The Construction Of Infrared/Magnetic Resonance Dual-modality Molecular Probe And Its Application In Cell Labeling

Stem cells have been used for treating various diseases due to its differentiation potential and better migration properties. Especially it has good therapeutic effect on cardiac cerebral diseases, neurological disorders and other common clinical diseases. The umbilical cord mesenchymal stem cells (HUMSC) which type are between the adult stem cells and embryonic stem cells and discovered lately. HUMSC possess the low immunogenicity and powerful proliferation property. Therefore, HUMSC own great significance for cell-therapy.Practically, for stem cell therapy, the effective and noninvasive imaging technologies to determine the inject site and get a real-time tracking the distribution of the implanted cells in vivo is important.Magnetic resonance imaging (MRI) possessed high spatial resolution, long-imaging window and noninvasive advantages which was widely used in clinic. The contrast agent-superparamagnetic iron oxide (SPIO) based on spin-spin relaxation (T2) has become widely used for the stem cell labeling due to its high sensitivity and excellent biological compatibility. At the same time, near infrared imaging (NIRF) as a sensitive, cheap, non-invasive and no radiation advantages has been widely used for real-time monitoring in vivo. The near infrared dye based on NIRF imaging which excitation wavelength is 650-900nm, this will greatly reduce the interference of background light due to less self-luminous by organization. And the common near infrared dyes IR-780 and DIR iodide has a very high quenching constant and the excited state lifetime, and they are very practical to be cell markers.In this study, Superparamagnetic iron oxide (SPIO) nanocrystals were prepared by mixing Fe(acac)3,1,2-hexadecanediol, oleic acid, and oleylamine via thermal decomposition method, which possesed monodisperse property and uniformly size. Then the contrast agents used for magnetic resonance imaging (MRI) and near-infrared fluorescence (NIRF) imaging by wrapping the SPIO nanocrystals and IR-780 dye with stearic acid-modified polyethylenimine (stPEI) and poly (beta-amino ester) (PBAE) modified PEI self-assembly. The result showed that the contrast agents was reasonably nano-sized and positive charged The size of stPEI-SPIO/IR-780 and PEI-PBAE-SPIO/DIR were 39.54±16nm and 82.55±34.1nm, in addition, the zeta potential is+55mV around. Moreover, the dual-modality contrast agent have showed effective bio and imaging compatibility for labeling and tracking HUMSCs both in vitro and in vivo. The prepared nanoparticles probes have high imaging relaxivity, which were 121.583 mM-1s-1 and 174.21 mM-1s-1 respectively. Moreover, the inject site of MRI image displayed can accurately coincide with NIRF image.