Use of perfluorochemical emulsions in cancer therapy

The effect of SiO2/Au core-shell nanoparticles on breast cancer cell's radiotherapy

INTRODUCTION

Recently it has been shown that radiation dose enhancement could be achievable in radiotherapy using nanoparticles (NPs). In this study, evaluation was made to determine efficiency of gold-silica shell-core NP in megavoltage irradiation of MCF7 breath cancer cells.

MATERIALS AND METHODS

Gold-silicon oxide shell-core NPs were obtained by conjugation of gold NP with amine or thiol functionalized silica NPs (AuN@SiO₂ and AuS@SiO₂). Cellular uptake and cytotoxicity of NPs were examined by fluorescent microscopy and MTT assay, respectively. MCF-7 breast cancer cells were treated with both NPs and irradiation was made with X-ray energies of 6 and 18 MV to the absorbed dose of 2, 4 and 8 Gy using Simense linear accelerator. The efficiency of radiation therapy was then evaluated by MTT and Brdu assay, DAPI staining and cell cycle analysis.

RESULTS

TEM images indicated that synthesized NPs had average diameter of 25 nm. Cellular uptake demonstrated that the internalization of AuS@SiO₂ and AuN@SiO₂ NPs amounted to 18% and 34%, 3 h post treatment, respectively. Nontoxicity of prepared NPs on MCF-7 cells was proved by MTT and Brdu assays as well as DAPI staining and cell cycle studies. The highest enhancement in radiation dose was observed in the cells that irradiated with radiation energy of 18 MV and absorbed of 8 Gy at NPs concentration of 200 ppm. The Brdu findings revealed that the cytotoxicity and apoptosis on MCF-7 cells are dose dependent with a significantly more death in AuN@SiO₂ (amine) exposed cells (p < .05). Analysis also revealed interruption in cell cycle by demonstrating lack of cells, in S phase in amine treated cells (AuN@SiO₂) at given dose of 8 Gy using 18 MV X-ray in comparison to thiol treated cells.

CONCLUSIONS

Based on the results of the study it can be concluded that the gold-silicon oxide shell-core NPs could play an effective role in radiotherapy of MCF-7 breast cancer cells.

Engineering blood: synthetic substitutes from fluorinated compounds

Concerns about blood safety and the logistical problems associated with conventional transfusion have fuelled the search for effective alternatives (so-called blood substitutes). Such materials include hemoglobin derivatives and those based on synthetic, highly fluorinated, inert organic compounds called perfluorochemicals (PFCs). PFCs dissolve large volumes of oxygen and other gases, are unreactive in the body, and are excreted primarily as a vapor by exhalation. Liquid PFCs are immiscible with blood and other body fluids, but can be injected safely into the bloodstream as submicron emulsions. Emulsified PFCs have been evaluated in clinical trials as temporary, intravascular tissue-oxygenating fluids. One such emulsion, a commercial perflubron-based, phospholipid-stabilized formulation, is in advanced clinical trials as an alternative to transfusing donated (allogeneic) blood during surgery. Basic and clinical studies have shown that this emulsion can adequately maintain tissue oxygenation during acute blood loss with no abnormal hemodynamic changes. The use of PFC emulsions as an efficacious, short-term transfusion alternative underpins the longer term objective of producing a totally synthetic, bioengineered blood substitute.

Benefit and risk perceptions in transfusion medicine: blood and blood substitutes

Blood transfusion is a remarkably safe, routine procedure in clinical medicine. However, little attention has focused on the perceptions of risk associated with the receipt of blood, blood products or 'blood substitutes'. It is pertinent to ask (i) what key stakeholder groups know about transfusion, (ii) how safe they perceive blood/blood products to be, (iii) how the latter information might influence their own and others' perceptions of risk linked to transfusion, and (iv) the extent to which approved blood substitutes might be preferred over autologous or donor blood. An appreciation of what stakeholders perceive to be the benefits and risks of the receipt of blood and blood substitutes will inform future transfusion strategies. To obtain such information, a programme of research has been initiated at Nottingham. Surveys have targeted key stakeholder groups, namely, UK adult blood donors and nondonors, anaesthetists, general practitioners and health care journalists. Experimental studies examining message framing and cueing have also been conducted with undergraduate students. Such research will improve misunderstandings about current issues associated with blood donation and transfusion against the backdrop of changing public trust of health care professionals and attitudes and expectations on blood safety and benefits of blood substitutes.

Fluorocarbon emulsions

Perfluorocarbon emulsions have been the topic of intense investigation for many years and presently there are still no absolute indications for their use in clinical practice. The relatively disappointing results of the early clinical studies, as a consequence of using low concentrations of a relatively underdeveloped emulsion, have been responsible for a largely negative impression and it is now essential that the newer second generation emulsions should be judged individually with regard to their efficacy and toxicity under different circumstances. Technological advancement in the fields of chemistry and detergent/emulsifier research will continue and new formulations are being developed which which will require to be tested in models in the laboratory. In the future, this class of drugs will continue to be the topic of intense investigation and their mechanisms of action, which are undoubtedly more complex than the simple carriage of dissolved gases in solution, will be clarified. However, whether fluorocarbon emulsions will ever be used as a 'blood substitute' as was originally anticipated is doubtful.