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The state-of-the-art sustained drug delivery systems are related to features to improve pharmacological transport through a controlled ratio between drug release and the desired therapeutic effect. Microspheres of biodegradable polymers, such as poly(lactic-co-glycolic acid) (PLGA), play an important role in these approaches, directing the release in a specific region of interest. In this way, the encapsulation of doxycycline (DOX) as a microbial agent turns the PLGA microspheres into a potential device for the treatment of topic oral diseases. Thus, this work aimed to produce DOX-loaded PLGA microspheres and see how they interfered with mesenchymal stem cell viability and in the sustained release in antimicrobial assays. Scanning electron microscopy showed the spherical microstructured pattern, revealing assorted sized distribution, with major diameters ranging 1-3 µm. The encapsulation efficiency presented a mean of 80% in both methods to obtain the microspheres (sonication and magnetic rotation). The DOX release test revealed a gradual and continuous profile of 30-40% between 120 and 168 h. Mesenchymal stem cells cultured in PLGA with or without DOX at several concentrations revealed no effect on the cell metabolic activity. Striking morphology changes were observed by confocal microscopy after 1 to 3 days under culture. The live/dead assay indicated that when microsphere densities were increased (from 10 to 100 µg/mL) cultured cells presented an internalized pattern of microspheres in both groups of PLGA containing DOX or not, while slight cell death signals were identified nearby microsphere clusters. Microbiological assays performed by the agar diffusion test pointed out that an inhibition zone was identified in Staphylococcus aureus (S. aureus) cultures at earlier times of DOX release. Despite the well-known use of PLGA as a drug delivery vehicle, when synthesized with DOX, it presents both characteristics of the desired treatment to prevent healthy tissue damage while avoiding bacterial growth in a microenvironment with anatomical features, such as grooves, projections, and other tough conditions that favor the development of oral diseases.

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A recent and quite promising technique for bone tissue engineering is the 3D printing, peculiarly regarding the production of high-quality scaffolds. The 3D printed scaffold strictly provides suitable characteristics for living cells, in order to induce treatment, reconstruction and substitution of injured tissue. The purpose of this work was to evaluate the behavior of the 3D scaffold based on Poly(L-co-D,L lactic acid-co-Trimethylene Carbonate) (PLDLA-TMC), which was designed in Solidworks™ software, projected in 3D Slicer™, 3D printed in filament extrusion, cultured with mesenchymal stem cells (MSCs) and tested in vitro and in vivo models. For in vitro study, the MSCs were seeded in a PLDLA-TMC 3D scaffold with 600 µm pore size and submitted to proliferation and osteogenic differentiation. The in vivo assays implanted the PLDLA-TMC scaffolds with or without MSCs in the calvaria of Wistar rats submitted to 8 mm cranial bone defect, in periods of 8-12 weeks. The results showed that PLDLA-TMC 3D scaffolds favored adherence and cell growth, and suggests an osteoinductive activity, which means that the material itself augmented cellular differentiation. The implanted PLDLA-TMC containing MSCs, showed better results after 12 weeks prior grafting, due the absence of inflammatory processes, enlarged regeneration of bone tissue and facilitated angiogenesis. Notwithstanding, the 3D PLDLA-TMC itself implanted enriched tissue repair; the addition of cells known to upregulate tissue healing reinforce the perspectives for the PLDLA-TMC applications in the field of bone tissue engineering in clinical trials.

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Bioreactor systems that allow the simulation of in vivo variables in a controlled in vitro environment, were a great advance in the field of tissue engineering. Due to the dynamic-mechanical features that some tissues present, 3D-engineered constructs often do not exhibit the biomechanical properties of these native tissues. Thus, a successful approach must not only achieve tissue repair but also restore its function after injury. Here, we describe a method to improve cell activity in 3D scaffolds in a dynamic bioreactor system through the application of mechanical compression and fluid flow for tissue engineering approaches.

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The experimental use of poly (alcohol-vinyl) (PVA) as a skin curative is increasing widely. However, the use of this hydrogel is challenging due to its favorable properties for microbiota growth. The association with silver nanoparticles (AgNPs) as an antimicrobial agent turns the match for PVA as a dressing, as it focuses on creating a physical barrier to avoid wound dehydration. When associated with extracellular components, such as the collagen matrix, the device obtained can create the desired biological conditions to act as a skin substitute. This study aimed to analyze the anti-microbiological activity and the in vitro and in vivo responses of a bilaminar device of PVA containing AgNPs associated with a membrane of collagen-hyaluronic acid (col-HA). Additionally, mesenchymal stem cells were cultured in the device to evaluate in vitro responses and in vivo immunomodulatory and healing behavior. The device morphology revealed a porous pattern that favored water retention and in vitro cell adhesion. Controlled wounds in the dorsal back of rat skins revealed a striking skin remodeling with new epidermis fulfilling all previously injured areas after 14 and 28 days. No infections or significant inflammations were observed, despite increased angiogenesis, and no fibrosis-markers were identified as compared to controls. Although few antibacterial activities were obtained, the addition of AgNPs prevented fungal growth. All results demonstrated that the combination of the components used here as a dermal device, chosen according to previous miscellany studies of low/mid-cost biomaterials, can promote skin protection avoiding infections and dehydration, minimize the typical wound inflammatory responses, and favor the cellular healing responses, features that give rise to further clinical trials of the device here developed.

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The search for new therapies and drugs that act as topical agents to relieve pain and control the inflammatory processes in burns always attracted interest in clinical trials. As an alternative to synthetic drugs, natural extracts are useful in the development of new strategies and formulations for improving the quality of life. The aim of this study was to develop a wound dressing using poly(l-co-d,l-lactic acid-co-trimethylene carbonate) (PLDLA-TMC) containing Schinus terebinthifolius Raddi (S.T.R.). S.T.R. is a native Brazilian plant known for its strong anti-inflammatory responses. The membrane of PLDLA-TMC + S. terebinthifolius Raddi was prepared at different concentrations of S.T.R. (5, 10, 15, and 50%). The Fourier transform infrared results showed no change in the PLDLA-TMC spectrum after S.T.R. addition, whereas the swelling test showed changes only in PLDLA-TMC + S.T.R. at 50%. The wettability measurements showed a mass loss due to the decrease in the contact angle in all samples after the S.T.R. addition in the polymer, whereas the S.T.R. release test showed a linear delivery pattern. The scanning electron microscopy analysis showed that S.T.R. was homogeneously distributed at only 5 and 10%. Tensile tests demonstrated an increase in Young's modulus and a reduction in the elongation till rupture of PLDLA-TMC after the addition of S.T.R. The biocompatibility in vitro evaluation with rat fibroblast cells seeded in the membranes of PLDLA-TMC + S.T.R. showed that although S.T.R. interfered in cell morphology, all concentrations tested showed that cells were able to adhere and proliferate during 7 days. Thus, S.T.R. at 50% was chosen to be tested for in vivo trials. The histological and immunohistochemistry results revealed an accelerated skin healing at 7 days after controlled secondary burns were introduced in the dorsal skin, with a striking total recovery of the epidermis and high rates of molecular activation of cell proliferation. Due to the known biocompatibility properties of PLDLA-TMC and its stable release of S.T.R., we strongly recommend S.T.R.-containing PLDLA-TMC as a curative device to favor skin healing.

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Calcium phosphate cement (CPC) that is based on α-tricalcium phosphate (α-TCP) is considered desirable for bone tissue engineering because of its relatively rapid degradation properties. However, such cement is relatively weak, restricting its use to areas of low mechanical stress. Wollastonite fibers (WF) have been used to improve the mechanical strength of biomaterials. However, the biological properties of WF remain poorly understood. Here, we tested the response of osteoblast-like cells to being cultured on CPC reinforced with 5% of WF (CPC-WF). We found that both types of cement studied achieved an ion balance for calcium and phosphate after 3 days of immersion in culture medium and this allowed subsequent long-term cell culture. CPC-WF increased cell viability and stimulated cell differentiation, compared to nonreinforced CPC. We hypothesize that late silicon release by CPC-WF induces increased cell proliferation and differentiation. Based on our findings, we propose that CPC-WF is a promising material for bone tissue engineering applications.

Assuntos

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The search for new therapies and drugs that act as topical agents to relieve pain and control the infectious processes in burns always attracted interest in clinical trials. As an alternative to synthetic drugs, the use of natural extracts is useful in the development of new strategies and formulations for improving the life quality. The aim of this study was to develop a wound dressing using Poly(L-co-D,L lactic acid-co-TMC) (PLDLA-co-TMC) containing aloe vera (AV). This natural plant extract is known for its modulatory effects under healing process. The membrane of PLDLA-co-TMC+aloe vera was prepared at different concentrations of AV (5, 10, 15 and 50%). The FTIR showed no change in the PLDLA-co-TMC spectrum after AV addition, while the swelling test showed changes only in PLDLA-co-TMC+AV at 50%. The wettability measurements showed decrease in the contact angle in all samples after the AV addition in the polymer, while the AV release test showed that PLDLA-co-TMC+50%AV sample has higher AV release rate than the sample with other AV concentrations. The SEM analysis showed that AV was homogeneously distributed at 5% only. Tensile tests demonstrated an increase in the Young's modulus and a reduction in the elongation till rupture of the PLDLA-co-TMC after the addition of AV. Biocompatibility in vitro evaluation with fibroblast cells seeded in the membranes of PLDLA-co-TMC+AV showed that the cells were able to adhere, proliferate and maintain mitochondrial activity in all AV concentrations tested. Due to the known skin medicinal properties attributed to AV and the results here obtained, we suggest that after in vivo trials, the PLDLA-co-TMC+AV should be a promising biomaterial for application as a device for skin curative and healing agent.

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The behavior of lyotropic biomimetic systems in drug delivery was reviewed. These behaviors are influenced by drug properties, the initial water content, type of lyotropic liquid crystals (LLC), swell ability, drug loading rate, the presence of ions with higher or less kosmotropic or chaotropic force, and the electrostatic interaction between the drug and the lipid bilayers. The in vivo interaction between LCC-drugs, and the impact on the bioavailability of drugs, was reviewed. The LLC with a different architecture can be formed by the self-assembly of lipids in aqueous medium, and can be tuned by the structures and physical properties of the emulsion. These LLC lamellar phase, cubic phase, and hexagonal phase, possess fascinating viscoelastic properties, which make them useful as a dispersion technology, and a highly ordered, thermodynamically stable internal nanostructure, thereby offering the potential as a sustained drug release matrix for drug delivery. In addition, the biodegradable and biocompatible nature of lipids demonstrates a minimum toxicity and thus, they are used for various routes of administration. This review is not intended to provide a comprehensive overview, but focuses on the advantages over non modified conventional materials and LLC biomimetic properties.

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Several materials are commercially available as substitutes for skin. However, new strategies are needed to improve the treatment of skin wounds. In this study, we developed and characterized a new device consisting of poly(lactic-co-glycolic acid) (PLGA) and collagen associated with mesenchymal stem cells derived from human adipose tissue. To develop the bilaminar device, we initially obtained a membrane of PLGA by dissolving the copolymer in chloroform and then produced a collagen type I scaffold by freeze-drying. The materials were characterized physically by gel permeation chromatography, scanning electron microscopy, and mass loss. Biological activity was assessed by cell proliferation assay. A preliminary study in vivo was performed with a pig model in which tissue regeneration was assessed macroscopically and histologically, the commercial device Integra being used as a control. The PLGA/collagen bilaminar material was porous, hydrolytically degradable, and compatible with skin growth. The polymer complex allowed cell adhesion and proliferation, making it a potentially useful cell carrier. In addition, the transparency of the material allowed monitoring of the lesion when the dressings were changed. Xenogeneic mesenchymal cells cultured on the device (PLGA/collagen/ASC) showed a reduced granulomatous reaction to bovine collagen, down-regulation of α-SMA, enhancement in the number of neoformed blood vessels, and collagen organization as compared with normal skin; the device was superior to other materials tested (PLGA/collagen and Integra) in its ability to stimulate the formation of new cutaneous tissue.

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Giardia lamblia is a pathogenic protozoan presenting as the main characteristic, the trophozoite capacity to adhere in host intestinal epithelium, infecting mammals, including humans. The clinical treatment of this disease is based on metronidazole (Mz) that acts as an alternative electron acceptor, and its reduction promotes DNA impairment. In veterinary treatment, one of the best options is pyrantel pamoate (Pm), which the mode of action has not elucidated yet. Different strategies for Giardia treatment have been explored to avoid side effects to the host. In this context, the efficiency of treatment combining drugs raise as an interesting alternative for protozoan diseases. Here, we evaluated in vitro synergic effect of Mz and Pm on trophozoites and on its adherence to IEC-6 cells. The treatment with Mz or Pm was effective on trophozoites, with IC(50)/24h values of 5.3±0.9 µM and 13.8±1.4 µM, respectively. The treatment of trophozoites with different combinations of Mz and Pm were also evaluated, as showed by fractional inhibitory concentration index (FICI) under 0.5 in all conditions tested, corresponding to the synergic effect. This synergic activity was also observed when the combinations of 5.3 µM Mz+0.4 µM Pm and 13.8 µM Pm+0.1 µM Mz induced a remarkable reduction in % adhesion (85-90% and 52-59%, respectively) and in number of adhered parasites per 100 cells. The low cytotoxicity to the host cells of the combinations, associated to the strong synergic potential of the combination, encourage us to further investigate its effect in in vivo models.

Assuntos