Human mesenchymal stem cell-derived iron oxide exosomes allow targeted ablation of tumor cells via magnetic hyperthermia.

Magnetic hyperthermia, or the heating of tissues using magnetic materials, is a promising approach for treating cancer. We found that human mesenchymal stem cells (MSCs) isolated from various tissues and MSCs expressing the yeast cytosine deaminase∷uracil phosphoribosyl transferase suicide fusion gene (yCD∷UPRT) can be labeled with Venofer, an iron oxide carbohydrate nanoparticle. Venofer labeling did not affect cell proliferation or the ability to home to tumors. All Venofer-labeled MSCs released exosomes that contained iron oxide. Furthermore, these exosomes were efficiently endocytosed by tumor cells. Exosomes from Venofer-labeled MSCs expressing the yCD∷UPRT gene in the presence of the prodrug 5-fluorocytosine inhibited tumor growth in a dose-dependent fashion. The treated tumor cells were also effectively ablated following induction of hyperthermia using an external alternating magnetic field. Cumulatively, we found that magnetic nanoparticles packaged into MSC exosomes are efficiently endocytosed by tumor cells, facilitating targeted tumor cell ablation via magnetically induced hyperthermia.

Comparative analysis of synthetic and nutraceutical antioxidants as possible neuroprotective agents.

Damage caused by oxidative stress in cases of neurodegenerative diseases such as Alzheimer's or Parkinson's has been proven to be irreversible. However, diet supplementation of antioxidants can be beneficial to the total antioxidant status of the human body. Given that oxidative stress is a principal cause of neurodegenerative disease, effective natural antioxidants could provide therapeutic options for these disorders. Therefore we investigated the antioxidant properties of two natural extracts and five synthetic compounds in lipid rich environment of liposomes with oxidation induced by Fenton's reagent. Antioxidant activity has been quantified using the Klein peroxidation index and oxygen uptake. Both natural extracts from Acai berry and Ginseng as well as all synthetic compounds - N-acetyl-L-cysteine, tocopherol, huperzines, caffeic acid and lipoic acid displayed good antioxidants properties, which confirm their suitability as neuroprotective agents.

Radiation enhanced efficiency of combined electromagnetic hyperthermia and chemotherapy of lung carcinoma using cisplatin functionalized magnetic nanoparticles.

The effect of trimodality treatment consisting of hyperthermia, cisplatin and radiation was investigated in two non-small lung carcinoma cell lines with different sensitivities to cisplatin. Hyperthermia treatment was performed using heat released via Neél and Brown relaxation of magnetic nanoparticles in an alternating magnetic field. Radiation with dose 1.5 Gy was performed after 15 min electromagnetic hyperthermia and cisplatin treatment. Electromagnetic hyperthermia enhanced cisplatin-induced radiosensitization in both the cisplatin-sensitive H460 (viability 11.2 +/- 1.8 %) and cisplatin-resistant A549 (viability 14.5 +/- 2.3 %) lung carcinoma cell line. Proposed nanotechnology based trimodality cancer treatment may have therefore important clinical applications.

Conceptual design of integrated microfluidic system for magnetic cell separation, electroporation, and transfection.

For the purposes of a successful ex vivo gene therapy we have proposed and analyzed a new concept of an integrated microfluidic system for combined magnetic cell separation, electroporation, and magnetofection. For the analysis of magnetic and electric field distribution (given by Maxwell equations) as well as dynamics of magnetically labeled cell and transfection complex, we have used finite element method directly interfaced to the Matlab routine solving Newton dynamical equations of motion. Microfluidic chamber has been modeled as a channel with height and length 1 mm and 1 cm, respectively. Bottom electrode consisted of 100 parallel ferromagnetic straps and the upper electrode was plate of diamagnetic copper. From the dynamics of magnetic particle motion we have found that the characteristic time-scales for the motion of cells (mean capture time âˆ¼ 4 s) and gene complexes (mean capture time âˆ¼ 3 min), when permanent magnets are used, are in the range suitable for efficient cell separation and gene delivery. The largest electric field intensity (∼10 kV/m) was observed at the edges of the microelectrodes, in the close proximity of magnetically separated cells, which is optimal for subsequent cell electroporation.

Yeast cell wall polysaccharides as antioxidants and antimutagens: can they fight cancer?

Polysaccharides represent the major part of the yeast cell wall dry weight and build the skeletal carcass defining cell wall stability and cell morphology (beta-D-glucans) or constitute amorphous matrix and cell surface fibrous material (mannans and mannoproteins). It is known that yeast cell wall beta-D-glucans reveal immunomodulating properties, which allows for their application in anti-infective and antitumor therapy. Recent data also suggest that polysaccharides reveal antioxidant activity that can result in their protective function as antioxidants, antimutagens, and antigenotoxic agents. The paper provides a review of our continuing research involving water-soluble derivatives of beta-D-glucan isolated from the baker's yeast Saccharomyces serevisiae and of a glucomannan isolated from the industrial yeast Candida utilis. The results are confronted with the available literature data. The derivatives of beta-D-glucan demonstrated potent inhibitory effect on lipid peroxidation comparable to that of the known antioxidants and exerted DNA protection from oxidative damage. The free radical scavenging activity was confirmed by spin-trap electron paramagnetic resonance. Antimutagenic and antigenotoxic activity of the yeast polysaccharides was demonstrated using yeast, bacterial, and algal models. The derivatives of beta-D-glucan exerted potent enhancement of tumor necrosis factor alpha (TNF-alpha) released from murine macrophages and revealed synergistic effect with cyclophosphamide in the treatment of Lewis lung carcinoma and two types of lymphosarcoma in murine models. The results indicate significant protective antioxidant, antimutagenic, and antigenotoxic activities of the yeast polysaccharides and imply their potential application in anticancer prevention/therapy.

Carboxymethylated (1 --> 3)-beta-D-glucan protects liposomes against ultraviolet light-induced lipid peroxidation.

In this study we have analyzed antioxidant capabilities of the carboxymethylated (1 --> 3)-beta-D-glucan (M(w) = 5.88 x 10(5)) against lipid peroxidation induced by ultraviolet (UV) radiation--UVA (320-400 nm), which is known to produce mainly singlet oxygen, (1)O(2) . Lipid peroxidation was monitored by measuring the absorption spectra of the conjugated dienes and quantified by Klein oxidation index. The results imply that the (1 --> 3)-beta-D-glucan derivative studied is an antioxidant with the scavenging ability lying between alpha-tocopherol and hyaluronic acid. Thus, glucan as a potential safe and effective dietary supplement may be used for a prolonged time for a systemic photoprotection of humans.

In vivo heating of magnetic nanoparticles in alternating magnetic field.

We have evaluated heating capabilities of new magnetic nanoparticles. In in vitro experiments they were exposed to an alternating magnetic field with frequency 3.5 MHz and induction 1.5 mT produced in three turn pancake coil. In in vivo experiments rats with injected magnetic nanoparticles were also exposed to an ac field. An optimal increase of temperature of the tumor to 44 degrees C was achieved after 10 minutes of exposure. Obtained results showed that magnetic nanoparticles may be easily heated in vitro as well as in vivo, and may be therefore useful for hyperthermic therapy of cancer.

Principles of magnetodynamic chemotherapy.

Basic principles of a novel method of cancer treatment are explained. Method is based on the thermal activation of an inactive prodrug encapsulated in magnetoliposomes via Neél and Brown effects of inductive heating of subdomain superparamagnetic particles to sufficiently high temperatures. This principle may be combined with targeted drug delivery (using constant magnetic field) and controlled release (using high-frequency magnetic field) of an activated drug entrapped in magnetoliposomes. Using this method drug may be applied very selectively in the particular site of organism and this procedure may be repeated several times using e.g. stealth magnetoliposomes which are circulating in a blood-stream for several days. Moreover the magnetoliposomes concentrated by external constant magnetic field in tumor vasculature may lead to embolic lesions and necrosis of a tumor body and further the heat produced for thermal activation of a drug enhances the effect of chemotherapy by local hyperthermic treatment of neoplastic cells.

Antioxidant properties of carboxymethyl glucan: comparative analysis.

Antioxidative capabilities of carboxymethylated (1 --> 3)-beta-D-glucan from Saccharomyces cerevisiae cell wall, alpha-tocopherol, and mannitol against lipid peroxidation in phosphatidylcholine liposomes induced by OH. radicals produced with Fenton's reagent (H(2)O(2)/Fe(2+)) were studied using absorption ultraviolet-visible spectrophotometry. It was found that (1 --> 3)-beta-D-glucan is an antioxidant with the scavenging ability lying between that of alpha-tocopherol, which is known to be incorporated in the lipid bilayer, and the water-soluble antioxidant, mannitol.

Spatial distribution of ion channel activity in biological membranes: the role of noise.

A new approach is proposed to model a collective ion channel dynamics. We have assumed that ion channels create a two-component spatio-temporal interaction field. Every channel at its current spatial location in membrane contributes permanently to this field with its state (open or closed) and coupling strength to other channels. This field is described by a reaction-diffusion equation, the transition of ion channel from closed to open state (and vice versa) is described by a master equation, and migration of channels in membrane is described by a set of Langevin equations coupled by the interaction field. Within this model, we have investigated critical conditions for spatial distribution of ion channel activity.

AC-magnetic field controlled drug release from magnetoliposomes: design of a method for site-specific chemotherapy.

Large unilamellar magnetoliposomes (MLs) with encapsulated doxorubicin (DOX) (anticancer drug) were prepared by reverse-phase evaporation. They were exposed to an alternating magnetic field with a frequency of 3.5 MHz and an induction of 1.5 mT produced in three-turn pancake coil. The results showed that magnetoliposomes could be specifically heated to 42 degrees C (phase transition temperature of a used lipid) in a few minutes and during this, the encapsulated doxorubicin is massively released.

High-gradient magnetic capture of ferrofluids: implications for drug targeting and tumor embolization.

One of the perspective methods of cancer chemotherapy is magnetic targeting of drugs to tumors. This task is usually accomplished using small permanent magnets attached near the desired sites. In this study a new much more effective approach is proposed which is based on a strong magnetic gradient using a ferromagnetic wire placed in a strong magnetic field. Feasibility of this approach has been evaluated by the formation of ferrofluid seals and measurement of maximum pressure the formed seal can resists. Using this method it is possible to capture even superparamagnetic particles with nanosize dimensions, therefore the method may have an interesting applications in biomedical sciences.

Free Radical Scavenging Activity of Scoparia dulcis Extract.

We studied the scavenging capabilities of an extract of Scoparia dulcis (a cosmopolitan weed widespread in Laos and Vietnam) for 1-diphenyl-2-picrylhydrazyl and measured hemoglobin-catalyzed linoleic acid peroxidation with an oxygen electrode. Our results demonstrated strong antioxidant activity corresponding to mitigation of the generation of hydroxyl radicals, a possible rationale for the observed therapeutic effects of this weed.

Blood-specific whole-body electromagnetic hyperthermia.

On the basis of the physical properties of magnetic fluids a new technique of whole-body hyperthermia is proposed. Subdomain dextran stabilized magnetite particles injected into the blood-stream can be efficiently heated using an external high-frequency magnetic field, which allows rapid and controllable delivery of heat to the patient's blood, which may be useful for the treatment of cancer and AIDS.

Resonant absorption of ultrasound energy as a method of HIV destruction.

A new method for eradicating human immunodeficiency virus (HIV) and other enveloped viruses is proposed. The method is based on the highly symmetric structure (e.g. icosahedral) of many viruses, which leads to a well-defined resonant frequency of ultrasound in the GHz range and which may be specifically absorbed by these structures and may subsequently lead to their irreversible damage.

Selective treatment of neoplastic cells using ferritin-mediated electromagnetic hyperthermia.

A new method of cancer treatment is proposed, based on the unique magnetic properties of ferritin iron core which, in alternating magnetic field of frequency approximately 100 kHz, is easily heated to temperatures sufficiently high to destroy neoplastic cells containing an excess of this protein, without damaging the normal cells.

Gene transfer-mediated intracellular photodynamic therapy.

The main limitation of photodynamic therapy is a very short penetrance length of the light in tissues. To overcome this shortcoming, a new method is proposed, where first a gene encoding protein luciferase is delivered using, e.g. adenovirus vector to the neoplastic cells and, after its expression, the photosensitizer, which should be activated, together with luciferin are injected to the organism. After their accumulation in the cancer cells, the photosensitizer activation is accomplished via light produced by chemiluminiscent reaction of luciferase and luciferin.

Site-specific in vivo targeting of magnetoliposomes using externally applied magnetic field.

Human serum albumin labeled with technetium-99m was encapsulated together with magnetite particles into phosphatidylcholine/cholesterol liposomes. In order to investigate the stability of this complex and its ability to be used for magnetic drug targeting, the in-vivo distribution after intravenous administration in rats was estimated. For in-vivo targeting an SmCo permanent magnet with intensity approximately 0.35 T was attached near the right kidney. Difference between the relative radioactivity in the magnetically targeted right kidney (25.92+/-5.84%) and non-targeted left kidney (0.93+/-0.05%) is sufficiently high for relevant clinical applications.

Enzymatic digestion of liposome-bound polysaccharides: evidence of bridging mechanism.

Laminarin, a water-soluble polysaccharide is known to induce aggregation and fusion of liposomes. Using laminarin specific lysing enzymes for multi-lamellar liposomes their aggregation was found to be fully reversible, in contrast to small unilamellar liposomes for which irreversible fusion is the main process. Moreover, our results indicate that these processes are probably mediated by the formation of polysaccharide cross-bridges between adjacent liposomes.

[Targeted and controlled release of drugs using magnetoliposomes]. / Cielený prenos a kontrolovatel'né uvol'novanie lieciv pomocou magnetolipozómov.

The present paper deals with a stable drug delivery system which allows to concentrate the drug in a desired site and its programmable release. For these purposes the present authors have suggested to use magnetoliposomes (liposomes with enwrapped magnetite particles in their bilayers) which are magnetosensitive and may be maneuvered to the given site in the organism. Due to the magnetite particles, which are strong microwave absorbers, magnetoliposomes can be heated to higher temperatures which may subsequently lead to a leakage of encapsulated drug. Influence of static magnetic field on liposomes in the blood-stream was analyzed theoretically. Fluorescence spectrophotometry was used to determine the relationship between doses of microwave radiation and the extent of drug release.