Hybrid nanovaccine for the co-delivery of the mRNA antigen and adjuvant

For efficient cancer vaccines, the antitumor function largely relies on cytotoxic T cells, whose activation can be effectively induced via antigen-encoding mRNA, making mRNA-based cancer vaccines an attractive approach for personalized cancer therapy. While the liposome-based delivery system enables the systemic delivery and transfection of mRNA, incorporating an adjuvant that is non-lipid like remains challenging, although the co-delivery of mRNA (antigen) and effective adjuvant is key to the activation of the cytotoxic T cells. This is because the presence of an adjuvant is important for dendritic cell maturation-another necessity for cytotoxic T cell activation. In the present work, we designed a poly (lactic-co-glycolic acid) (PLGA)-core/lipid-shell hybrid nanoparticle carrier for the co-delivery of mRNA and gardiquimod (adjuvant that cannot be incorporated into the lipid shell). We demonstrated in the present work that the co-delivery of mRNA and gardiquimod led to the effective antigen expression and DC maturation in vitro. The intravenous administration of the hybrid nanovaccine resulted in the enrichment of mRNA expression in the spleen and a strong immune response in vivo. The simultaneous delivery of the antigen and adjuvant both spatially and temporally via the core/shell nanoparticle carrier is found to be beneficial for tumor growth inhibition.

A core-shell structure QRu-PLGA-RES-DS NP nanocomposite with photothermal response-induced M2 macrophage polarization for rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is a degenerative joint disease caused by autoimmunity; for the effective treatment of RA while avoiding the side effects of conventional drugs, we have proposed a new therapeutic strategy to eliminate the inflammatory response in RA by regulating the immune system that promotes the transformation of M1-type macrophages to M2-type macrophages. Herein, we designed and synthesized a core-shell nanocomposite (QRu-PLGA-RES-DS NPs), which showed an effective therapeutic effect on RA by accurately inducing the polarization of M2 macrophages. In this system, the quadrilateral ruthenium nanoparticles (QRuNPs) with a photothermal effect were utilized as a core and the thermosensitive molecular poly (lactic-co-glycolic acid) (PLGA) modified with the targeted molecule dextran sulfate (DS) was employed as a shell. Then, the nanocarrier QRu-PLGA-DS NPs effectively improved the water solubility and targeting of resveratrol (RES) through self-assembly. Therefore, the QRu-PLGA-RES-DS NPs significantly enhanced the ability of RES to reverse the M1 type macrophages to the M2 type macrophages through an accurate release. In vivo experiments further demonstrated that the QRu-PLGA-RES-DS NPs could effectively accumulate in the lesion area with an exogenous stimulus, and this significantly enhanced the transformation of the M2 type macrophages and decreased the recruitment of the M1 type macrophages. Furthermore, the QRu-PLGA-RES-DS NPs effectively treated RA by eliminating the inflammatory response; in addition, photoacoustic imaging (PA) of the QRu NPs provided image guidance for the distribution and analysis of nanomedicine in inflammatory tissues. Hence, this therapeutic strategy promotes the biological applications of Ru-based nanoparticles in disease treatment.

A pro-angiogenic degradable Mg-poly(lactic-co-glycolic acid) implant combined with rhbFGF in a rat limb ischemia model

Site-specific controlled release of exogenous angiogenic growth factors, such as recombinant human basic fibroblast growth factor (rhbFGF), has become a promising approach to improve peripheral vascular disease. Here, we have developed an implant composed of spiral magnesium (Mg) and a coating made using poly(lactic-co-glycolic acid) (PLGA) with encapsulated rhbFGF (Mg-PLGA-rhbFGF). The encapsulated protein could release continually for 4weeks with well preserved bioactivity. We compared the angiogenic effect produced by Mg-PLGA-rhbFGF with that of a PLGA implant loaded with rhbFGF (PLGA-rhbFGF). The incorporation of Mg in the implant raised the microclimate pH in the polymer, which preserved the stability of rhbFGF. Mg-PLGA-rhbFGF exhibited advantages over PLGA-rhbFGF implant in terms of a cytocompatibility evaluation. An in vivo angiogenesis test further confirmed the efficacy of released rhbFGF. HE, CD31 and α-SMA staining revealed that the controlled release of rhbFGF from the Mg-PLGA-rhbFGF implant was superior in promoting angiogenesis compared with that of the PLGA-rhbFGF implant. Four weeks post-implantation, the capillary density of the Mg-PLGA-rhbFGF group was significantly higher than that of the PLGA-rhbFGF, control and the normal group (p<0.05, p<0.01 and p<0.01, respectively). Furthermore, the limb blood perfusion ratios of the Mg-PLGA-rhbFGF and PLGA-rhbFGF groups were dramatically increased, at 99.1±2.9% and 80.7±3.2%, respectively, whereas the ischemic limb did not recover in the control group. The biocompatibility of the implants was also evaluated. In conclusion, Mg-PLGA-based, sustained local delivery of rhbFGF promotes post-ischemic angiogenesis and blood flow recovery. The results suggest potential therapeutic usefulness of Mg-PLGA-rhbFGF for tissue ischemia.

STATEMENT OF SIGNIFICANCE

Magnesium (Mg)-based implant has been already used in patients with critical limb ischemia. Site-specific controlled release of recombinant human basic fibroblast growth factor (rhbFGF), has become a promising approach to improve peripheral vascular disease. We report here on a novel combination implant composed of spiral magnesium and a coating made using poly(lactic-co-glycolic acid) (PLGA) with encapsulated rhbFGF (Mg-PLGA-rhbFGF). The preparation method does not involve any complex processes and results in a high encapsulation efficiency (approximately 100%). The degradation of metal Mg raise the microclimate pH in the PLGA polymer, which could well preserve the bioactivity of rhbFGF incorporated in the implant. Mg-PLGA-based, sustained local delivery of rhbFGF promotes post-ischemic angiogenesis and blood flow recovery in rat limb ischemic model. This work marks the first report for controlled release of rhbFGF in combination with metal Mg, and suggests potential therapeutic usefulness of Mg-PLGA-rhbFGF for tissue ischemia.

Mussel-inspired PLGA/polydopamine core-shell nanoparticle for light induced cancer thermochemotherapy

Most photothermal converting systems are not biodegradable, which bring the uneasiness when they are administered into human body due to the uncertainty of their fate. Hereby, we developed a mussel-inspired PLGA/polydopamine core-shell nanoparticle for cancer photothermal and chemotherapy. With the help of an anti-EGFR antibody, the nanoparticle could effectively enter head and neck cancer cells and convert near-infrared light to heat to trigger drug release from PLGA core for chemotherapy as well as ablate tumors by the elevated temperature. Due to the unique nanoparticle concentration dependent peak working-temperature nature, an overheating or overburn situation can be easily prevented. Since the nanoparticle was retained in the tumor tissue and subsequently released its payload inside the cancer cells, no any doxorubicin-associated side effects were detected. Thus, the developed mussel-inspired PLGA/polydopamine core-shell nanoparticle could be a safe and effective tool for the treatment of head and neck cancer.

STATEMENT OF SIGNIFICANCE

The described EGFR targeted PLGA/polydopamine core-shell nanoparticle (PLGA/PD NP) is novel in the following aspects: Different from most photothermal converting nanomaterials, PLGA/PD NP is biodegradable, which eliminates the long-term safety concerns thwarting the clinical application of photothermal therapy. Different from most photothermal nanomaterials, upon NIR irradiation, PLGA/PD NP quickly heats its surrounding environment to a NP concentration dependent peak working temperature and uniquely keeps that temperature constant through the duration of light irradiation. Due to this unique property an overheating or overburn situation for the adjacent healthy tissue can be easily avoided. The PLGA/PD NP releases its payload through detaching PD shell under NIR laser irradiation. The EGFR-targeted doxorubicin-loaded PLGA/PD NP effectively eradicate head and neck tumor in vivo through the synergism of photothermal therapy and chemotherapy while not introducing doxorubicin associated cardiotoxicity.

Photoresponsive lipid-polymer hybrid nanoparticles for controlled doxorubicin release

Currently, photoresponsive nanomaterials are particularly attractive due to their spatial and temporal controlled drug release abilities. In this work, we report a photoresponsive lipid-polymer hybrid nanoparticle for remote controlled delivery of anticancer drugs. This hybrid nanoparticle comprises three distinct functional components: (i) a poly(D,L-lactide-co-glycolide) (PLGA) core to encapsulate doxorubicin; (ii) a soybean lecithin monolayer at the interface of the core and shell to act as a molecular fence to prevent drug leakage; (iii) a photoresponsive polymeric shell with anti-biofouling properties to enhance nanoparticle stability, which could be detached from the nanoparticle to trigger the drug release via a decrease in the nanoparticle's stability under light irradiation. In vitro results revealed that this core-shell nanoparticle had excellent light-controlled drug release behavior (76% release with light irradiation versus 10% release without light irradiation). The confocal microscopy and flow cytometry results also further demonstrated the light-controlled drug release behavior inside the cancer cells. Furthermore, a CCK8 assay demonstrated that light irradiation could significantly improve the efficiency of killing cancer cells. Meanwhile, whole-animal fluorescence imaging of a tumor-bearing mouse also confirmed that light irradiation could trigger drug release in vivo. Taken together, our data suggested that a hybrid nanoparticle could be a novel light controlled drug delivery system for cancer therapy.

PLGA-soya lecithin based micelles for enhanced delivery of methotrexate: Cellular uptake, cytotoxic and pharmacokinetic evidences

Biocompatible and biodegradable polymers like PLGA have revolutionized the drug delivery approaches. However, poor drug loading and substantially high lipophilicity, pave a path for further tailing of this promising agent. In this regard, PLGA was feathered with biocompatible phospholipid and polymeric micelles were developed for delivery of Methotrexate (MTX) to cancer cells. The nanocarriers (114.6nm±5.5nm) enhanced the cytotoxicity of MTX by 2.13 folds on MDA-MB-231 cells. Confocal laser scanning microscopy confirmed the increased intracellular delivery. The carrier decreased the protein binding potential and enhanced the bioavailable fraction of MTX. Pharmacokinetic studies vouched substantial enhancement in AUC and bioresidence time, promising an ideal carrier to effectively deliver the drug to the site of action. The developed nanocarriers offer potential to deliver the drug in the interiors of cancer cells in an effective manner for improved therapeutic action.

Controlled and Sequential Delivery of Fluorophores from 3D Printed Alginate-PLGA Tubes

Controlled drug delivery systems, that include sequential and/or sustained drug delivery, have been utilized to enhance the therapeutic effects of many current drugs by effectively delivering drugs in a time-dependent and repeatable manner. In this study, with the aid of 3D printing technology, a novel drug delivery device was fabricated and tested to evaluate sequential delivery functionality. With an alginate shell and a poly(lactic-co-glycolic acid) (PLGA) core, the fabricated tubes displayed sequential release of distinct fluorescent dyes and showed no cytotoxicity when incubated with the human embryonic kidney (HEK293) cell line or bone marrow stromal stem cells (BMSC). The controlled differential release of drugs or proteins through such a delivery system has the potential to be used in a wide variety of biomedical applications from treating cancer to regenerative medicine.

Chitosan-modified PLGA polymeric nanocarriers with better delivery potential for tamoxifen

Breast cancer is believed as the second most common cause of cancer-related deaths in women for which tamoxifen is frequently prescribed. Despite many promises, tamoxifen is associated with various challenges like low hydrophilicity, poor bioavailability and dose-dependent toxicity. Therefore, it was envisioned to develop tamoxifen- loaded chitosan-PLGA micelles for potential safe and better delivery of this promising agent. The chitosan-PLGA copolymer was synthesised and characterised by Fourier Transform-Infrared, Ultraviolet-visible and Nuclear Magnetic Resonance spectroscopic techniques. The drug-loaded nanocarrier was characterised for drug-pay load, micrometrics, surface charge and morphological attributes. The developed system was evaluated for in-vitro drug release, haemolytic profile, cellular-uptake, anticancer activity by cytotoxicity assay and dermatokinetic studies. The developed nano-system was able to substantially load the drug and control the drug release. The in-vitro cytotoxicity offered by the system was significantly enhanced vis-a-vis plain drug, and there was no substantial haemolysis. The IC₅₀ values were significantly decreased and the nanocarriers were uptaken by MCF-7 cells, noticeably. The carrier was able to locate the drug in the interiors of rat skin in considerable amounts to that of the conventional product. This approach is promising as it provides a biocompatible and effective option for better delivery of tamoxifen.

Development of Alendronate-conjugated Poly (lactic-co-glycolic acid)-Dextran Nanoparticles for Active Targeting of Cisplatin in Osteosarcoma

In this study, we developed a novel poly (lactic-co-glycolic acid)-dextran (PLD)-based nanodelivery system to enhance the anticancer potential of cisplatin (CDDP) in osteosarcoma cells. A nanosized CDDP-loaded PLGA-DX nanoparticle (PLD/CDDP) controlled the release rate of CDDP up to 48 h. In vitro cytotoxicity assay showed a superior anticancer effect for PLD/CDDP and with an appreciable cellular uptake via endocytosis-mediated pathways. PLD/CDDP exhibited significant apoptosis of MG63 cancer cells compared to that of free CDDP. Approximately ~25% of cells were in early apoptosis phase after PLD/CDDP treatment comparing to ~15% for free CDDP after 48h incubation. Similarly, PLD/CDDP exhibited ~30% of late apoptosis cells comparing to only ~8% for free drug treatment. PLD/CDDP exhibited significantly higher G2/M phase arrest in MG63 cells than compared to free CDDP with a nearly 2-fold higher arrest in case of PLD/CDDP treated group (~60%). Importantly, PLD/CDDP exhibited a most significant anti-tumor activity with maximum tumor growth inhibition. The superior inhibitory effect was further confirmed by a marked reduction in the number of CD31 stained tumor blood vessels and decrease in the Ki67 staining intensity for PLD/CDDP treated animal group. Overall, CDDP formulations could provide a promising and most effective platform in the treatment of osteosarcoma.

Use of Polylactide-Co-Glycolide-Nanoparticles for Lysosomal Delivery of a Therapeutic Enzyme in Glycogenosis Type II Fibroblasts

Glycogenosis type II, or Pompe Disease, is a lysosomal storage disease caused by the deficiency of acid alpha-glucosidase (GAA), leading to glycogen accumulation in muscles. A recombinant human GAA (rhGAA, Myozyme®) is currently used for enzyme replacement therapy. Despite its efficacy in most of patients, some of them show a diminished response to the treatment with rapidly progressive clinical deterioration, due to immuno-mediated enzyme inactivation. To demonstrate that Nanoparticles (NPs) could be profitably exploited to carry macromolecules, PLGA NPs loaded with rhGAA (GAA-NPs) were prepared by double emulsion solvent evaporation. Their surface morphology, particle size, zeta-potential and biochemical activity were assessed. "Pulse and chase" experiments were made by administrating GAA-NPs on patients' fibroblasts. Biochemical activity tests showed a more efficient cellular uptake of rhGAA loaded to NPs and a more significant stability of the enzyme (up to 7 days) in vitro, if compared to the same amount of rhGAA free enzyme. This data allows to envision in vivo experiments, in significant animal models, to further characterize lysosomal enzyme loaded-NPs' efficacy and toxicity.

Fenofibrate subcellular distribution as a rationale for the intracranial delivery through biodegradable carrier

Fenofibrate, a well-known normolipidemic drug, has been shown to exert strong anticancer effects against tumors of neuroectodermal origin including glioblastoma. Although some pharmacokinetic studies were performed in the past, data are still needed about the detailed subcellular and tissue distribution of fenofibrate (FF) and its active metabolite, fenofibric acid (FA), especially in respect to the treatment of intracranial tumors. We used high performance liquid chromatography (HPLC) to elucidate the intracellular, tissue and body fluid distribution of FF and FA after oral administration of the drug to mice bearing intracranial glioblastoma. Following the treatment, FF was quickly cleaved to FA by blood esterases and FA was detected in the blood, urine, liver, kidney, spleen and lungs. We have also detected small amounts of FA in the brains of two out of six mice, but not in the brain tumor tissue. The lack of FF and FA in the intracranial tumors prompted us to develop a new method for intracranial delivery of FF. We have prepared and tested in vitro biodegradable poly-lactic-co-glycolic acid (PLGA) polymer wafers containing FF, which could ultimately be inserted into the brain cavity following resection of the brain tumor. HPLC-based analysis demonstrated a slow and constant diffusion of FF from the wafer, and the released FF abolished clonogenic growth of glioblastoma cells. On the intracellular level, FF and FA were both present in the cytosolic fraction. Surprisingly, we also detected FF, but not FA in the cell membrane fraction. Electron paramagnetic resonance spectroscopy applied to spin-labeled phospholipid model-membranes revealed broadening of lipid phase transitions and decrease of membrane polarity induced by fenofibrate. Our results indicate that the membrane-bound FF could contribute to its exceptional anticancer potential in comparison to other lipid-lowering drugs, and advocate for intracranial delivery of FF in the combined pharmacotherapy against glioblastoma.

[Delta12-prostaglandinJ2-nano capsule up-regulates growth factor expression and enhances bone regeneration in rats]

OBJECTIVE

To investigate the effect of local delivery of delta12-prostaglandinJ2-loaded poly (lactic-co-glycolic acid) (Δ(12)-PGJ2-NC) on growth factors expression and bone formation.

METHODS

Δ(12)-PGJ2-NC was prepared by the emulsion solvent diffusion method. The physical and chemical properties of the nanoparticles were evaluated by particle size analysis, transmission electron microscopy, drug-loading ratio and the in vitro release study. Then standardized transcortical defect (5.0 mm × 1.5 mm) was conducted in the femur of 48 male Wistar rats which were randomly divided into four groups (n = 12), S, K, F, and N. Thirty microliter of saline (S), unloaded nanoparticles (K), Δ(12)-PGJ2 (F) and Δ(12)-PGJ2-NC(N) in a collagen vehicle were delivered inside a titanium chamber fixed over the defect. Then, four subgroups were randomly divided in each group named as D3, D7, D14, and D28 (n = 3) according to the days 3, 7, 14, and 28 after the surgery. At days 3, 7, 14, and 28, the mRNA expression of the bone morphogenetic protein-6 (BMP-6), platelet-derived growth factor-B (PDGF-B) in defect aera was analyzed by real time quantitive-polymerase blotting. HE staining was employed to reveal new bone formation in weeks 2 and 4.

RESULTS

Δ(12)-PGJ2-NC appeared opalescent white and remained relatively stable, with an average particle size of (135.2 ± 0.85) nm. The images from transmission electron microscopy showed that Δ(12)-PGJ2-NC was spherical in shape and homogeneously distributed. The encapsulation efficiency of Δ(12)-PGJ2 with the poly (lactic-co-glycolic acid) (PLGA) nanocapsules was about 92%. The in vitro release of Δ(12)-PGJ2-NC at 37 °C showed a sustained fashion and the average accumulated amount was 30%, 52%, 77%, 91%, and 98% respectively, at 0.5, 1, 2, 4 and 6 h. Compared with the animals treated with saline, after dose of 100 mg/L Δ(12)-PGJ2 and Δ(12)-PGJ2-NC apllication, the mRNA expression level of BMP-6, PDGF-B increased significantly (P < 0.05, P < 0.001). The protein expression of BMP-6, Ephrin-B2 also was up-regulated. Histomorphometry revealed that new bone formation increased at the same dose of 100 mg/L. But the unloaded nanoparticles did not have the same effect (P > 0.05).

CONCLUSIONS

A stable Δ(12)-PGJ2 loaded nanoparticle was successfully prepared. Δ(12)-PGJ2-NC may upregulate the expression of BMP-6, PDGF-B and Ephrin-B2, and promote new bone formation in bone defect area.

Modified poly(lactic-co-glycolic acid) nanoparticles for enhanced cellular uptake and gene editing in the lung

Surface-modified poly(lactic-co-glycolic acid) (PLGA)/poly(β-aminoester)(PBAE)nanoparticles (NPs) have shown great promise in gene delivery. In this work, the pulmonary cellular uptake of these NPs is evaluated and surface-modified PLGA/PBAE NPs are shown to achieve higher cellular association and gene editing than traditional NPs composed of PLGA or PLGA/PBAE blends alone.

[Kinetics of methyluracil release from bioresorbable polymeric carriers]

Bioresorbable poly(lactic-co-glycolic) matrix-carriers containing 20 wt. % of 6-methyluracil (MU) have been prepared by supercritical fluid monolithization without organic solvents. Raman spectroscopy was used to analyze both the spatial distribution MU over polymer matrices and the MU release kinetics from the carrier into phosphate buffer solution. It was found that, during the first 24 h, the amount of released MU did not exceed 15-20% of its encapsulated content. After that, the MU release kinetics passed to almost linear regime with simultaneous retarding of the process. On the 40th day of observation, the MU content in solution reached up to 80% of its initial content in the carriers. Thus, using 6-methyluracil as a model, it was shown that the proposed bioresorbable and bioactive composites can be used as matrix-carriers for targeted and long-term drug release.

A drug-perfluorocarbon nanoemulsion with an ultrathin silica coating for the synergistic effect of chemotherapy and ablation by high-intensity focused ultrasound

The synergistic effect of chemotherapy and ablation using high-intensity focused ultrasound (HIFU) is realized with a newly developed drug-delivery system. The system comprises an ultrathin silica shell surrounding a poly(lactic-co-glycolic acid) nanoemulsion core containing the drug (CPT) and a perfluorocarbon (PFOB). This nanosystem presents many advantages in drug delivery, such as excellent structural stability, high drug-loading capacity, and rapid HIFU-mediated drug release.

In vivo toxicity and biodistribution of intraperitoneal and intravenous poly-L-lysine and poly-L-lysine/poly-L-glutamate in rats

The combination of two differently charged polypeptides, poly-L-lysine (PL) and poly-L-glutamate (PG), has shown excellent postsurgical antiadhesive properties. However, the high molecular, positively charged PL is toxic in high doses, proposed as lysis of red blood cells. This study aims to elucidate the in vivo toxicity and biodistribution of PL and complex bound PLPG comparing intravenous and intraperitoneal administration. Fifty-six Sprague-Dawley rats were used in a model with repeated blood samples within 30 min examining blood gases and blood smears. Similarly, FITC labelled PL were used to track bio distribution and clearance of PL, given as single dose and complex bound to PG after intravenous and intraperitoneal administration. Tissue for histology and immunohistochemistry was collected. Blood gases and blood smears as well as histology points to a toxic effect of high dose PL given intravenously but not after intraperitoneal administration. The toxic effect is exerted through endothelial disruption and subsequent bleeding in the lungs, provoking sanguineous lung edema. FITC-labelled PL experiments reveal a rapid clearance with differences between routes and complex binding. This study advocates a new theory of the toxic effects in vivo of high molecular PL. PLPG complex is safe to use as antiadhesive prevention based on this toxicity study given that PL is always intraperitoneally administered in combination with PG and that the dose is adequate.

Bioabsorbable fixation devices in trauma and bone surgery: current clinical standing

Bioabsorbable fixation devices are increasingly used in trauma, orthopedic and craniomaxillofacial surgery. The devices are essentially made of polylactic acid and/or polyglycolic acid polymers. Ultra-high-strength implants are manufactured from such polymers using self-reinforcing techniques. Implants are available for stabilization of fractures, osteotomies, bone grafts and fusions, as well as for reattachment of ligaments, tendons, meniscal tears and other soft tissue structures. As these implants are completely absorbed, the need for a removal operation is overcome and long-term interference with tendons, nerves and the growing skeleton is avoided. The risk of implant-associated stress shielding, peri-implant osteoporosis and infections is reduced. Implants do not interfere with clinical imaging. Current clinical use of bioabsorbable devices is reviewed.

Engineering polymeric microparticles as theranostic carriers for selective delivery and cancer therapy

Multifunctional polymeric nano- and microparticles are engineered as theranostic carriers and their selective size-dependent cellular uptake is demonstrated. It is found that effective uptake and accumulation of nanoparticles occurs in both normal and cancer cells, whereas, that of microparticles occurs in cancer cells but not in normal cells, allowing cancer cells to be specifically targeted for local drug delivery.

The comparison of different daidzein-PLGA nanoparticles in increasing its oral bioavailability

The aim of this research was to increase the oral bioavailability of daidzein by the formulations of poly(lactic-co-glycolic) acid (PLGA) nanoparticles loaded with daidzein. Amongst the various traditional and novel techniques of preparing daidzein-loaded PLGA nanoparticles, daidzein-loaded phospholipid complexes PLGA nanoparticles and daidzein-loaded cyclodextrin inclusion complexes PLGA nanoparticles were selected. The average drug entrapment efficiency, particle size, and zeta potential of daidzein-loaded phospholipid complexes PLGA nanoparticles and daidzein-loaded cyclodextrin inclusion complexes PLGA nanoparticles were 81.9% ± 5%, 309.2 ± 14.0 nm, -32.14 ± 2.53 mV and 83.2% ± 7.2%, 323.2 ± 4.8 nm, -18.73 ± 1.68 mV, respectively. The morphological characterization of nanoparticles was observed with scanning electron microscopy by stereological method and the physicochemical state of nanoparticles was valued by differential scanning calorimetry. The in vitro drug-release profile of both nanoparticle formulations fitted the Weibull dynamic equation. Pharmacokinetic studies demonstrated that after oral administration of daidzein-loaded phospholipid complexes PLGA nanoparticles and daidzein-loaded cyclodextrin inclusion complexes PLGA nanoparticles to rats at a dose of 10 mg/kg, relative bioavailability was enhanced about 5.57- and 8.85-fold, respectively, compared to daidzein suspension as control. These results describe an effective strategy for oral delivery of daidzein-loaded PLGA nanoparticles and might provide a fresh approach to enhancing the bioavailability of drugs with poor lipophilic and poor hydrophilic properties.

Development and evaluation of olanzapine-loaded PLGA nanoparticles for nose-to-brain delivery: in vitro and in vivo studies

Olanzapine (OZ) is a second-generation or atypical antipsychotic which selectively binds to central dopamine D₂ and serotonin (5-HT(2c)) receptors. It has poor bioavailability due to hepatic first-pass metabolism and low permeability into the brain due to efflux by P-glycoproteins. The present investigation aimed to prepare a nanoparticulate drug delivery system of OZ using poly(lactic-co-glycolic acid) (PLGA) for direct nose-to-brain delivery to provide brain targeting and sustained release. PLGA nanoparticles (NP) were prepared by the nanoprecipitation technique and characterized by entrapment efficiency, particle size, zeta potential, modulated temperature differential scanning calorimetry (MTDSC) and X-ray diffraction (XRD) studies. The NP were evaluated for in vitro release, ex vivo diffusion, toxicity and pharmacokinetic studies. The NP were 91.2±5.2 nm in diameter and had entrapment efficiency 68.91±2.31%. MTDSC studies indicated broadening of the drug peak and a shift in the polymer peak, possibly due to physical interaction or H-bonding between the carbonyl groups of PLGA and the NH groups of OZ, and also due to the plasticization effect of OZ on PLGA. XRD studies indicated a decrease in the crystallinity of OZ or amorphization. In vitro drug release showed a biphasic pattern with initial burst release and, later, sustained release (43.26±0.156% after 120 h), following the Fickian diffusion-based release mechanism. Ex vivo diffusion through sheep nasal mucosa showed 13.21±1.59% of drug diffusion in 210 min from NP. Histopathological study of sheep nasal mucosa showed no significant adverse effect of OZ-loaded NP. In vivo pharmacokinetic studies showed 6.35 and 10.86 times higher uptake of intranasally delivered NP than OZ solution delivered through intravenous (IV) and intranasal (IN) route, respectively. These results proved that OZ could be transported directly to the brain after IN delivery of PLGA NP, enhanced drug concentration in the brain and would therefore be effective in improving the treatment of central nervous system disorders.

Biological evaluation of 5-fluorouracil nanoparticles for cancer chemotherapy and its dependence on the carrier, PLGA

Nanoscaled devices have great potential for drug delivery applications due to their small size. In the present study, we report for the first time the preparation and evaluation of antitumor efficacy of 5-fluorouracil (5-FU)-entrapped poly (D, L-lactic-co-glycolic acid) (PLGA) nanoparticles with dependence on the lactide/glycolide combination of PLGA. 5-FU-loaded PLGA nanoparticles with two different monomer combinations, 50-50 and 90-10 were synthesized using a modified double emulsion method, and their biological evaluation was done in glioma (U87MG) and breast adenocarcinoma (MCF7) cell lines. 5-FU-entrapped PLGA 50-50 nanoparticles showed smaller size with a high encapsulation efficiency of 66%, which was equivalent to that of PLGA 90-10 nanoparticles. Physicochemical characterization of nanoparticles using differential scanning calorimetry and X-ray diffraction suggested the presence of 5-FU in molecular dispersion form. In vitro release studies showed the prolonged and sustained release of 5-FU from nanoparticles with both the PLGA combinations, where PLGA 50-50 nanoparticles showed faster release. Nanoparticles with PLGA 50-50 combination exhibited better cytotoxicity than free drug in a dose- and time-dependent manner against both the tumor cell lines. The enhanced efficiency of PLGA 50-50 nanoparticles to induce apoptosis was indicated by acridine orange/ethidium bromide staining. Cell cycle perturbations studied using flow cytometer showed better S-phase arrest by nanoparticles in comparison with free 5-FU. All the results indicate that PLGA 50-50 nanoparticles possess better antitumor efficacy than PLGA 90-10 nanoparticles and free 5-FU. Since, studies have shown that long-term exposure of ailing tissues to moderate drug concentrations is more favorable than regular administration of higher concentration of the drug; our results clearly indicate the potential of 5-FU-loaded PLGA nanoparticles with dependence on carrier combination as controlled release formulation to multiplex the therapeutic effect of cancer chemotherapy.

Penetration and distribution of PLGA nanoparticles in the human skin treated with microneedles

This study was designed to investigate the penetration and the distribution of poly(d,l-lactic-co-glycolic acid) (PLGA) nanoparticles in the human skin treated with microneedles. Fluorescent nanoparticles were prepared to indicate the transdermal transport process of the nanoparticles. Permeation study was performed on Franz-type diffusion cells in vitro. The distribution of nanoparticles was visualized by confocal laser scanning microscopy (CLSM) and quantified by high performance liquid chromatography (HPLC). CLSM images showed that nanoparticles were delivered into the microconduits created by microneedles and permeated into the epidermis and the dermis. The quantitative determination showed that (i) the permeation of nanoparticles into the skin was enhanced by microneedles, but no nanoparticle reached the receptor solution; (ii) much more nanoparticles deposited in the epidermis than those in the dermis; (iii) the permeation was in a particle size-dependent manner; and (iv) the permeation increased with the nanoparticle concentration increasing until a limit value was reached. These results suggested that microneedles could enhance the intradermal delivery of PLGA nanoparticles. The biodegradable nanoparticles would sustain drug release in the skin and supply the skin with drug over a prolonged period. This strategy would prove to be useful for topical drug administration.

Cationic surface modification of PLG nanoparticles offers sustained gene delivery to pulmonary epithelial cells

Biodegradable polymeric nanoparticles are currently being explored as a nonviral gene delivery system; however, many obstacles impede the translation of these nanomaterials. For example, nanoparticles delivered systemically are inherently prone to adsorbing serum proteins and agglomerating as a result of their large surface/volume ratio. What is desired is a simple procedure to prepare nanoparticles that may be delivered locally and exhibit minimal toxicity while improving entry into cells for effectively delivering DNA. The objective of this study was to optimize the formulation of poly(D,L-lactide-co-glycolide) (PLG) nanoparticles for gene delivery performance to a model of the pulmonary epithelium. Using a simple solvent diffusion technique, the chemistry of the particle surface was varied by using different coating materials that adsorb to the particle surface during formation. A variety of cationic coating materials were studied and compared to more conventional surfactants used for PLG nanoparticle fabrication. Nanoparticles (approximately 200 nm) efficiently encapsulated plasmids encoding for luciferase (80-90%) and slowly released the same for 2 weeks. In A549 alveolar lung epithelial cells, high levels of gene expression appeared at day 5 for certain positively charged PLG particles and gene expression was maintained for at least 2 weeks. In contrast, PEI gene expression ended at day 5. PLG particles were also significantly less cytotoxic than PEI suggesting the use of these vehicles for localized, sustained gene delivery to the pulmonary epithelium.

Formulation, characterization and evaluation of curcumin-loaded PLGA nanospheres for cancer therapy

BACKGROUND

Among the potent anticancer agents, curcumin has been found to be very efficacious against many different types of cancer cells. However, the major disadvantage associated with the use of curcumin is its low systemic bioavailability when administered orally due to its poor aqueous solubility. Our present work investigated the efficiency of encapsulation of curcumin in poly (lactic-coglycolic acid) (PLGA) nanospheres using solid/oil/water emulsion solvent evaporation method.

MATERIALS AND METHODS

The nanospheres were formulated and then characterized for percent yield, encapsulation efficiency, surface morphology, particle size, drug distribution studies, drug polymer interaction studies and in vitro drug release profiles.

RESULTS

Our studies showed the successful formation of smooth and spherical curcumin-loaded PLGA nanospheres, with an encapsulation efficiency of 90.88+/-0.14%. The particle size distribution showed a range of 35 nm to 100 nm, with the mean particle size being 45 nm. Evaluation of these curcumin-loaded nanospheres was carried out in prostate cancer cell lines. Results showed robust intracellular uptake of the nanospheres in the cells. Cell viability studies revealed that the curcumin-loaded nanospheres were able to exert a more pronounced effect on the cancer cells as compared to free curcumin.

CONCLUSION

Our studies achieved successful formulation of curcumin loaded PLGA nanospheres, thus indicating that nanoparticle-based formulation of curcumin has high potential as an adjuvant therapy for clinical application in prostate cancer.

Tetraidothyroacetic acid (tetrac) and tetrac nanoparticles inhibit growth of human renal cell carcinoma xenografts

Renal cell carcinoma is the most lethal of the common urologic malignancies, with no available effective therapeutics. Tetrac (tetraiodothyroacetic acid) is a deaminated analogue of L-thyroxine (T(4)) that blocks the pro-angiogenesis actions of T(4) and 3, 5, 3'-triiodo-L-thyronine as well as other growth factors at the cell surface receptor for thyroid hormone on integrin alphavbeta3. Since this integrin is expressed on cancer cells and also on endothelial and vascular smooth cells, the possibility exists that Tetrac may act on both cell types to block the proliferative effects of thyroid hormone on tumor growth and tumor-related angiogenesis. To test this hypothesis, we determined the effect of Tetrac on tumor cell proliferation and on related angiogenesis of human renal cell carcinoma (RCC). We used two models: tumor cell implants in the chick chorioallantoic membrane (CAM) system and xenografts in nude mice. To determine the relative contribution of the nuclear versus the plasma membrane action of Tetrac, we compared the effects of unmodified Tetrac to Tetrac covalently linked to poly (lactide-co-glycolide) as a nanoparticle (Tetrac NP) that acts exclusively at the cell surface through the integrin receptor. In the CAM model, Tetrac and Tetrac NP (both at 1 microg/CAM) arrested tumor-related angiogenesis and tumor growth. In the mouse xenograft model, Tetrac and Tetrac NP promptly reduced tumor volume (p<0.01) when administered daily for up to 20 days. Animal weight gain was comparable in the control and treatment groups. Overall, the findings presented here provide evidence for the anti-angiogenic, and anti-tumor actions of Tetrac and Tetrac NP and suggest their potential utility in the treatment of renal cell carcinoma.

An innovative, quick and convenient labeling method for the investigation of pharmacological behavior and the metabolism of poly(DL-lactide-co-glycolide) nanospheres

Nanoparticles of poly(DL-lactide-co-glycolide) (PLGA) in the size range 90-150 nm were produced using the physicochemical method with solvent/non-solvent systems. The encapsulation of the ascorbic acid in the polymer matrix was performed by homogenization of the water and organic phases. In vitro degradation and release tests of PLGA nanoparticles with and without encapsulated ascorbic acid were studied for more than 60 days in PBS and it has been determined that PLGA completely degrades within this period, fully releasing all encapsulated ascorbic acid. The cytotoxicity of PLGA and PLGA/ascorbic acid 85/15% nanoparticles was examined with human hepatoma cell lines (HepG2 ECACC), in vitro. The obtained results indicate that neither PLGA nanospheres nor PLGA/ascorbic acid 85/15% nanoparticles significantly affected the viability of the HepG2 cells. The investigation of the distribution and pharmacokinetics of PLGA is crucial for the effective prediction of host responses to PLGA in particular applications. Thus we present a method of labeling PLGA nanospheres and PLGA/ascorbic acid 85/15 wt% nanoparticles by (99m)Tc which binds outside, leaving the cage intact. This enables a quick and convenient investigation of the pharmacological behavior and metabolism of PLGA. The biodistribution of (99m)Tc-labeled PLGA particles with and without encapsulated ascorbic acid after different periods of time of their installation into rats was examined. PLGA nanospheres with encapsulated ascorbic acid exhibit prolonged blood circulation accompanied by time-dependent reduction in the lungs, liver and spleen, and addition in the kidney, stomach and intestine. The samples were characterized by x-ray diffraction, scanning electron microscopy, stereological analysis, transmission electron microscopy, ultraviolet spectroscopy and instant thin layer chromatography.

Feasibility of biodegradable PLGA common bile duct stents: an in vitro and in vivo study

The current study investigates the feasibility of using a biodegradable polymeric stent in common bile duct (CBD) repair and reconstruction. Here, poly(L-lactide-co-glycolide) (PLGA, molar ratio LA/GA = 80/20) was processed into a circular tube- and dumbbell-shaped specimens to determine the in vitro degradation behavior in bile. The morphology, weight loss, and molecular weight changes were then investigated in conjunction with evaluations of the mechanical properties of the specimen. Circular tube-shaped PLGA stents with X-ray opacity were subsequently used in common bile duct exploration (CBDE) and primary suturing in canine models. Next, X-ray images of CBD stents in vivo were compared and levels of serum liver enzymes and a histological analysis were conducted after stent transplantation. The results showed that the PLGA stents exhibited the required biomedical properties and spontaneously disappeared from CBDs in 4-5 weeks. The degradation period and function match the requirements in repair and reconstruction of CBDs to support the duct, guide bile drainage, and reduce T-tube-related complications.

Influence of the vehicle on the properties and efficacy of microparticles containing amphotericin B

New microparticles containing amphotericin B (AMB) have been developed and manufactured by spray drying. To this end albumin, polylactic-co-glycolic acids (PLGA) and poly(sebacic anhydride) have been employed as drug carriers. The selection of the solvent used to disperse the drug and the vehicle before spray drying was critical on production yields and physical properties of the microparticles. Once particle size, morphology and dispersability in some aqueous media were shown to be acceptable for an intravenous administration, in vivo efficacy was evaluated and compared with the reference medicine Fungizone. Microparticles prepared with albumin, albumin heated at a high temperature, some kinds of PLGA or polyanhydride, as well as Fungizone, were tested in an experimental hamster model of infection with Leishmania infantum, by evaluating the evolution of parasitic burdens in spleen, liver and antibody responses. After the injection of three doses corresponding to 2 mg of AMB per kilogram each, diverse reactions were reported depending on the vehicle. The best dispersability, reduction of parasites and antibody response were achieved when the treatment was performed with AMB in albumin microspheres.

Body distribution of poly(D,L-lactide-co-glycolide) copolymer degradation products in rats

Poly (D,L-lactide-co-glycolide) (PLGA) copolymers are among the few synthetic polymers approved for human use, but the biocompatibility of PLGA-derived oligomers and particles remains questionable. Here, high molecular weight PLGA (Mw=32,000) was radiolabeled with (125)I in chloroform solution, and the body distribution of PLGA copolymer degradation products was examined following subcutaneous implantation of round (125)I-PLGA films on the back of Sprague Dawley rats. Autoradiographic images of the PLGA implant taken at 2, 4, 6, 8, 10, and 12 weeks revealed that the central portion of the film degraded much more rapidly than the marginal portions. Examination of the body compartment distribution at these time points revealed that over one-half of the radioactivity was recovered from skin. The remaining radioactivity was concentrated in the blood, liver, and kidneys. Radioactivity steadily appeared in the blood and remained elevated up to 12 weeks after implantation, while the liver to kidney distribution began to decrease after 6 weeks. Cumulatively, these results indicate that the clearance of degraded particles and fragments from the implantation site is extremely delayed. Moreover, the degraded particles and fragments were selectively concentrated in the liver and kidneys, following release of degraded products into the bloodstream from the implantation site.

PLGA nanoparticles of different surface properties: Preparation and evaluation of their body distribution

The opsonization or removal of nanoparticulate drug carriers from the body by the reticuloendothelial system (RES) is a major obstacle that hinders the efficiency of the nanoparticulate drug delivery systems. Therefore, several methods of camouflaging or masking nanoparticles (NPs) have been developed to increase their blood circulation half-life. In this study, rhodamine B isothiocyanate (RBITC) loaded NPs were fabricated by an emulsification/solvent diffusion method. The surface of NPs was then modified using either poly ethylene glycol (PEG) or block copolymer of ethylene oxide and propylene oxide, Poloxamer 407 (POL). The surface treatment was carried out using two different methods: (a) co-incorporation of the surface modifying agents (SMAs) into NPs and (b) the external surface adsorptions method and both of these methods were done only by physical incorporation of the SMAs into the NPs, without the need of special chemical reagents. The biodistribution properties of the NPs were then measured. The results confirmed that the surface treatment of the NPs using co-incorporation of the SMAs into NPs is more efficient in increasing the blood circulation half-life of the NPs when compared with the external surface adsorptions method.

Distribution of PLGA nanoparticles in chinchilla cochleae

OBJECTIVES

To study the distribution of polylactic/glycolic acid-encapsulated iron oxide nanoparticles (PLGA-NPs) in chinchilla cochleae after application on the round window membrane (RWM).

STUDY DESIGN AND SETTING

Six chinchillas (12 ears) were equally divided into controls (no treatments) and experimentals (PLGA-NP with or without magnetic exposure). After 40 minutes of PLGA-NP placement on the RWM, perilymph was withdrawn from the scala tympani. The RWM and cochleae were fixed with 2.5% glutaraldehyde and processed for transmission electron microscopy.

RESULTS

Nanoparticles were found in cochleae with or without exposure to magnet forces appearing in the RWM, perilymph, endolymph, and multiple locations in the organ of Corti. Electron energy loss spectroscopy confirmed iron elements in nanoparticles.

CONCLUSION

The nanoparticles were distributed throughout the inner ear after application on the chinchilla RWM, with and without magnetic forces.

SIGNIFICANCE

PLGA-NP applied to the RWM may have potential for sustained therapy to the inner ear.

Lectin-conjugated PLGA nanoparticles loaded with thymopentin: Ex vivo bioadhesion and in vivo biodistribution

The conjugation of lectins onto PLGA nanoparticles has been demonstrated to effectively improve the intestinal absorption of thymopentin. In this study, thymopentin-loaded nanoparticles made from fluorescein isothiocyanate labeled PLGA were modified with wheat germ agglutinin (WGA). The specific bioadhesion of nanoparticles on rat intestinal mucosa was studied ex vivo. An important increase of interaction between WGA-conjugated nanoparticles and the intestinal segments was observed compared with that of the unconjugated one (p<0.05). Fluorescence photomicrographs confirmed the bioadhesion of WGA-conjugated nanoparticles on intestinal villous epithelium as well as Peyer's patches. Biodistribution of nanoparticles was evaluated using tissues obtained from rats, to which nanoparticles were orally administered. The highest amount of WGA-conjugated nanoparticles was detected in small intestine, suggesting an increase of intestinal bioadhesion and endocytosis. The systemic uptake was as high as 6.48-13.4% of dose at 1 day and 7.32-15.26% at 7 days, which representing an increase of almost 1.4-3.1 fold across the intestine compared to <4.9% of the unconjugated one. The enhanced uptake was related to the increasing of WGA density on nanoparticles. These results further revealed the promising potential of lectin-conjugated nanoparticles on the improvement of intestinal bioadhesion and absorption for oral drug delivery.

Targeting the central nervous system: In vivo experiments with peptide-derivatized nanoparticles loaded with Loperamide and Rhodamine-123

Polymeric nanoparticles (Np) represent one of the most innovative non-invasive approaches for the drug delivery to the central nervous system (CNS). It is known that the ability of the Np to cross the Blood Brain Barrier (BBB), thus allowing the drugs to exert their pharmacological activity in the central nervous district, is linked to their surface characteristics. Recently it was shown that the biocompatible polyester poly(d,l-lactide-co-glycolide) (PLGA) derivatized with the peptide H(2)N-Gly-l-Phe-d-Thr-Gly-l-Phe-l-Leu-l-Ser(O-beta-d-Glucose)-CONH(2) [g7] was a useful starting material for the preparation of Np (g7-Np); moreover, fluorescent studies showed that these Np were able to cross the BBB. In this research, g-7 Np were loaded with Loperamide in order to assess their ability as drug carriers for CNS, and with Rhodamine-123, in order to qualitatively determine their biodistribution in different brain macro-areas. A pharmacological evidence is given that g7-Np are able to cross the BBB, ensuring, for the first time, a sustained release of the embedded drug, and that these Np are able to reach all the brain areas here examined. The ability to enter the CNS appears to be linked to the sequence of the peptidic moiety present on their surface.

An investigation into the influence of drug lipophilicity on the in vivo absorption profiles from subcutaneous microspheres and in situ forming depots

Drug lipophilicity is known to have a major influence on in vivo drug absorption from intramuscularly and subcutaneously administered solutions. Indeed, chemical modification to increase drug lipophilicity is used to enable sustained drug release from solutions. In contrast to the wealth of knowledge on drug release from simple solutions, the influence of drug lipophilicity on its release from controlled release formulations, such as, microparticles and in situ forming depots, have not been systematically studied. Controlled release vehicles are designed to 'control' drug release, hence, in vitro studies show negligible influence of drug lipophilicity on release. The situation could however be different in vivo, due to interactions between the vehicle and biological tissue. We therefore investigated the influence of drug lipophilicity on its in vivo release in rats from two controlled release formulations, PLGA microparticles and in situ forming depots. Both systems exhibited a burst drug release. Subsequent to the burst release, we found that lipophilicity did not influence the rate or extent of drug absorption from the two formulations over a 10-day study period, which would imply that drug partitioning out of the depots was not the main mechanism of drug release from both formulations. This study must however be repeated with a greater number of animals to increase its power.

Poly(vinyl alcohol)-graft-poly(lactide-co-glycolide) nanoparticles for local delivery of paclitaxel for restenosis treatment

Catheter-based local delivery of biodegradable nanoparticles (NP) with sustained release characteristics represents a therapeutic approach to reduce restenosis. Paclitaxel-loaded NP consisting of poly(vinyl alcohol)-graft-poly(lactide-co-glycolide) (PVA-g-PLGA) with varying PLGA chain length as well as poly(lactide-co-glycolide) (PLGA), were prepared by a solvent evaporation technique. NP of <180 nm in diameter characterized by photon correlation spectroscopy (PCS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) are spherical and show smooth surfaces. Yields typically range from 80 to 95% with encapsulation efficiencies between 77 and 87%. The extent of initial in vitro paclitaxel release was affected by the PVA-g-PLGA composition. Blank nanoparticles from PVA(300)-g-PLGA(30) and PVA(300)-g-PLGA(15) showed excellent biocompatibility in rabbit vascular smooth muscle cells (RbVSMC) at polymer concentrations of 0.37 mg/ml. Paclitaxel-loaded NP have an increased antiproliferative effect on cells in comparison to free drug. Confocal laser scanning microscopy of RbVSMC confirmed cellular uptake of nanoparticles composed of fluorescently labeled PVA(300)-g-PLGA(15) loaded with Oregon Green labeled paclitaxel. Cells showed a clearly increased fluorescence activity with a co-localization of paclitaxel and polymer nanoparticles during incubation with particle suspension. To evaluate the antirestenotic effect in vivo, paclitaxel-loaded nanoparticles were administered locally to the wall of balloon-injured rabbit iliac arteries using a porous balloon catheter. As a result a 50% reduction in neointimal area in vessel segments treated with paclitaxel-loaded nanoparticles compared to control vessel segments could be observed (local paclitaxel nanoparticle treated segments 0.80+/-0.19 mm(2), control segments 1.58+/-0.6 mm(2); p<0.05).

Estradiol loaded PLGA nanoparticles for oral administration: Effect of polymer molecular weight and copolymer composition on release behavior in vitro and in vivo

The present investigation was aimed at optimization of estradiol loaded PLGA nanoparticulate formulations resulting in improved oral bioavailability and sustained release of estradiol by varying the molecular weight and copolymer composition of PLGA. Nanoparticles were prepared following emulsion-diffusion-evaporation method employing didodecyldimethyl ammonium bromide (DMAB) as stabilizer. The effect of polymer molecular weight and copolymer composition on particle properties and release behavior (in vitro and in vivo) has been reported. Drug release in vitro decreased with increase in molecular weight and lactide content of PLGA. Zero order release was obtained with low molecular weight (14,500 and 45,000 Da) PLGA, while high molecular weight (85,000 and 213,000 Da) and different copolymer compositions followed square root of time (Higuchi's pattern) dependent release. The bioavailability of estradiol from nanoparticles was assessed in male Sprague Dawley (SD) rats at a dose of 1 mg estradiol/rat. The in vivo performance of the nanoparticles was found to be dependent on the particle size, polymer molecular weight and copolymer composition. The C(max) of drug in the plasma was dependent on the polymer molecular weight and composition while particle size was found to influence the duration of release, suggesting smaller is better. The histopathological examination revealed absence of any inflammatory response with the formulations prepared of low/high molecular weight or high lactide content polymers for the studied period. Together, these results indicate that nanoparticulate formulations are ideal carriers for oral administration of estradiol having great potential to address the dose related issues of estradiol.

Development and evaluation of novel biodegradable microspheres based on poly(d,l-lactide-co-glycolide) and poly(ε-caprolactone) for controlled delivery of doxycycline in the treatment of human periodontal pocket: In vitro and in vivo studies

This study reports on the development of novel biodegradable microspheres prepared by water-in-oil-water (W/O/W) double emulsion technique using the blends of poly(d,l-lactide-co-glycolide) (PLGA) and poly(epsilon-caprolactone) (PCL) in different ratios for the controlled delivery of doxycycline (DXY). Doxycycline encapsulation of up to 24% was achieved within the polymeric microspheres. Blend placebo microspheres, drug-loaded microspheres and pristine DXY were analyzed by Fourier transform infrared spectroscopy (FT-IR), which indicated no interaction between drug and polymers. Differential scanning calorimetry (DSC) on drug-loaded microspheres confirmed the polymorphism of DXY and indicated a molecular level dispersion of DXY in the microspheres. Scanning electron microscopy (SEM) confirmed the spherical nature and smooth surfaces of the microspheres produced. Mean particle size of the microspheres as measured by dynamic laser light scattering method ranged between 90 and 200 mum. In vitro release studies performed in 7.4 pH media indicated the release of DXY from 7 to 11 days, depending upon the blend ratio of the matrix. Up to 11 days, DXY concentrations in the gingival crevicular fluid were higher than the minimum inhibitory concentration of DXY against most of the periodontal pathogens. One of the developed formulations was subjected to in vivo efficacy studies in thirty sites of human periodontal pockets. Significant results were obtained with respect to both microbiological and clinical parameters up to 3 months even as compared to commercial DXY gel. Statistical analyses of the release data and in vivo results were performed using the analysis of variance (ANOVA) method.

Optimum conditions for efficient phagocytosis of rifampicin-loaded PLGA microspheres by alveolar macrophages

We examined the phagocytic activities of alveolar macrophages (NR8383 cells) toward poly(lactic-co-glycolic) acid (PLGA) microspheres (MS) loaded with the anti-tuberculosis agent rifampicin (RFP), the sizes of which were between 1 microm and 10 microm. We found that 1) the phagocytosis was dependent greatly on the particle size and the number of particles added; 2) macrophages phagocytosed considerably the PLGA microspheres loaded with RFP, the diameter of which was between 1 microm and 6 microm, but took up few 10-microm particles; 3) the population of the macrophages that phagocytosed 1-microm or 3-microm particles was larger than that of those phagocytosed 6- or 10-microm particles; 4) a considerable population of macrophages were not able to phagocytose even the 1- and 3-microm particles; 5) the most efficient deliveries of RFP into each macrophage cell and a large population of macrophages were achieved by the phagocytosis of 3-microm particles; and 6) phagocytosis did not affect macrophage viability in 4 h after the start of phagocytosis.

Synthesis and characterization of highly-magnetic biodegradable poly(d,l-lactide-co-glycolide) nanospheres

The objective of this study was to develop high magnetization, biodegradable/biocompatible polymer-coated magnetic nanospheres for biomedical applications. Magnetic spheres were prepared by a modified single oil-in-water emulsion-solvent evaporation method utilizing highly-concentrated hydrophobic magnetite and poly(d,l lactide-co-glycolide) (PLGA). Hydrophobic magnetite prepared using oleic acid exhibited high magnetite concentrations (84 wt.%) and good miscibility with biopolymer solvents to form a stable oily suspension. The oily suspension was then emulsified within an aqueous solution containing poly(vinyl alcohol). After rapid evaporation of the organic solvent, we obtained solid magnetic nanospheres. We characterized these spheres in terms of external morphology, microstructure, size and zeta potential, magnetite content and distribution within the nanospheres, and magnetic properties. The results showed good encapsulation where the magnetite distorted the smooth surface morphology only at the highest magnetite concentrations. The mean diameter was 360-370 nm with polydispersity indices of 0.12-0.20. We obtained high magnetite content (40-60%) and high magnetization (26-40 emu/g). The high magnetization properties were obtained while leaving sufficient polymer to retain drugs making these biodegradable spheres suitable as a potential platform for the design of magnetically-guided drug delivery and other in vivo biomagnetic applications.

[Pharmacodynamics of China-made rapamycin-polylactide-co-glycolide peripheral arterial eluting stent membrane: in vitro experiment]

OBJECTIVE

To evaluate the property and drug releasing pattern of the China-made rapamycin-polylactide-co-glycolide (PLGA) peripheral arterial eluting stent membrane.

METHODS

Rapamycin was put into PLGA so as to made rapamycin-PLGA complex. Twelve nickel-titanium self-expanding stents were dipped into the complex to make drug-eluting stents. Somatotype microscope was used to observe the macro-form of the surface of the eluting membrane, and atom force microscope was used to analyzing the three-dimensional appearance and surface roughness of the membrane. The stents were put into fluid with platelets to observe the form of platelets blood compatibility by scanning electron microscopy. The extra degradation of the coating layer, by putting the stents into a simulation system of internal environment. High efficacy liquid chromatography was used to study the pharmacokinetics of the stents. Standard curve and stimulative curve, and drug release curve of multiple stents were drawn and analyzed.

RESULTS

The membranes of all 12 stents had smooth surfaces and regular thickness and no membrane falling-off was observed. The platelets on the surfaces of the stents were inactivated and the number of the platelets adhering to the surfaces of the stents were reduced obviously in comparison with the blank control. PLGA degraded by 20% within 2 weeks and then the degradation speed accelerated until complete degradation occurred within 6 weeks, and the drug releasing lasted more than 50 days. The percentage of accumulative drug release was 11.02% in 24 hours, 41.23% in 9 days, and 79.44% in 30 days.

CONCLUSION

Smooth and even, and capable of controlling the drug release, rapamycin-PLGA peripheral arterial eluting stent membrane coating has the potential clinical value in preventing in-stent stenosis.

PLGA nanoparticles for oral delivery of cyclosporine: nephrotoxicity and pharmacokinetic studies in comparison to Sandimmune Neoral

The cyclosporine-loaded poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) were prepared by the emulsion-diffusion-evaporation method and were optimized for particle size and entrapment efficiency. The optimized particles were 143.3+/-8.7 nm in size with narrow size distribution and 71.9+/-1.7% entrapment efficiency at 20% w/w initial drug loading when prepared with 0.1% w/v of Didodecylmethylammonium bromide (DMAB) as stabilizer. These particulate carriers exhibited controlled in vitro release of cyclosporine for 23 days at a nearly constant rate and showed very good hemocompatibility in vitro. The nanoparticulate formulation showed significantly higher intestinal uptake as compared to Sandimmune Neoral and cyclosporine suspension. The relative bioavailability of nanoparticulate formulation was found to be 119.2% as compared to Sandimmune Neoral. A marked difference in the pharmacokinetic profile between nanoparticulate and Sandimmune Neoral formulations was observed where nanoparticulate formulation showed controlled release of cyclosporine over 5 days, on the other hand, the marketed formulation showed a sharp Cmax with a 3-day release profile. The nanoparticulate formulation exerted significantly lower nephrotoxicity in the rats as compared to Sandimmune Neoral, which was evidenced by lower blood urea nitrogen (BUN), plasma creatinine (PC) and malondialdehyde (MDA) levels in plasma and kidney. The results were further supported by the histopathological changes in kidneys. Together, these results indicate that PLGA NPs have greater potential for oral delivery of cyclosporine.

The preservation of phenotype and functionality of dendritic cells upon phagocytosis of polyelectrolyte-coated PLGA microparticles

Biodegradable microparticles (MP) represent a promising and efficient delivery system for parenteral vaccination. Recently, MP have also been explored as tool for the ex vivo antigen loading of professional antigen-presenting cells such as dendritic cells (DC) to be used as cellular vaccines. The purpose of this study was to investigate various polycationic coatings on poly(lactide-co-glycolide) (PLGA) MP, with regard to their effect on phenotypic and functional maturation of monocyte-derived DC (MoDC) that had previously been loaded with the MP in vitro. The preparation and concomitant coating of the PLGA was performed by means of a solvent extraction/evaporation method using a recently developed microextrusion-based technique. The polyelectrolytes tested for MP coating encompassed aminodextran, chitosan, poly(ethylene imine) (PEI), poly(L-lysine) and protamine. Uncoated and differently coated PLGA MP were fed to immature MoDC, which ingested efficiently the different MP types irrespective of their surface coating. The MP-loaded immature MoDC were then matured with the help of a cytokine/PGE-2 maturation cocktail. Here, the presence of the ingested MP did not affect the MoDC maturation in terms of expression of the surface markers CD80, CD83, CD86, HLA-DR and MMR, irrespective of the MP surface coating. Importantly, none of the PLGA MP types alone induced significant maturation of MoDC in the absence of the maturation cocktail. MP-loaded and subsequently matured MoDC expressed high levels of the chemokine receptor CCR7, whose functional activity was evidenced by the migration of MoDC towards CCL21, irrespective of the presence of ingested MP. Further, MP-loaded and subsequently matured MoDC also secreted comparable amounts of IL-10 and IL-12p70, irrespective of the presence of ingested MP except for PEI-coated PLGA MP, which enhanced significantly the secretion of IL-12p70 in mature MoDC. In conclusion, phenotypic and functional maturation of MoDC by means of a maturation cocktail remained unchanged irrespective of the presence of previously ingested differently coated PLGA MP. This offers interesting perspectives for using these particulate systems together with entrapped antigens for ex vivo loading of MoDC in view of cellular immunotherapy.

Release of diclofenac sodium from polylactide-co-glycolide 80/20 rods

Due to inflammatory reactions complicating bioabsorbable devices, the aim of this study was to develop and characterize bioabsorbable implants with anti-inflammatory drug releasing properties. Polylactide-co- glycolide (PLGA) 80/20 was compounded with diclofenac sodium (DS) to produce rods. Thermal properties were analyzed using differential scanning calorimetry (DSC). Inherent viscosity (eta(inh)) was measured to evaluate the drug effect on the extrude polymer. Drug release measurements were performed using UV-spectrophotometer. Five parallel samples from each type of rods were examined, first at 6 hour intervals, then on daily basis, and later twice a week. DS was released in 110 days from thinner rods and in 150 days from thicker rods. Drug release comprised a starting peak, slow release phase, then a high release phase, and a burst release phase. DSC analysis showed that DS containing rods had crystallinity in their structure. In conclusions, it is feasible to combine PLGA 80/20 and DS by using melt extrusion. Released DS concentrations reached local therapeutic levels, but the release profile was complex and therapeutic levels were not reached all the time.

Innovation in multifunctional bioabsorbable osteoconductive drug-releasing hard tissue fixation devices

We review in this paper the work performed by our group to develop multifunctional bioabsorbable ciprofloxacin releasing bone implants. Poly lactide-co-glycolide (PLGA 80/20 and polylactide (P(L/DL)LA 70/30) were used. Ciprofloxacin (CF) and bioactive glass (BaG) 13-93 were added. The mixture was then extruded and self-reinforced. CF release, mechanical strength, and the effect on S. epidermidis attachment and biofilm formation were evaluated. In rabbits, tissue reactions were assessed. Pull out strength was evaluated in cadaver bones. CF was released over 44 weeks (P(L/DL)LA) and 23-26 weeks (PLGA). Initial shear strength of the CF screws was 152 MPa (P(L/DL)LA) and 172 MPa (PLGA). Strength was retained for 12 weeks (P(L/DL)LA) and 9 weeks (PLGA). Histologically, CF releasing implants did not show much difference from control plain PLGA screws except for increased giant cells. CF miniscrews had lower pullout strength than the controls, but CF tacks had better values than controls. BaG led to a drop in pullout strength properties. Bacterial growth, attachment and biofilm formation on CF implants was significantly reduced when compared to controls. Accordingly, bioabsorbable multifunctional implants with appropriate CF release, mechanical, and biocompatibility properties are possible to develop and are considered appropriate to apply clinically.

Cyclosporine-loaded microspheres for treatment of uveitis: in vitro characterization and in vivo pharmacokinetic study

PURPOSE

A sustained intraocular level of immunosuppressive drug is desirable for the treatment of uveitis and other intraocular immune disorders. The objective of the present investigation was to assess the suitability of cyclosporine-loaded poly(lactic-co-glycolic acid) microspheres (CyS-PLGA-MS) to achieve this goal.

METHODS

A solvent-evaporation method was used in the preparation of CyS-PLGA-MS. These microspheres were characterized for drug loading, entrapment efficiency, and in vitro release by high-performance liquid chromatography, particle size by phase-contrast light microscopy and surface morphology by scanning electron microscopy. The 3H-CyS-PLGA-MS suspension was injected into the vitreous body of healthy rabbits, and the concentration of cyclosporine in various ocular tissues and blood at predetermined intervals was measured by a scintillation counting technique and the pharmacokinetic parameters were calculated. Intravitreous administration of 3H-CyS solution was conducted as the control.

RESULTS

The CyS-PLGA-MS was produced, with drug-loading ranging from 11% to 16% and a high entrapment efficiency from 86% to 98%. Microspheres were discrete, spherical particles with a diameter of approximately 50 microm. The CyS was constantly and slowly released from microspheres in the in vitro release experiment. Compared with CyS solution, microspheres prolonged the release of CyS and maintained therapeutic CyS concentrations for at least 65 days in disease-related tissues such as the choroid-retina and iris-ciliary body. The percentage of CyS released in vitro correlated well with the CyS distribution rate in vivo.

CONCLUSIONS

CyS-PLGA-MS, displaying sustained intraocular release of CyS and showing advantages over CyS solution, may meet clinical needs more efficiently.

Controlled release of huperzine A from biodegradable microspheres: In vitro and in vivo studies

The objective of the present work was to further study the in vitro characteristics, in vivo pharmacokinetics and pharmacodynamics of huperzine A (HupA) loaded biodegradable microspheres designed for sustained release of HupA over several weeks. A conventional o/w emulsion-solvent evaporation method was used to incorporate HupA, which is of interest in the palliative treatment of Alzheimer's disease (AD), into end-group uncapped poly(D,L-lactide-co-glycolide) (PLG-H). A prolonged in vitro drug release profile was observed, with a complete release of the incorporated drug within 5-6 weeks. The in vivo pharmacokinetics study of HupA loaded microspheres showed sustained plasma HupA concentration-time profile after subcutaneous injection into rats. The pharmacodynamics evaluated by determination of the activity of acetylcholinesterase in the rat cortex also showed a prolonged pharmacological response. Both the in vitro release and in vivo pharmacological responses correlated well with the in vivo pharmacokinetics profile. The results suggest the potential use of HupA-loaded biodegradable microspheres for treatment of AD over long periods.

Tissue response to polyglycolide, polydioxanone, polylevolactide, and metallic pins in cancellous bone: An experimental study on rabbits

The purpose of this study was to investigate, qualitatively and histoquantitatively, the tissue response of rabbit femur cancellous bone to polyglycolide (PGA), polydioxanone (PDS), polylevolactide (PLLA), and stainless steel pins under identical conditions. Eighty knees in 50 rabbits were operated on by inserting bioabsorbable pins (PGA, PDS, or PLLA) together with metallic Kirschner wire in 60, and two metallic Kirschner wires alone in 20 knees, while 20 knees served as intact controls. Follow-up times were 3, 6, 12, 24, and 52 weeks. Cancellous bone tissue response to implants was studied using histological, histomorphometrical, microradiographical, and oxytetracycline fluorescence methods. Residual fragments of PGA and PDS were seen at 24 weeks. Complete degradation of these polymers had taken place before 52 weeks. No signs of degradation of the PLLA pins were observed within the entire follow-up period. The osteoid formation surfaces at tissue implant-interface were statistically larger in all test groups as compared to intact controls. The number of macrophages at tissue implant-interfaces increased in all bioabsorbable implant specimens until 6 weeks, and with PGA until 12 weeks. No differences in the osseous response emerged when comparing groups of bioabsorbable implants with each other or with stainless steel group. Bioabsorbable pins and metallic Kirschner wires evoked an osteoconductive response in the cancellous bone surrounding implant, but the response intensity between implants displayed no differences. This suggests a simple, nonspecific walling-off new-bone front type of response. Consequently, the polymers possessed no specific osteostimulatory or osteoinhibitory properties. Within the follow-up, no significant differences in biocompatibility between the implants appeared, and no frank inflammatory foreign-body reactions occurred. The small-volume pins obviously did not exceed the local tissue tolerance and clearing capacity of the bone.

Influence of Nanoencapsulation on Human Skin Transport of Flufenamic Acid

The effect of the inclusion of flufenamic acid in poly(lactide-co-glycolide) nanoparticles on the transport of flufenamic acid into excised human skin was investigated. Penetration and permeation data were acquired using two different in vitro test systems: the Saarbrucken penetration model, where the skin acts as its own receptor medium, and the Franz diffusion cell, where the receptor medium is a buffer solution. For the stratum corneum, no differences were found between nanoencapsulated and free drug. Drug accumulation in the deeper skin layers and drug transport across human epidermis were slightly delayed for the nanoencapsulated drug compared to the free drug after shorter incubation times (<12 h). In contrast, after longer incubation times (>12 h), the nanoencapsulated drug showed a statistically significantly enhanced transport and accumulation (p < 0.05). Additionally, nanoencapsulated flufenamic acid was visualized by multiphoton fluorescence microscopy. Particles were found homogeneously distributed on the skin surface and within the dermatoglyphs, but no nanoparticles were detected within or between the corneocytes.

Preparation of DHAQ-loaded mPEG-PLGA-mPEG nanoparticles and evaluation of drug release behaviors in vitro/in vivo

This study describes the preparation and the evaluation of biodegradation monomethoxy (polyethylene glycol)-poly (lactide-co-glycolide)-monomethoxy (polyethyleneglycol) (mPEG-PLGA-mPEG, PELGE) nanoparticles (PELGE-NP) containing mitoxantrone (DHAQ) as a model drug. PELGE copolymers with various molar ratios of lactic to glycolic acid and different molecular weights and various content mPEG were synthesized by ring-opening polymerization. mPEG with weight-average molecular weight (Mw) 2,000 or 5,000 was introduced as a hydrophilic segment into a hydrophobic PLGA. A double emulsion method with dextran70 as stabilizer in the external aqueous phase was used to prepare the nanoparticles. The drug entrapment efficiencies were more than 80% and the mean diameters of the nanoparticles were less than 200 nm. Various PELGE was studied as biodegradable drug carriers and there in vitro/in vivo release profiles were examined. It was found that drug loading, polymer molecular weight, copolymer composition and end group modifications were critical factors affecting the in vitro/in vivo release properties. The amount of drug released increased as the mPEG contents increased and the molar ratios of lactic acid decreased in vitro. The intravenous (i.v.) administration of mPEG-PLGA-mPEG nanoparticles of DHAQ in mice resulted in prolonged DHAQ residence in systemic blood circulation compared to the intravenous administration of PLGA nanoparticles.