Antibacterial and in vitro anticancer activities of the antimicrobial peptide NRC-07 encapsulated in chitosan nanoparticles

Antimicrobial peptides (AMPs) are promising alternatives to conventional antibiotics and chemotherapy in the treatment of multidrug-resistant pathogens and drug-resistant cancers. Clinical application of AMPs is limited due to low stability and inefficient transport. Encapsulation in nanocarriers may improve their therapeutic potential. Chitosan nanoparticles (CS-NPs) are efficient carriers for proteins and peptides, improving the treatment of microbial infections and targeted drug delivery. We examined toxicity against cancer cell lines and antibacterial activities of the pleurocidin-like AMP NRC-07 upon encapsulation in CS-NPs by ionotropic gelation. The biological activities of various formulations of free and encapsulated NRC-07 and free nanoparticles were evaluated against Pseudomonas aeruginosa and breast cancer cells, using assays for cell viability and lactate dehydrogenase cytolysis with non-cancer cell lines as controls. NRC-07-containing nanoparticles decreased the bacterial and cancer cell viability in a concentration-dependent manner. Activities of encapsulated peptide were >2-fold higher than those of free NRC-07 peptide. Unloaded CS-NPs and free peptide were not cytotoxic against control cells. Encapsulation of NRC-07 into CS-NPs enhanced the antibacterial and selective cytotoxicity of the peptide, possibly enhancing anticancer activities. Encapsulation presents a promising tool for the development of efficient drug delivery systems.

A liposomal platform for the delivery of ion channel proteins for treatment of channelopathies - Application in therapy of cystic fibrosis

Channelopathies arise from ion channel dysfunction. Successful treatment entails delivery of functional ion channels to replace dysfunctional ones. Glycine receptor (GlyR)-rich cell membrane fragments (CMF) were previously delivered to target cell membranes using fusogenic liposomes. Here, cystic fibrosis transmembrane conductance regulator (CFTR)-bearing CMF were similarly delivered to target cells. We studied the effect of lipid composition on liposomes' ability to incorporate CMF and fuse with target cell membranes to deliver functional CFTR. Four formulations were prepared using thin-film hydration out of different lecithin sources, egg and soy lecithin (EL and SL), in the presence and absence of cholesterol (CHOL): EL + CHOL, EL-CHOL, SL + CHOL, and SL-CHOL. EL liposomes incorporated more CMF than SL liposomes, with CHOL only increasing CMF incorporation in SL liposomes. SL + CHOL fused better with target cell membranes than EL + CHOL. SL + CHOL and EL + CHOL equally delivered CFTR to target cell membranes, owing to the former's superior fusogenic capacity and the latter's superior CMF-incorporation capacity. SL-CHOL and EL-CHOL delivered CFTR to a lesser extent, indicating the importance of CHOL for fusion. Patch-clamp electrophysiology and confocal laser scanning microscopy (CLSM) confirmed CFTR delivery to target cell membranes by SL + CHOL. Therefore, CMF-bearing fusogenic liposomes offer a promising universal platform for the treatment of channelopathies.

Enhancement of mitochondrial function using NO releasing nanoparticles; a potential approach for therapy of Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia. Increasing evidence is showing the important role of mitochondrial dysfunction in AD. Mitochondria based oxidative stress, decrease in respiratory chain activity and ATP production are all associated with AD, hence indicating that the enhancement of mitochondrial function and biogenesis present a promising therapeutic approach for AD. Nitric oxide (NO) is an initiator of mitochondrial biogenesis. However, its gaseous nature and very short half-life limit the realization of its therapeutic potential. Additionally, its uncontrolled in-vivo distribution results in generalized vasodilation, hypotension among other off-target effects. Diazeniumdiolates (NONOates) are NO donors that release NO in physiological temperature and pH. Their encapsulation within a hydrophobic matrix carrier system could control the release of NO, and at the same time enable its delivery to the brain. In this work, PAPANONOate (PN) a NO donor was encapsulated in small (92 ± 7 nm) poly (lactic-co-glycolic acid) (PLGA) NPs. These NPs did not induce hemolysis upon intravenous administration and were able to accumulate in the brains of lipopolysaccharides (LPS) induced neurodegeneration mouse models. The encapsulation of PN within a hydrophobic PLGA matrix enabled the sustained release of NO from NPs (≈ 3 folds slower relative to free PN) and successfully delivered PN to brain. As a result, PN-NPs but not free PN resulted in an enhancement in memory and cognition in animals with neurodegeneration as determined by the Y-maze test. The enhancement in cognition was a result of increased mitochondria function as indicated by the increased production of ATP and Cytochrome C oxidase enzyme activity.

Nanoparticle Fraught Liposomes: A Platform for Increased Antibiotic Selectivity in Multidrug Resistant Bacteria

Increasing antibiotic concentrations within bacterial cells while reducing them in mammalian ones would ultimately result in an enhancement of antibacterial actions, overcoming multidrug resistance, all while minimizing toxicity. Nanoparticles (NPs) have been used in numerous occasions to overcome antibiotic resistance, poor drug solubility, and stability. However, the concomitant increase in antibiotic concentration in mammalian cells and the resultant toxicity are usually overlooked. Without compromising bacterial cell fusion, large liposomes (Lip) have been reported to show reduced uptake in mammalian cells. Therefore, in this work, small NP fraught liposomes (NP-Lip) were formulated with the aim of increasing NP uptake and antibiotic delivery in bacterial cells but not in mammalian ones. Small polylactic-co-glycolic acid NPs were therefore loaded with erythromycin (Er), an antibiotic with low membrane permeability that is susceptible to drug efflux, and 3c, a 5-cyanothiazolyl urea derivative with low solubility and stability. In vitro experiments demonstrated that the incorporation of small NPs into large Lip resulted in a reduction in NP uptake by HEK293 cells while increasing it in Gram-negative bacteria (Escherichia coli DH5α, E. coli K12, and Pseudomonas aeruginosa), consequently resulting in an enhancement of antibiotic selectivity by fourfold toward E. coli (both strains) and eightfold toward P. aeruginosa. Ocular administration of NP-Lip in a P. aeruginosa keratitis mouse model demonstrated the ability of Er/3c-loaded NP-Lip to result in a complete recovery. More importantly, in comparison to NPs, the ocular administration of NP-Lip showed a reduction in TNF-alpha and IL-6 levels, implying reduced interaction with mammalian cells in vivo. This work therefore clearly demonstrated how tailoring the nano-bio interaction could result in selective drug delivery and a reduction in toxicity.

Different Serum, Different Protein Corona! The Impact of the Serum Source on Cellular Targeting of Folic Acid-Modified Chitosan-Based Nanoparticles

The nanoparticle (NP) protein corona represents an interface between biological components and NPs, dictating their cellular interaction and biological fate. To assess the success of cellular targeting, NPs modified with targeting ligands are incubated with target cells in serum-free culture medium or in the presence of fetal bovine serum (FBS). In the former, the role of the corona is overlooked, and in the latter, the effects of a corona that does not represent the one forming in humans nor the respective disease state are considered. Via proteomic analysis, we demonstrate how the difference in the composition of FBS, sera from healthy human volunteers, and breast cancer patients (BrCr Pt) results in the formation of completely different protein coronas around the same NP. Successful in vitro targeting of breast cancer cells was only observed when NPs were incubated with target cells in the presence of BrCr Pt sera only. In such cases, the success of targeting was not attributed to the targeting ligand itself, but to the adsorption of specific serum proteins that facilitate NP uptake by cancer cells in the presence of BrCr Pt sera. This work therefore demonstrates how the serum source affects the reliability of in vitro experiments assessing NP-cell interactions and the consequent success or failure of active targeting and may in fact indicate an additional reason for the limited clinical success of drug targeting by NPs in cancer.

The other side to the use of active targeting ligands; the case of folic acid in the targeting of breast cancer

Due to its overexpression in cancer cells, the folate receptor (FR) is heavily exploited in the active targeting of nanoparticles (NPs). Its ligand, folic acid (FA) is as a consequence widely used as a NP targeting ligand. Although rather popular and successful in principle, recent data has shown that FA may result in breast cancer initiation and progression, which questions the suitability of FA as NP cancer targeting ligand. In this work, intravenous administration of free FA to healthy female mice resulted in breast tissue dysplasia, hyperplasia and in the increased expression of human epidermal growth factor receptor-2 (HER2), folate receptor (FR), cancer antigen 15-3 (CA15.3), vascular endothelial growth factor (VEGF), signal transducer and activator of transcription 3 (STAT3) and the pro-inflammatory cytokines, tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6) and interleukin-1β. In addition to the reduction in IL2. To evaluate the suitability and safety of FA as NP targeting ligand in breast cancer, small (≈ 150 nm) and large (≈ 500 nm) chitosan NPs were formulated and decorated with two densities of FA. The success of active targeting by FA was confirmed in two breast cancer cell lines (MCF-7 and MDA-MB-231 cells) in comparison to HEK293 cells. FA modified NPs that demonstrated successful active targeting in-vitro were assessed in-vivo. Upon intravenous administration, large NPs modified with a high density of FA accumulated in the breast tissue and resulted in similar effects as those observed with free FA. These results therefore question the suitability of FA as a targeting ligand in breast cancer and shed light on the importance of considering the activity (other than targeting) of the ligands used in NP active targeting.

Repurpose but also (nano)-reformulate! The potential role of nanomedicine in the battle against SARS-CoV2

The coronavirus disease-19 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) has taken the world by surprise. To date, a worldwide approved treatment remains lacking and hence in the context of rapid viral spread and the growing need for rapid action, drug repurposing has emerged as one of the frontline strategies in the battle against SARS-CoV2. Repurposed drugs currently being evaluated against COVID-19 either tackle the replication and spread of SARS-CoV2 or they aim at controlling hyper-inflammation and the rampaged immune response in severe disease. In both cases, the target for such drugs resides in the lungs, at least during the period where treatment could still provide substantial clinical benefit to the patient. Yet, most of these drugs are administered systemically, questioning the percentage of administered drug that actually reaches the lung and as a consequence, the distribution of the remainder of the dose to off target sites. Inhalation therapy should allow higher concentrations of the drug in the lungs and lower concentrations systemically, hence providing a stronger, more localized action, with reduced adverse effects. Therefore, the nano-reformulation of the repurposed drugs for inhalation is a promising approach for targeted drug delivery to lungs. In this review, we critically analyze, what nanomedicine could and ought to do in the battle against SARS-CoV2. We start by a brief description of SARS-CoV2 structure and pathogenicity and move on to discuss the current limitations of repurposed antiviral and immune-modulating drugs that are being clinically investigated against COVID-19. This account focuses on how nanomedicine could address limitations of current therapeutics, enhancing the efficacy, specificity and safety of such drugs. With the appearance of new variants of SARS-CoV2 and the potential implication on the efficacy of vaccines and diagnostics, the presence of an effective therapeutic solution is inevitable and could be potentially achieved via nano-reformulation. The presence of an inhaled nano-platform capable of delivering antiviral or immunomodulatory drugs should be available as part of the repertoire in the fight against current and future outbreaks.

Delivery of trans-membrane proteins by liposomes; the effect of liposome size and formulation technique on the efficiency of protein delivery

Channelopathies are disorders caused by reduced expression or impaired function of ion channels. Most current therapies rely on symptomatic treatment without addressing the underlying cause. We have recently established proof of principle for delivery of functional ion channel protein into the membrane of target cells using fusogenic liposomes incorporating glycine receptor (GlyR)-containing cell membrane fragments (CMF) that were formulated by thin film hydration. Here, the effect of liposome size and the formulation technique on the performance of the delivery vehicle was assessed. Three types of liposomes were prepared using lecithin and cholesterol, (i) small (SL), and (ii) large (LL) liposomes made by thin film hydration, and (iii) small liposomes prepared by vortex agitation (V-SL). All liposomes were evaluated for their ability to (i) incorporate GlyR-rich CMF, (ii) fuse with the cell membrane of target cells and (iii) deliver functional GlyR, as assessed by patch-clamp electrophysiology. SL prepared by thin film hydration offered the most effective delivery of glycine receptors that gave clear glycine-mediated currents in target cells. LL showed higher incorporation of CMF, but did not effectively fuse with the target cell membrane, while V-SL did not incorporate sufficient amounts of CMF. Additionally, SL showed minimalin vivotoxicity upon intrathecal injection in mice. Thus, liposome-mediated delivery of membrane proteins may be a promising therapeutic approach for the treatment of channelopathies.

Collagenase loaded chitosan nanoparticles for digestion of the collagenous scar in liver fibrosis: The effect of chitosan intrinsic collagen binding on the success of targeting

A variety of hepatic insults result in the accumulation of collagen-rich new extracellular matrix in the liver, ultimately culminating in liver fibrosis and cirrhosis. For such reasons, approaches looking into digestion of the collagen-rich extracellular matrix present an interesting therapeutic approach for cases of chronic liver disease, where the fibrotic scar is well established. Portal collagenase administration has recently led to the successful reversion of cirrhosis in an experimental rabbit model. Notwithstanding, the question of how such a sensitive therapeutic macromolecule could be administered in a less invasive manner, and in a way that preserves its functionality and avoids digestion of other non-hepatic vital collagen presents itself. Chitosan is a biodegradable polymer that has been reported to interact and bind to collagen. Chitosan nanoparticles (CS NPs) have also been reported to encapsulate therapeutic proteins, maintaining their functional form and protecting them from in-vivo degradation. For such reasons, CS NPs were loaded with collagenase and evaluated in-vitro and in-vivo for their ability to target and digest collagen. CS NPs were able to encapsulate collagenase (≈ 60% encapsulation efficiency) and release its content in active form. To determine whether chitosan's collagen interaction would enable NP collagen binding or whether the modification with collagen binding peptides (CBPs) is necessary, CS NPs were modified with the CBP; CCQDSETRTFY. Since the density of targeting ligand and the length of tether play a significant role in the success of active targeting, the surface of NPs was modified with different densities of the CBP either directly or using a polyethylene glycol (PEG) spacer. PEGylated NPs showed higher levels of CBP tagging; high, intermediate and low density of CBPs corresponded to 585.8 ± 33, 252.9 ± 25.3 and 56.5 ± 8.8 µg/mL for PEGylated NPs and 425.56 ± 12.67, 107.91 ± 10.3 and 49.86 ± 3.2 µg/mL for unPEGylated NPs, respectively. In-vitro collagen binding experiments showed that unmodified CS NPs were able to bind collagen and that modification with CBPs either directly or via PEG did not enhance collagen binding. In-vivo experiments demonstrated that unmodified CS NPs were able to reverse fibrosis with a survival rate of 100% at the end of the study, indicating the ability of CS NPs to deliver functional collagenase to the fibrotic liver and making the use of CBPs unnecessary.

Lipid Based Nanoparticles as Inherent Reversing Agents of Multidrug Resistance in Cancer

BACKGROUND

Multidrug resistance in cancer is the ability of a cancer cell to resist treatment with a wide range of structurally and functionally dissimilar chemotherapeutics. The resistant phenotype could arise in response to several cellular changes that ultimately result in a decrease in intracellular drug accumulation (or effectiveness), either by limiting cellular drug entry, or by expulsion of those molecules that have made it into the cell. Both blocking drug cellular entry and its expulsion are mostly brought about by the cell membrane. Several pharmaceutical excipients (mainly lipids, surfactants and amphililc copolymers) have been reported to reverse multidrug resistance by addressing cell membrane related changes resulting in low intracellular drug levels in resistant cells. These excipients are routinely used in the preparation of lipid based nanoparticles endowing inherent multidrug resistance reversing properties to these nanoparticles.

METHODS

In this review, cell membrane alterations resulting in multidrug resistance will be initially reviewed, followed by a discussion of the different types of lipid NPs and the potential held by the excipients used in their preparation in multidrug resistance reversal. Finally, a discussion on how lipid nanoparticles have been engineered and used in different occasions to enable multidrug resistance reversal is included.

CONCLUSION

The superior role held by lipid nanoparticles in comparison to free excipients will be highlighted.

MDR in cancer: Addressing the underlying cellular alterations with the use of nanocarriers

Multidrug resistance (MDR) is associated with a wide range of pathological changes at different cellular and intracellular levels. Nanoparticles (NPs) have been extensively exploited as the carriers of MDR reversing payloads to resistant tumor cells. However, when properly formulated in terms of chemical composition and physicochemical properties, NPs can serve as beyond delivery systems and help overcome MDR even without carrying a load of chemosensitizers or MDR reversing molecular cargos. Whether serving as drug carriers or beyond, a wise design of the nanoparticulate systems to overcome the cellular and intracellular alterations underlying the resistance is imperative. Within the current review, we will initially discuss the cellular changes occurring in resistant cells and how such changes lead to chemotherapy failure and cancer cell survival. We will then focus on different mechanisms through which nanosystems with appropriate chemical composition and physicochemical properties can serve as MDR reversing units at different cellular and intracellular levels according to the changes that underlie the resistance. Finally, we will conclude by discussing logical grounds for a wise and rational design of MDR reversing nanoparticulate systems to improve the cancer therapeutic approaches.

How successful is nuclear targeting by nanocarriers?

The nucleus is ultimately the final target for many therapeutics treating various disorders including cancers, heart dysfunction and brain disorders. Owing to their specialized cell uptake and trafficking mechanisms, nanoparticles (NPs) allow drug targeting where degradation sensitive therapeutics could be delivered to their target tissues and cell in active form and sufficient concentration. However, it has recently become increasingly obvious that cytosolic internalization of a drug molecule does not entail its interaction with its subcellular target and hence careful nanoparticle design and optimization is required to enable nuclear targeting. This review, discusses the barriers to NP nuclear delivery; crossing the cell membrane, endo/lysosomal escape, cytoplasmic trafficking and finally nuclear entry focusing on how NP synthesis and modification could allow for bypassing each of the aforementioned barriers and successfully reaching the nucleus. Examples of nuclear targeted NPs are also discussed, stressing on the critical aspects of nuclear targeting and pointing out how the disease state might change the normal NP path and how such change could be exploited to increase efficiency of nuclear targeting. Finally, the criteria set for the evaluation of nanocarriers for nuclear delivery are discussed highlighting that quantitative rather than qualitative evaluation is required to evaluate how successful nanocarriers for nuclear delivery are, particularly with regards to the amount of drug delivered and released in the nucleus.

Chitosan Nanoparticles for Nuclear Targeting: The Effect of Nanoparticle Size and Nuclear Localization Sequence Density

Many recently discovered therapeutic proteins exert their main function in the nucleus, thus requiring both efficient uptake and correct intracellular targeting. Chitosan nanoparticles (NPs) have attracted interest as protein delivery vehicles due to their biocompatibility and ability to escape the endosomes offering high potential for nuclear delivery. Molecular entry into the nucleus occurs through the nuclear pore complexes, the efficiency of which is dependent on NP size and the presence of nuclear localization sequence (NLS). Chitosan nanoparticles of different sizes (S-NPs ≈ 25 nm; L-NP ≈ 150 nm) were formulated, and they were modified with different densities of the octapeptide NLS CPKKKRKV (S-NPs, 0.25, 0.5, 2.0 NLS/nm(2); L-NPs, 0.6, 0.9, 2 NLS/nm(2)). Unmodified and NLS-tagged NPs were evaluated for their protein loading capacity, extent of cell association, cell uptake, cell surface binding, and finally nuclear delivery efficiency in L929 fibroblasts. To avoid errors generated with cell fractionation and nuclear isolation protocols, nuclear delivery was assessed in intact cells utilizing Förster resonance energy transfer (FRET) fluorometry and microscopy. Although L-NPs showed ≈10-fold increase in protein loading per NP when compared to S-NPs, due to higher cell association and uptake S-NPs showed superior protein delivery. NLS exerts a size and density dependent effect on nanoparticle uptake and surface binding, with a general reduction in NP cell surface binding and an increase in cell uptake with the increase in NLS density (up to 8.4-fold increase in uptake of High-NLS-L-NPs (2 NLS/nm(2)) compared to unmodified L-NPs). However, for nuclear delivery, unmodified S-NPs show higher nuclear localization rates when compared to NLS modified NPs (up to 5-fold by FRET microscopy). For L-NPs an intermediate NLS density (0.9 NLS/nm(2)) seems to provide highest nuclear localization (3.7-fold increase in nuclear delivery compared to High-NLS-L-NPs). Results indicate that a higher NLS density does not result in maximum protein nuclear localization and that a universal optimal density for NPs of different sizes does not exist.