Nanotoxicological study of downconversion Y2 O3 :Eu3+ luminescent nanoparticles functionalized with folic acid for cancer cells bioimaging.

Luminescent lanthanide downconversion nanoparticles (DCNPs) provide a combination of high luminescence intensity, sharp emission peaks with narrow bandwidth and a large Stokes' shift, leading to high-performance biomedical applications mainly for imaging. The purpose of this study is to present a nanotoxicological study of DCNPs Y2 O3 codoped with Eu3+ and functionalized with folic acid (FA). These assessments include cytotoxicity, genotoxicity, hemocompatibility, and in vitro inflammatory studies. We demonstrated by flow cytometry and confocal microscope the internalization of FA-DCNPs in breast cancer and melanoma cells. They were synthesized by sol-gel method and coated with a thin silica shell to make them biocompatible; also they were functionalized with amino groups and FA ligands that bind to the folate receptors (FR) located on the surface of the cancer cells studied. This functionalization enables the DCNPs to be internalized into the cancer cells via endocytosis by the conjugation FA-FR. The DCNPs were characterized with transmission electron microscope, Fourier transform infrared spectroscopy and photoluminescence. The nanotoxicological assessments demonstrated that both nanoparticles (bare and functionalized) are no cytotoxic and no genotoxic at the tested concentrations (0.01-20 µg/mL) in three cell lines (breast, skin cancer, and osteoblasts). Also they are hemocompatible and do not exert nitric oxide production in vitro by macrophages. The FA-DCNPs were clearly localized into the cell cytoplasm with bright red luminescence. Thus, herein we present a complete nanotoxicological study of FA-DCNPs Y2 O3 codoped with Eu3+ and we conclude that these nanoparticles are biocompatible and can be further used for cancer cells bioimaging.

On the safety of synoviorthesis in haemophilia.

One of the best procedures to prevent haem-arthrosis has been radioactive synovectomy (synoviorthesis). Since the first report of radioactive synovectomy in haemophilia of Ahlberg in 1971 [1], many centres adopted this procedure as the one of choice, through fibrosing the synovial membrane, prevent further haemarthrosis. Since 1976 we have performed 104 such radioactive synoviorthesis in 97 patients, age ranging from 6 to 40 years with a mean of 10 years. Sixty-five of these patients were under 12 years of age. The knees were injected in 61 cases, elbow in 26 cases, ankles in 14 cases and shoulders in three cases. The clinical results of this procedure show 80% of excellent results with no further bleeding. In case of failure, a new injection can be given in the same joint at a 6-month interval, or an injection for the same purpose in other joint. One of the criticisms against this method is the possible chromosomal damage induced by the radioactive material. In our centre, four studies have been carried out in order to see whether these changes, when they occur, are everlasting; all have demonstrated that chromosomal changes are reversible. The radioactive material used in the two first studies was Gold-189 (189Au). In 1978, 354 metaphases were studied with 61 ruptures, 17.23% (nonpremalign) and six structural changes, considered premalign (1.69%). Any number below 2% is considered not to be dangerous. A further study was done in 1982, in the same group of patients with a result of 21 ruptures (3.34%) and no structural changes. This demonstrated that the possible premalign changes disappeared with time. A third study was performed in a series of 13 patients that sustained radioactive synoviorthesis with Rhenium-186 (186Re) in November 1991. For comparison, we carried out a chromosomal study just before and 6 months after the radioactive material injection. The results confirmed that changes that could be linked to the radiation, appeared equally in nonirradiated patients, and those changes due to the radiation disappear with time, never reaching the dangerous zone of 2%. In the group treated with 186Re we studied an additional number of 130 metaphases with identical results and no structural changes. In a study on patients where 90Y was the radiocolloid, no premalign change was found before or after the synoviorthesis. It seems, in view of these results, that radioactive synovectomy is safe and gives great benefits to the haemophilic patients.