Poly(ethylene carbonate) Nanoparticles as Carrier System for Chemotherapy Showing Prolonged in vivo Circulation and Anti-Tumor Efficacy

Bioinspired zwitterionic triblock copolymers designed for colloidal drug delivery: 2 - Biological evaluation

In this work, poly(lactide) nanoparticles were equipped with a bioinspired coating layer based on poly[2-(methacryloyloxy)ethyl phosphorylcholine] and then evaluated when administered to the lungs and after intravenous injection. Compared to the plain counterparts, the chosen zwitterionic polymer shell prevented the coated colloidal formulation from aggregation and conditioned it for lower cytotoxicity, protein adsorption, complement activation and phagocytic cell uptake. Consequently, no interference with the biophysical function of the lung surfactant system could be detected accompanied by negligible protein and cell influx into the bronchoalveolar space after intratracheal administration. When injected into the central compartment, the coated formulation showed a prolonged circulation half-life and a delayed biodistribution to the liver. Taken together, colloidal drug delivery vehicles would clearly benefit from the investigated poly[2-(methacryloyloxy)ethyl phosphorylcholine]-based polymer coatings.

Using Compartments to Model Drug Delivery from Biodegradable Polymers

Polymeric drug delivery systems can improve patient compliance, decrease toxicity and prolong therapeutic effects for a wide range of therapeutic treatments, by controlling drug release. Polymer delivery system development can be facilitated by mathematical models. We present here a new compartmental model that will be more familiar to pharmaceutical professionals and equally as effective as common diffusion equation-based models. The compartmental model considers both polymer degradation and drug diffusion to predict drug release. The model is adapted into three different geometries for different polymer delivery scenarios: membranes, fibres and particles. Model parameters are derived in terms of diffusion coefficients. Polymer-drug binding interactions and distributions of fibre/particle diameters are incorporated to the model. The model is validated by comparison to common diffusion equation-based solutions and fitting to experimental data. It is shown how the model for drug release can be incorporated into existing distribution models to predict plasma concentrations of an in vivo administration. A user-friendly Python implementation of the model is available on Github, at https://github.com/spirt-t/compartments_model.

Microfluidic Assembly of siRNA-Loaded Micelleplexes for Tumor Targeting in an Orthotopic Model of Ovarian Cancer

The use of cationic polymers to interact with negatively charged siRNA via charge complexation to form polyelectrolyte complexes has been widely studied ever since the 1998 report on RNA interference. These polyelectrolyte complex formulations aim to overcome the many pitfalls associated with the use of RNA interference as a potential cancer therapy. The triblock copolymer polyethylenimine-polycaprolactone-polyethylene glycol (PEI-PCL-PEG) contains the cation PEI and has been shown to be an efficient carrier capable of complexing with nucleic acids for gene delivery. This copolymer system also allows for targeting moieties to be linked to the micelleplex, thereby exploiting overexpressed receptors (such as the folate receptor) located within tumors. Additionally, we demonstrated recently that microfluidic mixing of PEI-PCL-PEG nanoparticles allows for the rapid, scaled-up production of micelleplexes while maintaining small and uniform particle distributions. The preparation of small and reproducible particles is imperative for clinical translation of nanomedicine and for tumor targeting via systemic administration. Furthermore, to enable tracing of its deposition in vivo after its administration, micelleplexes can be radiolabeled. To assess tumor targeting over time, the noninvasive imaging technique single-photon emission computed tomography (SPECT) offers the ability to examine the same subject at multiple time points and generate biodistribution profiles. Since the biodistribution and tumor targeting of the therapeutic load of micelleplexes is of foremost interest, we recently described an approach to modify siRNA with a DTPA (diethylenetriaminepentaacetic acid) chelator. Herein, we explain the details of encapsulating indium-labeled siRNA via microfluidic mixing in PEI-PCL-PEG nanoparticles with a folic acid targeting ligand for assessment of their in vivo tumor targeting in an orthotopic ovarian cancer model.

Indium-Labeling of siRNA for Small Animal SPECT Imaging

Ever since the discovery of RNA interference (RNAi), therapeutic delivery of siRNA has attracted a lot of interest. However, due to the nature and structure of siRNA, a carrier is needed for any mode of systemic treatment. Furthermore, specific imaging techniques are required to trace where the deposition of the siRNA occurs throughout the body after treatment. Tracking in vivo siRNA biodistribution allows understanding and interpreting therapeutics effects and side effects. A great advantage of noninvasive imaging techniques such as SPECT imaging is that several time points can be assessed in the same subject. Thus, the time course of biodistribution or metabolic processes can be followed. Therefore, we have described an approach to modify siRNA with a DTPA (Diethylene Triamine Pentaacetic Acid) chelator in order to utilize an indium labeled siRNA for SPECT imaging. Here, we explain the details of the labeling and purification procedures.