The Effects of Placental Mesenchymal Stem Cells Labelled With Ultrasmall Superparamagnetic Iron Oxides on the Growth of Colorectal Cancer (CRC) Cells

Objective: To investigate the effects of human placental mesenchymal stem cells (PMSCs) labelled with ultrasmall superparamagnetic iron oxides (USPIOs) on the growth of colorectal cancer (CRC) cells and the feasibility of 3.0T MR in vivo tracer. Methods: PMSCs were labelled with USPIOs, the labeling efficiency was determined by Prussian blue-stained, and their biological characteristics were identified. A subcutaneous CRC HT-29 xenograft model in immunodeficient mice was established, and we attempted to consider the group was injected with labelled MSCs as experimental group. The growth and MR signal changes of xenograft tumors of nude mice was assessed, then, plot growth curve and analyzed the MR image quality in different sequences, obtained the pathological results after scan.Results: 1. USPIOs-labelled PMSCs had no significant influence on biological characteristics, such as cell viability, proliferation ability, and apoptosis rate (P> 0.05). 2. The regions with low signal value could be observed in the experimental group on the first day on the MR. On the 7th day, the regions with low signal value were narrowed, and in some tumors showed poor clarity, whereas the signal values did not significantly change. The trend of growth of tumors in mice in the experimental group before injection of PMSCs was similar to that of the control group, while growth rate of tumor in the experimental group on day 5 after injection of PMSCs was slightly lower than that in the control group, and the volume of tumor on day 14 was noticeably smaller than that in the control group. There was no significant difference in the positive expression rates of CD31, CD34, and Ki67 between the two groups (P> 0.05). 3. The tracing ability of T2* mapping sequences for USPIOs-labelled cells was superior than T2WI and T2 mapping sequences. Conclusion: USPIOs-labelled PMSCs had high labeling efficiency, while cell viability, proliferation ability, and apoptotic rate were not markedly influenced. labelled cells injected into CRC transplanted tumors were studied for a long period of time, and only a certain inhibitory effect on growth of tumor volume was noted, while no meaningful influence on tumor proliferation and angiogenesis was found.

Hydrophobically Coated Superparamagnetic Iron Oxides Nanoparticles Incorporated into Polymer-Based Nanocapsules Dispersed in Water

This paper reports the characterization of iron oxide magnetic nanoparticles obtained via the thermal decomposition of an organometallic precursor, which were then loaded into nanocapsules prepared via the emulsification process in the presence of an amphiphilic derivative of chitosan. The applied synthetic method led to the formation of a hydrophobic layer on the surface of nanoparticles that enabled their loading in the hydrophobic liquid inside of the polymer-based capsules. The average diameter of nanoparticles was determined to be equal to 15 nm, and they were thoroughly characterized using X-ray diffraction (XRD), magnetometry, and Mössbauer spectroscopy. A core–shell structure consisting of a wüstite core and maghemite-like shell was revealed, resulting in an exchange bias effect and a considerable magnetocrystalline anisotropy at low temperatures and a superparamagnetic behavior at room temperature. Importantly, superparamagnetic behavior was observed for the aqueous dispersion of the nanocapsules loaded with the superparamagnetic nanoparticles, and the dispersion was shown to be very stable (at least 48 weeks). The results were analyzed and discussed with respect to the potential future applications of these nanoparticles and nanocapsules based on biopolymers as platforms designed for the magnetically navigated transport of encapsulated hydrophobic substances.

Preparation and characterization of peptide modified ultrasmall superparamagnetic iron oxides used as tumor targeting MRI contrast agent

As desirable contrast agents for magnetic resonance imaging (MRI), ultrasmall superparamagnetic iron oxides (USPIOs) modified with targeting ligands are considered to be the most effective strategies to achieve better imaging contrast at lower dose.