Inter-nanocarrier and nanocarrier-to-cell transfer assays demonstrate the risk of an immediate unloading of dye from labeled lipid nanocapsules

Release studies constitute a fundamental part of the nanovector characterization. However, it can be difficult to correctly assess the release of lipophilic compounds from lipid nanocarriers using conventional assays. Previously, we proposed a method including an extraction with oil to measure the loading stability of lipophilic dyes in lipid nanocapsules (LNCs). The method indicated a rapid release of Nile Red from LNCs, while the loading of lipophilic carbocyanine dyes remained stable. This method, although interesting for a rapid screening of the fluorescence labeling stability of nanocarriers, is far from what happens in vivo, where lipid acceptor phases are nanostructured. Here, lipophilic dye loading stability has been assessed, by monitoring dye transfer from LNCs toward stable colloidal lipid nanocompartments, i.e. non-loaded LNCs, using new methodology based on size exclusion chromatography (SEC) and Förster Resonance Energy Transfer (FRET). Dye transfer between LNCs and THP-1 cells (as model for circulating cells) has also been studied by FACS. The assays reveal an almost instantaneous transfer of Nile Red between LNCs, from LNCs to THP-1 cells, between THP-1 cells, and a reversal transfer from THP-1 cells to LNCs. On the contrary, there was no detectable transfer of the lipophilic carbocyanine dyes. Dye release was also analyzed using dialyses, which only revealed a very slow release of Nile Red from LNCs, demonstrating the weakness of membrane based assays for investigations of the lipophilic compound loading stability in lipid nanocarriers. These results highlight the importance of using relevant release assays, and the potential risk of an immediate unloading of lipophilic fluorescent dyes from lipid nanocarriers, in the presence of a lipid acceptor nanocompartment. Some misinterpretations of cellular trafficking and in vivo biodistribution of fluorescent nanoparticles should be avoided

Passive and specific targeting of lymph nodes: the influence of the administration route

Patients diagnosed with an advanced-stage cancer present a dismal prognosis due to the presence of metastases. From the primary tumor, the cancer cells are disseminated via lymphatic circulation; metastases develop initially in lymph nodes. Therefore, the targeting of lymph nodes needs to be improved in the design of future chemotherapy, and one way to ensure this targeting is by using the subcutaneous (SC) route. Using lipid nanocapsules (LNCs) (40 nm and fluorescently-labeled with DiD) as nanocarriers, a correlation between the SC injection site (behind the neck, the right and left flanks, and above the tail) for LNC administration and specific lymph node accumulation (left and right cervical, axillary and inguinal lymph nodes) was achieved for Sprague-Dawley rats. The pharmacokinetic and biodistribution profiles confirmed the absence of LNCs in systemic circulation after SC administration due to the optimal size of the LNCs. With appropriate SC administration, LNCs can accumulate in specific lymph nodes, whereas IV administration led to a weak accumulation of LNCs in all lymph nodes. Specific accumulation followed the lymph flow: bottom-up from the lower to upper limbs and top down from the head, with two lymph circulation partitions: right upper limb and the rest. Administration above the tail presented high inguinal and axillary lymph node accumulation whereas weak accumulation was observed after administration behind the neck. LNCs administered in the left flank only accumulated in the left inguinal and axillary lymph nodes, whereas left and right inguinal and axillary lymph nodes presented accumulation after administration in the right flank. Cervical lymph nodes, in the opposite direction of lymph flow, were never targeted after SC administration, whatever the injection site

Nanovectors for Neurotherapeutic Delivery Part II: Polymeric Nanoparticles

Despite major advances in intracranial surgery and delivery of drugs to the brain, treatment of neurological diseases remains one of the great medical challenges of our days. The complexity of the organ makes surgical procedures complicated, and conventional systemic delivery of drugs to the brain is hampered by low drug selectivity and low drug partitioning over the blood-brain barrier. Due to the high social and economic impacts related to diseases of the central nervous system, development of new improved treatments of brain related disorders is of significant value, both for the patient and for the society. Nanomedicine is a rapidly growing field in the development of novel therapies for treatments of brain pathologies. The scientific progress in nanotechnology has resulted in several new innovative nano-assemblies, with promising medical potentials. Therapeutic benefits related to the use of nanovectors includes, reduced chemical and enzymatic degradation of drugs, increased uptake over biological barriers, improved selectivity by surface modification using targeting ligands, and reduced toxic side effects in non-target tissue. This review discusses various applications of polymeric nanoparticles as nanovectors in treatment of neuronal diseases, specifically illustrated for Alzheimer’s and Parkinson’s diseases and Glioblastoma

Recent advances in nanocarrier-loaded gels: Which drug delivery technologies against which diseases?

The combination of pharmaceutical technologies can be a wise choice for developing innovative therapeutic strategies. The association of nanocarriers and gels provides new therapeutic possibilities due to the combined properties of the two technologies. Gels support the nanocarriers, localize their administration to the target tissue, and sustain their release. In addition to the properties afforded by the gel, nanocarriers can provide additional drug sustained release or different pharmacokinetic and biodistribution profiles than those from nanocarriers administered by the conventional route to improve the drug therapeutic index. This review focuses on recent (over the last ten years) in vivo data showing the advances and advantages of using nanocarrier-loaded gels. Liposomes, micelles, liquid and solid lipid nanocapsules, polymeric nanoparticles, dendrimers, and fullerenes are all nanotechnologies which have been recently assessed for medical applications, such as cancer therapy, the treatment of cutaneous and infectious diseases, anesthesia, the administration of antidepressants, and the treatment of unexpected diseases, such as alopecia

Modified antimetabolites-loaded lipid nanocapsules to enhance antitumor immunity

Introduction : Myeloid­derived suppressor cells (MDSCs) are critical players of tumor­induced immunosuppression in mouse models and cancer patients. They accumulate in the spleen and cancers of tumor­bearing hosts where they suppress T­cell activation, proliferation and cytotoxic function [1]. Previous studies demonstrated that some anticancer agents, in addition to their cytotoxic effects on tumor cells, were able to affect MDSCs. This occurs for antimetabolites like 5­fluorouracile (5­FU) and Gemcitabine (Gem) [2]. In this work, the potential activity of novel lipophilic 5­FU and Gem derivatives encapsulated into lipid nanocapsules (LNCs) to target monocytic (M­)MDSC subset and tumor cells (pancreatic B6KPC3) was assessed. The aim was to study the immunogenic and anticancer properties of innovative nanosystems. Methods: Gem and 5­FU were modified to obtain mono­lauroyl­derivatives (Gem­C12 and 5­FU­C12). The derivatives were purified by chromatography on silica column and characterized by nuclear magnetic resonance. Blank and loaded­LNCs were prepared using the phase inversion process [3]. Physico­chemical characterization (size, dispersity, zeta potential and encapsulation efficiency) was performed. To study the in vitro induction of M­MDSCs, the immunosuppressive activity and internalization assays of GemC­12­loaded LNCs, mouse bone marrow cells cultured in presence of GM­CSF and IL­6 were used. To investigate the efficacy of 5­FU­C12­loaded LNCs, B6KPC3 cells were employed. Finally, as a preliminary in vivo study, the biodistribution of fluorescent­loaded LNCs (i.v. or s.c.) using tumor­bearing mice (EG7­OVA subcutaneous model) was evaluated. Results: Lipophilic derivatives, 5FU­C12 and Gem­C12, were synthetized. The yield of the products recovered was 60% and 40% for 5FU­C12 and Gem­C12, respectively. Blank, 5FU­C12 and Gem­C12­loaded LNCs showed an average size of 60 nm, dispersity index below 0.1 and neutral surface charge. The encapsulation efficiency of drugs was close to 100%. In vitro and in vivo studies highlighted that Gem­C12­loaded LNCs were internalized and depleted selectively M­MDSCs. Using K6PC3, we demonstrated that 5­FU­C12­loaded LNCs exerted a toxic effect comparable to the commercial 5FU­solution. In vivo studies following i.v. or s.c. administration of fluorescent­loaded LNCs showed that LNCs reached peripheral tissues. As compared with i.v., following s.c. injection, fluorescent signal increased with time in the spleen, suggesting a slow LNCs absorption. Conclusions : In the present study, lipophilic 5­FU­C12 and Gem­C12­loaded LNC were obtained. Gem­C12­ loaded LNCs were able to target M­MDSCs in vivo and in vitro. Besides, 5­FU­C12­loaded LNCs showed efficacy as anticancer drug in a pancreatic cell line. Further in vitro and in vivo therapeutic evaluations would disclose the full potential of these novel LNCs.