while the contralateral was left untreated (controls). Animals were sacrificed at 5, 10, 40 and 60 days from surgery. Histological, immunohistochemical and histomorphometric analyses were performed to evaluate muscle regeneration, neovascularization, fibrosis and inflammation. The presence of metaplasia zones, calcifications and heterotopic ossification were also assessed. PRFM treated muscles exhibited an improved muscular regeneration, an increase in neovascularization, and a slight reduction of fibrosis compared with controls. No differences were detected for inflammation. Metaplasia, ossification and heterotopic calcification were not detected. This preliminary morphological experimental study shows that PRFM use can improve muscle regeneration and long-term vascularization. Since autologous blood products are safe, PRFM may be a useful and handy product in clinical treatment of muscle injuries.

Antibiotic-modified hydrogel coatings on titanium dental implants

Implant-associated infections represent an occasional but serious problem in dental and/or orthopaedic surgery. A possible solution to prevent the initial bacterial adhesion may be the coating of the implant surface with a thin layer of antibiotic-loaded biocompatible polymer. Hydrogels are one of the promising and versatile materials as antibiotic controlled release systems. In this work, antibiotic-modified poly(ethylene-glycol diacrylate) hydrogel coatings on titanium substrates were prepared by electrochemical polymerization and tested against methicillin resistant Staphylococcus aureus (ATCC 33591). Two different methods to load vancomycin and ceftriaxone were used. We show that the proposed titanium coatings displayed an interesting antibacterial activity, however, further studies on their effective cytotoxicity will furnish evidence of their real clinical efficacy.

In vitro evaluation of mesenchymal stem cell isolation possibility from different intra-oral tissues

Mesenchymal stem cells (MSCs) are of great interest for the regeneration of tissues and organs. Bone marrow is the first sources of MSCs, but in the recent years there has been interest in other tissues for the isolation of these pluripotent cells. In this study, we investigated the features of MSCs isolated from different oral regions in order to evaluate their potential application in the regeneration of damaged maxillofacial tissues. Sampling from human periodontal ligament, dental pulp, maxillary periosteum as well as bone marrow were collected in order to obtain different stem cell populations. Cells were morphologically and immunophenotipically characterized. Their proliferation potential and their ability to differentiate in osteoblasts were also assessed. All tested cell population showed a similar fibroblast-like morphology and superimposable immunophenotype. Slight differences were observed in proliferation and differentiation potential. Cells isolated from human periodontal ligament, dental pulp, maxillary periosteum had the characteristics of stem cells. Considering their peculiar feature they may alternatively represent interesting cell sources in stem cell-based bone/periodontal tissue regeneration approaches.

PHEMA-based thin hydrogel films for biomedical applications

Poly(2-hydroxyethyl methacrylate) based thin coatings were electro-synthesized by cyclic voltammetry on Au-coated quartz crystal surfaces to study different solid—liquid interfacial processes. By varying the electrochemical parameters and the presence or not of a crosslinking agent, films were obtained with thicknesses ranging from 5 to 90 nm. Surface characterization was performed by X-ray photoelectron spectroscopy, atomic force microscopy, and static contact angle measurements. Using quartz crystal microbalance with dissipation monitoring to investigate the relationship between the film thickness and the swelling behavior, it was found that these characteristics can be modulated by varying either the number of voltammetric cycles or the presence of the crosslinker. Cell adhesion and biocompatibility tests indicate that these film coatings were suitable for biomedical applications.

Ciprofloxacin-modified electrosynthesized hydrogel coatings to prevent titanium-implant-associated infections

New promising and versatile materials for the development of in situ sustained release systems consisting of thin films of either poly(2-hydroxyethyl methacrylate) or a copolymer based on poly(ethylene-glycol diacrylate) and acrylic acid were investigated. These polymers were electrosynthesized directly on titanium substrates and loaded with ciprofloxacin (CIP) either during or after the synthesis step. X-ray photoelectron spectroscopy was used to check the CIP entrapment efficiency as well as its surface availability in the hydrogel films, while high-performance liquid chromatography was employed to assess the release property of the films and to quantify the amount of CIP released by the coatings. These systems were then tested to evaluate the in vitro inhibition of methicillin-resistant Staphylococcus aureus (MRSA) growth. Moreover, a model equation is proposed which can easily correlate the diameter of the inhibition haloes with the amount of antibiotic released. Finally, MG63 human osteoblast-like cells were employed to assess the biocompatibility of CIP-modified hydrogel coatings.

Oxidative stress defense in human-skin-derived mesenchymal stem cells versus human keratinocytes: Different mechanisms of protection and cell selection

Stem cells are undifferentiated cells with the capacity for self-renewal and differentiation. Here we have determined the susceptibility to oxidative stress of isolated mesenchymal stem cells from human skin (S-MSCs) in comparison with keratinocytes, which are differentiated cells of the same lineage. To induce pro-oxidant conditions, S-MSCs and keratinocytes were exposed to 0.5mM H(2)O(2) for 2 h, with oxidative effects analyzed after 4, 12, 24, and 48 h of recovery, in terms of cell growth, vitality, apoptosis, DNA damage, variations in individual antioxidant defense and total oxyradical scavenging capacity toward peroxyl and hydroxyl radicals. The data indicate different abilities across these two cell types to counteract this oxidative stress, which reflects stress that would normally be experienced by these cells under basal conditions. Human keratinocytes seem to have much greater antioxidant defense to counteract the oxidative injury to which they are continuously exposed in the skin. The S-MSCs are surrounded by a complex microenvironment that protects them from external insults, and so they do not have a particularly efficient defense system, and they were generally less responsive to enhanced pro-oxidant challenge. S-MSCs seem particularly prone to apoptotic events, which might thus represent their primary defense mechanism against stress.

Biocompatibility of Poly(Acrylic Acid) Thin Coatings Electro-synthesized onto TiAlV-based Implants

The protection of metal orthopedic implants against corrosion is a crucial medical problem. It was found that electrochemical polymerization of thin, passive poly(acrylic acid) (PAA) films on titanium and TiAlV substrates provides good anti-corrosion properties. In this work, an investigation of anti-corrosion features was carried out to clarify the hypothesis of the presence of an electrostatic contribution to the performance of a PAA coating. Ion release tests were performed at three different pHs; the pH dependence of the polymer swelling was examined by quartz crystal microbalance with dissipation monitoring, to establish the role of this phenomenon on the polymer barrier properties. The potential application of these PAA thin films as biocompatible protective coatings for metal implants and compatibility towards MG-63 human osteoblast-like cells was assessed.

Osteoinduction properties of different growth factors on cells from non-union patients: in vitro study for clinical application

This report compares the effect of rhBMPs and PRG on cells derived from human non-union sites. Treatment of non-union continues to be a challenging task for the trauma surgeon often resulting in unsatisfactory results and long-term morbidity. Over the past two decades, the possibility to use growth factors in bone regeneration has been investigated. In this study we compared the in vitro capability of two recombinant human bone morphogenetic proteins (rhBMP-2 and rhBMP-7) and activated platelet-rich plasma (PRG) to stimulate proliferation and/or differentiation of cells derived from non-union patients. Cells derived from the lesion sites, osteoblasts and mesenchymal stem cells (MSCs) derived from other bone sites of the same patients were used. Treatment with rhBMP-7 or rhBMP-2 showed an improvement in the expression of osteoblastic markers (osteonectin and osteocalcin) in cells derived from human non-union sites. This enhancement was more marked in MSCs, while no significant changes were observed in osteoblast cultures. The PRG treatment produced in all analysed samples a considerable increase in cell proliferation without affecting cell differentiation. On the basis of our results, for an effective biological treatment of non-unions, small amounts of autologous bone marrow (MSCs) are necessary in the lesion site in order to provide both growth factors and a sufficient number of responsive cells. Finally, our results prove that sequential timing administration of PRG and rhBMPs may be used in new therapeutic strategy.

Rapid-prototyped and salt-leached PLGA scaffolds condition cell morpho-functional behavior

Three dimensional scaffolds microfabricated using pressure-assisted microsyringe (PAM) with controlled geometry and porous membranes obtained using salt leaching were both tested with three different cell types to identify an optimal microstructural architecture for tissue engineering. MG63 (osteoblast-like cells) were used as models of mesenchymal bone tissue and human endothelial cells and NCTC2544 (keratinocytes) represented two epithelial tissues. Both porosity and stiffness of PLGA structures were measured, and cell morphology and cytoskeletal organization analyzed using SEM and actin labeling. The results show that overall the PAM scaffolds, which have a repeated and regular microstructure, are more biocompatible than the random pore salt-leached membranes, and that surface morphology as well as substrate stiffness modulates cell behavior.

Vitamin K and D association stimulates in vitro osteoblast differentiation of fracture site derived human mesenchymal stem cells

There is growing interest in osteoinductive agents for fracture healing especially in patients with non-union or delayed-union fractures. The aim of the present study is the assessment of the association of Vitamins D3 and K1 on proliferation and differentiation of human mesenchymal stem cells (hMSCs) derived from fracture sites in view of a possible clinical use. The synergic effect of Vitamin D3 and Vitamin K2 in preventing osteoporosis has been documented in clinical practice; however no reports investigating this association for fracture healing are present. Our data show a different outcome on cell proliferation linked to the different timing of drug administration as well as a synergic effect of the two vitamins on cell differentiation. The high level of osteocalcin and carboxylated osteocalcin detected in hMSCs treated with the association of the two vitamins in comparison with controls and with single vitamin administration underline the differentiation of these cells into osteoblastic phenotype. Our results indicate for the first time that vitamin D3 and K1 association is able to modulate in vitro the differentiation towards osteoblastic phenotype of hMSCs derived from fracture sites, thus offering clinicians a promising and low-cost strategy for reparative osteogenesis.

Resin-based dentin restorative materials under accelerated ageing: bio-functional behavior

OBJECT

The aim of the present study was the evaluation of the effect of different polishing and finishing procedures on Filtek Z250 FZ ESPE restorative material. Particularly, the consequence of artificial aging (UV-irradiation) on this resin-based dental material was investigated determining also its outcome on cell behavior.

METHODS

96 specimens of restorative material were prepared using a light emitting diode curing unit and randomly divided into four finishing and polishing groups: (I) No treatment (FZ); (II) Identoflex rubbers (ID); (III) Enhance System (EN) and (IV) Sof-Lex Pop-on XT discs (SF). The surface morphology of native and artificially aged materials was assessed with Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). FTIR and biological (biocompatibility and bacterial adhesion) analyses were also performed.

RESULTS

Among all, the ID procedure represented an acceptable compromise for efficiency of polymerization and biocompatibility both before and after artificial ageing. SF and EN techniques showed better interactions with the biological environment.

CONCLUSION

UV artificial ageing of the tested specimens has shown an acceleration of the surface degrading processes, favoring a possible decrease in the mechanical properties and the release of toxic free radicals. Finishing and polishing procedure seemed to affect the photodegrading pathways, even though no differences among the techniques were observed. As the cytotoxicity of materials undergoing accelerated aging is relevant, further improvement of dental restorative materials are required to limit the long-term biological damage.

HA/alginate hybrid composites prepared through bio-inspired nucleation

Poorly crystalline apatite has been directly nucleated on self-assembling alginate chains by neutralization synthesis to obtain a biomimetic artificial bone-like composite. It has been observed that in preparing HA/alginate composites, Ca2+ ions present on the apatitic surface cross-link the alginate chains to produce a material with different morphology and thermal stability, both functions of the HA/alginate weight ratio. In vitro tests were performed on different samples in terms of both the HA/alginate ratio and synthesis temperature. All the samples were cultured for seven days with MG63 osteoblast-like cells and then underwent morphological and biochemical analyses (MTT and ALP tests). Scaffolds showed a different solubility into the culture media, which was related to the temperature of synthesis and to the HA/alginate ratio. All our data confirm the ability of the tested materials to favour cell growth and to maintain their osteoblastic functionality, at least during the examined period.

Exploring the damage limitation possibilities of mineral fibres for future integrated solutions: an in vitro study

Owing to their possible carcinogenic effect, asbestos and other silica derivatives have been identified as priority substances for risk reduction and prevention of pollution. Neutralisation procedures have thus become a topical research subject in many European and American countries. In the present study, silica derivatives (asbestos-containing and asbestos substitutes like slag wool, rock wool, cement asbestos) were fully impregnated with an epoxy resin according to the procedure used for the in situ impregnation with viscous polymeric media, which penetrate and cement the fibres in place and reduce the risk of their dispersion in air. Untreated and treated samples were used to investigate their in vitro interaction with a human continuous epithelial cell line (NCTC 2544 keratinocytes) and test the resin's efficiency in passivating the surface activity of the fibrous particulate. SEM and morpho-quantitative data evidenced that impregnation with the epoxy resin modifies the mineral fibres' bioactivity (reduction of cell adhesion and decreased spread/round cell ratio) and demonstrated the value of in vitro cell testing after passivation as a risk-assessment procedure. These tests could be used for the rapid determination of the level of passivation of new synthetic mineral fibrous materials subjected to resin impregnation.

Fabricated hyalS micropatterns and surface guidance of NCTC 2544 continuous cell line: an in vitro study

Surface topography is important in establishing tissue organisation adjacent to implants, smooth surfaces generally being associated with fibrous encapsulation. By virtue of its large hydrated molecular volume and its capacity to form molecular matrix, hyaluronic acid can expand the interfibrillar collagen spaces to allow the movement of cells, although it can also hamper their locomotion. Low molecular-weight hyaluronan can also stimulate cell proliferation, especially at low concentrations. The aim of the present work was to evaluate in vitro the growth and migratory behaviour of NCTC 2544 keratinocytes cultured on different materials microstructured with hyaluronic acid or sulfated hyaluronic acid to assess the possibility of using these devices in the repair process of soft tissues. Ultrastructural morphological analyses, morphometric evaluations and detection of cytoskeletal elements were performed. Our observations provide evidence that micrometer-size parallel grooves of hyaluronic acid can influence cell growth behaviour since cells seeded onto the microstructured substrate arranged themselves according to a shape and an orientation that clearly reflected the chemotropism exerted on them by the two forms of acid. These data also highlight the importance of accurate microtexture fabrication. We intend to follow up these in vitro studies with in vivo experimental applications using PET and gelatin substrates structured with HyalS to evaluate wound healing responses, and to extend our investigations of the cytoskeletal modifications induced by different microstructures.

[Bio-metabolic changes produced by 2 commercial fluoride-containing compounds on human keratinocytes]

BACKGROUND

Although fluoride has been used for decades either systemically or topically to prevent dental caries, the cellular and molecular mechanisms underlying its action are poorly understood.

METHODS

An in vitro study of the human keratinocyte cell line NCTC 2544 was conducted in the presence of two different fluoride-containing commercial compounds (Zymafluor and Elmex) to investigate their toxicity threshold and the sequence of events involved in fluoride ion toxicity in this cell population. The toxicity threshold was determined by incubating cells with rising concentrations of Zymafluor and Elmex for 20 h. The study of the sequence of events involved in ion toxicity was performed through a time-effect study by exposing cells to 4 mM fluoride ions and testing them at 2, 6, and 20 h. Cell viability and ultrastructural parameters were assessed: degree of confluence, semiquantitative assessment of dead cells and debris in the supernatant, and morphology.

RESULTS

Ultrastructural morphological analysis showed different cell behaviours with the two compounds; moreover, their toxic effect appeared to be both concentration- and time-dependent.

CONCLUSIONS

These data underline the susceptibility of the intracellular communication system to fluoride and show that exceeding the therapeutic dose of fluoride involves substantial risk of toxicity.

Biochemistry, histology and clinical uses of chitins and chitosans in wound healing

Biodegradability, biocompatibility and capacity to promote the synthesis of hyaluronan are main characteristics of chitin-derived wound healing materials, whose biological significance in the human body depends largely on the actions that certain hydrolases exert on them. The resulting chitooligomers stimulate various cells, while the released monomers are phosphorylated and incorporated into hyaluronan, keratan sulphate and chondroitin sulphate, components of the intracellular matrix and connective tissue. The healing process favoured by these materials is examined in terms of macrophage activation, cytokine production by macrophages and fibroblasts, antiinflammatory action, angiogenesis stimulation, granulation and scar formation. Current biomedical applications are illustrated by the treatment of leg ulcers, the use of skin substitutes, and the regeneration of bone, nerve and meniscus tissues.

In vitro and in vivo assessment of bone-implant interface: a comparative study

The present in vitro and in vivo comparison of three bioactive (HA, AP40, RKKP) and three bioinert (Ti6-Al4-V, Al2O3, ZrO2) materials was undertaken to identify which of them provide(s) the most suitable coating for prostheses implanted in patients with altered metabolic status. The experimental design included in vitro tests with human osteoblasts and morphological observations by scanning electron microscopy. For the in vivo evaluation, the materials were implanted in the femoral condyle of ovariectomised and intact female rats, and two months after surgery an X-ray microanalytical study was performed. The in vitro study showed good biocompatibility with all materials. Microanalysis evidenced a similar behaviour with all materials except the two biological glasses. The differences in Ca and P content observed between intact and ovariectomised rats can be explained by the intrinsic capability of biological glasses to undergo surface modifications in the presence of alterations of the bone metabolism. Thus, their use seems to be indicated in recipients with osteoporotic pathologies.

Osteoblast behaviour in the presence of bisphosphonates: ultrastructural and biochemical in vitro studies

OBJECTIVE

A positive balance in bone remodelling is an important goal of bone metabolism both in the presence of the osteoporotic processes characteristic of ageing and, especially, of prosthetic implants. The aim of the present work was to obtain new information about the initial steps of osteoblastic growth in an in vitro osteoblastic model in the presence of two bisphosphonates.

METHODS

Experiments were performed with Alendronate and Neridronate, two molecules used in the therapy of osteoporosis. Since differentiating features into osteoblastic cells are known to parallel the presence in the cytoplasm of alkaline phosphatase and osteocalcin, we also carried out immunohistochemical typing.

RESULTS

Good differentiation and osteoblastic activity were generally observed in the cells in contact with these compounds, except for 10(-4) Neridronate, where biochemical data clearly indicated its toxic effect on the cells.

CONCLUSION

The detection of osteoblastic markers associated with an ultrastructural picture of correct organellar morphology in our cultures further supports the hypothesis of a metabolically positive action of these molecules on osteoblasts.

N,N-dicarboxymethyl chitosan as delivery agent for bone morphogenetic protein in the repair of articular cartilage

Bone morphogenetic protein (BMP), associated with N,N-dicarboxymethyl chitosan, is used to induce or facilitate the repair of articular cartilage lesions. This association is intended for the synergistic potentiation of the respective biological effects. Data show that BMP-7 enhances the in vivo proliferation of cells with chondrocytes phenotype in the articular environment, leading to partial healing of the articular surface of the lesions. N,N-dicarboxymethyl chitosan is found to be useful as a molecular carrier or drug delivery agent.

Study of the interface reactions between cells and a biocompatible ceramic

Preliminary results on the modifications induced by the growth of a Chinese Hamster Ovary (CHO) cell line on the surface of a CORD 1014 ceramic cordierite are reported. Results proved that cells strongly modify the crystallography and the chemical composition of the surface and near surface regions of the cordierite.

An experimental study in X-ray spectroscopy of the zirconium (Ca-PSZ) - bone interface. Microanalytic evaluation of the osteogenetic response

Ultrastructural difractometric and chemical evaluations of calcium partially stabilized zirconium (Ca-PSZ) implants were performed in an in vivo study on animals in order to evaluate its biological behaviour. The chemical-morphological investigations demonstrated the presence of an osteogenetic activity at the bone-biomaterial interface. The new-osteogenesis was preceded by the formation of a loose connective tissue around the implants. This mesenchymal-type tissue without a capsular organization, allowing modulation of the mechanical forces to which the implant is subject, could be considered a positive event in the osteogenetic process and not a sign of future failure of the implant. Finally, microanalytical investigations carried out on non-implanted and implanted Ca-PSZ tools suggested that the surface of this ceramic material does not undergo modification once it has been inserted in the biological environment (12 months).

Stimulatory effect on bone formation exerted by a modified chitosan

A novel modified chitosan carrying covalently linked imidazole groups (average molecular weight 700,000, degree of substitution 0.28, degree of acetylation 0.08) was used to stimulate bone formation in an animal model. Lesions (7 mm diameter) were surgically made in the femoral condyle of sheep and treated with the modified chitosan. Within 40 d after surgery, the neoformed tissue occluded the surgical hole and assumed a trabecular structure in the peripheral area of the lesion, while looking like a mineralization nodule in the central part in association with a fibrous component. In the control, no sign of osteoinduction or reparative process was observed and bone marrow was rich in adipocytes.