Lipid-Saporin Nanoparticles for the Intracellular Delivery of Cytotoxic Protein to Overcome ABC Transporter-Mediated Multidrug Resistance In Vitro and In Vivo

Targeted delivery of cytotoxic proteins via lipid-based nanoparticles to primary Langerhans cells

Targeted delivery has emerged as a critical strategy in the development of novel therapeutics. The advancement of nanomedicine hinges on the safe and precise cell-specific delivery of protein-based therapeutics to the immune system. However, major challenges remain, such as developing an efficient delivery system, ensuring specificity, minimizing off-target effects, and attaining effective intracellular localization. Our strategy utilizes lipid-based nanoparticles conjugated with a glycomimetic ligand. These nanoparticles selectively bind to langerin, a C-type lectin receptor expressed on Langerhans cells in the skin. We opted for cytotoxic proteins, namely cytochrome c and saporin, as model proteins to showcase the potential of delivering intact proteins to Langerhans cells. These proteins are recognized for their ability to induce apoptosis upon entry into the cytosol. We observed specific killing of cells expressing langerin in vitro, and in primary Langerhans cells isolated from mouse and human skin ex vivo with minimal off target effects. By delivering functional proteins within lipid nanoparticles to Langerhans cells, our approach offers new potential to deliver effective therapeutics with minimal side effects.

A bioinspired pseudopeptide-based intracellular delivery platform enhances the cytotoxicity of a ribosome-inactivating protein through multiple death pathways

Saporin is a 28 621 Da protein and plant toxin possessing rRNA N-glycosidase activity. Due to its potent ribosome-inactivating ability, saporin is commonly studied as an anticancer agent. However, its enzymatic activity is greatly hindered by its poor plasma membrane permeability. To overcome this barrier, we used a bioinspired intracellular delivery platform based on the pH-responsive pseudopeptide, poly(L-lysine isophthalamide) grafted with L-phenylalanine at a stoichiometric molar percentage of 50% (PP50). PP50 was co-incubated with saporin (PP50/saporin) in a mildly acidic pH environment to aid intracellular delivery and increase saporin's therapeutic potential. We demonstrated that PP50 greatly enhanced the cytotoxicity of saporin in the 2D monolayer of A549 cells and 3D A549 multicellular spheroids whilst remaining non-toxic when administered alone. To elucidate the mechanism of cell death, we assessed the activation of caspases, the inhibition of protein synthesis, the onset of apoptosis and the mechanism of PP50/saporin entry. Inhibition of protein synthesis and activation of caspases 3/7, 8 and 9 were found to occur before the onset of apoptosis and cell death. PP50/saporin was also shown to rely on micropinocytosis and caveolae-mediated endocytosis for cell entry. In addition, fluorescein isothiocyanate-labelled saporin (FITC-saporin) was localized within the cytoplasm and nuclei when delivered with Cyanine5-labelled PP50 (Cy5-PP50). Taken together, this suggests that multiple pathways are triggered to initiate apoptosis and cell death in cells treated with PP50/saporin. Therefore, these results make PP50 a potential intracellular delivery platform for the internalization of protein therapeutics.

Enzyme-catalyzed synthesis of selenium-doped manganese phosphate for synergistic therapy of drug-resistant colorectal cancer

BACKGROUND

The development of multidrug resistance (MDR) during postoperative chemotherapy for colorectal cancer substantially reduces therapeutic efficacy. Nanostructured drug delivery systems (NDDSs) with modifiable chemical properties are considered promising candidates as therapies for reversing MDR in colorectal cancer cells. Selenium-doped manganese phosphate (Se-MnP) nanoparticles (NPs) that can reverse drug resistance through sustained release of selenium have the potential to improve the chemotherapy effect of colorectal cancer.

RESULTS

Se-MnP NPs had an organic-inorganic hybrid composition and were assembled from smaller-scale nanoclusters. Se-MnP NPs induced excessive ROS production via Se-mediated activation of the STAT3/JNK pathway and a Fenton-like reaction due to the presence of manganese ions (Mn²⁺). Moreover, in vitro and in vivo studies demonstrated Se-MnP NPs were effective drug carriers of oxaliplatin (OX) and reversed multidrug resistance and induced caspase-mediated apoptosis in colorectal cancer cells. OX@Se-MnP NPs reversed MDR in colorectal cancer by down-regulating the expression of MDR-related ABC (ATP binding cassette) transporters proteins (e.g., ABCB1, ABCC1 and ABCG2). Finally, in vivo studies demonstrated that OX-loaded Se-MnP NPs significantly inhibited proliferation of OX-resistant HCT116 (HCT116/DR) tumor cells in nude mice.

CONCLUSIONS

OX@Se-MnP NPs with simple preparation and biomimetic chemical properties represent promising candidates for the treatment of colorectal cancer with MDR.

Tailoring combinatorial lipid nanoparticles for intracellular delivery of nucleic acids, proteins, and drugs

Lipid nanoparticle (LNP)-based drug delivery systems have become the most clinically advanced non-viral delivery technology. LNPs can encapsulate and deliver a wide variety of bioactive agents, including the small molecule drugs, proteins and peptides, and nucleic acids. However, as the physicochemical properties of small- and macromolecular cargos can vary drastically, every LNP carrier system needs to be carefully tailored in order to deliver the cargo molecules in a safe and efficient manner. Our group applied the combinatorial library synthesis approach and in vitro and in vivo screening strategy for the development of LNP delivery systems for drug delivery. In this Review, we highlight our recent progress in the design, synthesis, characterization, evaluation, and optimization of combinatorial LNPs with novel structures and properties for the delivery of small- and macromolecular therapeutics both in vitro and in vivo. These delivery systems have enormous potentials for cancer therapy, antimicrobial applications, gene silencing, genome editing, and more. We also discuss the key challenges to the mechanistic study and clinical translation of new LNP-enabled therapeutics.

Interest of extracellular vesicles in regards to lipid nanoparticle based systems for intracellular protein delivery

Compared to chemicals that continue to dominate the overall pharmaceutical market, protein therapeutics offer the advantages of higher specificity, greater activity, and reduced toxicity. While nearly all existing therapeutic proteins were developed against soluble or extracellular targets, the ability for proteins to enter cells and target intracellular compartments can significantly broaden their utility for a myriad of exiting targets. Given their physical, chemical, biological instability that could induce adverse effects, and their limited ability to cross cell membranes, delivery systems are required to fully reveal their biological potential. In this context, as natural protein nanocarriers, extracellular vesicles (EVs) hold great promise. Nevertheless, if not present naturally, bringing an interest protein into EV is not an easy task. In this review, we will explore methods used to load extrinsic protein into EVs and compare these natural vectors to their close synthetic counterparts, liposomes/lipid nanoparticles, to induce intracellular protein delivery.

Doxorubicin/Nucleophosmin Binding Protein-Conjugated Nanoparticle Enhances Anti-leukemia Activity in Acute Lymphoblastic Leukemia Cells in vitro and in vivo

Acute lymphoblastic leukemia (ALL) is an aggressive malignancy. Adults with ALL have more than 50% relapse rates. We have previously validated that overexpression of nucleophosmin (NPM) is involved in the multidrug resistance (MDR) development during ALL; and a synthetically engineered recombinant NPM binding protein (NPMBP) has been developed in our group; NPMBP and doxorubicin (DOX) can be conjugated in a nanoparticle-based drug delivery system named DOX-PMs-NPMBP to counteract MDR during ALL. Here, we evaluated the antileukemia potential of DOX-PMs-NPMBP in resistant ALL cells. This study demonstrates that DOX-PMs-NPMBP significantly enhances chemosensitivity to DOX in ALL cells. Despite at variable concentrations, both resistant and primary ALL cells from relapsed patients were sensitive to DOX-PMs-NPMBP. In detail, the half maximal inhibitory concentration (IC50) values of DOX-PMs-NPMBP were between 1.6- and 7.0-fold lower than those of DOX in cell lines and primary ALL cells, respectively; and apoptotic cells ratio was over 2-fold higher in DOX-PMs-NPMBP than DOX. Mechanistically, p53-driven apoptosis induction and cell cycle arrest played essential role in DOX-PMs-NPMBP-induced anti-leukemia effects. Moreover, DOX-PMs-NPMBP significantly inhibited tumor growth and prolonged mouse survival of ALL xenograft models; and no systemic toxicity occurrence was observed after treatment during follow-up. In conclusion, these data indicate that DOX-PMs-NPMBP may significantly exert growth inhibition and apoptosis induction, and markedly improve DOX antileukemia activity in resistant ALL cells. This novel drug delivery system may be valuable to develop as a new therapeutic strategy against multidrug resistant ALL.