Pharmacology of nanocarriers on the microscale: importance of uptake mechanisms and intracellular trafficking for efficient drug delivery

Receptor-targeted nanoparticles modulate cannabinoid anticancer activity through delayed cell internalization

Δ9-tetrahydrocannabinol (Δ9-THC) is known for its antitumor activity and palliative effects. However, its unfavorable physicochemical and biopharmaceutical properties, including low bioavailability, psychotropic side effects and resistance mechanisms associated to dosing make mandatory the development of successful drug delivery systems. In this work, transferring (Tf) surface-modified Δ9-THC-loaded poly(lactide-co-glycolic) nanoparticles (Tf-THC-PLGA NPs) were proposed and evaluated as novel THC-based anticancer therapy. Furthermore, in order to assess the interaction of both the nanocarrier and the loaded drug with cancer cells, a double-fluorescent strategy was applied, including the chemical conjugation of a dye to the nanoparticle polymer along with the encapsulation of either a lipophilic or a hydrophilic dye. Tf-THC PLGA NPs exerted a cell viability decreased down to 17% vs. 88% of plain nanoparticles, while their internalization was significantly slower than plain nanoparticles. Uptake studies in the presence of inhibitors indicated that the nanoparticles were internalized through cholesterol-associated and clathrin-mediated mechanisms. Overall, Tf-modification of PLGA NPs showed to be a highly promising approach for Δ9-THC-based antitumor therapies, potentially maximizing the amount of drug released in a sustained manner at the surface of cells bearing cannabinoid receptors.

Mechanisms of transport of polymeric and lipidic nanoparticles across the intestinal barrier

Unraveling the mechanisms of nanoparticle transport across the intestinal barrier is essential for designing more efficient nanoparticles for oral administration. The physicochemical parameters of the nanoparticles (e.g., size, surface charge, chemical composition) dictate nanoparticle fate across the intestinal barrier. This review aims to address the most important findings regarding polymeric and lipidic nanoparticle transport across the intestinal barrier, including the evaluation of critical physicochemical parameters of nanoparticles that affect nanocarrier interactions with the intestinal barrier.

Single-particle tracking for studying nanomaterial dynamics: applications and fundamentals in drug delivery

Many macromolecular therapeutics could potentially treat genetic disorders and cancer. They have, however, not yet reached the clinical stage owing to a lack of suitable carriers that can bring the therapeutics from the administration site to the subcellular site in target cells. One of the reasons that is hindering the development of such carriers is the limited knowledge of their transport dynamics and intracellular processing. Single-particle tracking (SPT) microscopy, thanks to its single molecule sensitivity and its broad applicability, has found its entry in the field of drug delivery to get an answer to these questions. This review aims to introduce the fundamentals of SPT to the drug delivery community and highlight the most recent discoveries obtained with SPT in the field of drug delivery.

Mass spectrometry and imaging analysis of nanoparticle-containing vesicles provide a mechanistic insight into cellular trafficking

Rational design of nanocarriers for drug delivery approaches requires an unbiased knowledge of uptake mechanisms and intracellular trafficking pathways. Here we dissected these processes using a quantitative proteomics approach. We isolated intracellular vesicles containing superparamagnetic iron oxide polystyrene nanoparticles and analyzed their protein composition by label-free quantitative mass spectrometry. The proteomic snapshot of organelle marker proteins revealed that an atypical macropinocytic-like mechanism mediated the entry of nanoparticles. We show that the entry mechanism is controlled by actin reorganization, atypical macropinocytic signaling, and ADP-ribosylation factor 1. Additionally, our proteomics data demonstrated a central role for multivesicular bodies and multilamellar lysosomes in trafficking and final nanoparticle storage. This was confirmed by confocal microscopy and cryo-TEM measurements. By quantitatively analyzing the protein composition of nanoparticle-containing vesicles, our study clearly defines the routes of nanoparticle entry, intracellular trafficking, and the proteomic milieu of a nanoparticle-containing vesicle.

Drug delivery without nanoparticle uptake: delivery by a kiss-and-run mechanism on the cell membrane

Nearly all concepts of nanocarriers as drug delivery devices rely on intracellular uptake. Instead, we demonstrate an alternative concept for rapid and specific delivery of cargo by nanoparticles to TIP47+/ADRP+ lipid droplets. The model can serve as a novel strategy for the non-invasive delivery of drugs by releasing hydrophobic cargo, in our case a model dye, through a kiss-and-run mechanism between nanoparticles and the cell membrane.