Biliana Nikolova

Electrodelivery of Drugs into Cancer Cells in the Presence of Poloxamer 188

In the present study it is shown that poloxamer 188, added before or immediately after an electrical pulse used for electroporation, decreases the number of dead cells and at the same time does not reduce the number of reversible electropores through which small molecules (cisplatin, bleomycin, or propidium iodide) can pass/diffuse. It was suggested that hydrophobic sections of poloxamer 188 molecules are incorporated into the edges of pores and that their hydrophilic parts act as brushy pore structures. The formation of brushy pores may reduce the expansion of pores and delay the irreversible electropermeability. Tumors were implanted subcutaneously in both flanks of nude mice using HeLa cells, transfected with genes for red fluorescent protein and luciferase. The volume of tumors stopped to grow after electrochemotherapy and the use of poloxamer 188 reduced the edema near the electrode and around the subcutaneously growing tumors.

Delivery of size-controlled long-circulating polymersomes in solid tumours, visualized by quantum dots and optical imaging in vivo

The present study was designed to investigate whether poly-ion complex hollow vesicles (polymersomes), based on chemically modified chitosan, are appropriate for passive tumour targeting in the context of their application as drug carriers. The experiments were performed on colon cancer-grafted mice. The mice were subjected to anaesthesia and injected intravenously with water-soluble nanoparticles: (1) QD705-labelled polymersomes (average size ∼120 nm; size distribution ∼10%) or (2) native QD705. The optical imaging was carried out on Maestro EX 2.10 In Vivo Imaging System (excitation filter 435–480 nm; emission filter 700 nm, longpass). In the case of QD705, the fluorescence appeared in the tumour area within 1 min after injection and disappeared completely within 60 min. A strong fluorescent signal was detected in the liver on the 30th minute. The visualization of tumour using QD705 was based only on angiogenesis. In the case of QD705-labelled polymersomes, the fluorescence appeared in the tumour area immediately after injection with excellent visualization of blood vessels in the whole body. A strong fluorescent signal was detected in the tumour area within 16 hours. This indicated that QD705-labelled polymersomes were delivered predominantly into the tumour due to their long circulation in the bloodstream and enhanced permeability and retention effect. A very weak fluorescent signal was found in the liver area. The data suggest that size-controlled long-circulating polymersomes are very promising carriers for drug delivery in solid tumours, including delivery of small nanoparticles and contrast substances.

New Insights in the Gene Electrotransfer Process: Evidence for the Involvement of the Plasmid DNA Topology

Electropermeabilization is a non-viral method that can be used to transfer plasmid DNA (pDNA) into cells and tissues. According the applications and considered tissues, this safe method can be less efficient than the viral approaches. Biophysical mechanisms of gene electrotransfer are not entirely known. Contrary to small molecules that have direct and fast access to the cytoplasm, pDNA is electrophoretically pushed towards the permeabilized membrane where it forms a complex before being transferred into the cytoplasm. In order to understand the biophysical mechanisms of gene electrotransfer and in this way to improve it, we investigated the dependence of the topology of pDNA i.e. linear versus supercoiled on both pDNA/membrane interaction and gene expression. Our results revealed that: i) even if pDNA/membrane interactions are only slightly affected by the topology of pDNA, ii) gene transfer and expression are strongly influenced by it. Indeed, the linearization of pDNA leads to a decrease in the transfection level.

New Modality for Electrochemotherapy of Surface Tumors

ABSTRACT Electrochemotherapy is based on electroporation, which creates aqueous pathways in the cell membrane as a result of applied short intensive electric field usually generated by high voltage electrical pulses. The phenomenon enhances the simultaneous administration of cytotoxic drugs. Recently, several researchers forewarn of some adverse effects that could occur with electrochemotherapy of tumors located close to the heart. We developed equipment Chemipulse III, consisting of portable low-cost electroporator, QRS synchronizer and module for long-term recording of pulse parameters. It is designed for data collection of the pulse parameters and the impedances of treated patients with surface tumors without risk of heart complications but with enhanced means for electrical safety of both patient and physician. The new instrument is with battery supply, enhanced protection against electrical hazards both for the patient and the physician, autonomy providing for more than 200 shocks with one battery charging. The data could be used to support the optimization of the voltage shock setting and the evaluation of the procedure effectiveness. The results obtained show high efficiency of the improved approach (new modality) for electrochemotherapy. Thirty-seven patients with a total of 47 lesions of Ca basocellulare, Ca spinocellulare and Kaposi Sarcoma were treated with electrochemotherapy using intralesional application of bleomycin and new developed equipment Chemipulse III. The electrotreatment was done by 16 biphasic rectangular pulses, 50+50 μs duration each, with a 20 μs interval between both phases and a pause of 880 μs between the bipolar pulses. The equipment with QRS synchronizer is mandatory in cases of electrochemotherapy of patients with pacemakers and patients with heart problems. Erythema and slight edema at the site of the treated lesions occurred in most of the patients and disappeared in a few days, one week at most.

Treatment of Melanoma by Electroporation of Bacillus Calmette-Guerin

ABSTRACT Electrochemotherapy could be considering as a good method for treatment of cutaneous and subcutaneous tumor lesions. Here we report the case of 59 year-old woman with melanoma malignum cutis, who developed after axillary dissection, cutaneous metastasis not appropriate for surgical operation. Electrochemotherapy with BCG vaccine resulted in good local control of the disease, with a complete response of treated melanoma lesion.

Vitamin K: Redox-modulation, prevention of mitochondrial dysfunction and anticancer effect

This review is directed to the redox-modulating properties and anticancer effect of vitamin K. The concept is focused on two aspects: (i) redox-cycle of vitamin K and its effect on the calcium homeostasis, “oncogenic” and “onco-suppressive” reactive oxygen species and the specific induction of oxidative stress in cancer; (ii) vitamin K plus C as a powerful redox-system, which forms a bypass between mitochondrial complexes II and III and thus prevents mitochondrial dysfunction, restores oxidative phosphorylation and aerobic glycolysis, modulates the redox-state of endogenous redox-pairs, eliminates the hypoxic environment of cancer cells and induces cell death. The analyzed data suggest that vitamin C&K can sensitize cancer cells to conventional chemotherapy, which allows achievement of a lower effective dose of the drug and minimizing the harmful side-effects. The review is intended for a wide audience of readers - from students to specialists in the field.