Poly(lactic-co-glycolic Acid)-polyethylene Glycol Research Articles

Panaxatriol exerts anti-senescence effects and alleviates osteoarthritis and cartilage repair fibrosis by targeting UFL1

IntroductionOsteoarthritis (OA), the most common degenerative joint disease, can eventually lead to disability. However, no safe or effective intervention is currently available. Therefore, there is an urgent need to develop effective drugs that reduce cartilage damage and treat OA. ObjectivesThis study aimed to ascertain the potential of panaxatriol, a natural small molecule, as a therapeutic drug for alleviating the progression of OA. MethodsAn in vitro culture of human cartilage explants and C28/I2 human chondrocytes and an in vivo surgically induced OA mouse model were used to evaluate the chondroprotective effect of panaxatriol. The Drug Affinity Responsive Target Stability assay, CRISPR-Cas9 assay, Whole-transcriptome RNA sequencing analysis and agonist or antagonist assays were used to identify the target and potential signaling pathways of panaxatriol. Poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG) was used to construct the sustained-release system of panaxatriol. ResultsPanaxatriol protected against OA by regulating chondrocyte metabolism. Ubiquitin-fold modifier 1-specific E3 ligase 1 (UFL1) was identified as a novel target of panaxatriol. Whole transcriptome RNA sequencing showed that UFL1 was closely related to cell senescence. Panaxatriol inhibited chondrocyte senescence through UFL1/forkhead box O1 (FOXO1)/P21 and UFL1/NF-κB/SASPs signaling pathways. It also could inhibit fibrocartilage formation during cartilage repair via the UFL1/FOXO1/Collagen 1 signaling pathway. Finally, we constructed a sustained-release system for panaxatriol based on PLGA-PEG, which reduced the number of intra-articular injections, thereby alleviating joint swelling and injury. ConclusionsPanaxatriol exerts anti-senescence effects and has the potential to delay OA progression and reduce cartilage repair fibrosis by targeting UFL1.

Extension Effect of Poly(Lactic-Co-Glycolic Acid)-Polyethylene Glycol Encapsulated Bupivacaine on Postoperative Neuroblockade in Cardiothoracic Surgery

This research was aimed to evaluate extension effect of poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA/PEG) thermosensitive hydrogel-encapsulated bupivacaine (BUP) on neuroblockade in cardiothoracic surgery and explore the potential adoption of this thermosensitive hydrogel as a drug carrier for postoperative neuroblockade. An animal experimental design was adopted. First, PLGA/PEG thermosensitive hydrogel was prepared and BUP was encapsulated as the drug carrier and evaluated. Then, 40 rats were selected for thoracic surgery and randomly rolled into experimental group (injection of hydrogel in the cardiothoracic region for neuroblockade after cardiothoracic surgery) and control group (conventional BUP injection). The neuroblockade effects (maximum possible effect (MPE), sensory and motor blockade duration) in the two groups of rats were compared and analyzed. The Results showed that gel-microsphere (Gel-MS) composite drug delivery system was successfully prepared, which exhibited a complete 3D porous structure and favorable encapsulation effect for BUP. Rheological testing showed favorable hardness (G′) and viscosity (G″) for Gel-MS/BUP (GMB). The experimental group exhibited a notably prolonged period of 100% MPE with a slower rate of decline versus controls. Sensory blockade and motor blockade durations in the experimental group rats were (22.4±3.8) h and (22.7±3.5) h, respectively, both markedly longer than those in the control group rats (P <0.05). In Conclusion, Gel/MS-BUP demonstrated a remarkable extension effect on neuroblockade in cardiothoracic surgery, indicating its potential adoption value in prolonging anesthesia duration.

A Self-Disguised Nanospy for Improving Drug Delivery Efficiency via Decreasing Drug Protonation.

Nanoscale drug carriers play a crucial role in reducing side effects of chemotherapy drugs. However, the mononuclear phagocyte system (MPS) and the drug protonation after nanoparticles (NPs) burst release still limit the drug delivery efficiency. In this work, a self-disguised Nanospy is designed to overcome this problem. The Nanospy is composed of: i) poly (lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG) loading doxorubicin is the core structure of the Nanospy. ii) CD47 mimic peptides (CD47p) is linked to NPs which conveyed the "don't eat me" signal. iii) 4-(2-aminoethyl) benzenesulfonamide (AEBS) as the inhibitor of Carbonic anhydrase IX (CAIX) linked to NPs. Briefly, when the Nanospy circulates in the bloodstream, CD47p binds to the regulatory protein α (SIRPα) on the surface of macrophages, which causes the Nanospy escapes from phagocytosis. Subsequently, the Nanospy enriches in tumor and the AEBS reverses the acidic microenvironment of tumor. Due to above characteristics, the Nanospy reduces liver macrophage phagocytosis by 25% and increases tumor in situ DOX concentration by 56% compared to PLGA@DOX treatment. In addition, the Nanospy effectively inhibits tumor growth with a 63% volume reduction. This work presents a unique design to evade the capture of MPS and overcomes the influence of acidic tumor microenvironment (TME) on weakly alkaline drugs.

Low intensity ultrasound-mediated drug-loaded nanoparticles intravaginal drug delivery: an effective synergistic therapy scheme for treatment of vulvovaginal candidiasis

PurposeVulvovaginal candidiasis (VVC) is a mucosal infection of the female lower genital tract for which treatment using conventional antifungal drugs shows limited effectiveness. Herein, amphotericin B-loaded poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG) nanoparticles (AmB-NPs) were fabricated and combined with low intensity ultrasound (US) to mediate AmB-NPs intravaginal drug delivery to achieve productive synergistic antifungal activity in a rabbit model of VVC.MethodsPolymeric AmB-NPs were fabricated by a double emulsion method and the physical characteristics and biosafety of nanoparticles were analyzed. The distribution and tissue permeability of nanoparticles after intravaginal ultrasound irradiation (1.0 MHz, 1.0 W/cm2, 5 min, 50% duty ratio) were observed in the vagina. The synergistic therapeutic activity of US-mediated AmB-NPs treatment was evaluated using an experimental rabbit model of VVC. Vaginal C. albicans colony counts, the pathological structure of the vagina epithelium, and Th1/Th2/Th17-type cytokine and oxidative stress levels were analyzed to investigate the therapeutic effect in vivo.ResultsThe prepared AmB-NPs showed an obvious shell and core structure with uniform size and good dispersion and displayed high biosafety and US-sensitive slow drug release. Ultrasound significantly enhanced nanoparticle transport through the mucus and promoted permeability in the vaginal tissue. US-mediated AmB-NPs treatment effectively increased drug sensitivity, even in the presence of the vaginal mucus barrier in vitro. On the seventh day after treatment in vivo, the combination treatment of AmB-NPs and US significantly reduced the fungal load in the vagina, achieving over 95% clearance rates, and also improved the pathological epithelium structural damage and glycogen secretion function. The expression of Th1 (IFN-γ, IL-2) and Th17 (IL-17) cytokines were significantly increased and Th2 (IL-6, IL-10) cytokines significantly decreased in the US + AmB-NP group. Furthermore, US-mediated AmB-NPs treatment effectively increased C. albicans intracellular reactive oxygen species (ROS) levels and promoted vaginal oxidation and antioxidants to normal levels.ConclusionUS-mediated drug-loaded nanoparticles with intravaginal drug delivery exhibited a productive synergistic antifungal effect, which may provide a new non-invasive, safe, and effective therapy for acute or recurrent fungal vaginitis.Graphical

Transplantation of bioengineered Reelin-loaded PLGA/PEG micelles can accelerate neural tissue regeneration in photothrombotic stroke model of mouse.

Ischemic stroke is characterized by extensive neuronal loss, glial scar formation, neural tissue degeneration that leading to profound changes in the extracellular matrix, neuronal circuitry, and long‐lasting functional disabilities. Although transplanted neural stem cells (NSCs) can recover some of the functional deficit after stroke, retrieval is not complete and repair of lost tissue is negligible. Therefore, the current challenge is to use the combination of NSCs with suitably enriched biomaterials to retain these cells within the infarct cavity and accelerate the formation of a de novo tissue. This study aimed to test the regenerative potential of polylactic‐co‐glycolic acid‐polyethylene glycol (PLGA‐PEG) micelle biomaterial enriched with Reelin and embryonic NSCs on photothrombotic stroke model of mice to gain appropriate methods in tissue engineering. For this purpose, two sets of experiments, either in vitro or in vivo models, were performed. In vitro analyses exhibited PLGA‐PEG plus Reelin‐induced proliferation rate (Ki‐67+ NSCs) and neurite outgrowth (axonization and dendritization) compared to PLGA‐PEG + NSCs and Reelin + NSCs groups (p < 0.05). Besides, neural differentiation (Map‐2+ cells) was high in NSCs cultured in the presence of Reelin‐loaded PLGA‐PEG micelles (p < 0.05). Double immunofluorescence staining showed that Reelin‐loaded PLGA‐PEG micelles increased the number of migrating neural progenitor cells (DCX+ cells) and mature neurons (NeuN+ cells) around the lesion site compared to the groups received PLGA‐PEG and Reelin alone after 1 month (p < 0.05). Immunohistochemistry results showed that the PLGA/PEG plus Reelin significantly decreased the astrocytic gliosis and increased local angiogenesis (vWF‐positive cells) relative to the other groups. These changes led to the reduction of cavity size in the Reelin‐loaded PLGA‐PEG+NSCs group. Neurobehavioral tests indicated Reelin‐loaded PLGA‐PEG+NSCs promoted neurological outcome and functional recovery (p < 0.05). These results indicated that Reelin‐loaded PLGA‐PEG is capable of promoting NSCs dynamic growth, neuronal differentiation, and local angiogenesis following ischemic injury via providing a desirable microenvironment. These features can lead to neural tissue regeneration and functional recovery.

Optimising PLGA-PEG Nanoparticle Size and Distribution for Enhanced Drug Targeting to the Inflamed Intestinal Barrier.

Oral nanomedicines are being investigated as an innovative strategy for targeted drug delivery to treat inflammatory bowel diseases. Preclinical studies have shown that nanoparticles (NPs) can preferentially penetrate inflamed intestinal tissues, allowing for targeted drug delivery. NP size is a critical factor affecting their interaction with the inflamed intestinal barrier and this remains poorly defined. In this study we aimed to assess the impact of NP particle size (PS) and polydispersity (PDI) on cell interaction and uptake in an inflamed epithelial cell model. Using 10, 55 and 100 mg/mL poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG), NPs of 131, 312 and 630 nm PS, respectively, were formulated by solvent dispersion. NP recovery was optimised by differential centrifugation to yield NPs of decreased and unimodal size distribution. NP-cell interaction was assessed in healthy and inflamed caco-2 cell monolayers. Results show that NP interaction with caco-2 cells increased with increasing PS and PDI and was significantly enhanced in inflamed cells. Trypan blue quenching revealed that a significant proportion of multimodal NPs were primarily membrane bound, while monomodal NPs were internalized within cells. These results are interesting as the PS and PDI of NPs can be optimised to allow targeting of therapeutic agents to the epithelial membrane and/or intracellular targets in the inflamed intestinal epithelium.

Characterization of liver cancer-targeted doxorubicin coupling segmented copolymer nanomicelles and its inhibitory effect on hepatocellular carcinoma HepG2 and Huh7 cells

Objective To investigate the characterization of doxorubicin (DOX) coupling segmented copolymer nanomicelles with dual effects of passive and active targeting to liver cancer and its antineoplastic function in vitro. Methods DOX was covalently conjugated to a terminal hydroxyl group of poly lactic-co-glycolic acid-poly ethylene glycol (PLGA-PEG) diblock copolymer to form DOX-PLGA-PEG. The formation of amido bond was determined by using fourier transform infrared spectroscopy (FTIR) and magnetic resonance method. Amphiphatic diblock copolymer DOX-PLGA-PEG could self-assemble to form nanomicelles in an aqueous phase by dialysis method. The DOX-PLGA-PEG targeted micelles decorated with liver cancer HAb18 F (ab')2 specific antibody were prepared by using physical bonding method. The size and the scattering scope of nanomicelles was determined by using granulometer and dynamic light scattering (DLS). Micelle morphology was examined by using scanning electron microscopy (SEM). The drug loading rate and entrapment rate of DOX-PLGA-PEG micelles or targeted micelles were measured by using ultraviolet spectrophotometry method, and stimulated release in vitro experiment was done. After administration of 2 mg/ml DOX-PLGA-PEG or targeted micelles, cell morphology change of liver cancer HepG2 and Huh7 was observed by using the phase-contrast photomicrography. After administration of 1 mg/ml DOX-PLGA-PEG or targeted micelles, cell survival was analyzed by using plate clone formation assay. Results The spectrum peak was around 1 575 cm-1 under the observation of FTIR, which was accord with the location of the peak of amido bond. Activating with p-nitrophenyl chloroformate, DOX was covalently conjugated to PLGA-PEG to produce DOX-PLGA-PEG via a carbamate linkage between the primary amine group in DOX and the terminal hydroxyl group in PLGA-PEG. DLS measurements showed that the diameter of DOX-PLGA-PEG micelles and targeted micelles was (55.0±6.3) nm and (87.6±9.3) nm, respectively, and polydispersity index was 0.098 and 0.142, respectively. SEM micrographs revealed that these nanomicelles had a spherical morphology and relatively smooth surface. Drug loading rate of DOX-PLGA-PEG micelles and targeted micelles was (2.4±0.2)% and (2.2±1.9)%, and the entrapment rate was (91.7±5.3)% and (87.5±4.8)%, respectively. The drug release curve in vitro of DOX-PLGA-PEG micelles and targeted micelles exhibited a biphasic pattern characterized by a fast initial release, followed by a slower and continuous release. The amount of the drug release rate was about 30% within 5 d, and 25% within 6 h. After 2 mg/ml DOX-PLGA-PEG micelles and targeted micelles, the cell morphology of liver cancer HepG2 and Huh7 had the impaired change, and the part of the cells were dead, the clonality decreased. The effect of targeted micelles was more significant compared with DOX-PLGA-PEG micelles. After DOX-PLGA-PEG micelles and targeted micelles, the survival rates of HepG2 and Huh7 cells were decreased with time, and the effect of targeted micelles was more effective compared with DOX-PLGA-PEG micelles (all P < 0.05). The 50% effective inhibition of the targeted micelles and DOX-PLGA-PEG micelles was obtained in 2.4 d and 5.5 d, respectively for Huh7 cells. At these time points, DOX concentration was 1.15 μg/ml and 1.24 μg/ml, respectively. The 50% effective inhibition of targeted micelles and DOX-PLGA-PEG micelles was obtained in 3.3 d and 7.4 d, respectively for HepG2 cells. At these time points, DOX concentration was 1.20 μg/ml and 1.31 μg/ml. Conclusion DOX nanomicelles with dual effects of passive and active targeting can release a large number of active drugs in vitro, which plays an obvious inhibitory role in the cell proliferation of liver cancer HepG2 and Huh7 cells. Key words: Liver neoplasms; Doxorubicin; Drug delivery systems; Molecular targeted therapy; Targeted micelles

PPARγ agonist-loaded PLGA-PEG nanocarriers as a potential treatment for Alzheimer's disease: in vitro and in vivo studies.

ObjectiveThe first aim of this study was to develop a nanocarrier that could transport the peroxisome proliferator-activated receptor agonist, pioglitazone (PGZ) across brain endothelium and examine the mechanism of nanoparticle transcytosis. The second aim was to determine whether these nanocarriers could successfully treat a mouse model of Alzheimer’s disease (AD).MethodsPGZ-loaded nanoparticles (PGZ-NPs) were synthesized by the solvent displacement technique, following a factorial design using poly (lactic-co-glycolic acid) polyethylene glycol (PLGA-PEG). The transport of the carriers was assessed in vitro, using a human brain endothelial cell line, cytotoxicity assays, fluorescence-tagged nanocarriers, fluorescence-activated cell sorting, confocal and transmission electron microscopy. The effectiveness of the treatment was assessed in APP/PS1 mice in a behavioral assay and by measuring the cortical deposition of β-amyloid.ResultsIncorporation of PGZ into the carriers promoted a 50x greater uptake into brain endothelium compared with the free drug and the carriers showed a delayed release profile of PGZ in vitro. In the doses used, the nanocarriers were not toxic for the endothelial cells, nor did they alter the permeability of the blood–brain barrier model. Electron microscopy indicated that the nanocarriers were transported from the apical to the basal surface of the endothelium by vesicular transcytosis. An efficacy test carried out in APP/PS1 transgenic mice showed a reduction of memory deficit in mice chronically treated with PGZ-NPs. Deposition of β-amyloid in the cerebral cortex, measured by immunohistochemistry and image analysis, was correspondingly reduced.ConclusionPLGA-PEG nanocarriers cross brain endothelium by transcytosis and can be loaded with a pharmaceutical agent to effectively treat a mouse model of AD.

Optimization, Biopharmaceutical Profile and Therapeutic Efficacy of Pioglitazone-loaded PLGA-PEG Nanospheres as a Novel Strategy for Ocular Inflammatory Disorders.

The main goal of this study was to encapsulate Pioglitazone (PGZ), in biodegradable polymeric nanoparticles as a new strategy for the treatment of ocular inflammatory processes. To improve their biopharmaceutical profile for the treatment of ocular inflammatory disorders, nanospheres (NSs) of PGZ were formulated by factorial design with poly (lactic-co-glycolic acid) polyethylene glycol (PLGA-PEG). Interactions drug-polymer have been carried out by spectroscopic (X-ray spectroscopy, FTIR) and thermal methods (DSC). The PGZ-NSs were tested for their in vitro release profile, cytotoxicity, and ocular tolerance (HET-CAM® test); ex vivo corneal permeation, and in vivo inflammatory prevention and bioavailability. The optimized system showed a negative surface charge of -13.9mV, an average particle size (Zav) of around 160nm, a polydispersity index (PI) below 0.1, and a high encapsulation efficiency (EE) of around 92%. According to the DSC results, the drug was incorporated into the NSs polymeric matrix. The drug release was sustained for up to 14h. PGZ-NSs up to 10μg/ml exhibited no retinoblastoma cell toxicity. The ex vivo corneal and scleral permeation profiles of PGZ-NSs showed that retention and permeation through the sclera were higher than through the cornea. Ocular tolerance in vitro and in vivo demonstrated the non-irritant character of the formulation. The in vivo anti-inflammatory efficacy of developed PGZ-NSs indicates this colloidal system could constitute a new approach to prevent ocular inflammation.

Engineering vascularized soft tissue flaps in an animal model using human adipose–derived stem cells and VEGF+PLGA/PEG microspheres on a collagen-chitosan scaffold with a flow-through vascular pedicle

Insufficient neovascularization is associated with high levels of resorption and necrosis in autologous and engineered fat grafts. We tested the hypothesis that incorporating angiogenic growth factor into a scaffold–stem cell construct and implanting this construct around a vascular pedicle improves neovascularization and adipogenesis for engineering soft tissue flaps. Poly(lactic-co-glycolic-acid/polyethylene glycol (PLGA/PEG) microspheres containing vascular endothelial growth factor (VEGF) were impregnated into collagen-chitosan scaffolds seeded with human adipose-derived stem cells (hASCs). This setup was analyzed in vitro and then implanted into isolated chambers around a discrete vascular pedicle in nude rats. Engineered tissue samples within the chambers were harvested and analyzed for differences in vascularization and adipose tissue growth. In vitro testing showed that the collagen-chitosan scaffold provided a supportive environment for hASC integration and proliferation. PLGA/PEG microspheres with slow-release VEGF had no negative effect on cell survival in collagen-chitosan scaffolds. In vivo, the system resulted in a statistically significant increase in neovascularization that in turn led to a significant increase in adipose tissue persistence after 8 weeks versus control constructs. These data indicate that our model—hASCs integrated with a collagen-chitosan scaffold incorporated with VEGF-containing PLGA/PEG microspheres supported by a predominant vascular vessel inside a chamber—provides a promising, clinically translatable platform for engineering vascularized soft tissue flap. The engineered adipose tissue with a vascular pedicle could conceivably be transferred as a vascularized soft tissue pedicle flap or free flap to a recipient site for the repair of soft-tissue defects.

Biodegradable PLGA-b-PEG polymeric nanoparticles: synthesis, properties, and nanomedical applications as drug delivery system

During the past decades many synthetic polymers have been studied for nanomedicine applications and in particular as drug delivery systems. For this purpose, polymers must be non-toxic, biodegradable, and biocompatible. Polylactic-co-glycolic acid (PLGA) is one of the most studied polymers due to its complete biodegradability and ability to self-assemble into nanometric micelles that are able to entrap small molecules like drugs and to release them into body in a time-dependent manner. Despite fine qualities, using PLGA polymeric nanoparticles for in vivo applications still remains an open challenge due to many factors such as poor stability in water, big diameter (150–200 nm), and the removal of these nanocarriers from the blood stream by the liver and spleen thus reducing the concentration of drugs drastically in tumor tissue. Polyethylene glycol (PEG) is the most used polymers for drug delivery applications and the first PEGylated product is already on the market for over 20 years. This is due to its stealth behavior that inhibits the fast recognition by the immune system (opsonization) and generally leads to a reduced blood clearance of nanocarriers increasing blood circulation time. Furthermore, PEG is hydrophilic and able to stabilize nanoparticles by steric and not ionic effects especially in water. PLGA–PEG block copolymer is an emergent system because it can be easily synthesized and it possesses all good qualities of PLGA and also PEG capability so in the last decade it arose as one of the most promising systems for nanoparticles formation, drug loading, and in vivo drug delivery applications. This review will discuss briefly on PLGA-b-PEG synthesis and physicochemical properties, together with its improved qualities with respect to the single PLGA and PEG polymers. Moreover, we will focus on but in particular will treat nanoparticles formation and uses as new drug delivery system for nanomedical applications.

Development and Validation of an HPLC Method Using Fluorescence Detection for the Quantitative Determination of Curcumin in PLGA and PLGA-PEG Nanoparticles

In this paper, a rapid and effective chromatographic procedure for determining the curcumin encapsulation efficiency in poly(lactic-co-glycolic acid) (PLGA) and poly(lactic-co-glycolic acid)-polyethyleneglycol (PLGA-PEG) nanoparticles via reversed-phase high-performance liquid chromatography (RP-HPLC) using a fluorescence detector and low flow rate is described. Chromatographic runs were performed on a RP C18 column (250 mm x 4.6 mm, 5 μm) with a mixture of ethanol, water and acetonitrile (80:10:10, v/v/v) as the mobile phase and a flow rate of 0.8 mL/min in the isocratic mode. Curcumin was detected using a fluorescence detector operating at an excitation wavelength of 365 nm and an emission wavelength of 512 nm. This method was validated in terms of the selectivity, linearity, precision, accuracy, robustness, limit of detection and limit of quantitation. The analytical curve was linear over the concentration range of 1– 50 μg/mL, and the limits of detection and quantitation were 9.65 and 50 ng/ml, respectively. The mean recovery for curcumin was 101.14 ± 2.8% (n = 9). The intra- and inter-assay coefficients of variation were less than 3.73%. The method was robust for changes in the mobile phase, column temperature and flow rate. The maximum relative standard deviation was 3.08%. The method was successfully used to determine the encapsulation efficiency of curcumin in PLGA and PLGA-PEG nanoparticles. Keywords: Biodegradable polymers, Curcumin, Encapsulation efficiency, Fluorescence, HPLC, Nanoparticles, Particle size, PLGA, PLGA-PEG, Validation

Pharmacokinetics of curcumin-loaded PLGA and PLGA–PEG blend nanoparticles after oral administration in rats

The aim of this study was to assess the potential of nanoparticles to improve the pharmacokinetics of curcumin, with a primary goal of enhancing its bioavailability. Polylactic-co-glycolic acid (PLGA) and PLGA–polyethylene glycol (PEG) (PLGA–PEG) blend nanoparticles containing curcumin were obtained by a single-emulsion solvent-evaporation technique, resulting in particles size smaller than 200nm. The encapsulation efficiency was over 70% for both formulations. The in vitro release study showed that curcumin was released more slowly from the PLGA nanoparticles than from the PLGA–PEG nanoparticles. A LC–MS/MS method was developed and validated to quantify curcumin in rat plasma. The nanoparticles were orally administered at a single dose in rats, and the pharmacokinetic parameters were evaluated and compared with the curcumin aqueous suspension. It was observed that both nanoparticles formulations were able to sustain the curcumin delivery over time, but greater efficiency was obtained with the PLGA–PEG nanoparticles, which showed better results in all of the pharmacokinetic parameters analyzed. The PLGA and PLGA–PEG nanoparticles increased the curcumin mean half-life in approximately 4 and 6h, respectively, and the Cmax of curcumin increased 2.9- and 7.4-fold, respectively. The distribution and metabolism of curcumin decreased when it was carried by nanoparticles, particularly PLGA–PEG nanoparticles. The bioavailability of curcumin-loaded PLGA–PEG nanoparticles was 3.5-fold greater than the curcumin from PLGA nanoparticles. Compared to the curcumin aqueous suspension, the PLGA and PLGA–PEG nanoparticles increased the curcumin bioavailability by 15.6- and 55.4-fold, respectively. These results suggest that PLGA and, in particular, PLGA–PEG blend nanoparticles are potential carriers for the oral delivery of curcumin.

The effect of Rho kinase inhibition on capsule formation using local delivery of Y-27632

Introduction. Despite current developments in surgery and manufacturing technology, capsular contracture is still the most common late complication associated with breast implant surgery. This proposed study was designed to investigate the effect of Rho kinase inhibition on capsule formation. Rho kinases are pivotal regulators of several aspects of cell behavior and contribute to reorganization of the actin cytoskeleton, formation of stress fibers, and cell migration in the wound environment. They activate NF-κB by inducing I-κB kinase, which lead to activation of inflammatory pathways during wound healing. However, these responses may yield to extensive inflammatory effect which triggers an uncontrolled synthetic process, as seen in burns. We hypothesized that Rho kinase signaling pathway is up regulated in capsular contracture, which leads to excessive fibrosis, and inhibition of this pathway prevents contracture. This study aims to demonstrate the dynamic interaction between Rho kinase pathway and capsular contracture. Methods. Forty adult, Sprague-Dawley rats were utilized for this project. Animals were classified into two main groups: Group A ( n = 20): Only Silicon Implant; and Group B ( n = 10): Silicon Implant + Rho kinase Inhibitor (Y-27632). Silicon hemispheric implants of 2.5 cm in diameter were placed dorsally beneath the panniculus carnosus away from the incision into 20 Sprague-Dawley rats . Y-27632 was delivered by a biodegradable drug delivery method which is Polylactic-coglycolic acid/polyethylene glycol (PLGA/PEG) microspheres to provide long-term inhibition of the rho kinase signaling system. One milliliter of 10 mM Y-27632 was delivered into the vicinity of implant in 10 rats utilizing PLGA/PEG microspheres. Animals were sacrificed after 2 and 4 weeks for tissue processing. Obtained capsules were stained by Hematoxylin--Eosin and Masson’s trichrome stain to demonstrate architectural changes in capsules. Statistical analysis was performed using Student’s t-test ( P < 0.05). Results. Capsule formation was noted in both groups at 2 and 4 weeks. Capsule thickness was not significantly different between groups. However, histological analysis of Masson’s trichrome stained capsule specimens revealed that rho kinase inhibition led to a significant decrease in collagen deposition in Rho kinase inhibited group, an important architectural change in the capsule. Morphometric analysis using ImagePro software demonstrated that this change in collagen deposition was statistically significant ( P < 0.05). Conclusions. Down regulation of Rho kinase activity results in alterations in capsule architecture. These findings suggest that Rho kinase-mediated signaling pathway is a promising new target for prevention capsular contracture.

Augmentation of Adipofascial Flaps Using the Long-Term Local Delivery of Insulin and Insulin-Like Growth Factor-1

The adipofascial flaps currently described in the literature frequently lack the volume requirements for reconstructive goals. In this study, the authors examined the use of long-term local delivery of insulin and insulin-like growth factor-1 (IGF-1) using polylactic-coglycolic acid/polyethylene glycol (PLGA/PEG) microspheres to augment inguinal adipofascial flaps based on the inferior epigastric vessels in the rat. Two flap models, the island flap and the limited dissection flap, were used to demonstrate simultaneous treatment and pretreatment modalities, respectively. Experimental groups received 12.5 mg of insulin microspheres (carrying 1 IU of insulin) plus 12.5 mg of IGF-1 microspheres (carrying 2.5 microg of IGF-1). A group undergoing the operation only (no treatment with microspheres) and a group treated with blank microspheres (no growth factor) served as external controls for the surgical procedure and the drug delivery device, respectively. In all groups (n = 5 animals in each), the contralateral flap served as an internal control. Upon harvest on postoperative day 28, the insulin and IGF-1-treated flaps in both models weighed statistically more than the internal control flaps and the two external control flaps. Likewise, on gross inspection, the adipogenic growth factor-treated flaps had greater volumes than the internal control flap groups and both of the external control flap groups (operation only and blank microspheres). Other intergroup comparisons suggested the absence of a systemic insulin and IGF-1 effect on adiposity. A histomorphometric analysis suggested (1) that insulin and IGF-1 treatment does not alter flap cell composition and (2) that flap augmentation is secondary to the stimulation of cell proliferation and adipocytic differentiation rather than the hypertrophy of mature adipocytes. Further evidence in favor of cell proliferation and differentiation was the discovery of nonanatomic, ectopic fat islands on the pedicle sheath of the treated flaps and the lack of variation in cell size distribution among groups. The authors concluded that the long-term local delivery of insulin and IGF-1 with PLGA/PEG microspheres is an effective method of adipofascial flap augmentation; this method increases the number of mature adipocytes rather than increasing the size of preexisting cells.

De novo adipose tissue generation through long-term, local delivery of insulin and insulin-like growth factor-1 by PLGA/PEG microspheres in an in vivo rat model: a novel concept and capability.

This study was undertaken to characterize the duration of long-term growth factor delivery by poly(lactic-co-glycolic-acid)-polyethylene glycol (PLGA/PEG) microspheres and to evaluate the potential of long-term delivery of insulin and insulin-like growth factor-1 (IGF-1) for the de novo generation of adipose tissue in vivo. PLGA/PEG microspheres containing insulin and IGF-1, separately, were produced by a double-emulsion solvent-extraction technique. In the first phase of the experiment, the in vitro release kinetics of the microspheres were evaluated for the optical density and polyacrylamide gel electrophoresis of solutions incubated with insulin-containing microspheres for four different periods of time (n = 1). The finding of increased concentrations of soluble insulin with increased incubation time confirmed continual protein release. In the second stage of the experiment, 16 rats were divided equally into four study groups (insulin, IGF-1, insulin + IGF-1, and blank microspheres) (n = 4). Insulin and IGF-1 containing microspheres were administered directly to the deep muscular fascia of the rat abdominal wall to evaluate the potential for de novo adipose tissue generation via adipogenic differentiation from native nonadipocyte cell pools in vivo. Animals treated with blank microspheres served as an external control group. At the 4-week harvest period, multiple ectopic islands of adipose tissue were observed on the abdominal wall of the animals treated with insulin, IGF-1, and insulin + IGF-1 microspheres. Such islands were not seen in the blank microsphere group. Hematoxylin and eosin-stained sections of the growth factor groups demonstrated mature adipocytes interspersed with fibrous tissue superficial to the abdominal wall musculature and continuous with the fascia. Oil-Red-O stained sections demonstrated that these cells contained lipid. Computer-aided image analysis of histologic sections confirmed that there were statistically significant increases in the amount of "ectopic" adipose neotissue developed on the abdominal wall of animals treated with growth factor microspheres. In conclusion, this study confirms the long-term release of proteins from PLGA/PEG microspheres up to 4 weeks and demonstrates the potential of long-term local insulin and IGF-1 to induce adipogenic differentiation to mature lipid-containing adipocytes from nonadipocyte cell pools in vivo at 4 weeks.