Macrophages – The Key Actors in Adipose Tissue Remodeling and Dysfunction

Adipose tissue (AT) is a very important endocrine and paracrine organ that regulates other tissues and organs. Dysfunction of AT leads to a wide range of disorders like obesity, insulin resistance, diabetes mellitus, cardiac disorders, tumors and others. Adipose tissue macrophages (ATMs) are the key actors in AT remodeling and dysfunction. Their role in AT dysfunction is nowadays increasingly investigated, but still their interplay and molecular mechanisms of actions have not been fully elucidated. In this chapter, we summarized the current knowledge about the role of macrophages in AT remodeling, dysfunction and related disorders and indicate the potential directions for future research

Osteogenic differentiation of dental pulp stem cells influenced by synthesized calcium phosphate-based nanomaterial in vitro

Dental pulp stem cells (DPSCs) are mesenchymal stem cells that may have a versatile and abundant application in regenerative medicine and dentistry due to their availability, possibility of isolation from different types of teeth and potential to differentiate into several cell types. In recent years, there is an emerging trend of the use of nanomaterials in medicine and dentistry that, by virtue of their unique properties, have become very attractive as a tool for the treatment of bone tissue defects. The aim of our study was to examine the potential of synthesized nanomaterial, intended for bone tissue engineering and regenerative applications, biphasic calcium phosphate coated with poly-D,L-lactide-co-glycolide (CP/PLGA), to influence the osteogenic differentiation of DPSCs. Cells were obtained from the mature healthy teeth by outgrowth of the cells from undigested pulp pieces during culturing, in standard cell culture conditions. Cells were subjected to osteogenic differentiation for seven and 14 days by culturing the cells with two concentrations of CP/PLGA nanoparticles in the presence or absence of osteogenic supplements in the media. Osteogenic differentiation was assessed by phase contrast microscopy as well as by Von Kossa and Alizarin Red S staining of formed inorganic deposits. The results showed that CP/PLGA influenced osteogenesis in concentration-dependent manner and differently in osteogenic and standard cell culture media. The use of calcium phosphate-based nanomaterials in combination with DPSCs, under certain conditions, could be a promising approach in regenerative medicine and dentistry

COMPARATIVE REVIEW OF GINGIVAL RETRACTION AGENTS

In order to obtain an adequate impression of demarcation line area of a prepared tooth located in or below the gingival edge it is necessary to perform the dilatation and drying of the gingival sulcus using retraction cord impregnated with adequate retraction agents. The aim of the study was to carry out comparative analysis of advantages and disadvantages of commercially available gingival retraction agents. Commercial retraction agents include astringents (metal salts) and vasoconstrictors on the basis of epinephrine. Further research should be aimed at examining the possibility of using sympathomimetic vasoconstrictors (tetrahydrosolin and oxymetasolin) for gingival retraction

Comparative study of the effects of different nanomaterials on the viability of human osteoblast-like cells

The aim of this study was to compare the effects of two types of nanomaterials, cobalt-exchanged hydroxyapatite (CoHAp) and calcium phosphate/poly-(DL-lactide-co-glycolide) (CP/PLGA), on the viability of Saos-2 osteoblast-like cells, using MTT test. We have examined the suspension of this materials in the following concentrations: 1.6, 8, 40, 200, 1000 and 2500 μg/ml, as well as extracts in concentration range from 2,5% to 100%. Both materials showed cytotoxic effect at higher concentrations of suspension and extract, respectively, but they were not cytotoxic at lower concentrations. CP/PLGA acted stronger cytotoxic compared to CoHAp, regardless of whether it is examined suspension or extract. CoHAp in small concentrations of suspension and extract acted slightly stimulatory on cells. This suggests that CoHAp may have advantage for use in the in vivo systems

Scanning electron microscopy study of changes in nanoparticles surface under in vitro simulated physiological conditions

In this study we observed the changes in surface of nanoparticles of two different nanomaterials, cobalt-substituted hydroxyapatite (CoHAp) and calcium phosphate/poly-(DLlactide-co-glycolide) (CP/PLGA) that occurred under simulated physiological conditions in vitro. Both nanomaterials were incubated in an appropriate volume of Dulbecco's Modified Eagle Medium (DMEM) for 3 days at 37 0C and then the medium was removed and materials were dried. Surface changes of nanoparticles were studied by scanning electron microscopy (SEM). Results of SEM analysis show that changes in the size and shape of the nanoparticles took place. These changes can be explained by interactions of nanomaterials with DMEM. In the case of CP/PLGA it was probably the result of polymer degradation and changes in CoHAp nanoparticles were probably the result of ion exchange

In vitro testing of genotoxic and apoptotic potential of two synthesized nanomaterials by DNA fragmentation assay

Nanomaterials represent a relatively new and developing class of materials that are widely used because of their unique mechanical and physiochemical properties. Due to the particles’ size and the ability to easily enter the cells and interact with different cellular components, nanoparticles can exhibit toxic effects in biological systems, so it is necessary to conduct a thorough in vitro biocompatibility testing. Our aim was to examine the in vitro genotoxic and apoptotic potential of two different synthesized nanomaterials intended for bone tissue engineering and regenerative applications: biphasic calcium phosphate coated with poly- D,L-lactide-co-glycolide (CP/PLGA) and cobalt-substituted hydroxyapatite (CoHAp), by DNA fragmentation assay. NB4 cells (acute promyelocytic leukemia cell line) were incubated with different concentrations of CP/PLGA and CoHAp nanomaterials for 24 hours. Cells cultured in standard medium, without nanomaterials, were used as negative control and cells treated with hydrogen peroxide were used as positive control. After incubation with materials the genomic DNA was extracted from the cells and applied on horizontal agarose gel electrophoresis. The results of DNA fragmentation assay were observed on gel documentation system. Higher examined concentrations of CP/PLGA caused DNA fragmentation at some extent with DNA laddering at approximately 180 bp which is characteristic for later stages of apoptosis, while DNA laddering was not seen in the case of CoHAp at the same concentrations. Although both materials are in the form of nanoparticles, a different effect in apoptotic DNA fragmentation was observed which suggests that the chemical composition of nanomaterials notably affects the genotoxicity and apoptosis potential in addition to the particle size

Application of Adipose-Derived Stem Cells in Treatment of Bone Tissue Defects

Despite excellent self-regeneration capacity of bone tissue, there are some large bone defects that cannot be healed spontaneously. Numerous literature data in the field of cell-based bone tissue engineering showed that adipose-derived stem cells (ADSCs) after isolation could be subsequently applied in a one-step approach for treatment of bone defect, without previous in vitro expansion and osteoinduction. However, standard approaches usually involve in vitro expansion and osteoinduction of ADSCs as an additional preparation step before its final application. Bioreactors are also used for the preparation of ADSC-based graft prior application. The commonly used approaches are reviewed, and their outcomes, advantages, disadvantages, as well as their potential for successful application in the treatment of bone defects are discussed. Difficulty in spontaneous healing of bone defects is very often due to poor vascularization. To overcome this problem, numerous methods in bone tissue engineering (BTE) were developed. We focused on freshly isolated stromal vascular fraction (SVF) cells and ADSCs in vitro induced into endothelial cells (ECs) as cells with vasculogenic capacity for the further application in bone defect treatment. We have reviewed orthotopic and ectopic models in BTE that include the application of SVFs or ADSCs in vitro induced into ECs, with special reference to co-cultivation

Residual monomer content determination in some acrylic denture base materials and possibilities of its reduction

Background/Aim. Polymethyl methacrylate is used for producing a denture basis. It is a material made by the polymerization process of methyl methacrylate. Despite of the polymerization type, there is a certain amount of free methyl methacrylate (residual monomer) incorporated in the denture, which can cause irritation of the oral mucosa. The aim of this study was to determine the amount of residual monomer in four different denture base acrylic resins by liquid chromatography and the possibility of its reduction. Methods. After the polymerization, a postpolymerization treatment was performed in three different ways: in boiling water for thirty minutes, with 500 W microwaves for three minutes and in steam bath at 22º C for one to thirty days. Results. The obtained results showed that the amount of residual monomer is significantly higher in cold polymerizing acrylates (9.1-11%). The amount of residual monomer after hot polymerization was in the tolerance range (0.59- 0.86%). Conclusion. The obtained results denote a low content of residual monomer in the samples which have undergone postpolymerization treatment. A lower percent of residual monomer is established in samples undergone a hot polymerization

Examination of the influence of nanomaterials calcium phosphate/poly(DL-lactide-co-glycolide) and cobalt-exchanged hydroxyapatite on the viability of Saos-2 cells

We have examined the effect of extracts of the calcium phosphate/poly(DL-lactide-co-glycolide) (CP/PLGA) and cobalt-exchanged hydroxyapatite (CoHAp), on the viability of Saos2 osteoblastlike cells. Extracts were prepared by incubation for 3 days at 37°C in the cultivation medium. Conductivity and pH value of extracts were measured before viability assay. Cell viability was estimated by MTT test performed after 24 h incubation of cells with various concentrations of extracts. Extract of CP/PLGA acted more cytotoxic on osteoblasts than the extract of CoHAp. This difference in the effect of examined extracts can be explained by their different pH value and conductivity

Changes of HAp/PLLA biocomposites and tissue reaction after subcutaneous implantation

Experimental and clinical studies have shown that HAp granules and powder may be successfully applied in reconstruction of bone defects. Composite HAp/PLLA biomaterial embodies good characteristics of each of these biomaterials. Differences in porosity, microstructure, compressive consistency as well as in bioresorbility of HAp/PLLA are achieved by using PLLA of different mole masses. The aim of this study was to analyse light microscopy of the tissue reaction and changes of implants made of combination of syngeneic bone fragments and HAp/PLLA biocomposites with PLLA molecule mass of 430 000 (HP2) and 50 000 (HP3). The mice were divided into 4 experimental studies, 8 animals each. Two groups underwent implantation one group of mice was falsely operated, and one group was used for general control. Pathohistological analysis of implants was performed three months after subcutaneous implantation. Phagocytosis of HAp/ PLLA and bone was noticed on both implants’ preparations. Blood vessels were also noticed confirming the process of angiogenesis around the implants’ particles. The holes around particles of biocomposites and bone fragments represented the signs of their resorption. The presence of multinuclear cells between implants’ particles was observed and it was more prominent in HP3 implants. Osteogenesis is more intense in HP3 and ectopic hematopoesis is present. Our results show that designed HAp/PLLA biocomposites have good biocompatibility, their combination with bone fragments of a vital bone enables osteogenesis and hematopoesis and these processes are more prominent if PLLA biocomposite with lower molecular mass was used