Daunorubicin-loaded magnetic nanoparticles of Fe3O4 overcome multidrug resistance and induce apoptosis of K562-n/VCR cells in vivo

Cancer stem cells and strategies for targeted drug delivery

Cancer stem cells (CSCs) are a small proportion of cancer cells with high tumorigenic activity, self-renewal ability, and multilineage differentiation potential. Standard anti-tumor therapies including conventional chemotherapy, radiation therapy, and molecularly targeted therapies are not effective against CSCs, and often lead to enrichment of CSCs that can result in tumor relapse. Therefore, it is hypothesized that targeting CSCs is key to increasing the efficacy of cancer therapies. In this review, CSC properties including CSC markers, their role in tumor growth, invasiveness, metastasis, and drug resistance, as well as CSC microenvironment are discussed. Further, CSC-targeted strategies including the use of targeted drug delivery systems are examined.

Magnetic thermosensitive micelles with upper critical solution temperature for NIR triggered drug release

Smart micelles which undergo dramatic property changes in response to temperature have aroused extensive interest in specific cancer therapy.

Shape and Size-Dependent Magnetic Properties of Fe3O4 Nanoparticles Synthesized Using Piperidine

In this article, we proposed a facile one-step synthesis of Fe₃O₄ nanoparticles of different shapes and sizes by co-precipitation of FeCl₂ with piperidine. A careful investigation of TEM micrographs shows that the shape and size of nanoparticles can be tuned by varying the molarity of piperidine. XRD patterns match the standard phase of the spinal structure of Fe₃O₄ which confirms the formation of Fe₃O₄ nanoparticles. Transmission electron microscopy reveals that molar concentration of FeCl₂ solution plays a significant role in determining the shape and size of Fe₃O₄ nanoparticles. Changes in the shape and sizes of Fe₃O₄ nanoparticles which are influenced by the molar concentration of FeCl₂ can easily be explained with the help of surface free energy minimization principle. Further, to study the magnetic behavior of synthesized Fe₃O₄ nanoparticles, magnetization vs. magnetic field (M-H) and magnetization vs. temperature (M-T) measurements were carried out by using Physical Property Measurement System (PPMS). These results show systematic changes in various magnetic parameters like remanent magnetization (Mr), saturation magnetization (Ms), coercivity (Hc), and blocking temperature (T _B) with shapes and sizes of Fe₃O₄. These variations of magnetic properties of different shaped Fe₃O₄ nanoparticles can be explained with surface effect and finite size effect.

Comparison of the interactions of daunorubicin in a free form and attached to single-walled carbon nanotubes with model lipid membranes

In this work the interactions of an anticancer drug daunorubicin (DNR) with model thiolipid layers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE) were investigated using Langmuir technique. The results obtained for a free drug were compared with the results recorded for DNR attached to SWCNTs as potential drug carrier. Langmuir studies of mixed DPPTE-SWCNTs-DNR monolayers showed that even at the highest investigated content of the nanotubes in the monolayer, the changes in the properties of DPPTE model membranes were not as significant as in case of the incorporation of a free drug, which resulted in a significant increase in the area per molecule and fluidization of the thiolipid layer. The presence of SWCNTs-DNR in the DPPTE monolayer at the air-water interface did not change the organization of the lipid molecules to such extent as the free drug, which may be explained by different types of interactions playing crucial role in these two types of systems. In the case of the interactions of free DNR the electrostatic attraction between positively charged drug and negatively charged DPPTE monolayer play the most important role, while in the case of SWCNTs-DNR adducts the hydrophobic interactions between nanotubes and acyl chains of the lipid seem to be prevailing. Electrochemical studies performed for supported model membranes containing the drug delivered in the two investigated forms revealed that the surface concentration of the drug-nanotube adduct in supported monolayers is comparable to the reported surface concentration of the free DNR incorporated into DPPTE monolayers on gold electrodes. Therefore, it may be concluded that the application of carbon nanotubes as potential DNR carrier allows for the incorporation of comparable amount of the drug into model membranes with simultaneous decrease in the negative changes in the membrane structure and organization, which is an important aspect in terms of side effects of the drug.

Nanotechnology applications in hematological malignancies (Review)

A major limitation to current cancer therapies is the development of therapy-related side-effects and dose limiting complications. Moreover, a better understanding of the biology of cancer cells and the mechanisms of resistance to therapy is rapidly developing. The translation of advanced knowledge and discoveries achieved at the molecular level must be supported by advanced diagnostic, therapeutic and delivery technologies to translate these discoveries into useful tools that are essential in achieving progress in the war against cancer. Nanotechnology can play an essential role in this aspect providing a transforming technology that can translate the basic and clinical findings into novel diagnostic, therapeutic and preventive tools useful in different types of cancer. Hematological malignancies represent a specific class of cancer, which attracts special attention in the applications of nanotechnology for cancer diagnosis and treatment. The aim of the present review is to elucidate the emerging applications of nanotechnology in cancer management and describe the potentials of nanotechnology in changing the key fundamental aspects of hematological malignancy diagnosis, treatment and follow-up.

Iron oxide nanoparticles for magnetically-guided and magnetically-responsive drug delivery

In this review, we discuss the recent advances in and problems with the use of magnetically-guided and magnetically-responsive nanoparticles in drug delivery and magnetofection. In magnetically-guided nanoparticles, a constant external magnetic field is used to transport magnetic nanoparticles loaded with drugs to a specific site within the body or to increase the transfection capacity. Magnetofection is the delivery of nucleic acids under the influence of a magnetic field acting on nucleic acid vectors that are associated with magnetic nanoparticles. In magnetically-responsive nanoparticles, magnetic nanoparticles are encapsulated or embedded in a larger colloidal structure that carries a drug. In this last case, an alternating magnetic field can modify the structure of the colloid, thereby providing spatial and temporal control over drug release.

Wogonin reverses multi-drug resistance of human myelogenous leukemia K562/A02 cells via downregulation of MRP1 expression by inhibiting Nrf2/ARE signaling pathway

Constitutive NF-E2-related factor 2 (Nrf2) activation has been recently reported to play a pivotal role in enhancing cell survival and resistance to anticancer drugs in many tumors. Previously, much effort has been devoted to the investigation of blocking Nrf2 function in cultured cells and cancer tissues, but few researches have been undertaken to evaluate the precise mechanism of flavonoids-induced sensitivity by inhibiting Nrf2. In this study, we investigated the reversal effect of Wogonin, a flavonoid isolated from the root of Scutellaria baicalensis Georgi, in resistant human myelogenous leukemia. Data indicated that Wogonin had strong reversal potency by inhibiting functional activity and expression of MRP1 at both protein and mRNA in adriamycin (ADR)-induced resistant human myelogenous leukemia K562/A02 cells. Consequently, the inhibition of MRP1 by Wogonin was dependent on Nrf2 through the decreased binding ability of Nrf2 to antioxidant response element (ARE). Further research revealed Wogonin modulated Nrf2 through the reduction of Nrf2mRNA at transcriptional processes rather than RNA degradation, which is regulated by the PI3K/Akt pathway. Moreover, DNA-PKcs was found to be involved in the Wogonin-induced downregulation of Nrf2 mRNA at transcriptional levels. In summary, these results clearly demonstrated the effectiveness of using Wogonin via inhibiting Nrf2 to combat chemoresistance and suggested that Wogonin can be developed into an efficient natural sensitizer for resistant human myelogenous leukemia.

Nanodrug delivery in reversing multidrug resistance in cancer cells

Different mechanisms in cancer cells become resistant to one or more chemotherapeutics is known as multidrug resistance (MDR) which hinders chemotherapy efficacy. Potential factors for MDR includes enhanced drug detoxification, decreased drug uptake, increased intracellular nucleophiles levels, enhanced repair of drug induced DNA damage, overexpression of drug transporter such as P-glycoprotein(P-gp), multidrug resistance-associated proteins (MRP1, MRP2), and breast cancer resistance protein (BCRP). Currently nanoassemblies such as polymeric/solid lipid/inorganic/metal nanoparticles, quantum dots, dendrimers, liposomes, micelles has emerged as an innovative, effective, and promising platforms for treatment of drug resistant cancer cells. Nanocarriers have potential to improve drug therapeutic index, ability for multifunctionality, divert ABC-transporter mediated drug efflux mechanism and selective targeting to tumor cells, cancer stem cells, tumor initiating cells, or cancer microenvironment. Selective nanocarrier targeting to tumor overcomes dose-limiting side effects, lack of selectivity, tissue toxicity, limited drug access to tumor tissues, high drug doses, and emergence of multiple drug resistance with conventional or combination chemotherapy. Current review highlights various nanodrug delivery systems to overcome mechanism of MDR by neutralizing, evading, or exploiting the drug efflux pumps and those independent of drug efflux pump mechanism by silencing Bcl-2 and HIF1α gene expressions by siRNA and miRNA, modulating ceramide levels and targeting NF-κB. “Theragnostics” combining a cytotoxic agent, targeting moiety, chemosensitizing agent, and diagnostic imaging aid are highlighted as effective and innovative systems for tumor localization and overcoming MDR. Physical approaches such as combination of drug with thermal/ultrasound/photodynamic therapies to overcome MDR are focused. The review focuses on newer drug delivery systems developed to overcome MDR in cancer cell.

Reversal of ATP-binding cassette drug transporter activity to modulate chemoresistance: why has it failed to provide clinical benefit?

Enhanced drug extrusion from cells due to the overexpression of the ATP-binding cassette (ABC) drug transporters inhibits the cytotoxic effects of structurally diverse and mechanistically unrelated anticancer agents and is a major cause of multidrug resistance (MDR) of human malignancies. Multiple compounds can suppress the activity of these efflux transporters and sensitize resistant tumor cells, but despite promising preclinical and early clinical data, they have yet to find a role in oncologic practice. Based on the knowledge of the structure, function, and distribution of MDR-related ABC transporters and the results of their preclinical and clinical evaluation, we discuss probable reasons why these inhibitors have not improved the outcome of therapy for cancer patients. We also outline new MDR-reversing strategies that directly target ABC transporters or circumvent relevant signaling pathways.

Identification of DMSA-Coated Fe3O4 Nanoparticles Induced-Apoptosis Response Genes in Human Monocytes by cDNA Microarrays

This study investigated the cell apoptosis and gene expression profiles of human THP-1 monocytes in order to identify the molecular mechanism of cell apoptosis induced by meso-2,-3-dimercaptosuccinnic acid-coated Fe3O4magnetic nanoparticles. Cell apoptosis was visualized with flow cytometry after treated by 50 and 100 μg/ml Fe3O4nanoparticles, and the gene expression profiles were detected with Affymetrix Human Genome U133 Plus 2.0 GeneChips® microarrays. The transmission electron microscopy obserbation revealed that THP-1 cells were effectively labeled by the Fe3O4nanoparticles. The internalized Fe3O4nanoparticles increased cell apoptosis in a dose-dependent manner, but not decreased cell viability significantly. The cDNA microarray results showed that hundreds of genes were significantly regulated at the concentration of 50 and 100 μg/ml, and the level of these genes exhibited a dose response, includingCD14,CD86,CFLAR,IL-1,NFKBIA,NLRC4,NAIPandAIP3. The Fe3O4nanoparticles treatments resulted in significantly altered in Toll-like receptor signaling pathway, NOD-like receptor signaling pathway, and Cell apoptosis signaling pathway. Gene ontology analysis of these differentially expressed genes demonstrated that mainly up-regulated genes were related to cytokine production and cell apoptosis. These results showed that the Fe3O4nanoparticles induced THP-1 cells apoptosis and the level of lots of genes involved in extrinsic apoptosis pathway differentially expressed, which further revealed demonstrated the relation between Fe3O4MNPs treatment and cell apoptosis.

Nano-hole induction by nanodiamond and nanoplatinum liquid, DPV576, reverses multidrug resistance in human myeloid leukemia (HL60/AR)

Recently nanoparticles have been extensively studied and have proven to be a promising candidate for cancer treatment and diagnosis. In the current study, we examined the chemo-sensitizing activity of a mixture of nanodiamond (ND) and nanoplatinum (NP) solution known as DPV576, against multidrug-resistant (MDR) human myeloid leukemia (HL60/AR) and MDR-sensitive cells (HL60). Cancer cells were cultured with different concentrations of daunorubicin (DNR) (1 × 10 ⁻⁹−1 × 10 ⁻⁶ M) in the presence of selected concentrations of DPV576 (2.5%–10% v/v). Cancer cell survival was determined by MTT assay, drug accumulation by flow cytometry and confocal laser scanning microscopy (CLSM), and holes and structural changes by atomic force microscopy (AFM). Co-treatment of HL60/AR cells with DNR plus DPV576 resulted in the reduction of the IC₅₀ to 1/4th. This was associated with increased incidences of holes inside the cells as compared with control untreated cells. On the other hand, HL60 cells did not show changes in their drug accumulation post-treatment with DPV576 and DNR. We conclude that DPV576 is an effective chemo-sensitizer as indicated by the reversal of HL60/AR cells to DNR and may represent a potential novel adjuvant for the treatment of chemo-resistant human myeloid leukemia.

Synergistic effect of a combination of nanoparticulate Fe3O4 and gambogic acid on phosphatidylinositol 3-kinase/Akt/Bad pathway of LOVO cells

Background:

The present study evaluated whether magnetic nanoparticles containing Fe₃O₄ could enhance the activity of gambogic acid in human colon cancer cells, and explored the potential mechanisms involved.

Methods:

Cytotoxicity was evaluated by MTT assay. The percentage of cells undergoing apoptosis was analyzed by flow cytometry, and cell morphology was observed under both an optical microscope and a fluorescence microscope. Reverse transcriptase polymerase chain reaction and Western blot assay were performed to determine the transcription of genes and expression of proteins, respectively.

Results:

Gambogic acid could inhibit proliferation of LOVO cells in a dose-dependent and time-dependent manner and induce apoptosis, which was dramatically enhanced by magnetic nanoparticles containing Fe₃O₄. The typical morphological features of apoptosis in LOVO cells were observed after treatment comprising gambogic acid with and without magnetic nanoparticles containing Fe₃O₄. Transcription of cytochrome c, caspase 9, and caspase 3 genes was higher in the group treated with magnetic nanoparticles containing Fe₃O₄ and gambogic acid than in the groups that received gambogic acid or magnetic nanoparticles containing Fe₃O₄, but transcription of phosphatidylinositol 3-kinase, Akt, and Bad genes decreased. Notably, expression of cytochrome c, caspase 9, and caspase 3 proteins in the group treated with gambogic acid and magnetic nanoparticles containing Fe₃O₄ was higher than in the groups receiving magnetic nanoparticles containing Fe₃O₄ or gambogic acid, while expression of p-PI3K, p-Akt, p-Bad, pro-caspase 9, and pro-caspase 3 degraded.

Conclusion:

Magnetic nanoparticles containing Fe₃O₄ can enhance apoptosis induced by gambogic acid which may be closely related to regulation of the PI3K/Akt/Bad pathway in the treatment of human colon cancer.

Long circulating lectin conjugated paclitaxel loaded magnetic nanoparticles: a new theranostic avenue for leukemia therapy

Amongst all leukemias, Bcr-Abl positive chronic myelogenous leukemia (CML) confers resistance to native drug due to multi drug resistance and also resistance to p53 and fas ligand pathways. In the present study, we have investigated the efficacy of microtubule stabilizing paclitaxel loaded magnetic nanoparticles (pac-MNPs) to ascertain its cytotoxic effect on Bcr-Abl positive K562 cells. For active targeted therapy, pac-MNPs were functionalized with lectin glycoprotein which resulted in higher cellular uptake and lower IC₅₀ value suggesting the efficacy of targeted delivery of paclitaxel. Both pac-MNPs and lectin conjugated pac-MNPs have a prolonged circulation time in serum suggesting increased bioavailability and therapeutics index of paclitaxel in vivo. Further, the molecular mechanism pertaining to pac-induced cytotoxicity was analyzed by studying the involvement of different apoptotic pathway proteins by immunoblotting and quantitative PCR. Our study revealed simultaneous activation of JNK pathway leading to Bcr-Abl instability and the extrinsic apoptotic pathway after pac-MNPs treatment in two Bcr-Abl positive cell lines. In addition, the MRI data suggested the potential application of MNPs as imaging agent. Thus our in vitro and in vivo results strongly suggested the pac-MNPs as a future prospective theranostic tool for leukemia therapy.

Mesoporous silica nanoparticles loading doxorubicin reverse multidrug resistance: performance and mechanism

Multidrug resistance (MDR) is one of the major obstacles for successful chemotherapy in cancer. One of the effective approaches to overcome MDR is to use nanoparticle-mediated drug delivery to increase drug accumulation in drug resistant cancer cells. In this work, we first report that the performance and mechanism of an inorganic engineered delivery system based on mesoporous silica nanoparticles (MSNs) loading doxorubicin (DMNs) to overcome the MDR of MCF-7/ADR (a DOX-resistant and P-glycoprotein (P-gp) over-expression cancer cell line). The experimental results showed that DMNs could enhance the cellular uptake of doxorubicin (DOX) and increase the cell proliferation suppression effect of DOX against MCF-7/ADR cells. The IC(50) of DMNs against MCF-7/ADR cells was 8-fold lower than that of free DOX. However, an improved effect of DOX in DMNs against MCF-7 cells (a DOX-sensitive cancer cell line) was not found. The increased cellular uptake and nuclear accumulation of DOX delivered by DMNs in MCF-7/ADR cells was confirmed by confocal laser scanning microscopy, and could result from the down-regulation of P-gp and bypassing the efflux action by MSNs themselves. The cellular uptake mechanism of DMNs indicated that the macropinocytosis was one of the pathways for the uptake of DMNs by MCF-7/ADR cells. The in vivo biodistribution showed that DMNs induced a higher accumulation of DOX in drug resistant tumors than free DOX. These results suggested that MSNs could be an effective delivery system to overcome multidrug resistance.

Effect of interaction of magnetic nanoparticles of Fe₃O₄ and artesunate on apoptosis of K562 cells

The present study evaluated whether the magnetic nanoparticles of Fe₃O₄ (MNPs-Fe₃O₄) could enhance the activity of artesunate (ART), and to explore its potential mechanisms. Cytotoxicity of the copolymer of ART with MNPs-Fe₃O₄ on K562 cells was detected by MTT assay and the apoptosis rate of K562 cells was measured by flow cytometry. Protein expression levels of bcl-2, bax, bcl-rambo, caspase-3, and survivin in K562 cells were measured by Western blot. After being incubated with the copolymer of ART with MNPs-Fe₃O₄ for 48 hours, the growth inhibition rate of K562 cells was significantly increased compared with that of K562 cells treated with ART alone (P < 0.05), and the apoptosis rate of K562 cells was increased significantly compared with that of K562 cells treated with ART alone, suggesting that MNPs-Fe₃O₄ can enhance the activity of ART. Interestingly, the copolymer-induced cell death was attenuated by caspase inhibitor Z-VAD-FMK. Our results also showed that treatment with the copolymer of MNPs-Fe₃O₄ and ART increased the expression of bcl-2, bax, bcl-rambo, and caspase-3 proteins, and decreased the expression of survivin protein in K562 cells compared with ART treatment alone. These results suggest that MNPs-Fe₃O₄ can enhance ART-induced apoptosis, which may be related to the upregulation of bcl-rambo and downregulation of survivin.

Novel magnetic iron oxide nanoparticles coated with poly(ethylene imine)-g-poly(ethylene glycol) for potential biomedical application: synthesis, stability, cytotoxicity and MR imaging

Magnetic iron oxide nanoparticles have found application as contrast agents for magnetic resonance imaging (MRI) and as switchable drug delivery vehicles. Their stabilization as colloidal carriers remains a challenge. The potential of poly(ethylene imine)-g-poly(ethylene glycol) (PEGPEI) as stabilizer for iron oxide (γ-Fe₂O₃) nanoparticles was studied in comparison to branched poly(ethylene imine) (PEI). Carrier systems consisting of γ-Fe₂O₃-PEI and γ-Fe₂O₃-PEGPEI were prepared and characterized regarding their physicochemical properties including magnetic resonance relaxometry. Colloidal stability of the formulations was tested in several media and cytotoxic effects in adenocarcinomic epithelial cells were investigated. Synthesized γ-Fe₂O₃ cores showed superparamagnetism and high degree of crystallinity. Diameters of polymer-coated nanoparticles γ-Fe₂O₃-PEI and γ-Fe₂O₃-PEGPEI were found to be 38.7 ± 1.0 nm and 40.4 ± 1.6 nm, respectively. No aggregation tendency was observable for γ-Fe₂O₃-PEGPEI over 12 h even in high ionic strength media. Furthermore, IC₅₀ values were significantly increased by more than 10-fold when compared to γ-Fe₂O₃-PEI. Formulations exhibited r₂ relaxivities of high numerical value, namely around 160 mM⁻¹ s⁻¹. In summary, novel carrier systems composed of γ-Fe₂O₃-PEGPEI meet key quality requirements rendering them promising for biomedical applications, e.g. as MRI contrast agents.

Nanomedicine for targeted cancer therapy: towards the overcoming of drug resistance

Anticancer drug resistance almost invariably emerges and poses major obstacles towards curative therapy of various human malignancies. In the current review we will distinguish between mechanisms of chemoresistance that are predominantly mediated by ATP-driven multidrug resistance (MDR) efflux transporters, typically of the ATP-binding cassette (ABC) superfamily, and those that are independent of such drug efflux pumps. In recent years, multiple nanoparticle (NP)-based therapeutic systems have been developed that were rationally designed to overcome drug resistance by neutralizing, evading or exploiting various drug efflux pumps and other resistance mechanisms. NPs are being exploited for selective drug delivery to tumor cells, to cancer stem/tumor initiating cells and/or to the supportive cancer cell microenvironment, i.e. stroma or tumor vasculature. Some of these NPs are currently undergoing preclinical in vivo studies as well as advanced stages of clinical evaluation with promising results. Nanovehicles harboring a payload of therapeutic drug combinations for the selective targeting and elimination of tumor cells as well as the simultaneous overcoming of mechanisms of drug resistance are a subject of intense research efforts, some of which are expected to enter clinical trials in the near future. In the present review we highlight novel approaches to selectively target cancer cells and overcome drug resistance phenomena, through the use of various nanometric drug delivery systems. In the near future, it is anticipated that innovative theragnostic nanovehicles will be developed which will harbor four major components: (1) a selective targeting moiety, (2) a diagnostic imaging aid for the localization of the malignant tumor and its micro- or macrometastases, (3) a cytotoxic, small molecule drug(s) or novel therapeutic biological(s), and (4) a chemosensitizing agent aimed at neutralizing a resistance mechanism, or exploiting a molecular "Achilles hill" of drug resistant cells. We propose to name these envisioned four element-containing nanovehicle platform, "quadrugnostic" nanomedicine. This targeted strategy holds promise in paving the way for the introduction of highly effective nanoscopic vehicles for cancer therapeutics while overcoming drug resistance.

Synthesis and antitumor efficacy of daunorubicin-loaded magnetic nanoparticles

Background

A promising approach to optimize the disposition of daunorubicin-loaded magnetic nanoparticles (DNR-MNPs) was developed to minimize serious side effects of systematic chemotherapy for cancer.

Methods

The physical properties of DNR-MNPs were investigated and their effect on leukemia cells in vitro was evaluated by a standard WST-1 cell proliferation assay. Furthermore, cell apoptosis and intracellular accumulation of DNR were determined by FACSCalibur flow cytometry.

Results

Our results showed that the majority of MNPs were spherical and their sizes were from 10 to 20 nm. The average hydrodynamic diameter of DNR-MNPs in water was 94 nm. The in vitro release data showed that the DNR-MNPs have excellent sustained release property. Proliferation of K562 cells was inhibited in a dose-dependent manner by DNR in solution (DNR-Sol) or by DNR-MNPs. The IC₅₀ for DNR-MNPs was slightly higher than that for DNR-Sol. DNR-MNPs also induced less apoptosis in K562 cells than did DNR-Sol. Detection of fluorescence intensity of intracellular DNR demonstrated that DNR-MNPs could be taken up by K562 cells and persistently released DNR in cells.

Conclusion

Our study suggests that optimized DNR-MNPs formulation possesses sustained drug-release and favorable antitumor properties, which may be used as a conventional dosage form for antitumor therapy.

Pharmacokinetic parameters and tissue distribution of magnetic Fe(3)O(4) nanoparticles in mice

BACKGROUND

This study explored the pharmacokinetic parameters and tissue distribution of magnetic iron oxide nanoparticles (Fe(3)O(4) MNPs) in imprinting control region (ICR) mice.

METHODS

The Fe(3)O(4) MNPs were synthesized by chemical coprecipitation, and their morphology and appearance were observed by transmission electron microscopy. ICR mice were divided into a control group and a Fe(3)O(4) MNP-treated group. Probable target organs in ICR mice were observed, and the pharmacokinetic parameters and biodistribution of Fe(3)O(4) MNPs in tissues were identified using atomic absorption spectrophotometry.

RESULTS

Fe(3)O(4) MNPs were spherical with a well distributed particle diameter, and were distributed widely in various target organs and tissues including the heart, liver, spleen, lungs, kidneys, brain, stomach, small intestine, and bone marrow. The majority of Fe(3)O(4) MNPs were distributed to the liver and the spleen. Fe(3)O(4) MNP levels in brain tissue were higher in the Fe(3)O(4) MNP-treated group than in the control group, indicating that Fe(3)O(4) MNPs can penetrate the blood-brain barrier.

CONCLUSION

These results suggest that the distribution of Fe(3)O(4) MNPs was mostly in the liver and spleen, so the curative effect of these compounds could be more pronounced for liver tumors. Furthermore, Fe(3)O(4) MNPs might be used as drug carriers to overcome physiologic barriers.

Reversal of multidrug resistance by magnetic Fe3O4 nanoparticle copolymerizating daunorubicin and MDR1 shRNA expression vector in leukemia cells

In many instances, multidrug resistance (MDR) is mediated by increasing the expression at the cell surface of the MDR1 gene product, P-glycoprotein (P-gp), a 170-kD energy-dependent efflux pump. The aim of this study was to investigate the potential benefit of combination therapy with magnetic Fe₃O₄ nanoparticle [MNP (Fe₃O₄)] and MDR1 shRNA expression vector in K562/A02 cells. For stable reversal of “classical” MDR by short hairpin RNA (shRNA) aiming directly at the target sequence (3491–3509, 1539–1557, and 3103–3121 nucleotide) of MDR1 mRNA. PGC silencer-U6-neo-GFP-shRNA/MDR1 called PGY1–1, PGY1–2, and PGY1–3 were constructed and transfected into K562/A02 cells by lipofectamine 2000. After transfected and incubated with or without MNP (Fe₃O₄) for 48 hours, the transcription of MDR1 mRNA and the expression of P-gp were detected by quantitative real-time PCR and Western-blot assay respectively. Meanwhile intracellular concentration of DNR in K562/A02 cells was detected by flow cytometry (FCM). PGC silencer-U6-neo-GFP-shRNA/MDR1 was successfully constructed, which was confirmed by sequencing and PGY1–2 had the greatest MDR1 gene inhibitory ratio. Analysis of the reversal ratio of MDR, the concentration of daunorubicin (DNR) and the transcription of MDR1 gene and expression of P-gp in K562/A02 showed that combination of DNR with either MNP (Fe₃O₄) or PGY1–2 exerted a potent cytotoxic effect on K562/A02 cells, while combination of MNP (Fe₃O₄) and PGY1–2 could synergistically reverse multidrug resistance. Thus our in vitro data strongly suggested that a combination of MNP (Fe₃O₄) and shRNA expression vector might be a more sufficient and less toxic anti-MDR method on leukemia.

Effect of Fe(3)O(4)-magnetic nanoparticles on acute exercise enhanced KCNQ(1) expression in mouse cardiac muscle

While the potential impact of magnetic nanoparticles (MNPs) has been widely explored in almost all medical fields, including cardiology, one question remains; that is whether MNPs interfere with cardiac physiological processes such as the expression and function of ion channels, especially in vivo. KCNQ(1) channels are richly expressed in cardiac myocytes and are critical to the repolarization of cardiac myocytes. In this study, we evaluated the effects of Fe(3)O(4)-magnetic nanoparticles (MNPs-Fe(3)O(4)) on the expression of KCNQ(1) in cardiac muscle of mice at rest and at different times following a single bout of swimming (SBS). Firstly, we demonstrated that the expression levels of KCNQ(1) channels are significantly up-regulated in mice following a SBS by means of reverse transcription polymerase chain reaction (RT-PCR) and western-blot. After treating mice with normal saline or pure MNPs-Fe(3)O(4) separately, we studied the potential effect of MNPs-Fe(3)O(4) on the expression profile of KCNQ(1) in mouse cardiac muscle following a SBS. A SBS increased the transcription of KCNQ(1) at 3 hours post exercise (3PE) 164% +/- 24% and at 12 hours post exercise (12PE) by 159% +/- 23% (P < 0.05), and up-regulated KCNQ(1) protein 161% +/- 27% at 12PE (P < 0.05) in saline mice. In MNPs-Fe(3)O(4) mice, KCNQ(1) mRNA increased by 151% +/- 14% and 147% +/- 12% at 3 and 12 PE, respectively (P <0.05). Meanwhile, an increase of 152% +/- 14% in KCNQ(1) protein was also detected at by 12PE. These results indicated that the administration of MNPs-Fe(3)O(4) did not cause any apparent effects on the expression profile of KCNQ(1) in rested or exercised mice cardiac muscle. Our studies suggest a novel path of KCNQ(1) current adaptations in the heart during physical exercise and in addition provide some useful information for the biomedical application of MNPs which are imperative to advance nanomedicine.