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Hearing loss is a prevalent disability worldwide. Dexamethasone (Dex) is commonly used to treat hearing loss, administered either systemically or locally. However, targeted delivery of Dex to the inner ear remains challenging, which limits its therapeutic efficacy. This study aimed to develop new methods to improve Dex delivery to the inner ear and enhance its treatment effect. Mastoid, intraperitoneal, and intratympanic delivery routes for Dex were investigated in guinea pig cochlea. Liquid chromatography-mass spectrometry and immunohistochemistry were employed to compare the distribution of Dex in the perilymph and tissue uptake. Poly (lactic- co -glycolic acid) nanoparticles loaded with Dex (PLGA-NPs-Dex) were prepared, and their transport mechanism across the round window membrane (RWM) was explored. Among the three delivery routes, mastoid administration produced the highest Dex concentration in the perilymph. Compared to the control, PLGA-NPs-Dex provided significantly enhanced protection against lipopolysaccharide- and noise-induced hearing damage following mastoid administration. Mastoid delivery provides an accessible route for drug delivery to the inner ear and nanoparticle-based systems via this route represent a viable strategy for treating inner ear diseases. This approach caused less damage to the inner ear, making it a promising option for clinical use in treating hearing loss. Mastoid approach was a novel method for local drug delivery into the inner ear. PLGA-NPs-Dex showed a significantly better hearing-protective effect against lipopolysaccharides- and noise-induced damages following mastoid delivery. [Display omitted] • Mastoid approach was a novel method for local drug delivery into the inner ear. • Mastoid administration yielded the higher concentration of Dex in the perilymph than the traditional delivery routes. • PLGA-NPs-Dex was prepared and the transport mechanism of it across the round window membrane was studied • PLGA-NPs-Dex showed a better hearing-protective effect against LPS- and noise-induced damages following mastoid delivery. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is considered one of the biggest threats to public health worldwide. Methicillin-resistant S. aureus is the causative agent of a number of infections and lung colonization in people suffering from cystic fibrosis. Moreover, a growing body of evidence links the microbiome to the development of cancer, as well as to the success of the treatment. In this view, the development of novel antibiotics is of critical importance, and SV7, a novel antibiotic active against MRSA at low concentrations, represents a promising candidate. However, the low aqueous solubility of SV7 hampers its therapeutic translation. In this study, SV7 was encapsulated in poly(lactic- co -glycolic acid) (PLGA) nanoparticles (NPs) to improve the solubility profile, to ensure sustained release and eventually support deposition in the airways. Furthermore, PLGA NPs were formulated as dry powder to extend their shelf-life and were shown to efficiently target intracellular infections. After identifying a formulation with suitable physico-chemical characteristics, SV7-loaded NPs were investigated in vitro in terms of inhibitory activity against MRSA, and their safety profile in lung epithelial cells. Subsequently, the activity against MRSA intracellular infections was investigated in a co-culture model of MRSA and macrophages. To test the translatability of our findings, SV7-loaded NPs were tested in vivo in a Galleria mellonella infection model. In conclusion, SV7-loaded NPs showed a safe profile and efficient inhibitory activity against MRSA at low concentrations. Furthermore, their activity against intracellular infections was confirmed, and was retained in vivo , rendering them a promising candidate for treatment of MRSA lung infections. [Display omitted] [ABSTRACT FROM AUTHOR]

The treatment landscape for opioid use disorder (OUD) faces challenges stemming from the limited efficacy of existing medications, poor adherence to prescribed regimens, and a heightened risk of fatal overdose post-treatment cessation. Therefore, there is a pressing need for innovative therapeutic strategies that enhance the effectiveness of interventions and the overall well-being of individuals with OUD. This study explored the therapeutic potential of nor-Levo-α-acetylmethadol (nor-LAAM) to treat OUD. We developed sustained release nor-LAAM-loaded poly (lactic- co -glycolic acid) (PLGA) microparticles (MP) using a hydrophobic ion pairing (HIP) approach. The nor-LAAM-MP prepared using HIP with pamoic acid had high drug loading and exhibited minimal initial burst release and sustained release. The nor-LAAM-MP was further optimized for desirable particle size, drug loading, and release kinetics. The lead nor-LAAM-MP (F4) had a relatively high drug loading (11 wt%) and an average diameter (19 μm) and maintained a sustained drug release for 4 weeks. A single subcutaneous injection of nor-LAAM-MP (F4) provided detectable nor-LAAM levels in rabbit plasma for at least 15 days. We further evaluated the therapeutic efficacy of nor-LAAM-MP (F4) in a well-established fentanyl-addiction rat model, and revealed a marked reduction in fentanyl choice and withdrawal symptoms in fentanyl-dependent rats. These findings provide insights into further developing long-acting nor-LAAM-MP for treating OUD. It has the potential to offer a new effective medication to the existing sparse armamentarium of products available to treat OUD. [Display omitted] [ABSTRACT FROM AUTHOR]

In vitro-In vivo correlation (IVIVC) is a main focus of the pharmaceutical industry, academia and the regulatory sectors, as this is an effective modelling tool to predict drug product in vivo performance based on in vitro release data and serve as a surrogate for bioequivalence studies, significantly reducing the need for clinical studies. Till now, IVIVCs have not been successfully developed for in situ forming implants due to the significantly different in vitro and in vivo drug release profiles that are typically achieved for these dosage forms. This is not unexpected considering the unique complexity of the drug release mechanisms of these products. Using risperidone in situ forming implants as a model, the current work focuses on: 1) identification of critical attributes of in vitro release testing methods that may contribute to differences in in vitro and in vivo drug release from in situ forming implants; and 2) optimization of the in vitro release method, with the aim of developing Level A IVIVCs for risperidone implants. Dissolution methods based on a novel Teflon shape controlling adapter along with a water non-dissolvable glass fiber membrane (GF/F) instead of a water dissolvable PVA film (named as GF/F-Teflon adapter and PVA-Teflon adapter, respectively), and an in-house fabricated Glass slide adapter were used to investigate the impact of: the surface-to-volume ratio, water uptake ratio, phase separation rate (measured by NMP release in 24 h post injection in vitro or in vivo), and mechanical pressure on the drug release patterns. The surface-to-volume ratio and water uptake were shown to be more critical in vitro release testing method attributes compared to the phase separation rate and mechanical pressure. The Glass slide adapter-based dissolution method, which allowed for the formation of depots with bio-mimicking surface-to-volume ratios and sufficient water uptake, has the ability to generate bio-relevant degradation profiles as well as in vitro release profiles for risperidone implants. For the first time, a Level A IVIVC (rabbit model) has been successfully developed for in situ forming implants. Release data for implant formulations with slightly different PLGA molecular weights (MWs) were used to develop the IVIVC. The predictability of the model passed external validation using the reference listed drug (RLD), Perseris®. IVIVC could not be developed when formulations with different PLGA molar ratios of lactic acid to glycolic acid (L/G) were included. The present work provides a comprehensive understanding of the impact of the testing method attributes on drug release from in situ forming implants, which is a valuable practice for level A IVIVC development. [Display omitted] [ABSTRACT FROM AUTHOR]

Tumor heterogeneity and drug resistance have been invincible features of cancer for its complete cure. Despite the advent of immunotherapy, the expansion and diversification of cancer cells evolved even in the absence or presence of drug treatment discourage additional therapeutic interventions. For the eradication of cancer cells, therefore, an 'all-at-once' strategy is required, which exploits both target-selective chemotherapy and non-selective physicotherapy. Multifactorial microcapsules comprising gold nanoparticles (AuNPs) and a self-assembly protein of α-synuclein (αS) were fabricated, in which hydrophobic and hydrophilic drugs could be separately encapsulated by employing lipid-based inverted micelles (IMs). Their combined physico-chemical therapeutic effects were examined since they also contained both membrane-disrupting IMs and heat-generating AuNPs upon irradiation as physicotherapeutic agents. For the optimal enclosure of IMs containing hydrophilic drugs, a porous inner skeleton made of poly(lactic- co -glycolic acid) was introduced, which would play the roles of not only compartmentalizing the internal space but also enhancing proteolytic disintegration of the microcapsules to discharge and stabilize IMs to the outside. In fact, hydrophobic paclitaxel and hydrophilic doxorubicin showed markedly enhanced drug efficacy when delivered in the IM-containing microcapsules exhibiting the 'quantal' release of both drugs into the cells whose integrity could be also affected by the IMs. In addition, the remnants of αS-AuNP microcapsules produced via proteolysis also caused cell death through photothermal effect. The multifactorial microcapsules are therefore considered as a promising anti-cancer drug carrier capable of performing combinatorial selective and non-selective chemical and physical therapies to overcome tumor heterogeneity and drug resistance. [Display omitted] • Multifactorial system for combined chemical and physical anti-cancer therapeutics. • Protein-mediated gold nanoparticle assembly encapsulating inverted micelles (IMs). • Protease-dependent release of hydrophobic/hydrophilic drugs from PLGA-stabilized IMs. • Facilitated intracellular drug delivery via membrane-disrupting IMs. • Photothermal therapy utilizing shell clusters that absorb near-infrared light. [ABSTRACT FROM AUTHOR]

Different types of ibuprofen-loaded, poly (D,L lactic- co -glycolic acid) (PLGA)-based implants were prepared by 3D printing (Droplet Deposition Modeling). The theoretical filling density of the mesh-shaped implants was varied from 10 to 100%. Drug release was measured in agarose gels and in well agitated phosphate buffer pH 7.4. The key properties of the implants (and dynamic changes thereof upon exposure to the release media) were monitored using gravimetric measurements, optical microscopy, Differential Scanning Calorimetry, Gel Permeation Chromatography, and Scanning Electron Microscopy. Interestingly, drug release was similar for implants with 10 and 30% filling density, irrespective of the experimental set-up. In contrast, implants with 100% filling density showed slower release kinetics, and the shape of the release curve was altered in agarose gels. These observations could be explained by the existence (or absence) of a continuous aqueous phase between the polymeric filaments and the "orchestrating role" of substantial system swelling for the control of drug release. At lower filling densities, it is sufficient for the drug to be released from a single filament. In contrast, at high filling densities, the ensemble of filaments acts as a much larger (more or less homogeneous) polymeric matrix, and the average diffusion pathway to be overcome by the drug is much longer. Agarose gel (mimicking living tissue) hinders substantial PLGA swelling and delays the onset of the final rapid drug release phase. This improved mechanistic understanding of the control of drug release from PLGA-based 3D printed implants can help to facilitate the optimization of this type of advanced drug delivery systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Spray-dried poly(lactic- co -glycolic acid) (PLGA) peptide-loaded microspheres have demonstrated similar long-term in vitro release kinetics compared to those produced by the solvent evaporation method and commercial products. However, the difficult-to-control initial burst release over the first 24 h after administration presents an obstacle to product development and establishing bioequivalence. Currently, detailed information about underlying mechanisms of the initial burst release from microspheres is limited. We investigated the mechanism and extent of initial burst release using 16 previously developed spray-dried microsphere formulations of the hormone drug, leuprolide acetate, with similar composition to the commercial 1-month Lupron Depot® (LD). The burst release kinetics was measured with a previously validated continuous monitoring system as well as traditional sample-and-separate methods. The changes in pore structure and polymer permeability were investigated by SEM imaging and the uptake of a bodipy-dextran probe. In vitro results were compared to pharmacokinetics in rats over the same interval. High-burst, spray-dried microspheres were differentiated in the well-mixed continuous monitoring system but reached an upper limit when measured by the sample-and-separate method. Pore-like occlusions observed by confocal microscopy in some formulations indicated that particle swelling may have contributed to probe diffusion through the polymer phase and showed the extensive internal pore structure of spray-dried particles. Continuous monitoring revealed a rapid primary (1°) phase followed by a constant-rate secondary (2°) release phase, which comprised ∼80% and 20% of the 24-hr release, respectively. The ratio of 1° phase duration (t 1°) and the characteristic probe diffusion time (τ) was highly correlated to 1° phase release for spray dried particles. Of the four spray-dried formulations administered in vivo, three spray-dried microspheres with similar polymer density showed nearly ideal linear correlation between in vivo absorption and well-mixed in vitro release kinetics over the first 24 h. By contrast, the more structurally dense LD and a more-dense in-house formulation showed a slight lag phase in vivo relative to in vitro. Furthermore, in vitro dimensionless times (t burst /τ) were highly correlated with pharmacokinetic parameters for spray-dried microspheres but not for LD. While the correlation of increases in effective probe diffusion and 1° phase release strongly suggests diffusion through the polymer matrix as a major release mechanism both in vitro and in vivo, a fixed lower limit for this release fraction implies an alternative release mechanism. Overall, continuous monitoring release and probe diffusion appears to have potential in differentiating between leuprolide formulations and establishing relationships between in vitro release and in vivo absorption during the initial burst period. [Display omitted] [ABSTRACT FROM AUTHOR]

Poly (lactic- co -glycolic acid) (PLGA) microspheres have been one of the most successful products for slow drug release. While distribution of drugs in microspheres might be a fundamental factor affecting drug release, it has been often overlooked. Indeed, very few studies are available on the distribution of drugs in microspheres with complex morphology like golf ball-shaped microspheres. In this paper, the distribution of rotigotine in golf ball-shaped microspheres (GSRM) was investigated by argon ion milling, combined with scanning electron microscopy and energy dispersive X-ray spectroscopy (AIM-SEM-EDS). Rotigotine in GSRM was clearly observed in two forms, respectively in an aggregated state and as a molecular dispersion. The distribution of palmitic acid in the microspheres (used as an additive to reduce burst release) was also demonstrated: 10% was found on the microspheres' surface while 90% separated from the polymer to form small particles inside the microspheres onto which rotigotine aggregated through hydrogen bonding interactions. In in-vitro release studies we observed that first the phase-separated palmitic acid/rotigotine particles dissolved and released the drug, followed by the release of the molecularly dispersed rotigotines by osmosis. We also found that rotigotine accelerated the degradation and reduced the glass transition temperature of PLGA, which played an important role as well in the release of the drug from GSRM. Finally, two linear Level A in vitro - in vivo correlations were established and validated, indicating that the in vitro release testing could be a meaningful predictor for the in vivo performance of GSRM. Our work demonstrates the importance of studying drug distribution in complex microspheres to understand drug release. [Display omitted] • Drug distribution of GSRM was characterized by AIM-SEM-EDS for the first time. • Both aggregated and molecularly dispersed rotigotine were observed in GSRM. • Formation mechanism of GSRM was a phase-separation mechanism of ternary system. • Drug release profiles of GSRM was linked to drug distribution. • Two Level A IVIVCs with good predictability were successfully developed. [ABSTRACT FROM AUTHOR]

Surgical removal remains the predominant treatment strategy for triple-negative breast cancer (TNBC). However, risks that include high locoregional recurrence and remote metastasis threaten patient survival and quality of life after surgery. In this study, a hydrogel based on poly (ethylene glycol) dimethacrylate and sericin methacryloyl was fabricated by photopolymerization to fill the resection cavity and prevent recurrence. The obtained hydrogel exhibited mechanical properties compatible with breast tissue and facilitated postsurgical wound management by promoting tissue regeneration. The DNA methylation inhibitor decitabine (DEC) and poly (lactic- co -glycolic acid)-encapsulated phytochemical gambogic acid (GA) were loaded into the hydrogel. The as-prepared hydrogel promoted fast release of DEC and sustained release of GA, leading to gasdermin E -mediated tumor cell pyroptosis and activating antitumor immune responses. Inducing postsurgical tumor cell pyroptosis inhibited local tumor recurrence and lung metastasis. While the dual-drug-loaded hydrogel system cured less than half of tumor-bearing mice, the cured mice survived for over half a year. These findings indicate that our hydrogel system is an excellent biocompatible platform for postsurgical TNBC therapy. [Display omitted] [ABSTRACT FROM AUTHOR]

The pH inside the aqueous pores of poly(lactic- co -glycolic acid) (PLGA) microspheres, often termed microclimate pH (μ pH), has been widely evaluated in vitro and shown to commonly be deleterious to pH-labile encapsulated drug molecules. However, whether the in vitro μ pH is representative of the actual in vivo values has long been remained a largely unresolved issue. Herein we quantitatively mapped, for the first time, the in vivo μ pH distribution kinetics inside degrading PLGA microspheres by combining two previously validated techniques, a cage implant system and confocal laser scanning microscopy. PLGA (50/50, Mw = 24–38 kDa, acid-end capped and ester-capped) microsphere formulations with and without encapsulating exenatide, a pH-labile peptide that is known to be unstable when pH > 4.5, were administered to rats subcutaneously via cage implants for up to 6 weeks. The results were compared with two different in vitro conditions. Strikingly, the in vivo μ pH developed similarly to the low microsphere concentration in vitro condition with 1- μ m nylon bags but very different from conventional high microsphere concentration sample-and-separate conditions. Improved maintenance of stable external pH in the release media for the former condition may have been one important factor. Stability of exenatide remaining inside microspheres was evaluated by mass spectrometry and found that it was steadily degraded primarily via pH-dependent acylation with a trend that slightly paralleled the changes in μ pH. This methodology may be useful to elucidate pH-triggered instability of PLGA encapsulated drugs in vivo and for improving in vivo -predictive in vitro conditions for assessing general PLGA microsphere performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Cancer vaccines have recently garnered tremendous interest. However, the targeted delivery of antigens and adjuvants to dendritic cells (DCs) still remains challenging. In this study, we developed glycosylated poly(lactic- co -glycolic acid) nanoparticles (NPs) loaded with the SIINFEKL peptide (OVA) as a tumor-specific antigen and CpG oligodeoxynucleotide (CpG) as an adjuvant for an effective DC-targeted cancer vaccine. Surface modification of NPs with galactose (Gal) or mannose (Man) was carried out by a double-emulsion solvent evaporation method, and the products were respectively named OVA-CpG Gal-NPs and OVA-CpG Man-NPs. They exhibited a uniform particle size, high loading capacity, robust stability, and extended release. The OVA-CpG Gal-NPs were found to rapidly enhance antigen uptake and DC maturation. In the in vivo study, OVA-CpG Gal-NPs via intravenous (i.v.), intranasal (i.n.) and subcutaneous (s.c.) routes had rapidly accumulated in the spleen. Moreover, the non-glycosylated OVA-CpG NPs after s.c. immunization could rapidly be trafficked to distal lymph nodes and sustained higher levels. All of these formulations increased the level of cluster of differentiation 4-positive (CD4+) T cells and interferon (IFN)-γ in the spleen, then promoted the cytotoxic CD8+ tumor-infiltrating lymphocytes against E.G7-OVA lymphomas. In conclusion, galactosylated NPs provided an effective platform to enhance the DC targeting to induce cellular immunity and T-cell recruitment into tumor sites in vivo, thus showing great potential to be developed as a prophylactic vaccine for cancer immunotherapy. [Display omitted] [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is resistant to current immunotherapy. This poor outcome mainly results from the immunosuppressive characteristics of tumor microenvironment (TME). Accumulating evidence indicates that some chemotherapy agents trigger immunogenic cell death (ICD), providing a promising strategy to remodel the immunosuppressive TME. The role of Plumbagin (PLB, a naphthoquinone compound from Plumbago zeylanica L.) as the ICD inducer for HCC cells was confirmed in this study. Dihydrotanshinone I (DIH, a phenanthraquinone compound of Salvia miltiorrhiza) functioned as the ICD enhancer by generating the reactive oxygen species (ROS). A poly(D,L-lactic- co -glycolic acid) (PLGA)-based nanoparticle (NP) was used to co-encapsulate PLB, DIH and NH 4 HCO 3 (a pH sensitive adjuvant). This NP was further coated with the mannose-inserted erythrocyte membrane to produce a nanoformulation. This nanoformulation significantly increased the half-life and tumor targeting of two drugs in orthotopic HCC mice, generating chemo-immunotherapeutic effects for reversal of immunosuppressive TME. Consequently, the biomimetic nanoformulation loaded with low doses of PLB and DIH achieved significantly longer survival of HCC mice, without causing toxic signs. Our study demonstrates a promising strategy for remodeling the immunosuppressive TME of liver cancer. Co-delivery of Plumbagin and Dihydrotanshinone I using biomimetic NPs for reversal of immunosuppressive TME in HCC. [Display omitted] • Plumbagin functions as an ICD inducer against HCC. • Dihydrotanshinone I generates ROS to enhance the ICD effects of PLB. • A biomimetic co-nanoformulation reverses the immunosuppressive tumor microenvironment of HCC. [ABSTRACT FROM AUTHOR]

Radiation-induced proctitis (RIP) is a debilitating adverse event that occurs commonly during lower abdominal radiotherapy. The lack of prophylactic treatment strategies leads to diminished patient quality of life, disruption of radiotherapy schedules, and limitation of radiotherapy efficacy due to dose-limiting toxicities. Semisynthetic glycosaminoglycan ethers (SAGE) demonstrate protective effects from RIP. However, low residence time in the rectal tissue limits their utility. We investigated controlled delivery of GM-0111, a SAGE analogue with demonstrated efficacy against RIP, using a series of temperature-responsive polymers to compare how distinct phase change behaviors, mechanical properties and release kinetics influence rectal bioaccumulation. Poly(lactic acid)- co -(glycolic acid)- block -poly(ethylene glycol)- block -poly(lactic acid)- co -(glycolic acid) copolymers underwent macroscopic phase separation, expelling >50% of drug during gelation. Poloxamer compositions released GM-0111 cargo within 1 h, while silk-elastinlike copolymers (SELPs) enabled controlled release over a period of 12 h. Bioaccumulation was evaluated using fluorescence imaging and confocal microscopy. SELP-415K, a SELP analogue with 4 silk units, 15 elastin units, and one elastin unit with lysine residues in the monomer repeats, resulted in the highest rectal bioaccumulation. SELP-415K GM-0111 compositions were then used to provide localized protection from radiation induced tissue damage in a murine model of RIP. Rectal delivery of SAGE using SELP-415K significantly reduced behavioral pain responses, and reduced animal mass loss compared to irradiated controls or treatment with traditional delivery approaches. Histological scoring showed RIP injury was ameliorated for animals treated with GM-0111 delivered by SELP-415K. The enhanced bioaccumulation provided by thermoresponsive SELPs via a liquid to semisolid transition improved rectal delivery of GM-0111 to mice and radioprotection in a RIP model. [Display omitted] [ABSTRACT FROM AUTHOR]

This article presents a comprehensive review on controlled release hormonal contraceptive systems that include transdermal patches, intravaginal rings (IVRs), intrauterine devices (IUDs), injectables and subdermal implants. These systems represent a substantial advance from traditional oral contraceptive pills, to improve upon safety, efficiency, and compliance among women. The widespread use of controlled release systems is hindered by limitations, which are discussed in this review. Biodegradable polymers such as poly (lactic- co -glycolic acid) and polycaprolactone have been used to formulate subdermal implants and injectable microspheres to eliminate the need for implant removal and reduce provider intervention. To address low permeability in transdermal patches, permeation enhancers such as alkanols, fatty acids, prodrugs, and vesicular delivery for steroids have been investigated. Local anesthetics in the form of creams, gels and sprays have been evaluated to alleviate the pain associated with IUD insertion. Among methods for device fabrication, 3D printing has emerged as a potential approach for fabricating customizable IVRs and IUDs. Several other modified delivery systems such as transdermal microneedle patches, in situ forming injectable implants, microspheres embedded in implants and IVRs addressing multiple clinical conditions have been investigated for controlled release of contraceptive hormones. To ensure drug release at zero-order rates, empirical and theoretical modelling have been extensively employed and evaluated. The limitations of low predictive power associated with empirical modelling may be overcome through theoretical modelling and simulation that consider underlying mechanisms. Newer approaches such as Monte Carlo based simulation and deep learning models based on artificial neural networks can prove highly beneficial in developing precise contraceptive delivery system, to enhance the quality of life for women worldwide. Unlabelled Image • · Controlled release hormonal contraceptives include transdermal patches, intravaginal rings, injectables and implants. • Biodegradable polymers can be used to formulate long acting systems such as implants and injectable microparticles. • 3D printing can be used to fabricate customizable vaginal rings and intrauterine devices. • · Artificial Neural Networks can be employed to ensure zero order drug release from long-acting formulations. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) has recently emerged as a novel gaseous mediator with protective actions in the treatment of pulmonary arterial hypertension (PAH). However, the therapeutic potential of H 2 S in PAH has been substantially hampered due to the lack of appropriate donors that could mimic the slow and continuous generation of H 2 S in vivo. Large porous microspheres (LPMs) have low density and large surface area leading to excellent absorption capabilities and aerodynamic properties. They are extensively studied as pulmonary delivery carriers for controlled and sustained release of drug molecules in the treatment of pulmonary disorders. Therefore, we hypothesized that LPMs containing H 2 S-releasing aspirin derivative (ACS14), a novel synthetic H 2 S donor may be a feasible option to facilitate the use of H 2 S in PAH treatment. LPMs were prepared with a biodegradable polymer, poly(lactic- co -glycolic acid) (PLGA) by a microfluidic technique. Surface morphology, lung deposition characteristics, safety and H 2 S release profiles of the formulation were evaluated. The resulting ACS14-containing LPMs (ACS14 MSs) displayed excellent aerodynamic properties (mass median aerodynamic diameter of 4.4 ± 0.4 μm), desirable drug loading and entrapment efficiency (25.8 ± 2.7% and 77.4 ± 6.9%, respectively) with slow and sustained H 2 S release for 24 h and negligible cytotoxicity (~95% cell viability). Daily intratracheally administered with ACS14 MSs elicited improvement in the severity of PAH in a rat model of monocrotaline-induced PAH, with comparable efficacy to oral administration with sildenafil, a conventional PAH treatment. It also inhibited the process of endothelial-to-mesenchymal transition (EndMT), an important process in vascular remodeling of PAH by suppressing the induction of NF-κB-Snail pathway. Moreover, ACS14 MSs dose-dependently inhibited TGF-β1-induced EndMT and the activation of NF-κB-Snail pathway in human pulmonary artery endothelial cells. In conclusion, our findings demonstrated that the designed microfluidics-assisted ACS14-containing LPMs have shown great potential to be used as an inhalable and efficacious H 2 S donor in the treatment of PAH. Graphical abstract of the sequential steps towards fabricating the H 2 S donor (ACS14)-encapsulated large porous architectures using the microfluidic technique and the mechanism involved in the treatment of PAH Unlabelled Image • Large porous PLGA microspheres containing ACS14 exhibit excellent aerodynamic properties with slow and sustained H2S release. • Inhalable large porous PLGA microspheres loaded with ACS14 elicit improvement in the severity of PAH in a rat model of PAH. • Large porous PLGA microspheres loaded with ACS14 inhibit the process of endothelial-to-mesenchymal transition by suppressing the induction of NF-κB-Snail pathway. • Inhalable large porous PLGA microspheres facilitate the use of ACS14 in the treatment of PAH. [ABSTRACT FROM AUTHOR]

Selective inhibition of microRNAs (miRNAs) offers a new avenue for cancer therapeutics. While most of the current anti-miRNA (antimiR) reagents target full length miRNAs, here we investigate novel nanoparticle-delivered short PNA probes containing cationic domains targeting the seed region of the miRNA for effective antimiR therapy. For proof of concept, we tested PNAs targeting miRNA-155 and employed poly(lactic- co -glycolic acid) (PLGA)-based nanoparticle formulation for delivery. A comprehensive evaluation of PLGA nanoparticles (NPs) containing short PNA probes showed significantly superior loading, release profile, and uniform size distribution, compared to conventional non-cationic PNA probes. Confocal microscopy and flow cytometry analyses showed efficient transfection efficiency and uniform distribution of PLGA NPs containing short PNA probes in the cytoplasm. Functional analysis also confirmed efficient miRNA-155 inhibition including an effect on its downstream target proteins. Further, reduced tumor growth was observed after systemic delivery of PLGA nanoparticles containing short PNA probes in vivo in a xenograft mouse model following inhibition of miR-155. There was no evidence of acute or chronic toxicity associated with systemic delivery of PLGA NPs containing short PNA probes in the mice. Overall, in this paper we present a novel antimiR strategy based on PLGA nanoparticle delivered short PNA probes for potential cancer therapy. Unlabelled Image • Short cationic anti-seed PNAs can efficiently inhibit the action of target oncomiRs. • PLGA NPs containing short arginine-PNAs exhibit superior transfection efficiency. • Short anti-seed PNA loaded PLGA NPs prevents tumor growth in a xenograft mice model of lymphoma. • Proposed anti-seed PNA strategy is cost effective and clinically translatable. [ABSTRACT FROM AUTHOR]

The occurrence of an implant-associated infection (IAI) with the formation of a persisting bacterial biofilm remains a major risk following orthopedic biomaterial implantation. Yet, progress in the fabrication of tunable and durable implant coatings with sufficient bactericidal activity to prevent IAI has been limited. Here, an electrospun composite coating was optimized for the combinatorial and sustained delivery of antibiotics. Antibiotics-laden poly(ε-caprolactone) (PCL) and poly'1q'(lactic-co glycolic acid) (PLGA) nanofibers were electrospun onto lattice structured titanium (Ti) implants. In order to achieve tunable and independent delivery of vancomycin (Van) and rifampicin (Rif), we investigated the influence of the specific drug-polymer interaction and the nanofiber coating composition on the drug release profile and durability of the polymer-Ti interface. We found that a bi-layered nanofiber structure, produced by electrospinning of an inner layer of [PCL/Van] and an outer layer of [PLGA/Rif], yielded the optimal combinatorial drug release profile. This resulted in markedly enhanced bactericidal activity against planktonic and adherent Staphylococcus aureus for 6 weeks as compared to single drug delivery. Moreover, after 6 weeks, synergistic bacterial killing was observed as a result of sustained Van and Rif release. The application of a nanofiber-filled lattice structure successfully prevented the delamination of the multi-layer coating after press-fit cadaveric bone implantation. This new lattice design, in conjunction with the multi-layer nanofiber structure, can be applied to develop tunable and durable coatings for various metallic implantable devices. This is particularly appealing to tune the release of multiple antimicrobial agents over a period of weeks to prevent early and delayed onset IAI. Unlabelled Image • Bi-layered electrospun nanofibers applied onto titanium implants to obtain a sustained release profile. • Co-delivery of Rifampicin and Vancomycin demonstrated a combinatorial bactericidal activity. • The nanofiber-filled lattice strategy resulted in a durable coating after surgical implantation. • Prevention of early and delayed implant infection was achieved with tuning the nanofibers and antibiotics parameters. [ABSTRACT FROM AUTHOR]

In periodontal treatment, patient differences in disease phenotype and treatment responses are well documented. Therefore, therapy duration and dosage should be tailored to the requirements of individual patients. To facilitate such personalized medication, a tunable and controllable system is needed to deliver drugs directly into the diseased periodontal pockets. The current study established a system to achieve different drug release rates and periods by incorporating bioactive agents into poly(lactic- co -glycolic acid) (PLGA) microspheres dispersed into a novel thermo-reversible polyisocyanopeptide (PIC) hydrogel. Specifically, two drugs, i.e. doxycycline and lipoxin, were separately loaded into acid-terminated and ester-capped PLGA by electrospraying. Different formulations were developed by loading the two kinds of PLGA microspheres with different mass ratios in the PIC gels. The results demonstrated that the PIC-PLGA vehicle exhibited appropriate injectability, long-term structural stability, and no obvious in vivo inflammatory response for the desired clinical application. Furthermore, the release profiles of drugs could be manipulated by adjusting the loaded mass ratio of acid- and ester- terminated PLGA microspheres in the PIC gels. The more ester-capped PLGA was used, the slower the release rate and the longer the release period, and vice versa. Additionally, the released drugs still preserved their bio-efficacy. This PIC-PLGA system can be further developed and tested in translational studies to demonstrate the final clinical benefit. Unlabelled Image [ABSTRACT FROM AUTHOR]

Spinal cord injury (SCI) induces pathological and inflammatory responses that create an inhibitory environment at the site of trauma, resulting in axonal degeneration and functional disability. Combination therapies targeting multiple aspects of the injury, will likely be more effective than single therapies to facilitate tissue regeneration after SCI. In this study, we designed a dual-delivery system consisting of a neuroprotective drug, minocycline hydrochloride (MH), and a neuroregenerative drug, paclitaxel (PTX), to enhance tissue regeneration in a rat hemisection model of SCI. For this purpose, PTX-encapsulated poly (lactic- co -glycolic acid) PLGA microspheres along with MH were incorporated into the alginate hydrogel. A prolonged and sustained release of MH and PTX from the alginate hydrogel was obtained over eight weeks. The obtained hydrogels loaded with a combination of both drugs or each of them alone, along with the blank hydrogel (devoid of any drugs) were injected into the lesion site after SCI (at the acute phase). Histological assessments showed that the dual-drug treatment reduced inflammation after seven days. Moreover, a decrease in the scar tissue, as well as an increase in neuronal regeneration was observed after 28 days in rats treated with dual-drug delivery system. Over time, a fast and sustained functional improvement was achieved in animals that received dual-drug treatment compared with other experimental groups. This study provides a novel dual-drug delivery system that can be developed to test for a variety of SCI models or neurological disorders. Unlabelled Image • A novel dual-drug delivery system was designed for SCI therapy. • A combination of a neuroprotective and neuroregenerative drug was loaded as treatment. • A prolonged sustained release of two drugs was obtained over eight weeks. • The dual-drug treatment reduced inflammation and increased neuronal regeneration. • The dual-drug treatment improved functional outcomes. [ABSTRACT FROM AUTHOR]

Different types of poly(lactic- co -glycolic acid) (PLGA)- and poly(lactic acid) (PLA)-based implants for controlled dexamethasone release were prepared by hot melt extrusion (HME). The lactic acid:glycolic acid ratio was varied (50:50, 75:25, 100:0) as well as the drug loading (1–15%). Resomer RG 502H, RG 752H and R 202H (all with –COOH end groups) were studied. The implants were characterized before and after exposure to phosphate buffer pH 7.4 at 37 °C. Interestingly, in all cases polymer swelling seems to play an "orchestrating" role for drug release: At early time points, the amounts of water penetrating into the systems are limited (since the macromolecules are hydrophobic and highly entangled). Consequently, only small amounts of drug can dissolve and the dissolved drug molecules are not sufficiently mobile to diffuse out to a noteworthy extent (negligible dexamethasone release for up to 6 weeks). However, the water that is able to enter the implants at early time points cleaves the polyesters right from the beginning. Due to the newly generated –COOH end groups and decreased chain length, the macromolecules become more and more hydrophilic and less entangled. In addition, water-soluble polymer degradation products build up a steadily increasing osmotic pressure, attracting water into the system. Once a critical polymer molecular weight threshold range (around 8 kDa) is reached, substantial implant swelling starts: The systems' volume increases up to 600–1700% and the water contents exceeds 80–90% (partially approaching 100%). Under these fundamentally altered conditions, significant drug amounts can dissolve and the dissolved drug molecules are sufficiently mobile to diffuse out of the implants: Drug release sets on. In brief, polymer swelling "orchestrates" the involved mass transport phenomena: It enables drug release after a certain lag time by fundamentally changing the conditions for drug dissolution and diffusion. Note that in other types of implants, additional mass transport phenomena might be involved, e.g. no burst release was observed from the investigated, initially non-porous implants. Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to understand the pore formation mechanisms of degrading poly(d , l -lactic -co- glycolic acid) (PLGA) microparticulate systems. This was investigated through an original microparticles cross-section imaging method. Atorvastatin (ATV)-loaded 16- to 18-μm spherical microparticles with polymers of varying molecular weights (8 to 45 kDa) were prepared. The evolution of the particles during in vitro drug release experiments was monitored in terms of molecular weight, pore formation and glass transition temperature. During the 2nd phase of release, two types of pores were observed: small pores near the particle's periphery and larger pores in the core. The pattern of pore formation was shown to be related to the shape of the drug release curve. At the onset of the 3rd phase, the polymer transitions to a less glassy state, allowing for the swelling of the microparticles. Overall, we present evidence that pore formation is not uniformly distributed throughout PLGA microparticles, and that it could determine the drug release kinetics. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

The blood–brain barrier (BBB) restricts the transport of potential therapeutic moieties to the brain. Direct targeting the brain via olfactory and trigeminal neural pathways by passing the BBB has gained an important consideration for delivery of wide range of therapeutics to brain. Intranasal route of transportation directly delivers the drugs to brain without systemic absorption, thus avoiding the side effects and enhancing the efficacy of neurotherapeutics. Over the last several decades, different drug delivery systems (DDSs) have been studied for targeting the brain by the nasal route. Novel DDSs such as nanoparticles (NPs), liposomes and polymeric micelles have gained potential as useful tools for targeting the brain without toxicity in nasal mucosa and central nervous system (CNS). Complex geometry of the nasal cavity presented a big challenge to effective delivery of drugs beyond the nasal valve. Recently, pharmaceutical firms utilized latest and emerging nasal drug delivery technologies to overcome these barriers. This review aims to describe the latest development of brain targeted DDSs via nasal administration. Chemical compounds studied in this article Carbopol 934p (PubChem CID: 6581) Carboxy methylcellulose (PubChem CID: 24748) Penetratin (PubChem CID: 101111470 ) Poly lactic- co -glycolic acid (PubChem CID: 23111554) Tween 80 (PubChem CID: 5284448 ) [ABSTRACT FROM AUTHOR]

Mineralocorticoid receptor (MR) contributes to retinal/choroidal homeostasis. Excess MR activation has been shown to be involved in pathogenesis of central serous chorioretinopathy (CSCR). Systemic administration of MR antagonist (MRA) reduces subretinal fluid and choroidal vasodilation, and improves the visual acuity in CSCR patients. To achieve long term beneficial effects in the eye while avoiding systemic side-effects, we propose the use of biodegradable spironolactone-loaded poly-lactic- co -glycolic acid (PLGA) microspheres (MSs). In this work we have evaluated the ocular tolerance of MSs containing spironolactone in rat' eyes. As previous step, we have also studied the tolerance of the commercial solution of canrenoate salt, active metabolite of spironolactone. PLGA MSs allowed in vitro sustained release of spironolactone for 30 days. Rat eyes injected with high intravitreous concentration of PLGA MSs (10 mg/mL) unloaded and loaded with spironolactone maintained intact retinal lamination at 1 month. However enhanced glial fibrillary acidic protein immunostaining and activated microglia/macrophages witness retinal stress were observed. ERG also showed impaired photoreceptor function. Intravitreous PLGA MSs concentration of 2 mg/mL unloaded and loaded with spironolactone resulted well tolerated. We observed reduced microglial/macrophage activation in rat retina compared to high concentration of MSs with normal retinal function according to ERG. Spironolactone released from low concentration of MSs was active in the rat retina. Low concentration of spironolactone-loaded PLGA MSs could be a safe therapeutic choice for chorioretinal disorders in which illicit MR activation could be pathogenic. [ABSTRACT FROM AUTHOR]

The skin is an attractive organ for immunization due to the presence of a large number of epidermal and dermal antigen-presenting cells. Hollow microneedles allow for precise and non-invasive intradermal delivery of vaccines. In this study, ovalbumin (OVA)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles with and without TLR3 agonist poly(I:C) were prepared and administered intradermally by hollow microneedles. The capacity of the PLGA nanoparticles to induce a cytotoxic T cell response, contributing to protection against intracellular pathogens, was examined. We show that a single injection of OVA-loaded PLGA nanoparticles, compared to soluble OVA, primed both adoptively transferred antigen-specific naïve transgenic CD8 + and CD4 + T cells with markedly high efficiency. Applying a triple immunization protocol, PLGA nanoparticles primed also endogenous OVA-specific CD8 + T cells. Immune response, following immunization with in particular anionic PLGA nanoparticles co -encapsulated with OVA and poly(I:C), provided protection against a recombinant strain of the intracellular bacterium Listeria monocytogenes , secreting OVA. Taken together, we show that PLGA nanoparticle formulation is an excellent delivery system for protein antigen into the skin and that protective cellular immune responses can be induced using hollow microneedles for intradermal immunizations. [ABSTRACT FROM AUTHOR]

Polymeric microneedle (MN) arrays continue to receive growing attention due to their ability to bypass the skin's stratum corneum barrier in a minimally-invasive fashion and achieve enhanced transdermal drug delivery and “targeted” intradermal vaccine administration. In this research work, we fabricated biodegradable bilayer MN arrays containing nano - microparticles for targeted and sustained intradermal drug delivery. For this study, model drug (vitamin D 3 , VD 3 )-loaded PLGA nano- and microparticles (NMP) were prepared by a single emulsion solvent evaporation method with 72.8% encapsulation of VD 3 . The prepared NMP were directly mixed 20% w/v poly(vinyl pyrrolidone) (PVP) gel, with the mixture filled into laser engineered micromoulds by high-speed centrifugation (30 min) to concentrate NMP into MN shafts. The particle size of PLGA NMP ranged from 300 nm to 3.5 μm and they retained their particle size after moulding of bilayer MN arrays. The relatively wide particle size distribution of PLGA NMP was shown to be important in producing a compact structure in bilayer conical, as well as pyramidal, MN, as confirmed by scanning electron microscopy. The drug release profile from PLGA NMP was tri-phasic, being sustained over 5 days. The height of bilayer MN arrays was influenced by the weight ratio of NMP and 20% w/v PVP. Good mechanical and insertion profiles (into a skin simulant and excised neonatal porcine skin) were confirmed by texture analysis and optical coherence tomography, respectively. Ex vivo intradermal neonatal porcine skin penetration of VD 3 NMP from bilayer MN was quantitatively analysed after cryostatic skin sectioning, with 74.2 ± 9.18% of VD 3 loading delivered intradermally. The two-stage novel processing strategy developed here provides a simple and easy method for localising particulate delivery systems into dissolving MN. Such systems may serve as promising means for controlled transdermal delivery and targeted intradermal administration. [ABSTRACT FROM AUTHOR]

In this study lipoplexes containing chemically modified messenger RNA (cmRNA) were incorporated into poly (lactic- co -glycolic acid) (PLGA) microspheres via water-in-oil-in-water (W/O/W) double emulsion solvent evaporation technique. The nanoparticle encapsulation by microparticle formation was optimized to achieve lipoplex release and maximum transfection efficiency in surrounding cells. It was possible to adjust characteristic features in surface topology and size of the PLGA-microspheres by varying the extent of lipoplex loading into the polymer matrix. The partial release of lipids and mRNA out of the microparticle system, their accumulation in cells and the production of encoded protein were visualized via fluorescence microscopy. These bioactive microspheres, containing cmRNA bearing lipoplexes, were developed for the incorporation of a therapeutic component into injectable calcium phosphate cements (CPC). Due to the incorporation of PLGA/lipoplex microspheres as a degradable entity, the porosity of the cement phase could additionally be adjusted. This approach of complex nanoparticle incorporation into polymer/cement composites represents a promising example for combining transcript therapy with biomechanical engineering. [ABSTRACT FROM AUTHOR]

Sustained pulmonary drug delivery is regarded as an effective strategy for local treatment of chronic lung diseases. Despite of the progress made so far, there remains a need for respirable drug loaded porous microparticles, where porosity of the microparticles can be readily engineered during the preparation process, with tunable sustained drug release upon lung deposition. In this work, polyvinyl pyrrolidone (PVP) was used as a novel porogen to engineer PLGA-based large porous particles (LPPs) using single emulsion method, with fine tuning of the porosity, sustained drug release both in vitro and in vivo. Using cinaciguat as the model drug, influence of PVP content and PLGA type on the properties of the LPPs was characterized, including geometric particle size, drug encapsulation efficiency, tap density, theoretical and experimental aerodynamic particle size, specific surface area, morphology, and in vitro drug release. Solid state of cinaciguat in the LPPs was studied based on DSC and X-ray analysis. LPPs retention in the rat lung was carried out using bronchoalveolar lavage fluid method. Raw 264.7 macrophage cells were used for LPPs uptake study. Pharmacodynamic study was performed in mini-pigs in a well-established model of pulmonary arterial hypertension (thromboxane challenge). It was demonstrated that porosity of the LPPs is tunable via porogen content variation. Cinaciguat can be released from the LPP in a controlled manner for over 168 h. Significant reduction of macrophage phagocytosis was presented for LPPs. Furthermore, LPPs was found to have extended retention time (~ 36 h) in the rat lung and accordingly, sustained pharmacodynamics effect was achieved in mini-pig model. Taken together, our results demonstrated that this simple PLGA based LPPs engineering using single emulsion method with PVP as porogen may find extensive application for the pulmonary delivery of hydrophobic drugs to realize tunable sustained effect with good safety profile. [ABSTRACT FROM AUTHOR]

Intimal hyperplasia (IH) is the major cause of grafted vessel occlusion and occurs frequently after bypass intervention. No pharmaceutical formulation is currently available to prevent this pathology. Local perivascular delivery of an appropriate active compound released in a time-dependent manner (from day one up to 4 weeks) is necessary for an efficient single-administration preventive therapy. To this aim, we propose the combination of gel and microparticles delivery system containing atorvastatin (ATV). The incorporation of ATV in a cross-linked hyaluronic acid gel, provided in vitro a fast release over 3 days, while ATV-loaded poly-lactic- co -glycolic acid (PLGA) microparticles dispersed in the gel gave a sustained release over 4 weeks. In vivo , ATV formulations were applied perivascularly in mice undergoing carotid artery ligation. IH was significantly reduced (‐ 68%) in presence of ATV incorporated in hyaluronic acid gel and encapsulated in microparticles compared to control. No significant IH alteration was observed when ATV was incorporated only in the gel (fast release) or only in the microparticles (slow release) demonstrating that a biphasic release of ATV is essential to interfere with the development of IH. ATV was detected in adjacent tissues 28 days after the intervention, showing the sustained presence of the drug in vivo . After four weeks ATV was not detected in remote tissues, except at a very low concentration (0.044 ng/mg) in the liver, suggesting a very low risk of systemic toxicity of locally delivered ATV. Additionally, the ex vivo data showed that ATV in solution permeates through isolated human saphenous veins and thus is a good candidate for perivascular delivery. Our data demonstrate that a local biphasic ATV release on the mice ligated carotid efficiently prevents the development of IH without apparent toxicity. [ABSTRACT FROM AUTHOR]

Nanoparticulate formulations for synthetic long peptide (SLP)-cancer vaccines as alternative to clinically used Montanide ISA 51- and squalene-based emulsions are investigated in this study. SLPs were loaded into TLR ligand-adjuvanted cationic liposomes and PLGA nanoparticles (NPs) to potentially induce cell-mediated immune responses. The liposomal and PLGA NP formulations were successfully loaded with up to four different compounds and were able to enhance antigen uptake by dendritic cells (DCs) and subsequent activation of T cells in vitro . Subcutaneous vaccination of mice with the different formulations showed that the SLP-loaded cationic liposomes were the most efficient for the induction of functional antigen-T cells in vivo , followed by PLGA NPs which were as potent as or even more than the Montanide and squalene emulsions. Moreover, after transfer of antigen-specific target cells in immunized mice, liposomes induced the highest in vivo killing capacity. These findings, considering also the inadequate safety profile of the currently clinically used adjuvant Montanide ISA-51, make these two particulate, biodegradable delivery systems promising candidates as delivery platforms for SLP-based immunotherapy of cancer. [ABSTRACT FROM AUTHOR]

Necrotic cell death occurs exclusively under pathological conditions, such as ischemic diseases. Necrosis imaging is of diagnostic value and enables early measurement of treatment efficiency in ischemic patients. Here we explored the targeted delivery of particles, with diameters of approximately 100 nm, 200 nm and 800 nm, consisting of a poly(lactic-co-glycolic acid) (PLGA) nanoparticle (NP) core coated with a polyethylene glycol-lipid (PEG) layer. Targeted delivery was facilitated by coupling the amino end group of the polyethylene glycol-layer to 800CW imaging agent, which specifically binds to intracellular proteins of cells that have lost membrane integrity, thus revealing the extent of the damaged area. We found that smaller NPs (100 nm), with an appropriate coating, diffuse throughout the traumatic brain injury (TBI) in mice. Optical imaging revealed that smaller (100-nm) PEG-coated NPs carrying 800CW penetrated deeper into the mouse brain than large 800CW containing NPs (800 nm). The importance of the 800CW as a ligand to target the necrotic tissue was further confirmed in living mice. The ability to achieve brain penetration with smaller NPs is expected to allow more uniform, longer-lasting, and effective delivery of drugs within the brain, and may find application in the treatment of stroke, brain tumors, neuroinflammation, and other brain diseases where the blood–brain barrier is compromised or where local delivery strategies are feasible. [ABSTRACT FROM AUTHOR]

The growth factor neuregulin (NRG) is one of the most promising candidates in protein therapy as potential treatment for myocardial infarction (MI). In the last few years, biomaterial based delivery systems, such as polymeric microparticles (MPs) made of poly(lactic co glycolic acid) and polyethylene glycol (PLGA and PEG–PLGA MPs), have improved the efficacy of protein therapy in preclinical studies. However, no cardiac treatment based on MPs has yet been commercialized since this is a relatively new field and total characterization of polymeric MPs remains mandatory before they reach the clinical arena. Therefore, the objective of this study was to characterize the in vivo release, bioactivity and biodegradation of PLGA and PEG–PLGA MPs loaded with biotinylated NRG in a rat model of MI. The effect of PEGylation in the clearance of the particles from the cardiac tissue was also evaluated. Interestingly, MPs were detected in the cardiac tissue for up to 12 weeks after administration. In vivo release analysis showed that bNRG was released in a controlled manner throughout the twelve week study. Moreover, the biological cardiomyocyte receptor (ErbB4) for NRG was detected in its activated form only in those animals treated with bNRG loaded MPs. On the other hand, the PEGylation strategy was effective in diminishing phagocytosis of these MPs compared to noncoated MPs in the long term (12 weeks after injection). Taking all this together, we report new evidence in favor of the use of polymeric PLGA and PEG–PLGA MPs as delivery systems for treating MI, which could be soon included in clinical trials. [ABSTRACT FROM AUTHOR]

Multipotent mesenchymal stem cells (MSCs) promise a therapeutic alternative for many debilitating and incurable diseases. However, one of the major limitations for the therapeutic application of human MSC (hMSC) is the lengthy ex vivo expansion time for preparing a sufficient amount of cells due to the low engraftment rate after transplantation. To solve this conundrum, a porous biodegradable polymeric microsphere was investigated as a potential scaffold for the delivery of MSCs. The modified water/oil/water (W 1 /O/W 2 ) double emulsion solvent evaporation method was used for the construction of porous microspheres. PEI 1.8k was blended with poly(lactic-co-glycolic acid) (PLGA) to enhance electrostatic cellular attachment to the microspheres. The porous PLGA/PEI 1.8k (PPP) particles demonstrated an average particle size of 290 μm and an average pore size of 14.3 μm, providing a micro-carrier for the MSC delivery. PPP particles allowed for better attachment of rMSCs than non-porous PLGA/PEI 1.8k (NPP) particles and non-porous (NP) and porous PLGA (PP) microspheres. rMSC successfully grew on the PPP particles for 2 weeks in vitro . Next, PPP particles loaded with 3 different amounts of hMSC showed increased in vivo engraftment rates and maintained the stemness characteristics of hMSC compared with hMSCs-alone group in rats 2 weeks after intramyocardial administration. These customized PPP particles for MSC delivery are a biodegradable and injectable scaffold that can be used for clinical applications. [ABSTRACT FROM AUTHOR]

In this work, the foreign body reaction (FBR) to small subcutaneous implants was compared between small (rodent) and large (swine) animal species for the first time. Dexamethasone-releasing poly(lactic-co-glycolic acid) microspheres/polyvinyl alcohol hydrogel composite coatings were adapted to prevent FBR to small, subcutaneous implants in a large animal model (Goettingen minipigs). The implants consisted of small silicon chips (used to mimic small medical devices) that were coated with the composite formulations. The stages of the FBR were compared with previous studies in rats (that used the same-sized implants); the onset and severity of chronic inflammation (collagen deposition) was identified as a key difference between the two species. In the absence of inflammation control, fibrosis was observed from day 7 post-implantation in minipigs, whereas in rats this did not occur until day 14. This is significant as swine skin is the most commonly used model for preclinical testing of dermal formulations. It was determined that for long-term prevention of the FBR (longer than 24 h), a lag phase in dexamethasone release between days 1 and 10 did not affect the anti-FBR properties of the implant in rats. However, continuous release of dexamethasone, with no lag phase, was necessary to prevent inflammation in minipigs (effective dexamethasone dose was 100 μg delivered immediately after implantation and 10 μg/day delivered continuously thereafter). This study offers significant insight into the translation of anti-FBR strategies across species, and showcases the importance of tailoring the controlled release kinetics of the formulation to the host response. [ABSTRACT FROM AUTHOR]

A biomimetic approach to organic solvent-free microencapsulation of proteins based on the self-healing capacity of poly ( dl )-lactic-co-glycolic acid (PLGA) microspheres containing glycosaminoglycan-like biopolymers (BPs), was examined. To screen BPs, aqueous solutions of BP [high molecular weight dextran sulfate (HDS), low molecular weight dextran sulfate (LDS), chondroitin sulfate (CS), heparin (HP), hyaluronic acid (HA), chitosan (CH)] and model protein lysozyme (LYZ) were combined in different molar and mass ratios, at 37 °C and pH 7. The BP-PLGA microspheres (20–63 μm) were prepared by a double water–oil–water emulsion method with a range of BP content, and trehalose and MgCO 3 to control microclimate pH and to create percolating pores for protein. Biomimetic active self-encapsulation (ASE) of proteins [LYZ, vascular endothelial growth factor165 (VEGF) and fibroblast growth factor (FgF-20)] was accomplished by incubating blank BP-PLGA microspheres in low concentration protein solutions at ~ 24 °C, for 48 h. Pore closure was induced at 42.5 °C under mild agitation for 42 h. Formulation parameters of BP-PLGA microspheres and loading conditions were studied to optimize protein loading and subsequent release. LDS and HP were found to bind > 95% LYZ at BP:LYZ > 0.125 w/w, whereas HDS and CS bound > 80% LYZ at BP:LYZ of 0.25–1 and < 0.33, respectively. HA-PLGA microspheres were found to be not ideal for obtaining high protein loading (> 2% w/w of LYZ). Sulfated BP-PLGA microspheres were capable of loading LYZ (~ 2–7% w/w), VEGF (~ 4% w/w), and FgF-20 (~ 2% w/w) with high efficiency. Protein loading was found to be dependent on the loading solution concentration, with higher protein loading obtained at higher loading solution concentration within the range investigated. Loading also increased with content of sulfated BP in microspheres. Release kinetics of proteins was evaluated in-vitro with complete release media replacement. Rate and extent of release were found to depend upon volume of release (with non-sink conditions observed < 5 ml release volume for ~ 18 mg loaded BP-PLGA microspheres), ionic strength of release media and loading solution concentration. HDS-PLGA formulations were identified as having ideal loading and release characteristics. These optimal microspheres released ~ 73–80% of the encapsulated LYZ over 60 days, with > 90% of protein being enzymatically active. Nearly 72% of immunoreactive VEGF was similarly released over 42 days, without significant losses in heparin binding affinity in the release medium. [ABSTRACT FROM AUTHOR]

Biodegradable, injectable depot formulations for long-term controlled drug release have improved therapy for a number of drug molecules and led to over a dozen highly successful pharmaceutical products. Until now, success has been limited to several small molecules and peptides, although remarkable improvements have been accomplished in some of these cases. For example, twice-a-year depot injections with leuprolide are available compared to the once-a-day injection of the solution dosage form. Injectable depots are typically prepared by encapsulation of the drug in poly(lactic- co -glycolic acid) (PLGA), a polymer that is used in children every day as a resorbable suture material, and therefore, highly biocompatible. PLGAs remain today as one of the few “real world” biodegradable synthetic biomaterials used in US FDA-approved parenteral long-acting-release (LAR) products. Despite their success, there remain critical barriers to the more widespread use of PLGA LARproducts, particularly for delivery of more peptides and other large molecular drugs, namely proteins. In this review, we describe key concepts in the development of injectable PLGA controlled-release depots for peptides and proteins, and then use this information to identify key issues impeding greater widespread use of PLGA depots for this class of drugs. Finally, we examine important approaches, particularly those developed in our research laboratory, toward overcoming these barriers to advance commercial LAR development. [ABSTRACT FROM AUTHOR]

Abstract: In the paper, we begin by describing polyethylene glycol–poly lactic acid-co-glycolic acid (PEG–PLGA) which was chosen as a typical model copolymer for the construction of nano-sized drug delivery systems and also the types of PEG–PLGA copolymers that were eluted. Following this we examine the structure-influenced drug delivery applications including nanoparticles, micelles and hydrogels. After that, the preparation methods for nano-sized delivery systems are presented. In addition, the drug loading mode of PEG–PLGA micelles is divided into three aspects. Finally, the drug release profiles of PEG–PLGA micelles, both in terms of their in vitro and in vivo characteristics, are represented. PEG–PLGA copolymers are very suitable for the construction of micelles as carriers for insoluble drugs. This article reviews the structure and the different structure-influenced applications of PEG–PLGA copolymers, concentrating on the application of PEG–PLGA micelles. [Copyright &y& Elsevier]

Abstract: Wound healing is a complex process involving many interdependent and overlapping sequences of physiological actions. The application of exogenous lactate released from poly (lactic-co-glycolic acid) (PLGA) polymer accelerated angiogenesis and wound healing processes. Curcumin is a well-known topical wound healing agent for both normal and diabetic-impaired wounds. Hence, we hypothesized that the PLGA nanoparticles encapsulating curcumin could much potentially accelerate the wound healing. In a full thickness excisional wound healing mouse model, PLGA–curcumin nanoparticles showed a twofold higher wound healing activity compared to that of PLGA or curcumin. Histology and RT-PCR studies confirmed that PLGA–curcumin nanoparticles exhibited higher re-epithelialization, granulation tissue formation and anti-inflammatory potential. PLGA nanoparticles offered various benefits for the encapsulated curcumin like protection from light degradation, enhanced water solubility and showed a sustained release of curcumin over a period of 8days. In conclusion, we demonstrated the additive effect of lactic acid from PLGA and encapsulated curcumin for the active healing of wounds. [Copyright &y& Elsevier]

Abstract: A lot of research has been carried out in the last decade to find a cure for neurodegenerative diseases especially Parkinson's disease but to little avail. In this study we have demonstrated the use of poly(lactic-co-glycolic acid) (PLGA)/collagen biodegradable microparticles formed using water-in-oil-in-water (W/O/W) double emulsion method, as a neurotrophic factor delivery vehicle. The microparticles were encapsulated with glial cell-derived neurotrophic factor (GDNF) fused with collagen binding peptide (CBP) immobilized to the inner collagen phase. The novelty lies in the strict regulation of release of GDNF-CBP from the microparticles as compared to a burst release from standard microparticles. The microparticles were demonstrated to be non-cytotoxic till 300μg/2×105 cells and revealed a maximum release of 250ng GDNF-CBP/mg microparticles in 0.3% collagenase. Differentiation of neural progenitor cells (NPCs) into mature neurons was demonstrated by co-culturing microparticles with cells in a medium containing collagenase which enabled the release of encapsulated GDNF-CBP, signaling the differentiation of NPCs into microtubule-associated protein 2 (MAP2)-expressing neurons. The successful ability of these microparticles to deliver neurotrophic factors and allow differentiation of NPCs into mature neurons provides some scope in its use for the treatment of Parkinson's disease and other neurodegenerative diseases. [Copyright &y& Elsevier]

Abstract: Many autoimmune diseases and other chronic inflammatory disorders are characterized by defective FoxP3+ regulatory T-cell (Treg) mediated suppression. A potential treatment option for these disorders is to increase the number and activity of Tregs locally. Both PLGA (poly-lactic-co-glycolic acid) and TMC-TPP (N-trimethyl chitosan tripolyphosphate) nanoparticles (NP) have been described to enhance T cell activation upon nasal application. Since, PLGA NP and TMC-TPP NP differentially affect CD4+ T-cell differentiation, we investigated in vitro the capacity of both delivery systems to trigger retinoic acid (RA) production in dendritic cells (DCs) as a strategy to enhance the induction of FoxP3+ T-cells. We generated ovalbumin (OVA)-encapsulated PLGA NP and TMC-TPP NP that were similar in size (400nm) but differed in their surface charge and other physico-chemical properties. We demonstrate that OVA-specific T-cells that are activated by cervical lymph node (CLN)-derived DCs treated with PLGA NP or TMC-TPP NP show more FoxP3 expression than T-cells that are activated by inguinal lymph node (ILN) cells. We demonstrate that only OVA-encapsulated PLGA NP enhance the induction of FoxP3 in activated T-cells via a TGF-β and RA dependent mechanism by enhancing retinaldehyde dehydrogenase enzyme (RALDH) expression in CLN-derived DCs that is required for RA production. Additionally, detailed analysis of the CD4+ T-cell response reveals that PLGA NP induce both IL-10 and IFN-γ production, while TMC-TPP NP induce mainly Th17 production. Underlining that both APC origin and NP characteristics determine the expression level of FoxP3 in activated T-cells. In conclusion, our data suggest that PLGA NP enhance the induction of FoxP3+ T-cells in the CLN through modulation of DC function and we suggest that they might be a suitable nasal delivery system to treat a wide variety of autoimmune diseases and other chronic inflammatory disorders. [Copyright &y& Elsevier]

Abstract: Embryoid bodies (EBs) generated from embryonic stem cells are used to study processes of differentiation within a three dimensional (3D) cell environment. In many instances however, EBs are dispersed to single cell suspensions with a subsequent monolayer culture. Moreover, where the 3D integrity of an EB is maintained, cytokines or drugs of interest to stimulate differentiation are often added directly to the culture medium at fixed concentrations and effects are usually limited to the outer layers of the EB. The aim of this study was to create an EB model with localised drug and or growth factor delivery directly within the EB. Using poly(DL-lactic acid-co-glycolic acid) microparticles (MPs) with an average diameter of 13μm, we have demonstrated controllable incorporation of defined numbers of MPs within human ES cell derived EBs, down to 1 MP per EB. This was achieved by coating MPs with human ES cell lysate and centrifugation of specific ratios of ES cells and MPs to form 3D aggregates. Using MPs loaded with simvastatin (pro or active drug) or BMP-2, we have demonstrated osteogenic differentiation within the 3D aggregates, maintained in culture for up to 21days, and quantified by real time QPCR for osteocalcin. Immunostaining for RUNX2 and osteocalcin, and also histochemical staining with picrosirius red to demonstrate collage type 1 and Alizarin red to demonstrate calcium/mineralisation further demonstrated osteogenic differentiation and revealed regional staining associated with the locations of MPs within the aggregates. We also demonstrated endothelial differentiation within human ES cell-derived aggregates using VEGF loaded MPs. In conclusion, we demonstrate an effective and reliable approach for engineering stem aggregates with definable number of MPs within the 3D cellular structure. We also achieved localised osteogenic and endothelial differentiation associated with MPs releasing encapsulated drug molecules or cytokines directly within the cell aggregate. This provides a powerful tool for controlling and investigating differentiation within 3D cell cultures and has applications to drug delivery, drug discovery, stem cell biology, tissue engineering and regenerative medicine. [Copyright &y& Elsevier]

Abstract: Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) conjugated to a cell-penetrating peptide, TAT, was used to increase intracellular delivery of paclitaxel (PTX) to multi-drug resistant (MDR) cells. Efficient cellular uptake of the TAT-conjugated PLGA NPs was observed; however, it did not translate to increased killing of MDR cells. An investigation of drug release kinetics in phosphate-buffered saline containing Tween 80 led us to suspect that a significant fraction of the loaded PTX was released before efficient cellular uptake could occur. These results indicate that the increased cellular uptake of NPs does not always mean an enhanced drug effect and that it is critical to control both the location of NPs and the drug release from NPs together. Based on this study, we propose that two prevalent practices in NP research be reconsidered: first, the utility of a new NP system should be tested beyond the imaging level. Second, NP release kinetics should be monitored in a medium that can reflect the complexity of biological environment rather than a simple buffered saline. [Copyright &y& Elsevier]

Abstract: Current drug eluting stent (DES) technology is not optimized with regard to the pharmacokinetics of drug delivery. A novel, absorbable-coating sirolimus-eluting stent (AC-SES) was evaluated for its capacity to deliver drug more evenly within the intimal area rather than concentrating drug around the stent struts and for its ability to match coating erosion with drug release. The coating consisted of absorbable poly-lactide-co-glycolic acid (PLGA) and crystalline sirolimus deposited by a dry-powder electrostatic process. The AC-SES demonstrated enhanced drug stability under simulated use conditions and consistent drug delivery balanced with coating erosion in a porcine coronary implant model. The initial drug burst was eliminated and drug release was sustained after implantation. The coating was absorbed within 90days. Following implantation into porcine coronary arteries the AC-SES coating is distributed in the surrounding intimal tissue over the course of several weeks. Computational modeling of drug delivery characteristics demonstrates how distributed coating optimizes the load of drug immediately around each stent strut and extends drug delivery between stent struts. The result was a highly efficient arterial uptake of drug with superior performance to a clinical bare metal stent (BMS). Neointimal thickness (0.17±0.07mm vs. 0.28±0.11mm) and area percent stenosis (22±9% vs. 35±12%) were significantly reduced (p<0.05) by the AC-SES compared to the BMS 30days after stent implantation in an overlap configuration in porcine coronary arteries. Inflammation was significantly reduced in the AC-SES compared to the BMS at both 30 and 90days after implantation. Biocompatible, rapidly absorbable stent coatings enable the matching of drug release with coating erosion and provide for the controlled migration of coating material into tissue to reduce vicissitudes in drug tissue levels, optimizing efficacy and reducing potential toxicity. [Copyright &y& Elsevier]

Abstract: Polymer microspheres for controlled release of therapeutic protein from within an implantable scaffold were produced and analysed using complimentary techniques to probe the surface and bulk chemistry of the microspheres. Time of Flight – Secondary Ion Mass Spectrometry (ToF-SIMS) surface analysis revealed a thin discontinuous film of polyvinyl alcohol (PVA) surfactant (circa 4.5nm thick) at the surface which was readily removed under sputtering with C60. Atomic Force Microscopy (AFM) imaging of microspheres before and after sputtering confirmed that the PVA layer was removed after sputtering revealing poly(lactic-co-glycolic) acid(PLGA). Scanning electron microscopy showed the spheres to be smooth with some shallow and generally circular depressions, often with pores in their central region. The occurrence of the protein at the surface was limited to areas surrounding these surface pores. This surface protein distribution is believed to be related to a burst release of the protein on dissolution. Analysis of the bulk properties of the microspheres by confocal Raman mapping revealed the 3D distribution of the protein showing large voids within the pores. Protein was found to be adsorbed at the interface with the PLGA oil phase following deposition on evaporation of the solvent. Protein was also observed concentrated within pores measuring approximately 2μm across. The presence of protein in large voids and concentrated pores was further scrutinised by ToF-SIMS of sectioned microspheres. This paper demonstrates that important information for optimisation of such complex bioformulations, including an understanding of the release profile can be revealed by complementary surface and bulk analysis allowing optimisation of the therapeutic effect of such formulations. [Copyright &y& Elsevier]

Abstract: Biodegradable poly(lactide-co-glycolide) (PLGA) microspheres (MS) deliver antigens and toll like receptor (TLR) ligands to antigen presenting cells (APC) in vitro and in vivo. PLGA-MS-microencapsulated model antigens are efficiently presented on MHC class I and II molecules of dendritic cells and stimulate strong cytotoxic and T helper cell responses enabling the eradication of pre-existing model tumors. The application of tumor lysates as a source of antigen for immunotherapy has so far not been very successful also due to a lack of suitable delivery systems. In this study we used PLGA-MS with co-encapsulated tumor lysates and CpG oligodeoxynucleotides (CpG-ODN) as well as microencapsulated polyI:C in order to elicit anti-tumor responses. Immunization of mice with such mixtures of MS yielded substantial cytotoxic T cell (CTL) responses and interfered with tumor growth in TRAMP mice, a pre-clinical transgenic mouse model of prostate carcinoma, which has previously resisted dendritic cell‐based therapy. As an important step towards clinical application of PLGA-MS, we could show that γ-irradiation of PLGA-MS sterilized the MS, without reducing their efficacy in eliciting CTL and anti-tumor responses in subcutaneous tumor grafts. Since PLGA is approved for clinical application, sterilized PLGA-MS containing tumor lysates and TLR ligands hold promise as anti-tumor vaccines against prostate carcinoma in humans. [Copyright &y& Elsevier]

Abstract: The main objective of this study was to characterize and find mechanisms to prevent acylation of therapeutic peptides encapsulated in glucose-star poly(d,l-lactic-co-glycolic acid) (PLGA) microspheres. The effect of addition of divalent cation salts CaCl2, MnCl2 as well as carboxymethyl chitosan (CMCS) on inhibition of acylation of octreotide (Oct), salmon calcitonin (sCT), and human parathyroid hormone (hPTH) was evaluated. Peptide content and integrity inside the degrading microspheres was monitored by reversed-phase high performance liquid chromatography (HPLC) and mass spectrometry during release incubation under physiological conditions. The extent of peptide acylation was strongly inhibited in the formulations containing divalent cations and/or CMCS as excipients, although specific effects were dependent on the specific peptide and excipient combinations. Both inorganic cations improved stability of Oct and hPTH but not sCT. Addition of CMCS alone was ineffective. Combining inorganic cations with CMCS improved stability of Oct and sCT but it had no effect on hPTH stability. The operative stabilization mechanisms are consistent with blocking peptide–PLGA interactions by a) directly competing for PLGA interactions with dications and/or b) increasing peptide affinity in the stabilizer phase within PLGA pores. Hence, inorganic multivalent cations are general stabilizers against peptide acylation, the effect of which may be augmented in certain instances with addition of CMCS. [Copyright &y& Elsevier]

Abstract: We have developed a local anesthetic-eluting suture system which would combine the function and ubiquity of the suture for surgical repair with the controlled release properties of a biodegradable polymeric matrix. Drug-free and drug-loaded poly(lactic-co-glycolic acid) (PLGA) sutures were fabricated by electrospinning, with or without the local anesthetic bupivacaine. The tensile strength of the electrospun sutures decreased as drug content increased, but strains remained relatively similar across all groups. Sutures released their entire drug payload over the course of 12days and maintained approximately 12% of their initial tensile strength after 14days of incubation in vitro. In a rat skin wound model, local analgesia was achieved 1day after surgery and lasted approximately 1week in 90% of treated animals (n =10, p <0.05), and all wounds were able to heal normally without the need for further reinforcement. The sutures caused tissue reaction in vivo that was comparable to that seen with a commercially available suture composed of PLGA. Such sutures may enhance perioperative analgesia and mitigate the need for standard postoperative opioid analgesics. [Copyright &y& Elsevier]

Abstract: Neurotrophin-3 (NT-3) has shown promise in regenerative strategies after spinal cord injury; however, sustained local delivery is difficult to achieve by conventional methods. Controlled release from poly(lactic-co-glycolic acid) (PLGA) nanoparticles has been studied for numerous proteins, yet achieving sustained release of bioactive proteins remains a challenge. To address these issues, we designed a composite drug delivery system comprised of NT-3 encapsulated in PLGA nanoparticles dispersed in an injectable hydrogel of hyaluronan and methyl cellulose (HAMC). A continuum model was used to fit the in vitro release kinetics of an NT-3 analog from a nanoparticle formulation. Interestingly, the model suggested that the linear drug release observed from composite HAMC was due to a diffusion-limiting layer of methyl cellulose on the particle surface. We then studied the effects of processing parameters and excipient selection on NT-3 release, stability, and bioactivity. Trehalose was shown to be the most effective additive for stabilizing NT-3 during sonication and lyophilization and PLGA itself was shown to stabilize NT-3 during these processes. Of four excipients tested, 400g/mol poly(ethylene glycol) was the most effective during nanoparticle fabrication, with 74% of NT-3 detected by ELISA. Conversely, co-encapsulation of magnesium carbonate with NT-3 was the most effective in maintaining NT-3 bioactivity over 28days according to a cell-based axonal outgrowth assay. Together, the modeling and optimized processing parameters provide insight critical to designing a controlled bioactive release formulation for ultimate testing in vivo. [Copyright &y& Elsevier]