In vitro release characteristics and cellular uptake of poly(D,L-lactic-co-glycolic acid) nanoparticles for topical delivery of antisense oligodeoxynucleotides

Insights on Development Aspects of Polymeric Nanocarriers: The Translation from Bench to Clinic

Scientists are focusing immense attention on polymeric nanocarriers as a prominent delivery vehicle for several biomedical applications including diagnosis of diseases, delivery of therapeutic agents, peptides, proteins, genes, siRNA, and vaccines due to their exciting physicochemical characteristics which circumvent degradation of unstable drugs, reduce toxic side effects through controlled release, and improve bioavailability. Polymers-based nanocarriers offer numerous benefits for in vivo drug delivery such as biocompatibility, biodegradability, non-immunogenicity, active drug targeting via surface modification, and controlled release due to their pH—and thermosensitive characteristics. Despite their potential for medicinal use, regulatory approval has been achieved for just a few. In this review, we discuss the historical development of polymers starting from their initial design to their evolution as nanocarriers for therapeutic delivery of drugs, peptides, and genes. The review article also expresses the applications of polymeric nanocarriers in the pharmaceutical and medical industry with a special emphasis on oral, ocular, parenteral, and topical application of drugs, peptides, and genes over the last two decades. The review further examines the practical, regulatory, and clinical considerations of the polymeric nanocarriers, their safety issues, and directinos for future research.

In Vitro Release Test of Nano-drug Delivery Systems Based on Analytical and Technological Perspectives

Background:

Nanotech products are gaining more attention depending on their advantages for improving drug solubility, maintenance of drug targeting, and attenuation of drug toxicity. In vitro release test is the critical physical parameter to determine the pharmaceutical quality of the product, to monitor formulation design and batch-to-batch variation.

Methods:

Spectrophotometric and chromatographic methods are mostly used in quantification studies from in vitro release test of nano-drug delivery systems. These techniques have advantages and disadvantages with respect to each other considering dynamic range, selectivity, automation, compatibility with in vitro release media and cost per sample.

Results:

It is very important to determine the correct kinetic profile of active pharmaceutical substances. At this point, the analytical method used for in vitro release tests has become a very critical parameter to correctly assess the profiles. In this review, we provided an overview of analytical methods applied to the in vitro release assay of various nanopharmaceuticals.

Conclusion:

This review presents practical direction on analytical method selection for in vitro release test on nanopharmaceuticals. Moreover, precautions on analytical method selection, optimization and validation were discussed.

Förster Resonance Energy Transfer-Based Stability Assessment of PLGA Nanoparticles in Vitro and in Vivo

The knowledge of in vitro and in vivo stability of polymeric nanoparticles is vital for the development of clinical formulations for drug delivery and cell labeling applications. Förster resonance energy transfer (FRET)-based fluorescence labeling approaches are promising tools to study nanoparticle stability under different physiological conditions. Here, we present the FRET-based stability assessment of poly(lactic-co-glycolic acid) (PLGA) nanoparticles encapsulating BODIPY-FL12 and Nile Red as the donor and acceptor, respectively. The stability of PLGA nanoparticles is studied via monitoring the variations of fluorescence emission characteristics along with colloidal characterization. Accordingly, PLGA nanoparticles are colloidally stable for more than 2 weeks when incubated in aqueous buffers in situ, whereas in vitro particle degradation starts in between 24 and 48 h, reaching a complete loss of FRET at 72 h as shown with fluorescence microscopy imaging and flow cytometry analysis. PLGA nanoparticles systemically administered to mice predominantly accumulate in the liver, in which FRET no longer takes place at time points as early as 24 h postadministration as determined by ex vivo organ imaging and flow cytometry analysis. The results of this study expand our knowledge on drug release and degradation behavior of PLGA nanoparticles under different physiological conditions, which will prove useful for the rational design of PLGA-based formulations for various applications that can be translated into clinical practice.

Folate and Borneol Modified Bifunctional Nanoparticles for Enhanced Oral Absorption

Oral delivery is considered the preferred route of administration due to its convenience and favorable compliance. Here, docetaxel (DTX) loaded polylactic-co-glycolic acid (PLGA) nanoparticles, coated with polyethyleneimine⁻folic acid (PEI-FA) and polyethyleneimine⁻borneol (PEI-BO), were designed to enhance oral absorption (FA/BO-PLGA-NPs). The FA/BO-PLGA-NPs were spherical and smooth with an average size of (137.0 ± 2.1) nm. Encapsulation efficiency (EE%) and drug loading (DL%) were (80.3 ± 1.8)% and (2.3 ± 0.3)%, respectively. In vitro release studies showed that approximately 62.1% of DTX was released from FA/BO-PLGA-NPs in media at pH 7.4. The reverted gut sac method showed that the absorption of FA/BO-PLGA-NPs in the intestines was approximately 6.0 times that of DTX. Moreover, cellular uptake suggested that the obtained FA/BO-PLGA-NPs could be efficiently internalized into Caco-2 cells via FA-mediated active targeting and BO-mediated P-glycoprotein (P-gp) inhibition. Pharmacokinetics study demonstrated that after oral administration of DTX at a dose of 10 mg/kg in FA/BO-PLGA-NPs, the bioavailability of FA/BO-PLGA-NPs was enhanced by approximately 6.8-fold compared with that of DTX suspension. FA/BO-PLGA-NPs caused no obvious irritation to the intestines. Overall, the FA/BO-PLGA-NP formulation remarkably improved the oral bioavailability of DTX and exhibited a promising perspective in oral drug delivery.

Sustained Connexin43 Mimetic Peptide Release From Loaded Nanoparticles Reduces Retinal and Choroidal Photodamage

Purpose

To evaluate the long-term effect on inflammation and inflammasome activation of intravitreally delivered connexin43 mimetic peptide (Cx43MP) in saline or incorporated within nanoparticles (NPs) for the treatment of the light-damaged rat eye.

Methods

Light-induced damage to the retina was created by exposure of adult albino Sprague-Dawley rats to intense light for 24 hours. A single dose of Cx43MP, Cx43MP-NPs, or saline was injected intravitreally at 2 hours after onset of light damage. Fluorescein isothiocyanate (FITC)-labelled Cx43MP-NPs were intravitreally injected to confirm delivery into the retina. Electroretinogram (ERG) recordings were performed at 24 hours, 1 week, and 2 weeks post cessation of light damage. The retinal and choroidal layers were analyzed in vivo using optical coherence tomography (OCT) and immunohistochemistry was performed on harvested tissues using glial fibrillary acidic protein (GFAP), leukocyte common antigen (CD45), and Cx43 antibodies.

Results

FITC was visualized 30 minutes after injection in the ganglion cell layer and in the choroid. Cx43MP and Cx43MP-NP treatments improved a-wave and b-wave function of the ERG compared with saline-injected eyes at 1 week and 2 weeks post treatment, and prevented photoreceptor loss by 2 weeks post treatment. Inflammation was also reduced and this was in parallel with downregulation of Cx43 expression.

Conclusions

The slow release of Cx43MP incorporated into NPs is more effective at treating retinal injury than a single dose of native Cx43MP in solution by reducing inflammation and maintaining both retinal structure and function. This NP preparation has clinical relevance as it reduces possible ocular complications associated with repeated intravitreal injections.

In situ polymerization of poly(γ-benzyl-l-glutamate) on mesoporous hydroxyapatite with high graft amounts for the direct fabrication of biodegradable cell microcarriers and their osteogenic induction

Large-scale cell culture for cell expansion in tissue engineering is currently a major focus of research. One method to achieve better cell amplification is to utilize microcarriers. In this study, different amounts of poly(γ-benzyl-l-glutamate) (PBLG) (from 11 wt% to 50 wt%) were grafted on mesoporous hydroxyapatite (MHA) by the in situ ring opening polymerization of γ-benzyl-l-glutamate N-carboxyanhydride (BLG-NCA), and biodegradable and biocompatible PBLG-g-MHA microcarriers were directly fabricated using the oil-in-water (O/W) solvent-evaporation technique for bone tissue engineering. The amount of grafted PBLG could be controlled by adjusting the feed ratio of MHA and BLG-NCA. The relationships between sphere morphology and graft amount or solution concentration were explored. Furthermore, cytological assays were performed to evaluate the biological properties of the PBLG-g-MHA microcarriers. For a solution concentration of 3% (w/v) and PBLG graft amounts of 33 wt% and 50 wt%, the microspheres could be harvested with optimal spherical shapes. In vitro cell culture revealed that the PBLG-g-MHA microspheres had favorable properties for cell proliferation and significantly enhanced the osteogenic differentiation of MC3T3-E1 cells and bone matrix formation.

Co-delivery of pemetrexed and miR-21 antisense oligonucleotide by lipid-polymer hybrid nanoparticles and effects on glioblastoma cells

Combination therapy using anticancer drugs and nucleic acid is a more promising strategy to overcome multidrug resistance in cancer and to enhance apoptosis. In this study, lipid-polymer hybrid nanoparticles (LPNs), which contain both pemetrexed and miR-21 antisense oligonucleotide (anti-miR-21), have been developed for treatment of glioblastoma, the most aggressive type of brain tumor. Prepared LPNs have been well characterized by particle size distribution and zeta potential measurements, determination of encapsulation efficiency, and in vitro release experiments. Morphology of LPNs was determined by transmission electron microscopy. LPNs had a hydrodynamic size below 100 nm and exhibited sustained release of pemetrexed up to 10 h. Encapsulation of pemetrexed in LPNs increased cellular uptake from 6% to 78%. Results of confocal microscopy analysis have shown that co-delivery of anti-miR-21 significantly improved accumulation of LPNs in the nucleus of U87MG cells. Nevertheless, more effective cytotoxicity results could not be obtained due to low concentration of anti-miR-21, loaded in LPNs. We expect that the effective drug delivery systems can be obtained with higher concentration of anti-miR-21 for the treatment of glioblastoma.

Low-intensity focused ultrasound mediated localized drug delivery for liver tumors in rabbits

OBJECTIVE

To explore the antitumor effects of low-intensity focused ultrasound (LIFU) mediated localized drug delivery of adriamycin-microbubble-PLGA nanoparticle complexes on rabbits VX2 liver tumor.

METHODS

ADM-NMCs were prepared by covalent linking of ADM-PLGA nanoparticles (ADM-NPs) to the shell of the microbubbles. A fixed water bag filled with microbubbles was subjected to LIFU and non-focused ultrasound respectively, and the ultrasound images of which were recorded before and after ultrasonication. A total of 54 VX2 liver tumor-burdened rabbits were divided into six groups randomly, including control, ADM-NPs combined with LIFU, microbubbles combined with LIFU, ADM-NPs and microbubbles combined with LIFU, ADM-NMCs combined with LIFU and ADM-NMCs combined with Non-FUS. The tumor volume and volume inhibition rate (VIR) of tumor progression were calculated and compared. Apoptotic cells were labeled by terminal deoxyuridine nick end. Proliferating cell nuclear antigen was detected by immunohistochemistry. The median survival time of the animals were recorded and compared.

RESULTS

ADM-NMCs were successfully prepared with an average diameter of 1721 nm. The highest VIR and apoptotic index (AI) were found in the group of ADM-NMCs combined with LIFU while the lowest proliferating index (PI) was simultaneously observed in this group. The median survival time of the rabbits in the ADM-NMCs combined with LIFU group was the longest (71days) among all groups.

CONCLUSIONS

ADM-NMCs combined with LIFU could inhibit the rabbits VX2 liver tumor progress by delaying the tumor proliferation and accelerating apoptosis, which presents a novel process for liver tumor targeting chemotherapy.

Nanoparticles in the ocular drug delivery

Ocular drug transport barriers pose a challenge for drug delivery comprising the ocular surface epithelium, the tear film and internal barriers of the blood-aqueous and blood-retina barriers. Ocular drug delivery efficiency depends on the barriers and the clearance from the choroidal, conjunctival vessels and lymphatic. Traditional drug administration reduces the clinical efficacy especially for poor water soluble molecules and for the posterior segment of the eye. Nanoparticles (NPs) have been designed to overcome the barriers, increase the drug penetration at the target site and prolong the drug levels by few internals of drug administrations in lower doses without any toxicity compared to the conventional eye drops. With the aid of high specificity and multifunctionality, DNA NPs can be resulted in higher transfection efficiency for gene therapy. NPs could target at cornea, retina and choroid by surficial applications and intravitreal injection. This review is concerned with recent findings and applications of NPs drug delivery systems for the treatment of different eye diseases.