poly-L-lactic-co-glycolic Acid Research Articles

Effect of Nanoparticle Weight on the Cellular Uptake and Drug Delivery Potential of PLGA Nanoparticles.

Biodegradable and biocompatible polymeric nanoparticles (NPs) stand out as a key tool for improving drug bioavailability, reducing the inherent toxicity, and targeting the intended site. Most importantly, the ease of polymer synthesis and its derivatization to add functional properties makes them potentially ideal to fulfill the requirements for intended therapeutic applications. Among many polymers, US FDA-approved poly(l-lactic-co-glycolic) acid (PLGA) is a widely used biocompatible and biodegradable co-polymer in drug delivery and in implantable biomaterials. While many studies have been conducted using PLGA NPs as a drug delivery system, less attention has been given to understanding the effect of NP weight on cellular behaviors such as uptake. Here we discuss the synthesis of PLGA NPs with varying NP weights and their colloidal and biological properties. Following nanoprecipitation, we have synthesized PLGA NP sizes ranging from 60 to 100 nm by varying the initial PLGA feed in the system. These NPs were found to be stable for a prolonged period in colloidal conditions. We further studied cellular uptake and found that these NPs are cytocompatible; however, they are differentially uptaken by cancer and immune cells, which are greatly influenced by NPs' weight. The drug delivery potential of these nanoparticles (NPs) was assessed using doxorubicin (DOX) as a model drug, loaded into the NP core at a concentration of 7.0 ± 0.5 wt % to study its therapeutic effects. The results showed that both concentration and treatment time are crucial factors for exhibiting therapeutic effects, as observed with DOX-NPs exhibiting a higher potency at lower concentrations. The observations revealed that DOX-NPs exhibited a higher cellular uptake of DOX compared to the free-DOX treatment group. This will allow us to reduce the recommended dose to achieve the desired effect, which otherwise required a large dose when treated with free DOX. Considering the significance of PLGA-based nanoparticle drug delivery systems, we anticipate that this study will contribute to the establishment of design considerations and guidelines for the therapeutic applications of nanoparticles.

"Combo" Multi-Target Pharmacological Therapy and New Formulations to Reduce Inflammation and Improve Endogenous Remyelination in Traumatic Spinal Cord Injury.

Spinal cord injury (SCI) is characterized by a cascade of events that lead to sensory and motor disabilities. To date, this condition is irreversible, and no cure exists. To improve myelin repair and limit secondary degeneration, we developed a multitherapy based on nanomedicines (NMeds) loaded with the promyelinating agent triiodothyronine (T3), used in combination with systemic ibuprofen and mouse nerve growth factor (mNGF). Poly-L-lactic-co-glycolic acid (PLGA) NMeds were optimized and loaded with T3 to promote sustained release. In vitro experiments confirmed the efficacy of T3-NMeds to differentiate oligodendrocyte precursor cells. In vivo rat experiments were performed in contusion SCI to explore the NMed biodistribution and efficacy of combo drugs at short- and long-term post-lesion. A strong anti-inflammatory effect was observed in the short term with a reduction of type M1 microglia and glutamate levels, but with a subsequent increase of TREM2. In the long term, an improvement of myelination in NG2-IR, an increase in MBP content, and a reduction of the demyelination area were observed. These data demonstrated that NMeds can successfully be used to obtain more controlled local drug delivery and that this multiple treatment could be effective in improving the outcome of SCIs.

Pioglitazone-incorporated microspheres alleviates cardiac dysfunction through macrophage polarization in a rat myocardial infarction model

Abstract Inflammatory processes are essential for the repair processes after myocardial infarction. Among inflammatory cells involved in this process, macrophages play a critical role through polarization in pro-inflammatory M1 or reparative M2 subtype. Pioglitazone, known as a treatment drug for diabetes mellitus, is reported to regulate macrophage polarization toward reparative M2 subtype. Poly L-lactic-co-glycolic acid (PLGA) has been widely accepted as the delivery carrier in drug delivery system (DDS). Here, we aimed to validate the therapeutic effects and investigate the mechanisms of DDS-based treatment using pioglitazone to left ventricular remodeling after myocardial infarction. Pioglitazone-incorporated PLGA microspheres (PGZ-MS) were prepared and the drug release profile was evaluated. The concentration of interleukin-10 secreted from murine bone marrow derived macrophages incubated with PGZ-MS was quantified in the culture supernatant. To validate the therapeutic potential of PGZ-MS in vivo, Sprague-Dawley rats were subjected to permanent left coronary artery ligation to induce myocardial infarction. Mock-MS (100 μg) or PGZ-MS (100 μg) was injected to the infarct region just after induction (n=9–11/group). Cardiac function and left ventricular size were assessed by echocardiography. At 28-day after surgery, rats were sacrificed, and excised hearts were evaluated histologically. PGZ-MS released 1.8±0.3% of incorporated PGZ within 24 hours and 29.5±1.2% within 14 days indicating sustained release of PGZ in vitro. PGZ-MS augmented Interleukin-10 release from bone marrow derived macrophages, indicating polarization toward reparative M2 subtype. PGZ-MS significantly ameliorated cardiac function after myocardial infarction (fractional shortening: MI vs MI+Mock-MS vs MI+PGZ-MS, 24.4±1.1 vs 24.3±1.6 vs 32.2±1.4%; P=0.0035) with reverse remodeling (wall thickness: MI vs MI+Mock-MS vs MI+PGZ-MS, 0.69±0.12 vs 0.71±0.13 vs 1.06±0.09; P=0.03). Immunohistochemical analyses revealed that PGZ-MS enhanced macrophage polarization toward reparative M2 subtype (ratio of reparative M2 macrophages: 0.39±0.03 vs 0.42±0.02 vs 0.54±0.02; P=0.0004) and attenuated apoptosis of cardiomyocytes in the ischemic border zone (MI vs MI+Mock-MS vs MI+PGZ-MS, 2.6±0.2 vs 1.9±0.2 vs 1.2±0.2 cells/field; P=0.002). In the present study, we confirmed that PGZ-MS could realize sustained release of pioglitazone which resulted in sustained effect of macrophage polarization and attenuated left ventricular remodeling accompanied with the amelioration of cardiac dysfunction and cardiomyocytes apoptosis. The strategy of DDS-based macrophage polarization might serve as a promising strategy in cardiac regenerative therapy for ischemic heart disease in the future. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grants-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan

Transferrin-Conjugated Docetaxel-PLGA Nanoparticles for Tumor Targeting: Influence on MCF-7 Cell Cycle.

Targeted drug delivery systems are commonly used to improve the therapeutic index of anti-cancer drugs by increasing their selectivity and reducing systemic distribution and toxicity. Ligand-conjugated nanoparticles (NPs) can be effectively applied for active chemotherapeutic targeting to overexpressed receptors of tumor cells. In this study, transferrin (Tf) was successfully conjugated with poly-l-lactic-co-glycolic acid (PLGA) using ethylene diamine confirmed by NMR, for the loading of docetaxel trihydrate (DCT) into PLGA nanoparticles (NPs). The DCT-loaded Tf-conjugated PLGA NPs were produced by an emulsion-solvent evaporation technique, and a 32 full factorial design was used to optimize the nanoparticle formulations. The DCT-loaded Tf-conjugated PLGA NPs were characterized by FTIR spectroscopy, differential scanning calorimetry, powder X-ray diffraction (PXRD), TEM, particle size, and zeta potential analysis. In vitro release kinetics confirmed that release of DCT from the designed formulations followed a zero-order kinetics and a diffusion controlled non-Fickian release profile. The DCT-loaded Tf-conjugated PLGA NPs were evaluated in vitro in MCF-7 cells for bioactivity assessment. Cytotoxicity studies confirmed that the Tf-conjugated PLGA NPs were more active than the non-conjugated counterparts. Cell uptake studies re-confirmed the ligand-mediated active targeting of the formulated NPs. From the cell cycle analysis, the anti-cancer activity of DCT-loaded Tf-conjugated PLGA NPs was shown to occur by arresting the G2/M phase.

Avulsion Fractures Osteosynthesis in Patients with Normal Bone Mineral Density and Osteoporosis

Objective: to compare the effectiveness of osteosynthesis for avulsion fractures using bioabsorbable versus titanium implants in patients differing in bone mineral density.Material and Methods. In the experimental phase of study, two groups of bone blocks were singled out from patients' femoral heads to assess the anchoring properties of the implant in osteoporotic and healthy bone. The first group included blocks of 31 patients with osteoporosis, the second one — 27 blocks of patients without osteoporosis. In the first group, cortical bioabsorbable Poly-L-Lactic/ co-glycolic acid (PLGA) screws were implanted into 13 bone blocks, titanium screws — into 10 bone blocks, and bioabsorbable pins (PLGA) — into 8 bone blocks. In the second group, 10 titanium screws, 10 bioabsorbable screws and 7 bioabsorbable pins were implanted. The anchorage of the implant in bone was evaluated by a pull-out test. Then, depending on the anchorage used, the studied bone blocks with osteoporosis, newly obtained from the first group, were divided into three groups for the purpose of evaluating the resistance to the damaging effects of the implant. In experiment, the osteosynthesis for avulsion fracture was simulated on these bone blocks. In the first group (11 bone blocks), the transosseous osteosynthesis of the bone fragment was carried out with a titanium screw, in the second group (9 bone blocks) with a bioabsobable screw, in the third group (11 bone blocks) with a bioabsorbable pin. The results of osteosynthesis were assessed based on how often a small bone fragment was damaged by an implant and on stability of the anchored implant. In the clinical phase of study, a comparative analysis of 65 surgical interventions (38 people with osteoporosis and 27 without osteoporosis) in patients with avulsion fractures was performed. In 24 cases, bioabsorbable screws were used for osteosynthesis, AO/ASIF titanium screws were used in 31 cases, and pins were used in 10 cases.Results. Experimental studies showed that the resistance to pull-out test of a bioabsorbable screw anchored in osteoporotic bone is 25.7% higher than a titanium screw. No statistically significant difference was found in bone without osteoporosis. Resistance to pull-out test of a bioabsorbable pin is 3% higher than a titanium screw. The model-based experiment with an avulsion fracture in osteoporotic bone using a titanium screw showed lower effectiveness of osteosynthesis: in 27.2% of cases the cortical titanium screw damaged a small bone fragment. Based on the clinical trial findings, no negative results were obtained using bioabsorbable anchorage. In 12.5% cases of osteosynthesis with a titanium screw, migration of a bone fragment was noted. The data obtained during the clinical study correlated with the experimental data. This makes the use of bioabsorbable implants advantageous.Conclusion. For avulsion fracture osteosynthesis in patients with normal bone mineral density, it is possible to use both titanium and biodegradable fixators with equivalent strength of fragment fixation. n osteosynthesis of fractures in patients with osteoporosis it is preferable to use bioabsorbable implants

Fatigue Test and Lifetime Prediction of Implantable Biocomposite Materials

Biocomposite materials consisting of Poly-L-Lactic-Co-Glycolic Acid (PLGA) and Hydroxyapatite (HA) were synthesized and mechanical properties have been observed by carrying out the fatigue test, for which accelerated tests have been conducted such that 20%, 30% and 40% of the yield strength have been applied in a repeated mode until a crack occurred on the load-applied points of test specimen. Based on the fatigue test results, the lifetime of test specimen (B10 life) was estimated. It was found that Weibull distribution (shape parameter=8.79) was the most proper one to describe the failure data obtained from the accelerated fatigue tests. B10 life at 5% of yield strength was estimated to be 335,764 cycles (Confidence Level=95%, lower limit) by applying an inverse power model.

Development of Biocomposite Based Anchor Screw System for Osteoporosis

With the recent advancements in arthroscopic surgery, the use of suture anchor has increased in the surgical treatment of rotator cuff tears. In the present study, we developed a suture anchor system for ligament reconstruction that can be applied to patients with osteoporosis or with low bone density. The anchor screws are made of biocomposites containing poly-L-lactic-co-glycolic acid (PLGA) and beta-tricalcium phosphate (β-TCP) in a 70:30 ratio. The suture anchor system consisted of medial and lateral screw. The lateral screw was designed in a hemicylindrical structure to prevent bone damage. The performance of the developed anchor screw was found to be greater than 402.5 N in a pull-out test.

Bone Marrow Stromal Cells Associated with Poly L-Lactic-Co-Glycolic Acid (PLGA) Nanofiber Scaffold Improve Transected Sciatic Nerve Regeneration.

Background: Although peripheral nerves show capacity for regeneration after injury to a certain extent, the extent of regeneration is not remarkable. Previous studies have suggested that through the production of growth factors or extracellular matrix components, mesenchymal stem cells may enhance nerve regeneration. Objectives: In the present study, the therapeutic potency of the Bone Marrow Stromal Cells (BMSCs) associated with Poly L-lactic-co-glycolic acid (PLGA) nanofiber Scaffolds on rat sciatic nerve repair was evaluated. Material and Methods: Thirty adult male Wistar rats (220-250 g) were divided randomly into six groups, including control 1 (transected sciatic nerve), control 2 (transected sciatic nerve and stitched), Sham, PLGA, BMSCs, and PLGA+BMSCs. Functional recovery was evaluated at the end of 2nd, 4th, 6th, and 8th weeks after surgery using sciatic functional index (SFI) and hot water test. After killing all rats at the end of 8th week, their sciatic nerves were removed, fixed, and processed for the histological examination and analysis by the Motic software. Results: A significant recovery of the sciatic nerve function was observed in the PLGA+BMSCs transplanted group at the 8th week after surgery as demonstrated by SFI and hot water findings. Histological examinations also showed a significant improvement in the PLGA+BMSCs group compared to the control 1, 2, Sham, PLGA and BMSCs groups. Conclusion: BMSCs associated with PLGA nanofiber scaffold might be useful for improving the functional peripheral nerve repair having some clinical outcome.

Functionalized Nanoscaffolds to Promote Osteogenic Differentiation in Adipose Derived Human Mesenchymal Stem Cells

Biocompatible polymers have been successfully implemented to generate nanofibers for bone tissue engineering. This work focused on generating and functionalizing Poly-l-Lactic-coGlycolic Acid (PLGA) nanofiber scaffolds in the range of 700 nm using the electrospinning technique. Our specific objective is to design synthetic biodegradable scaffolds comprising electrospun nanofibers that will not only be osteoconductive but also contain porosity for bone cell ingrowth enhanced with Adipose derived human Mesenchymal Stem Cells (AdhMSCs) and a sufficient amount of bioactive ingredient such as Demineralized Bone Matrix (DBM) that would serve as a more conducive framework for cell adhesion, proliferation, and differentiation. Cell-scaffolds and controls were subject to immunohistochemistry and visualized using laser scanning confocal microscopy. Osteocalcin and collagen were expressed the highest in cells grown on PLGA nanofibers but were low in cells grown on PLGA film or cells grown without PLGA. Cell viability data showed that PLGA did not cause any significant cell death, therefore mitigating biocompatibility concerns. Our results demonstrate that the nanoscaffolds support the cell proliferation and differentiation and can be used in osteogenic applications.

Adrenomedullin delivery in microsphere-scaffold composite for remodeling of the alveolar bone following tooth extraction: an experimental study in the rat

BackgroundAlveolar ridge resorption, as a significant problem in implant and restorative dentistry, has long been considered as an inevitable outcome following tooth extraction. Recently, adrenomedullin (ADM) is reported to be able to stimulate the proliferation and migration of various cells including osteoblasts. The purpose of this study was to investigate the influence of local ADM application in the tooth extraction socket in vivo.MethodsChitosan micropheres were developed by an emulsion-ionic cross-linking method for ADM delivery. Poly (L -lactic-co-glycolic) acid (PLGA) and nano-hydroxyapatite (nHA) were used to prepare scaffolds to contain the micrspheres with ADM. In vivo experiment was evaluated by transplanting the composite into the rat socket right after the incisor extraction. After 4, 8, 12 weeks implantation, radiographic and histological tests were carried out to evaluate the effect of released ADM on the alveolar bone.ResultsThe microspheres had a spherical structure and a relative rough and uniform surface, and the particle size was under a normal distribution, with the average diameter of 38.59 μm. The scaffolds had open and interconnected pores. In addition, the high porosity of the composite was 88.93%. Radiographic and histological examination revealed that the PLGA/nHA/CMs/ADM composite could accelerate the alveolar bone remodeling and reduce the residual ridge resorption compared with the PLGA/nHA/CMs scaffold.ConclusionsThe results of this study suggest that local application of ADM has the potential to preserve the residual alveolar ridge and accelerate the alveolar bone remodeling.

The regulation of focal adhesion complex formation and salivary gland epithelial cell organization by nanofibrous PLGA scaffolds

Nanofiber scaffolds have been useful for engineering tissues derived from mesenchymal cells, but few studies have investigated their applicability for epithelial cell-derived tissues. In this study, we generated nanofiber (250 nm) or microfiber (1200 nm) scaffolds via electrospinning from the polymer, poly-l-lactic-co-glycolic acid (PLGA). Cell-scaffold contacts were visualized using fluorescent immunocytochemistry and laser scanning confocal microscopy. Focal adhesion (FA) proteins, such as phosphorylated FAK (Tyr397), paxillin (Tyr118), talin and vinculin were localized to FA complexes in adult cells grown on planar surfaces but were reduced and diffusely localized in cells grown on nanofiber surfaces, similar to the pattern observed in adult mouse salivary gland tissues. Significant differences in epithelial cell morphology and cell clustering were also observed and quantified, using image segmentation and computational cell-graph analyses. No statistically significant differences in scaffold stiffness between planar PLGA film controls compared to nanofibers scaffolds were detected using nanoindentation with atomic force microscopy, indicating that scaffold topography rather than mechanical properties accounts for changes in cell attachments and cell structure. Finally, PLGA nanofiber scaffolds could support the spontaneous self-organization and branching of dissociated embryonic salivary gland cells. Nanofiber scaffolds may therefore have applicability in the future for engineering an artificial salivary gland.

Effect of ceramic filler content on the mechanical and thermal behaviour of poly-l-lactic acid and poly-l-lactic-co-glycolic acid composites for medical applications

One main application of resorbable poly-L-lactic acid (PLLA) and poly-L-lactic-co-glycolic acid (PLGA) based materials is in medical implants. In this study composites were made from PLLA and PLGA with hydroxyapatite (HAp) respective beta-tricalcium phosphate (beta-TCP) fillers. The filler content and particle size were varied, and the thermal properties as well as the mechanical strength of the composites were investigated. The composites were made by an extrusion compounding process giving 2-2.5 mm diameter sized profiles. The results verified that the thermal stability of the composites was reasonable during the optimized compounding conditions. Scanning electron microscopy revealed that the fillers were well dispersed in the polymer matrices. The mechanical properties were improved by the addition of the fillers. The optimum mechanical properties for the extruded profiles were obtained with the HAp fillers. The E-modulus was increased from 3.3 to 4.6 GPa by addition of filler particles (30 wt%) whereas the flexural strength was reduced from 133 to 106 MPa.

Silk Fibroin Microfluidic Devices.

Silk Fibroin Microfluidic Devices.