Synthesis and biomedical applications of functionalized fluorescent and magnetic dual reporter nanoparticles as obtained in the miniemulsion process

Mesenchymal stem cells (MSCs) represent a stem cell population present in adult tissues that can be isolated, expanded in culture, and characterized in vitro and in vivo. MSCs differentiate readily into chondrocytes, adipocytes, osteocytes, and they can support hematopoietic stem cells or embryonic stem cells in culture. Evidence suggests MSCs can also express phenotypic characteristics of endothelial, neural, smooth muscle, skeletal myoblasts, and cardiac myocyte cells. When introduced into the infarcted heart, MSCs prevent deleterious remodeling and improve recovery, although further understanding of MSC differentiation in the cardiac scar tissue is still needed. MSCs have been injected directly into the infarct, or they have been administered intravenously and seen to home to the site of injury. Examination of the interaction of allogeneic MSCs with cells of the immune system indicates little rejection by T cells. Persistence of allogeneic MSCs in vivo suggests their potential "off the shelf" therapeutic use for multiple recipients. Clinical use of cultured human MSCs (hMSCs) has begun for cancer patients, and recipients have received autologous or allogeneic MSCs. Research continues to support the desirable traits of MSCs for development of cellular therapeutics for many tissues, including the cardiovascular system. In summary, hMSCs isolated from adult bone marrow provide an excellent model for development of stem cell therapeutics, and their potential use in the cardiovascular system is currently under investigation in the laboratory and clinical settings.

To evaluate the effect of using the ferumoxides-poly-l-lysine (PLL) complex for magnetic cell labeling on the long-term viability, function, metabolism, and iron utilization of mammalian cells. PLL was incubated with ferumoxides for 60 minutes, incompletely coating the superparamagnetic iron oxide (SPIO) through electrostatic interactions. Cells were coincubated overnight with the ferumoxides-PLL complex, and iron uptake, cell viability, apoptosis indexes, and reactive oxygen species formation were evaluated. The disappearance or the life span of the detectable iron nanoparticles in cells was also evaluated. The iron concentrations in the media also were assessed at different time points. Data were expressed as the mean +/- 1 SD, and one-way analysis of variance and the unpaired Student t test were used to test for significant differences. Intracytoplasmic nanoparticles were stained with Prussian blue when the ferumoxides-PLL complex had magnetically labeled the human mesenchymal stem and HeLa cells. The long-term viability, growth rate, and apoptotic indexes of the labeled cells were unaffected by the endosomal incorporation of SPIO, as compared with these characteristics of the nonlabeled cells. In nondividing human mesenchymal stem cells, endosomal iron nanoparticles could be detected after 7 weeks; however, in rapidly dividing cells, intracellular iron had disappeared by five to eight divisions. A nonsignificant transient increase in reactive oxygen species production was seen in the human mesenchymal stem and HeLa cell lines. Labeled human mesenchymal stem cells did not differentiate to other lineage. A significant increase in iron concentration was observed in both the human mesenchymal stem and HeLa cell media at day 7. Magnetic cellular labeling with the ferumoxides-PLL complex had no short- or long-term toxic effects on tumor or stem cells.