Spermidine/Spermine N1-Acetyltransferase 1 (SAT1)-A Potential Gene Target for Selective Sensitization of Glioblastoma Cells Using an Ionizable Lipid Nanoparticle to Deliver siRNA

The Synergistic Benefit of Combination Strategies Targeting Tumor Cell Polyamine Homeostasis

Mammalian polyamines, including putrescine, spermidine, and spermine, are positively charged amines that are essential for all living cells including neoplastic cells. An increasing understanding of polyamine metabolism, its molecular functions, and its role in cancer has led to the interest in targeting polyamine metabolism as an anticancer strategy, as the metabolism of polyamines is frequently dysregulated in neoplastic disease. In addition, due to compensatory mechanisms, combination therapies are clinically more promising, as agents can work synergistically to achieve an effect beyond that of each strategy as a single agent. In this article, the nature of polyamines, their association with carcinogenesis, and the potential use of targeting polyamine metabolism in treating and preventing cancer as well as combination therapies are described. The goal is to review the latest strategies for targeting polyamine metabolism, highlighting new avenues for exploiting aberrant polyamine homeostasis for anticancer therapy and the mechanisms behind them.

Cationic nanocarriers: A potential approach for targeting negatively charged cancer cell

Cancer, a widespread and lethal disease, necessitates precise therapeutic interventions to mitigate its devastating impact. While conventional chemotherapy remains a cornerstone of cancer treatment, its lack of specificity towards cancer cells results in collateral damage to healthy tissues, leading to adverse effects. Thus, the quest for targeted strategies has emerged as a critical focus in cancer research. This review explores the development of innovative targeting methods utilizing novel drug delivery systems tailored to recognize and effectively engage cancer cells. Cancer cells exhibit morphological and metabolic traits, including irregular morphology, unchecked proliferation, metabolic shifts, genetic instability, and a higher negative charge, which serve as effective targeting cues. Central to these strategies is the exploitation of the unique negative charge characteristic of cancer cells, attributed to alterations in phospholipid composition and the Warburg effect. Leveraging this distinct feature, researchers have devised cationic carrier systems capable of enhancing the specificity of therapeutic agents towards cancer cells. The review delineates the underlying causes of the negative charge in cancer cells and elucidates various targeting approaches employing cationic compounds for drug delivery systems. Furthermore, it delves into the methods employed for the preparation of these systems. Beyond cancer treatment, the review also underscores the multifaceted applications of cationic carrier systems, encompassing protein and peptide delivery, imaging, photodynamic therapy, gene delivery, and antimicrobial applications. This comprehensive exploration underscores the potential of cationic carrier systems as versatile tools in the fight against cancer and beyond.

Lipid Nanoparticle-Based Inhibitors for SARS-CoV-2 Host Cell Infection

Purpose

The global pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the lingering threat to public health has fueled the search for effective therapeutics to treat SARS-CoV-2. This study aimed to develop lipid nanoparticle (LNP) inhibitors of SARS-CoV-2 entry to reduce viral infection in the nose and upper airway.

Methods

Two types of LNP formulations were prepared following a microfluidic mixing method. The LNP-Trap consisted of DOPC, DSPC, cholesterol, and DSPE-PEG-COOH modified with various spike protein binding ligands, including ACE2 peptide, recombinant human ACE2 (rhACE2) or monoclonal antibody to spike protein (mAb). The LNP-Trim consisted of ionizing cationic DLin-MC3-DMA, DSPC, cholesterol, and DMG-PEG lipids encapsulating siACE2 or siTMPRSS2. Both formulations were assayed for biocompatibility and cell uptake in airway epithelial cells (Calu-3). Functional assessment of activity was performed using SARS-CoV-2 spike protein binding assays (LNP-Trap), host receptor knockdown (LNP-Trim), and SARS-CoV-2 pseudovirus neutralization assay (LNP-Trap and LNP-Trim). Localization and tissue distribution of fluorescently labeled LNP formulations were assessed in mice following intranasal administration.

Results

Both LNP formulations were biocompatible based on cell impedance and MTT cytotoxicity studies in Calu-3 cells at concentrations as high as 1 mg/mL. LNP-Trap formulations were able to bind spike protein and inhibit pseudovirus infection by 90% in Calu-3 cells. LNP-Trim formulations reduced ACE2 and TMPRSS2 at the mRNA (70% reduction) and protein level (50% reduction). The suppression of host targets in Calu-3 cells treated with LNP-Trim resulted in over 90% inhibition of pseudovirus infection. In vivo studies demonstrated substantial retention of LNP-Trap and LNP-Trim in the nasal cavity following nasal administration with minimal systemic exposure.

Conclusion

Both LNP-Trap and LNP-Trim formulations were able to safely and effectively inhibit SARS-CoV-2 pseudoviral infection in airway epithelial cells. These studies provide proof-of-principle for a localized treatment approach for SARS-CoV-2 in the upper airway.

A Novel Riboflavin Formulation for Corneal Delivery Without Damaging Epithelial Cells

Purpose

This study aimed to evaluate the trans-epithelial permeability enhancement and cell damage caused by a novel riboflavin composition for corneal delivery.

Methods

We developed a trans-epithelial formulation of riboflavin for corneal delivery using 1,2-dioleoyl-3-dimethylammonium-propane (DODAP) and isostearic acid (ISA). The permeation enhancement was evaluated using an in vitro corneal epithelial cell culture system by measuring the amount of transferred riboflavin with high-performance liquid chromatography. Riboflavin permeation of MedioCROSS TE, a commercially available riboflavin formulation containing benzalkonium chloride, was also evaluated and compared to that of the DODAP/ISA formulation by changing the riboflavin concentration. The trans-epithelial electrical resistance (TEER) was measured after exposure to the samples in an in vitro corneal epithelial cell culture system to assess cytotoxicity.

Results

The DODAP/ISA formulation demonstrated greater permeation when used together than when each component was used individually. The permeation enhancement effect of the DODAP/ISA formulation was almost the same as that of MedioCROSS TE. However, when a 10-fold higher riboflavin concentration was used in the DODAP/ISA formulation, the permeation enhancement effect surpassed that of MedioCROSS TE. After 24 hours of exposure, the TEER of the DODAP/ISA formulation was higher than that of MedioCROSS TE, indicating that the DODAP/ISA formulation was less cytotoxic than MedioCROSS TE.

Conclusions

This study indicated that the DODAP/ISA formulation could serve as a less cytotoxic alternative to MedioCROSS TE. Further studies are required to determine the clinical efficacy and safety of the DODAP/ISA formulation in vivo.

Translational Relevance

This study may provide alternative procedures for corneal collagen crosslinking with less of a cytotoxic effect on corneal epithelial cells.

Use of Microfluidics to Prepare Lipid-Based Nanocarriers

Lipid-based nanoparticles (LBNPs) are an important tool for the delivery of a diverse set of drug cargoes, including small molecules, oligonucleotides, and proteins and peptides. Despite their development over the past several decades, this technology is still hindered by issues with the manufacturing processes leading to high polydispersity, batch-to-batch and operator-dependent variability, and limits to the production volumes. To overcome these issues, the use of microfluidic techniques in the production of LBNPs has sharply increased over the past two years. Microfluidics overcomes many of the pitfalls seen with conventional production methods, leading to reproducible LBNPs at lower costs and higher yields. In this review, the use of microfluidics in the preparation of various types of LBNPs, including liposomes, lipid nanoparticles, and solid lipid nanoparticles for the delivery of small molecules, oligonucleotides, and peptide/protein drugs is summarized. Various microfluidic parameters, as well as their effects on the physicochemical properties of LBNPs, are also discussed.