Magnetophoretic Delivery of a Tumor-Priming Agent for Chemotherapy of Metastatic Murine Breast Cancer

A Tri-Stimuli Responsive (Maghemite/PLGA)/Chitosan Nanostructure with Promising Applications in Lung Cancer

A (core/shell)/shell nanostructure (production performance ≈ 50%, mean diameter ≈ 330 nm) was built using maghemite, PLGA, and chitosan. An extensive characterization proved the complete inclusion of the maghemite nuclei into the PLGA matrix (by nanoprecipitation solvent evaporation) and the disposition of the chitosan shell onto the nanocomposite (by coacervation). Short-term stability and the adequate magnetism of the nanocomposites were demonstrated by size and electrokinetic determinations, and by defining the first magnetization curve and the responsiveness of the colloid to a permanent magnet, respectively. Safety of the nanoparticles was postulated when considering the results from blood compatibility studies, and toxicity assays against human colonic CCD-18 fibroblasts and colon carcinoma T-84 cells. Cisplatin incorporation to the PLGA matrix generated appropriate loading values (≈15%), and a dual pH- and heat (hyperthermia)-responsive drug release behaviour (≈4.7-fold faster release at pH 5.0 and 45 °C compared to pH 7.4 and 37 °C). The half maximal inhibitory concentration of the cisplatin-loaded nanoparticles against human lung adenocarcinoma A-549 cells was ≈1.6-fold less than that of the free chemotherapeutic. Such a biocompatible and tri-stimuli responsive (maghemite/PLGA)/chitosan nanostructure may found a promising use for the effective treatment of lung cancer.

Improving the Cellular Uptake of Biomimetic Magnetic Nanoparticles

Magnetococcus marinus magnetosome-associated protein MamC, expressed as recombinant, has been proven to mediate the formation of novel biomimetic magnetic nanoparticles (BMNPs) that are successful drug nanocarriers for targeted chemotherapy and hyperthermia agents. These BMNPs present several advantages over inorganic magnetic nanoparticles, such as larger sizes that allow the former to have larger magnetic moment per particle, and an isoelectric point at acidic pH values, which allows both the stable functionalization of BMNPs at physiological pH value and the molecule release at acidic (tumor) environments, simply based on electrostatic interactions. However, difficulties for BMNPs cell internalization still hold back the efficiency of these nanoparticles as drug nanocarriers and hyperthermia agents. In the present study we explore the enhanced BMNPs internalization following upon their encapsulation by poly (lactic-co-glycolic) acid (PLGA), a Food and Drug Administration (FDA) approved molecule. Internalization is further optimized by the functionalization of the nanoformulation with the cell-penetrating TAT peptide (TATp). Our results evidence that cells treated with the nanoformulation [TAT-PLGA(BMNPs)] show up to 80% more iron internalized (after 72 h) compared to that of cells treated with BMNPs (40%), without any significant decrease in cell viability. This nanoformulation showing optimal internalization is further characterized. In particular, the present manuscript demonstrates that neither its magnetic properties nor its performance as a hyperthermia agent are significantly altered due to the encapsulation. In vitro experiments demonstrate that, following upon the application of an alternating magnetic field on U87MG cells treated with BMNPs and TAT-PLGA(BMNPs), the cytotoxic effect of BMNPs was not affected by the TAT-PLGA enveloping. Based on that, difficulties shown in previous studies related to poor cell uptake of BMNPs can be overcome by the novel nanoassembly described here.

Folic Acid-Modified Nanoerythrocyte for Codelivery of Paclitaxel and Tariquidar to Overcome Breast Cancer Multidrug Resistance

The efflux of anticancer agents mediated by P-glycoprotein (P-gp) is one of the main causes of multidrug resistance (MDR) and eventually leads to chemotherapy failure. To overcome this problem, the delivery of anticancer agents in combination with a P-gp inhibitor using nanocarrier systems is considered an effective strategy. On the basis of the physiological compatibility and excellent drug loading ability of erythrocytes, we hypothesized that nanoerythrocytes could be used for the codelivery of an anticancer agent and a P-gp inhibitor to overcome MDR in breast cancer. Herein, a folic acid-modified nanoerythrocyte system (PTX/TQR NPs@NanoRBC-PEG/FA) was prepared to simultaneously transport paclitaxel and tariquidar, and the in vitro and in vivo characteristics of this delivery system were evaluated through several experiments. The results indicated that the average diameter and surface potential of this nanocarrier system were 159.8 ± 1.4 nm and -10.98 mV, respectively. Within 120 h, sustained release of paclitaxel was observed in both pH 6.5 media and pH 7.4 media. Tariquidar release from this nanocarrier suppressed the P-gp function of MCF-7/Taxol cells and significantly increased the intracellular paclitaxel level (p < 0.01 versus the PTX group). The results of the MTT assay indicated that the simultaneous transportation of paclitaxel and tariquidar could significantly inhibit the growth of MCF-7 cells or MCF-7/Taxol cells. After 48 h of incubation with PTX/TQR NPs@NanoRBC-PEG/FA, the viability of MCF-7 cells and MCF-7/Taxol cells decreased to 7.37% and 30.2%, respectively, and the IC50 values were 2.49 μM and 6.30 μM. Pharmacokinetic results illustrated that, compared with free paclitaxel, all test paclitaxel nanoformulations prolonged the drug release time and showed similar plasma concentration-time profiles. The peak concentration (Cmax), area under the curve (AUC0-∞), and half-life (t1/2) of PTX/TQR NPs@NanoRBC-PEG/FA were 3.33 mg/L, 6.02 mg/L·h, and 5.84 h, respectively. Moreover, this active targeting nanocarrier dramatically increased the paclitaxel level in tumor tissues. Furthermore, compared with those of the other paclitaxel formulations, the cellular reactive oxygen species (ROS) and malondialdehyde (MDA) levels of the PTX/TQR NPs@NanoRBC-PEG/FA group increased by 1.38-fold (p < 0.01) and 1.36-fold (p < 0.01), respectively, and the activities of superoxide dismutase (SOD) and catalase (CAT) decreased to 67.8% (p < 0.01) and 65.4% (p < 0.001), respectively. More importantly, in vivo antitumor efficacy results proved that the PTX/TQR NPs@NanoRBC-PEG/FA group exerted an outstanding tumor inhibition effect with no marked body weight loss and fewer adverse effects. In conclusion, by utilizing the inherent and advantageous properties of erythrocytes and surface modification strategies, this biomimetic targeted drug delivery system provides a promising platform for the codelivery of an anticancer agent and a P-gp inhibitor to treat MDR in breast cancer.

Co-Delivery of Paclitaxel by a Capsaicin Prodrug Micelle Facilitating for Combination Therapy on Breast Cancer

Poor anticancer ability, serious adverse reaction, and drug resistance against paclitaxel (PTX) have limited its clinical applications. When a mouse breast carcinoma cell line (4T1) was treated with both PTX and capsaicin (CAP), there was a synergistic anti-proliferative effect demonstrated with a combination index of 0.28. Therefore, a novel polyethylene glycol-derivatized CAP (PEG-Fmoc-CAP₂) polymeric prodrug micellar carrier was developed and further encapsulated with PTX for antitumor combination treatment. The PEG-Fmoc-CAP₂ polymeric micelles co-delivered with PTX achieved a 62.3% fraction of apoptotic cells in comparison to 45.4% fraction of apoptotic cells to that upon treatment with PTX alone. Comparable CAP amounts were found in the cell lysate treatment with PEG-Fmoc-CAP₂-conjugated micelles to that of free CAP-treated 4T1 cells after 12 h treatment. Pharmacokinetic and biodistribution studies showed that the micelles possessed much longer circulation time in blood and preferential tumor tissue accumulation compared to the Taxol solution. Importantly, PTX/CAP-loaded micelles exhibited superior in vivo antitumor activity on the inhibition rate of tumor growth than other treatments (70.5% tumor growth reduction in PTX/CAP micelle-treated mice vs 57.8, 43.3, and 23.8% of tumor growth inhibition rate in PTX/PEG-Fmoc-OA₂ micelles, Taxol, and PEG-Fmoc-CAP₂ micelle-treated mice, respectively). Thus, the dual-functional PEG-Fmoc-CAP₂ polymeric prodrug micelles are a promising co-delivery nanosystem for achieving synergistic antitumor efficacy of PTX and CAP.

In-vitro and in-vivo difference in gene delivery by lithocholic acid-polyethyleneimine conjugate

Polyethyleneimine (PEI) is widely used for the delivery of nucleic acids, but its clinical application is limited due to high cytotoxicity and instability in biological fluids. To overcome these challenges, linear PEI (2.5 kDa) was modified with lithocholic acid (LCA) to produce a LCA-PEI conjugate (lp), and its complex with plasmid DNA (pDNA) was covered with hyaluronic acid (HA). Ternary complexes of pDNA, lp, and HA ("DlpH") were prepared in different ratios and tested in cells and tumor-bearing mice for gene transfection efficiency. DlpH with a relatively high lp/pDNA ratio (Hi-DlpH) was more resistant to DNase and heparin treatment and showed more efficient gene transfection than DlpH with a lower lp/pDNA ratio (Lo-DlpH) in vitro. In contrast, Hi- and Lo-DlpH showed distinct transfection efficiency in vivo in a tumor-size dependent manner, where Hi-DlpH showed relatively high gene transfection in tumors of <300 mm³ but performed poorly in tumors of >500 mm³ and Lo-DlpH did the opposite. Tumor-associated macrophages, which increase with tumor growth and preferentially intercept Hi-DlpH, may account for the poor performance of Hi-DlpH in relatively large tumors. Accordingly, suggestions are made for future in vitro screening of new gene formulations to better predict their in vivo performances.