Amphiphilic polymers based on polyoxazoline as relevant nanovectors for photodynamic therapy.

An amphiphilic polymer (CmPOX) based on poly(2-methyl-2-oxazoline) linked to a hydrophobic part composed of an aliphatic chain ending with a photo-active coumarin group has been synthesized. It exhibits the ability of forming small polymeric self-assemblies, typically of ca. 10 nm in size, which were characterized by TEM, cryo-TEM and DLS. The nanocarriers were further formulated to yield photo-crosslinked systems by dimerization of coumarin units of coumarin-functionalized poly(methyl methacrylate) (CmPMMA) and CmPOX. The formed vectors were used to encapsulate Pheophorbide a, a known photosensitizer for photodynamic therapy. Cytotoxicity as well as phototoxicity experiments performed in vitro on human tumor cells revealed the great potential of these nanovectors for photodynamic therapy.

Elucidation of in vitro cellular steps induced by antitumor treatment with plasma-activated medium.

Numerous studies have reported cold atmospheric plasma cytotoxic activities in various cancer cell lines, either by direct exposure to non-thermal plasma or indirectly by activating a medium (plasma-activated medium, PAM) prior to cell treatment. We suggested the use of in vitro 3D tumor model spheroids to determine the potential of PAM for cancer therapy at the tissue scale, especially in human tumor tissue. This work aimed to better understand the effect of PAM on human colorectal tumor spheroids by describing the in vitro-induced-cell death kinetics and associated mechanisms to further improve its therapeutic potential. Tumor spheroid growth was delayed depending on contact time with PAM. Medium osmolarity was increased by activation with low temperature Helium plasma jet but it did not fully explain the observed growth delay. PAM impaired tumor cell viability through intracellular ATP depletion, leading within hours to both cell apoptosis and necrosis as well as mitochondrial oxidative stress. When successive treatments were spaced over time, cumulative effects on the growth delay of spheroids were observed. Taken together, these results demonstrated that plasma-activated liquids may represent a novel and efficient therapeutic method for the treatment of tumors, especially when successive treatments are applied.

Effects of Plasma Activated Medium on Head and Neck FaDu Cancerous Cells: Comparison of 3D and 2D Response.

OBJECTIVE: The aim of this work is to investigate the inhibitory effect of Plasma Activated Medium (PAM) on Head and Neck cancerous cells (FaDu). The response of FaDu cells in monolayer cultures and Multi Cellular Tumor Spheroids (MCTS) after treatment with different PAMs will be compared. BACKGROUND: Head and Neck squamous cell carcinoma is a widespread cancer that responds poorly to anticancer treatments such as chemotherapy and radiotherapy. Nowadays there is a growing interest in cold plasmas and their applications in cancer therapy. METHODS: A homemade helium plasma jet is used to produce PAM. The effects of PAM and hydrogen peroxide H2O2 on FaDu 2D cells cultures and MCTS were characterized by evaluating the cell viability with PrestoBlue test and by measuring the size of MCTS. RESULTS: One treatment with PAM induce cell detachment from MCTS since the first day in a PAM exposure dependent manner. This is due to the presence of H2O2 in PAM. However, a rapid spheroids regrowth is observed attributed to a resistance of FaDu cells to H2O2. After multiple treatments of MCTS with PAM we obtained an inhibition of cell growth. MCTS are brought out when comparing PAM effect on 2D versus MCTS. Inversely, PAM induces cell death in the case of 2D cell culture. CONCLUSION: PAM may be considered as a potentially efficient agent in the therapy of head and neck cancer. We also point out that MCTS is a more valuable model than 2D cell culture for the evaluation of the anti-cancer activity of PAM.

Analysis of reactive oxygen and nitrogen species generated in three liquid media by low temperature helium plasma jet.

In order to identify aqueous species formed in Plasma activated media (PAM), quantitative investigations of reactive oxygen and nitrogen species (ROS, RNS) were performed and compared to Milli-Q water and culture media without and with Fetal Calf Serum. Electron paramagnetic resonance, fluorometric and colorimetric analysis were used to identify and quantify free radicals generated by helium plasma jet in these liquids. Results clearly show the formation of ROS such as hydroxyl radical, superoxide anion radical and singlet oxygen in order of the micromolar range of concentrations. Nitric oxide, hydrogen peroxide and nitrite-nitrate anions (in range of several hundred micromolars) are the major species observed in PAM. The composition of the medium has a major impact on the pH of the solution during plasma treatment, on the stability of the different RONS that are produced and on their reactivity with biomolecules. To emphasize the interactions of plasma with a complex medium, amino acid degradation by means of mass spectrometry was also investigated using methionine, tyrosine, tryptophan and arginine. All of these components such as long lifetime RONS and oxidized biological compounds may contribute to the cytotoxic effect of PAM. This study provides mechanistic insights into the mechanisms involved in cell death after treatment with PAM.