Mannose-modified hyaluronic acid nanocapsules for the targeting of tumor-associated macrophages.

Tumor-associated macrophages (TAMs), a class of immune cells that play a key role in tumor immunosuppression, are recognized as important targets to improve cancer prognosis and treatment. Consequently, the engineering of drug delivery nanocarriers that can reach TAMs has acquired special relevance. This work describes the development and biological evaluation of a panel of hyaluronic acid (HA) nanocapsules (NCs), with different compositions and prepared by different techniques, designed to target macrophages. The results showed that plain HA NCs did not significantly influence the polarization of M0 and M2-like macrophages towards an M1-like pro-inflammatory phenotype; however, the chemical functionalization of HA with mannose (HA-Man) led to a significant increase of NCs uptake by M2 macrophages in vitro and to an improved biodistribution in a MN/MNCA1 fibrosarcoma mouse model with high infiltration of TAMs. These functionalized HA-Man NCs showed a higher accumulation in the tumor compared to non-modified HA NCs. Finally, the pre-administration of the liposomal liver occupying agent Nanoprimer™ further increased the accumulation of the HA-Man NCs in the tumor. This work highlights the promise shown by the HA-Man NCs to target TAMs and thus provides new options for the development of nanomedicine and immunotherapy-based cancer treatments.

A Nanoprimer To Improve the Systemic Delivery of siRNA and mRNA.

Despite tremendous interest in gene therapies, the systemic delivery of nucleic acids still faces substantial challenges. To successfully administer nucleic acids, one approach is to encapsulate them in lipid nanoparticles (LNPs). However, LNPs administered intravenously substantially accumulate in the liver where they are taken up by the reticuloendothelial system (RES). Here, we administer prior to the LNPs a liposome designed to transiently occupy liver cells, the Nanoprimer. This study demonstrates that the pretreatment of mice with the Nanoprimer decreases the LNPs' uptake by the RES. By accumulating rapidly in the liver cells, the Nanoprimer improves the bioavailability of the LNPs encapsulating human erythropoietin (hEPO) mRNA or factor VII (FVII) siRNA, leading respectively to more hEPO production (by 32%) or FVII silencing (by 49%). The use of the Nanoprimer offers a new strategy to improve the systemic delivery of RNA-based therapeutics.

Priming the body to receive the therapeutic agent to redefine treatment benefit/risk profile.

Many therapeutic agents offer a low useful dose (dose responsible for efficacy)/useless dose (dose eliminated or responsible for toxicity) ratio, mainly due to the fact that therapeutic agents must ensure in one single object all the functions required to deliver the treatment, which leads to compromises in their physico-chemical design. Here we introduce the concept of priming the body to receive the treatment by uncorrelating these functions into two distinct objects sequentially administered: a nanoprimer occupying transiently the main pathway responsible for therapeutic agent limited benefit/risk ratio followed by the therapeutic agent. The concept was evaluated for different nature of therapeutic agents: For nanomedicines we designed a liposomal nanoprimer presenting preferential hepatic accumulation without sign of acute toxicity. This nanoprimer was able to increase the blood bioavailability of nanomedicine correlated with a lower hepatic accumulation. Finally this nanoprimer markedly enhanced anti-tumor efficacy of irinotecan loaded liposomes in the HT-29 tumor model when compared to the nanomedicine alone. Then, for small molecules we demonstrated the ability of a cytochrome inhibitor loaded nanoprimer to increase efficacy of docetaxel treatment. These results shown that specific nanoprimers could be designed for each family of therapeutic agents to answer to their specific needs.

Nano-sized cytochrome P450 3A4 inhibitors to block hepatic metabolism of docetaxel.

Most drugs are metabolized by hepatic cytochrome P450 3A4 (CYP3A4), resulting in their reduced bioavailability. In this study, we present the design and evaluation of bio-compatible nanocarriers trapping a natural CYP3A4-inhibiting compound. Our aim in using nanocarriers was to target the natural CYP3A4-inhibiting agent to hepatic CYP3A4 and leave drug-metabolizing enzymes in other organs undisturbed. In the design of such nanocarriers, we took advantage of the nonspecific accumulation of small nanoparticles in the liver. Specific targeting functionalization was added to direct nanocarriers toward hepatocytes. Nanocarriers were evaluated in vitro for their CYP3A4 inhibition capacity and in vivo for their biodistribution, and finally injected 24 hours prior to the drug docetaxel, for their ability to improve the efficiency of the drug docetaxel. Nanoparticles of poly(lactic-co-glycolic) acid (PLGA) with a hydrodynamic diameter of 63 nm, functionalized with galactosamine, showed efficient in vitro CYP3A4 inhibition and the highest accumulation in hepatocytes. When compared to docetaxel alone, in nude mice bearing the human breast cancer, MDA-MB-231 model, they significantly improved the delay in tumor growth (treated group versus docetaxel alone, percent treated versus control ratio [%T/C] of 32%) and demonstrated a major improvement in overall survival (survival rate of 67% versus 0% at day 55).

A new opportunity for nanomedicines: Micellar cytochrome P450 inhibitors to improve drug efficacy in a cancer therapy model.

Nanomedicines are mainly used as drug delivery systems; here we evaluate a new application - to inhibit a drug's metabolism thereby enhancing its effective dose. Micelles containing the natural furanocoumarin 6',7'-dihydroxybergamottin (DHB), a known CYP450 inhibitor, were developed to transiently block hepatic CYP450-mediated drug metabolism and increase the bioavailability of the oncology drug docetaxel. Administered in mice 24h prior to the drug, DHB-micelles enhanced antitumor efficacy in the tumor xenograft models HT-29 and MDA-MB-231, when compared to the drug alone. These DHB-micelles have similar composition to marketed docetaxel-micelles for human use. Despite not being optimized in terms of targeting hepatocytes, they do represent the first injectable example of nanosized metabolism-blocking agents and open the way for further work on such nanomedicines in man.

Acetate- and thiol-capped monodisperse ruthenium nanoparticles: XPS, XAS, and HRTEM studies.

Monodisperse ruthenium nanoparticles were prepared by reduction of RuCl3 in 1,2-propanediol. The mean particle size was controlled by appropriate choice of the reduction temperature and the acetate ion concentration. Colloidal solutions in toluene were obtained by coating the metal particles with dodecanethiol. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XANES and EXAFS for the Ru K-absorption edge) were performed on particles of two different diameters, 2 and 4 nm, and in different environments, polyol/acetate or thiol. For particles stored in polyol/acetate XPS studies revealed superficial oxidation limited to one monolayer and a surface coating containing mostly acetate ions. Analysis of the EXAFS spectra showed both oxygen and ruthenium atoms around the ruthenium atoms with a Ru-Ru coordination number N smaller than the bulk value, as expected for fine particles. In the case of 2 nm acetate-capped particles N is consistent with particles made up of a metallic core and an oxidized monolayer. For 2 nm thiol-coated particles, a Ru-S bond was evidenced by XPS and XAS. For the 4 nm particles XANES and XPS studies showed that most of the ruthenium atoms are in the zerovalent state. Nevertheless, in both cases, when capped with thiol, the Ru-Ru coordination number inferred from EXAFS is much smaller than for particles of the same size stored in polyol. This is attributed to a structural disorganization of the particles by thiol chemisorption. HRTEM studies confirm the marked dependence of the structural properties of the ruthenium particles on their chemical environment; they show the acetate-coated particles to be single crystals, whereas the thiol-coated particles appear to be polycrystalline.