Ethanol enhanced in vivo gene delivery with non-ionic polymeric micelles inhalation

Assessment of the Oral Delivery of a Myelin Basic Protein Gene Promoter with Antiapoptotic bcl-xL (pMBP-bcl-xL) DNA by Cyclic Peptide Nanotubes with Two Aspect Ratios and Its Biodistribution in the Brain and Spinal Cord

Cyclo-(D-Trp-Tyr) peptide nanotubes (PNTs) were reported to be potential carriers for oral gene delivery in our previous study; however, the effect of the aspect ratio (AR) of these PNTs on gene delivery in vivo could affect penetration or interception in biological environments. The aim of this study was to assess the feasibility of cyclo-(D-Trp-Tyr) PNTs with two ARs as carriers for oral pMBP-bcl-x_L-hRluc delivery to the spinal cord to treat spinal cord injury (SCI). We evaluated the biodistribution of oligodendrocyte (OLG)-specific myelin basic protein gene promoter-driven antiapoptotic DNA (pMBP-bcl-x_L) to the brain and spinal cord delivered with cyclo-(D-Trp-Tyr) PNTs with large (L) and small (S) PNTs with two ARs. After complex formation, the length, width, and AR of the L-PNTs/DNA were 77.86 ± 3.30, 6.51 ± 0.28, and 13.75 ± 7.29 μm, respectively, and the length and width of the S-PNTs/DNA were 1.17 ± 0.52 and 0.17 ± 0.05 μm, respectively, giving an AR of 7.12 ± 3.17 as detected by scanning electron microscopy. Each of these three parameters exhibited significant differences (p < 0.05) between L-PNTs/DNA and S-PNTs/DNA. However, there were no significant differences (p > 0.05) between the L-PNTs and S-PNTs for either their DNA encapsulation efficiency (29.72 ± 14.19 and 34.31 ± 16.78%, respectively) or loading efficiency (5.15 ± 2.58 and 5.95 ± 2.91%). The results of the in vitro analysis showed that the S-PNT/DNA complexes had a significantly higher DNA release rate and DNA permeation in the duodenum than the L-PNT/DNA complexes. Using Cy5 and TM-rhodamine to individually and chemically conjugate the PNTs with plasmid DNA, we observed, using laser confocal microscopy, that the PNTs and DNA colocalized in complexes. We further confirmed the complexation between DNA and the PNTs using fluorescence resonance energy transfer (FRET). Data from an in vivo imaging system (IVIS) showed that there was no significant difference (p > 0.05) in PNT distribution between L-PNTs/DNA and S-PNTs/DNA within 4 h. However, the S-PNT/DNA group had a significantly higher DNA distribution (p < 0.05) in several organs, including the ilium, heart, lungs, spleen, kidneys, testes, brain, and spinal cord. Finally, we determined the bcl-x_L protein expression levels in the brain and spinal cord regions for the L-PNT/DNA and S-PNT/DNA complex formulations. These results suggested that either L-PNTs or S-PNTs may be used as potential carriers for oral gene delivery to treat SCI.

Biomolecules Turn Self-Assembling Amphiphilic Block Co-polymer Platforms Into Biomimetic Interfaces

Biological membranes constitute an interface between cells and their surroundings and form distinct compartments within the cell. They also host a variety of biomolecules that carry out vital functions including selective transport, signal transduction and cell-cell communication. Due to the vast complexity and versatility of the different membranes, there is a critical need for simplified and specific model membrane platforms to explore the behaviors of individual biomolecules while preserving their intrinsic function. Information obtained from model membrane platforms should make invaluable contributions to current and emerging technologies in biotechnology, nanotechnology and medicine. Amphiphilic block co-polymers are ideal building blocks to create model membrane platforms with enhanced stability and robustness. They form various supramolecular assemblies, ranging from three-dimensional structures (e.g., micelles, nanoparticles, or vesicles) in aqueous solution to planar polymer membranes on solid supports (e.g., polymer cushioned/tethered membranes,) and membrane-like polymer brushes. Furthermore, polymer micelles and polymersomes can also be immobilized on solid supports to take advantage of a wide range of surface sensitive analytical tools. In this review article, we focus on self-assembled amphiphilic block copolymer platforms that are hosting biomolecules. We present different strategies for harnessing polymer platforms with biomolecules either by integrating proteins or peptides into assemblies or by attaching proteins or DNA to their surface. We will discuss how to obtain synthetic structures on solid supports and their characterization using different surface sensitive analytical tools. Finally, we highlight present and future perspectives of polymer micelles and polymersomes for biomedical applications and those of solid-supported polymer membranes for biosensing.

Tissue-Clearing Techniques Enable Three-Dimensional Visualization of Aerosolized Model Compound and Lung Structure at the Alveolar Scale

In this study, we examined the usefulness of a tissue-clearing technique for the evaluation of the lung distribution of aerosolized drugs. An aerosol formulation of TexasRed dextran (70 kDa), a model compound of drug carrier for aerosolized drugs, was administered intrapulmonarily to mice using a MicroSprayer, and then DyLight 488-conjugated tomato lectin was administered intravenously to visualize general lung structure via the fluorescent labeling of alveolar and bronchial epithelial cells. Tissue clearing followed by laser scanning confocal microscopy enabled the three-dimensional visualization of intrapulmonary TexasRed dextran and the evaluation of its distribution at the alveolar scale without the preparation of thin tissue sections. These findings suggest that tissue-clearing techniques are useful for the evaluation of intrapulmonary distribution and development of pulmonary drug delivery systems.

In vitro and in vivo assessment of delivery of hydrophobic molecules and plasmid DNAs with PEO–PPO–PEO polymeric micelles on cornea

The stability and bio-distribution of genes or drug complexes with poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO–PPO–PEO, Pluronic F-68) polymeric micelles (PM) are essential for an effective nanosized PM delivery system. We used Förster resonance energy transfer (FRET) pairs with PM and measured the FRET ratio to assess the stability of PM in vitro and in vivo on the cornea. The FRET ratio reached a plateau at 0.8 with 3% PM. Differential scanning calorimetry measurement confirmed the complex formation of FRET pairs with PM. Confocal imaging with the fluorophores fluorescein isothiocyanate isomer I (FITC) and rhodamine B base (RhB) also showed the occurrence of FRET pairs in vitro. The fluorophores were mixed with 3% PM solution or the FITC-labeled PEO–PPO–PEO polymers (FITC-P) were mixed with RhB-labeled plasmids (RhB–DNA). In addition, the in vitro corneal permeation of FRET pair complexes with PM reached a 0.8 FRET ratio. One hour after eye drop administration, FRET pairs colocalized in the cytoplasm, and surrounded and entered the nuclei of cells in the cornea, and the polymers were located in the corneal epithelial layers, as detected through anti-PEG immunohistochemistry. Furthermore, fluorescence colocalization in the cytoplasm and cell nucleus of the corneal epithelium was confirmed in tissues where RhB or RhB–DNA complexed with FITC-P was found to accumulate. We demonstrate that at a concentration of 3%, PM can encapsulate FRET pairs or RhB–DNA and retain their integrity within the cornea 1 h after administration, suggesting the feasibility and stability of PEO–PPO–PEO polymers as a vehicle for drug delivery.

How do polymeric micelles cross epithelial barriers?

Non-parenteral delivery of drugs using nanotechnology-based delivery systems is a promising non-invasive way to achieve effective local or systemic drug delivery. The efficacy of drugs administered non-parenterally is limited by their ability to cross biological barriers, and epithelial tissues particularly present challenges. Polymeric micelles can achieve transepithelial drug delivery because of their ability to be internalized into cells and/or cross epithelial barriers, thereby delivering drugs either locally or systematically following non-parenteral administration. This review discusses the particular characteristics of various epithelial barriers and assesses their potential as non-parenteral routes of delivery. The material characteristics of polymeric micelles (e.g., size, surface charge, and surface decoration) and of unimers dissociated from polymeric micelles determine their interactions (non-specific and/or specific) with mucus and epithelial cells as well as their intracellular fate. This paper outlines the mechanisms governing the major modes of internalization of polymeric micelles into epithelial cells, with an emphasis on specific recent examples of the transport of drug-loaded polymeric micelles across epithelial barriers.

Oral gene delivery with cyclo-(D-Trp-Tyr) peptide nanotubes

The feasibility of cyclo-(D-Trp-Tyr) peptide nanotubes (PNTs) as oral gene delivery carriers was investigated in nude mice with eight 40 μg doses of pCMV-lacZ in 2 days at 3 h intervals. The association between DNA and PNTs, the DNase I stability of PNTs-associated DNA, and in vitro permeability of DNA were estimated. The results showed that the cyclo-(D-Trp-Tyr) PNTs self-associated at concentrations above 0.01 mg/mL. Plasmid DNA associated with PNTs with a binding constant of 3.2 × 10(8) M(-1) calculated by a fluorescence quenching assay. PNTs were able to protect DNA from DNase I, acid, and bile digestion for 50 min, 60 min, and 180 min, respectively. The in vitro duodenal apparent permeability coefficient of pCMV-lacZ calculated from a steady state flux was increased from 49.2 ± 21.6 × 10(-10) cm/s of naked DNA to 395.6 ± 142.2 × 10(-10) cm/s of pCMV-lacZ/PNT formulation. The permeation of pCMV-lacZ formulated with PNTs was found in an energy-dependent process. Furthermore, β-galatosidase (β-Gal) activity in tissues was quantitatively assessed using chlorophenol red-β-D-galactopyranoside (CPRG) and was significantly increased by 41% in the kidneys at 48 h and by 49, 63, and 46% in the stomach, duodenum, and liver, respectively, at 72 h after the first dose of oral delivery of pCMV-lacZ/PNT formulation. The organs with β-Gal activity were confirmed for the presence of pCMV-lacZ DNA with Southern blotting analysis and intracellular tracing the TM-rhodamine-labeled DNA and the presence of mRNA by reverse transcription-real time quantitative PCR (RT-qPCR). Another plasmid (pCMV-hRluc) encoding Renilla reniformis luciferase was used to confirm the results. An increased hRluc mRNA and luciferase in stomach, duodenum, liver, and kidney were detected by RT-qPCR, ex vivo bioluminescence imaging, luciferase activity quantification, and immunostaining, respectively.

Chitosan-Grafted Copolymers and Chitosan-Ligand Conjugates as Matrices for Pulmonary Drug Delivery

Recently, much attention has been given to pulmonary drug delivery by means of nanosized systems to treat both local and systemic diseases. Among the different materials used for the production of nanocarriers, chitosan enjoys high popularity due to its inherent characteristics such as biocompatibility, biodegradability, and mucoadhesion, among others. Through the modification of chitosan chemical structure, either by the addition of new chemical groups or by the functionalization with ligands, it is possible to obtain derivatives with advantageous and specific characteristics for pulmonary administration. In this paper, we discuss the advantages of using chitosan for nanotechnology-based pulmonary delivery of drugs and summarize the most recent and promising modifications performed to the chitosan molecule in order to improve its characteristics.

Disposition of drugs in block copolymer micelle delivery systems: from discovery to recovery

Since their discovery in the early 1980s, polymeric micelles have been the subject of several studies as delivery systems that can potentially improve the therapeutic performance and modify the toxicity profile of encapsulated drugs by changing their pharmacokinetic characteristics. The efforts in this area have led in recent years to the advancement of several polymeric micellar formulations to clinical trials, some of which have shown promise in changing the biodistribution of the incorporated drug after intravenous administration as a means of tumour-targeted drug delivery. Recently, the possible benefit of polymeric micellar delivery in enhancing the absorption and bioavailability of incorporated drugs from alternative routes of drug administration has attracted interest. This article provides an overview of the effect of polymeric micellar delivery on absorption, distribution, metabolism and excretion of incorporated therapeutic agents. It also aims to assess the current information on the performance of polymeric micellar delivery systems in modifying the pharmacokinetics/pharmacodynamics of the incorporated drugs in clinical trials, and to re-examine the important structural factors required for successful design of polymeric micellar delivery systems capable of inducing favourable changes in the pharmacokinetics of the encapsulated drug.

Solid lipid nanoparticles for pulmonary delivery of insulin

Growing attention has been given to the potential of pulmonary route as an alternative for non-invasive systemic delivery of therapeutic agents. In this study, novel nebulizer-compatible solid lipid nanoparticles (SLNs) for pulmonary drug delivery of insulin were developed by reverse micelle-double emulsion method. The influences of the amount of sodium cholate (SC) and soybean phosphatidylcholine (SPC) on the deposition properties of the nanoparticles were investigated. Under optimal conditions, the entrapment delivery (ED), respirable fraction (RF) and nebulization efficiency (NE) of SLNs could reach 96.53, 82.11 and 63.28%, respectively, and Ins-SLNs remained stable during nebulization. Fasting plasma glucose level was reduced to 39.41% and insulin level was increased to approximately 170 microIU/ml 4h after pulmonary administration of 20 IU/kg Ins-SLNs. A pharmacological bioavailability of 24.33% and a relative bioavailability of 22.33% were obtained using subcutaneous injection as a reference. Incorporating fluorescent-labelled insulin into SLNs, we found that the SLNs were effectively and homogeneously distributed in the lung alveoli. These findings suggested that SLNs could be used as a potential carrier for pulmonary delivery of insulin by improving both in vitro and in vivo stability as well as prolonging hypoglycemic effect, which inevitably resulted in enhanced bioavailability.

Bioavailability effect of methylprednisolone by polymeric micelles

PURPOSE

To investigate the effect of PEO-PPO-PEO polymeric micelles (PM) formulation on the bioavailability of methylprednisolone (MP), a treatment of spinal cord injury (SCI), to the blood and spinal cord (SC) of rabbits.

METHODS

The characteristic of MP formulated with PM (MP/PM) was evaluated by critical micelles concentration (CMC), dynamic light scattering (DLS), atomic force microscopy (AFM) and in vitro kinetic release measurements. HPLC was used to analyze the MP disposition in plasma and SC of rabbits receiving single dose intravenous administration. After MP/PM delivery, the mRNA and protein levels of anti-apoptotic marker, Bcl-x(L), were monitored by Reverse Transcription -Real-Time -Polymerase Chain Reaction (RT-qPCR) and Western blotting analysis, respectively.

RESULTS

At a concentration of 0.1% and at 25 degrees C, PEO-PPO-PEO copolymers formed micelles shown by fluorescence probe, DLS and solubility test. The size of the MP/PM was in an average of 60 nm with a single, rounded shape detected under AFM. Being formulated with 6% PM, MP had higher solubility (219.6 +/- 3.6 microg/ml) and release rate (11.1 +/- 0.4 ng min(1/2)) at 37 degrees C. After intravenously administrated with single dose of 1 mg/kg of MP/PM to rabbits, higher levels of MP in plasma and SC were detected compared to animals receiving an equal dose of MP, analyzed by HPLC. PM formulation markedly increased (7-fold) the plasma half-lives (t (1/2)) of MP (from 76.1 +/- 8.0 to 514.3 +/- 70.0 min). In addition, the SC t (1/2) of MP/PM also increased from 278 to 528 min. In SC, the mRNA level of Bcl-x(L) increased 4-fold in animals receiving MP/PM compared to that with MP alone at 7 h post-administration. Similar elevated Bcl-x(L) protein was also detected upon MP/PM administration compared to MP.

CONCLUSIONS

PM vehicle was able to deliver MP to improve its pharmacokinetic profile in plasma and SC with higher expression of anti-apoptotic Bcl-x(L) at both mRNA and protein levels.