Insights on the intracellular trafficking of PDMAEMA gene therapy vectors

Transient Destabilization of Biological Membranes Contributes to the Superior Performance of Star-Shaped PDMAEMA in Delivering pDNA

Nonviral DNA vectors are promising alternatives to viral ones. Their use in DNA medicine is limited by an inability to transfect, for example, nondividing or suspension cells. In recent years, star-shaped synthetic polycationic vectors, so called "Nanostars", have shown some promise in this regard, at least when compared to the "gold standard" in nonviral vectors, namely, linear poly(ethyleneimine) (l-PEI). It has been hypothesized that an ability to transiently destabilize cellular membranes is partially responsible for the phenomenon. This hypothesis is investigated here, taking human leukemia suspension cells (Jurkat cells) as an example. Contrary to l-PEI, the Nanostars promote the cellular uptake of small, normally membrane-impermeant molecules (trypan blue and propidium iodide) as well as that of fluorescent polystyrene beads (average diameter 100 nm). Since Nanostars, but not l-PEI, are apparently able to deliver DNA to nuclei of nondividing cells, nuclear uptake is, in addition, investigated with isolated cell nuclei. Our results provide evidence that Nanostars are more efficient than l-PEI in increasing the nuclear membrane association/permeability, allowing accumulation of their cargo on/in the nucleus.

Self-Assembled Multilayer Films for Time-Controlled Ocular Drug Delivery

The patient's compliance on the therapeutics to treat glaucoma is significantly low contributing for a fast evolution of the disease. This article presents an autonomous system with controlled release using an alpha2-adrenergic receptor agonist, brimonidine, usually used to treat glaucoma. More specifically, biocompatible and layer-by-layer drug delivery films containing monolayers with brimonidine encapsulated in polymer-β-cyclodextrin were prepared with the objective to obtain a system able to release precise amounts of drug at specific times. To delay the erosion-controlled drug release, we included nanosheets of graphene oxide and layers of a biodegradable polymer (poly-β-aminoester) between the drug-containing monolayers to obtain a time-controlled drug delivery system. An increase in the number of graphene oxide layers is proportional to the brimonidine release delay and its kinetic release can be tuned as a function of the number of layers. Two types of films with brimonidine encapsulated in β-cyclodextrin were analyzed. One of them composed of barrier layers with PBAE and another with two types of barrier layers, PBAE and graphene oxide. The results indicate that one graphene oxide bilayer can delay the brimonidine release for more than 24 h. In vitro assays confirmed that the films have a cell viability of 100%.

Glucose-responsive mesoporous silica nanoparticles to generation of hydrogen peroxide for synergistic cancer starvation and chemistry therapy

Background: The combination of novel starving therapy with chemotherapy is one of the most promising strategies to achieve an effective antitumor activity.

Methods: Herein, we developed a multifunctional mesoporous silica nanoparticle (MSNs-GOx/PLL/HA) coated with poly (L-lysine) (PLL) and hyaluronic acid (HA) for co-delivery of glucose oxidase (GOx) and anticancer drug paclitaxel (PTX) for cancer treatment for the first time. Compared to single chemotherapy, introduction of GOx would not only selectively trigger the consumption of intracellular glucose, leading to the interruption of energy supply, but also elevat the endogenous H₂O₂ level, inducing stronger therapeutic effects.

Results: The novel drug delivery system possessed desirable particle diameter of 40 nm and exhibited a pH-sensitive drug release behavior. An in vitro cellular uptake study indicated that MSNs-GOx/PLL/HA nanoparticles effectively enhanced the cellular uptake of drug in an apparently CD44 receptor-dependent manner, and delivered more cargo into cytoplasm via endolysosomal escape effect in presence of PLL. The nanoplatform has also demonstrated amplified synergistic therapeutic effects for remarkable tumor inhibition in a xenograft animal tumor model.

Conclusion: Consequently, the developed synergistic starving-like/chemotherapy may provide a potential platform for next generation cancer therapy.