Melissa Guada

Lipid nanoparticles for cancer therapy: state of the art and future prospects

Introduction: Cancer is a leading cause of death worldwide and it is estimated that deaths from this disease will rise to over 11 million in 2030. Most cases of cancer can be cured with surgery, radiotherapy or chemotherapy if they are detected at an early stage. However, current cancer therapies are commonly associated with undesirable side effects, as most chemotherapy treatments are cytotoxic and present poor tumor targeting. Areas covered: Lipid nanoparticles (LN) are one of the most promising options in this field. LN are made up of biodegradable generally recognized as safe (GRAS) lipids, their formulation includes different techniques, and most are easily scalable to industrial manufacture. LN overcome the limitations imposed by the need for intravenous administration, as they are mainly absorbed via the lymphatic system when they are administered orally, which improves drug bioavailability. Furthermore, depending on their composition, LN present the ability to cross the blood–brain barrier, thus opening up the possibility of targeting brain tumors. Expert opinion: The drawbacks of chemotherapeutic agents make it necessary to invest in research to find safer and more effective therapies. Nanotechnology has opened the door to new therapeutic options through the design of formulations that include a wide range of materials and formulations at the nanometer range, which improve drug efficacy through direct or indirect tumor targeting, increased bioavailability and diminished toxicity.

Lipid nanoparticles for cyclosporine A administration: development, characterization, and in vitro evaluation of their immunosuppression activity.

Cyclosporine A (CsA) is an immunosuppressant commonly used in transplantation for prevention of organ rejection as well as in the treatment of several autoimmune disorders. Although commercial formulations are available, they have some stability, bioavailability, and toxicity related problems. Some of these issues are associated with the drug or excipients and others with the dosage forms. With the aim of overcoming these drawbacks, lipid nanoparticles (LN) have been proposed as an alternative, since excipients are biocompatible and also a large amount of surfactants and organic solvents can be avoided. CsA was successfully incorporated into LN using the method of hot homogenization followed by ultrasonication. Three different formulations were optimized for CsA oral administration, using different surfactants: Tween® 80, phosphatidylcholine, taurocholate and Pluronic® F127 (either alone or mixtures). Freshly prepared Precirol nanoparticles showed mean sizes with a narrow size distribution ranging from 121 to 202 nm, and after freeze-drying were between 163 and 270 nm, depending on the stabilizer used. Surface charge was negative in all LN developed. High CsA entrapment efficiency of approximately 100% was achieved. Transmission electron microscopy was used to study the morphology of the optimized LN. Also, the crystallinity of the nanoparticles was studied by X-ray powder diffraction and differential scanning calorimetry. The presence of the drug in LN surfaces was confirmed by X-ray photoelectron spectroscopy. The CsA LN developed preserved their physicochemical properties for 3 months when stored at 4°C. Moreover, when the stabilizer system was composed of two surfactants, the LN formulations were also stable at room temperature. Finally, the new CsA formulations showed in vitro dose-dependent immuno-suppressive effects caused by the inhibition of IL-2 levels secreted from stimulated Jurkat cells. The findings obtained in this paper suggest that new lipid nanosystems are a good alternative to produce physicochemically stable CsA formulations for oral administration.

In Vitro Intestinal Co-Culture Cell Model to Evaluate Intestinal Absorption of Edelfosine Lipid Nanoparticles

Nanotechnology is providing a new therapeutic paradigm by enhancing drug efficacy and preventing side-effects. Edelfosine is a synthetic ether lipid analogue of platelet activating factor with high antitumor activity. The encapsulation of this potent antitumor drug in lipid nanoparticles increases its oral bioavailability; moreover, it prevents the hemolytic and gastrointestinal side-effects of the free drug. The literature points towards lymphatic absorption of lipid nanoparticles after oral administration, and previous in vitro and in vivo studies stress the protection against toxicity that these nanosystems provide. The present study is intended to assess the permeability of lipid nanoparticles across the intestinal barrier. Caco-2 monoculture and Caco-2/Raji co-culture were used as in vitro models of enterocytes and Microfold cells respectively. Results showed that free drug is internalized and possibly metabolized in enterocytes. These results do not correlate with those observed in vivo when edelfosine-lipid nanoparticles were administered orally in mice, which suggests that the microfold model is not a good model to study the absorption of edelfosine-lipid nanoparticles across the intestinal barrier in vitro.

Ultra high performance liquid chromatography-tandem mass spectrometry method for cyclosporine a quantification in biological samples and lipid nanosystems.

Cyclosporine A (CyA) is an immunosuppressant cyclic undecapeptide used for the prevention of organ transplant rejection and in the treatment of several autoimmune disorders. An ultra high performance liquid chromatography-tandem mass spectrometry method (UHPLC-MS/MS) to quantify CyA in lipid nanosystems and mouse biological matrices (whole blood, kidneys, lungs, spleen, liver, heart, brain, stomach and intestine) was developed and fully validated. Chromatographic separation was performed on an Acquity UPLC(®) BEH C18 column with a gradient elution consisting of methanol and 2mM ammonium acetate aqueous solution containing 0.1% formic acid at a flow rate of 0.6mL/min. Amiodarone was used as internal standard (IS). Retention times of IS and CyA were 0.69min and 1.09min, respectively. Mass spectrometer operated in electrospray ionization positive mode (ESI+) and multiple reaction monitoring (MRM) transitions were detected, m/z 1220.69→1203.7 for CyA and m/z 646→58 for IS. The extraction method from biological samples consisted of a simple protein precipitation with 10% trichloroacetic acid aqueous solution and acetonitrile and 5μL of supernatant were directly injected into the UHPLC-MS/MS system. Linearity was observed between 0.001μg/mL-2.5μg/mL (r≥0.99) in all matrices. The precision expressed in coefficient of variation (CV) was below 11.44% and accuracy in bias ranged from -12.78% to 7.99% including methanol and biological matrices. Recovery in all cases was above 70.54% and some matrix effect was observed. CyA was found to be stable in post-extraction whole blood and liver homogenate samples exposed for 6h at room temperature and 72h at 4°C. The present method was successfully applied for quality control of lipid nanocarriers as well as in vivo studies in BALB/c mice.

Reformulating cyclosporine A (CsA): More than just a life cycle management strategy

Cyclosporine A (CsA) is a well-known immunosuppressive agent that gained considerable importance in transplant medicine in the late 1970s due to its selective and reversible inhibition of T-lymphocytes. While CsA has been widely used to prevent graft rejection in patients undergoing organ transplant it was also used to treat several systemic and local autoimmune disorders. Currently, the neuro- and cardio-protective effects of CsA (CiCloMulsion®; NeuroSTAT®) are being tested in phase II and III trials respectively and NeuroSTAT® received orphan drug status from US FDA and Europe in 2010. The reformulation strategies focused on developing Cremophor® EL free formulations and address variable bioavailability and toxicity issues of CsA. This review is an attempt to highlight the progress made so far and the room available for further improvements to realize the maximum benefits of CsA.

Lipid nanoparticles enhance the absorption of cyclosporine A through the gastrointestinal barrier: In vitro and in vivo studies

In the present work, the feasibility of cyclosporine A lipid nanoparticles (CsA LN) for oral administration was investigated. Three CsA LN formulations were developed using Precirol as lipid matrix, one stabilized with Tween(®) 80 (Tw) and the other two with mixtures of phosphatidylcholine or Pluronic(®) F127 with taurocholate (Lec:TC and PL:TC, respectively). The physical characteristics of the LN were studied under gastrointestinal pH and their integrity was found to be dependent on the stabilizers. The in vitro intestinal permeability was assessed with a human colon adenocarcinoma cell model and in vivo pharmacokinetic and biodistribution studies were performed in Balb/c mice using Sandimmune Neoral(®) as reference. In vitro results showed the highest CsA permeability with the LN containing Lec:TC. In contrast, the best in vivo performance was achieved from the LN containing Tw. The bioavailability of CsA was matched and even enhanced with Precirol nanoparticles. This study suggests the suitability of LN as promising vehicles for CsA oral delivery.

Cyclosporine A-loaded lipid nanoparticles in inflammatory bowel disease

Cyclosporine A (CsA) is a well-known immunosuppressive agent used as rescue therapy in severe steroid-refractory ulcerative colitis (UC). However, toxicity issues associated with CsA when administered in its commercially available formulations have been reported in clinical practice. Since nanotechnology has been proposed as a promising strategy to improve safety and efficacy in the treatment of inflammatory bowel disease (IBD), the main purpose of this study was to evaluate the effect of oral administration of CsA-loaded lipid nanoparticles (LN) in the dextran sodium sulfate (DSS)-induced colitis mouse model using Sandimmune Neoral(®) as reference. The results showed that the formulations used did not decrease colon inflammation in terms of myeloperoxidase activity (MPO), tumor necrosis factor (TNF)-α expression, or histological scoring in the acute stage of the disease. However, further studies are needed in order to corroborate the efficacy of these formulations in the chronic phase of the disease.

Cyclosporine A lipid nanoparticles for oral administration: Pharmacodynamics and safety evaluation.

The pharmacodynamic effect and the safety of cyclosporine A lipid nanoparticles (CsA LN) for oral administration were investigated using Sandimmune Neoral® as reference. First, the biocompatibility of the unloaded LN on Caco-2 cells was demonstrated. The pharmacodynamic response and blood levels of CsA were studied in Balb/c mice after 5 and 10 days of daily oral administration equivalent to 5 and 15 mg/kg of CsA in different formulations. The in vivo nephrotoxicity after 15 days of treatment at the high dose was also evaluated. The results showed a significant decrease in lymphocyte count (indicator of immunosuppression) for the CsA LN groups which was not observed with Sandimmune Neoral®. CsA blood levels remained constant over the time after treatment with LN, whereas a proportional increase in drug blood concentration was observed with Sandimmune Neoral®. Therefore, CsA LN exhibited a better pharmacological response along with more predictable pharmacokinetic information, diminishing the risk of toxicity. Moreover, a nephroprotective effect against CsA related toxicity was observed in the histopathological evaluation when LN containing Tween® 80 were administered. Therefore, our preliminary findings suggest LN formulations would be a good alternative for CsA oral delivery, enhancing efficacy and reducing the risk of nephrotoxicity.

Urolithin A Mitigates Cisplatin-Induced Nephrotoxicity by Inhibiting Renal Inflammation and Apoptosis in an Experimental Rat Model

Cumulative kidney toxicity associated with cisplatin is severe and there is no clear consensus on the therapeutic management of the same. The pathogenesis involves activation of inflammatory and apoptotic pathways; therefore, regulating these pathways offers protection. Given the anti-inflammatory and antioxidant effects of urolithin A, a gut microbial metabolite of ellagic acid, our aim was to explore the potential use of urolithin A in the prevention of cisplatin-induced nephrotoxicity in an experimental rat model. For this purpose, animals received a single intraperitoneal dose of cisplatin (5 mg/kg body weight). Six hours prior to cisplatin administration, rats were orally treated with either ellagic acid or urolithin A (50 mg/kg body weight), followed by a daily dose of these compounds during the next 5 days. At the end, plasma and kidneys were collected for analysis. Cisplatin-induced kidney damage was revealed by a significant rise in the plasma creatinine levels accompanied by significant morphologic changes in tubules, T cell Ig and mucin domain-containing protein-1, ionized calcium-binding adapter molecule 1, as well as a marked increase in the number of apoptotic cells localized in tubules. Cisplatin also reduced nitric oxide synthase 3 and nuclear factor kappa-light-chain-enhancer of activated B cells resulting in regulation of various inflammatory cytokines. Urolithin A effectively attenuated cisplatin-induced kidney damage and showed significantly greater effect than its precursor ellagic acid on preserving the normal kidney architecture by downregulating the proinflammatory cytokines. In summary, urolithin A mitigates cisplatin-induced nephrotoxicity in rats by modulation of the inflammatory cascade and inhibition of the proapoptotic pathway.

Next Generation Precision-Polyesters Enabling Optimization of Ligand–Receptor Stoichiometry for Modular Drug Delivery

The success of receptor-mediated drug delivery primarily depends on the ability to optimize ligand-receptor stoichiometry. Conventional polyesters such as polylactide (PLA) or its copolymer, polylactide-co-glycolide (PLGA), do not allow such optimization due to their terminal functionality. We herein report the synthesis of 12 variations of the PLA-poly(ethylene glycol) (PEG) based precision-polyester (P2s) platform, permitting 5-12 periodically spaced carboxyl functional groups on the polymer backbone. These carboxyl groups were utilized to achieve variable degrees of gambogic acid (GA) conjugation to facilitate ligand-receptor stoichiometry optimization. These P2s-GA combined with fluorescent P2s upon emulsification form nanosystems (P2Ns) of size <150 nm with GA expressed on the surface. The P2Ns outclass conventional PLGA-GA nanosystems in cellular uptake using caco-2 intestinal model cultures. The P2Ns showed a proportional increase in cellular uptake with an increase in relative surface GA density from 0 to 75%; the slight decline for 100% GA density was indicative of receptor saturation. The intracellular trafficking of P2Ns in live caco-2 cells demonstrated the involvement of endocytic pathways in cellular uptake. The P2Ns manifest transferrin receptor (TfR) colocalization in ex vivo intestinal tissue sections, despite blocking of the receptor with transferrin (Tf) noncompetitively, i.e., independently of receptor occupation by native ligand. The in vivo application of P2Ns was demonstrated using cyclosporine (CsA) as a model peptide. The P2Ns exhibited modular release in vivo, as a function of surface GA density. This approach may contribute to the development of personalized dose regimen.