In vivo imaging of colon mucosa targeted gadolinium-loaded chitosan particles in mice with MRI / 中华放射学杂志

ABSTRACT

Objective To synthesize a novel vector of chitosan-particles loaded with gadolinium (Gd-CPs) and observe the adhesion and absorption of the particles in the colon wall of mice with MR imaging in-vivo.Methods Chitosan particles (CPs) with and without gadolinium loaded were synthesized with the emulsion-droplet coalescence method.Sixteen mice were randomly classified into two groups.The suspension with Gd-CPs or with CPs was infused into the rectum of the 8 mice of each group,respectively.MR scans were performed before,during and 40 minutes after infusion for each mouse.Samples of the colon correlated to the enhanced area were obtained for electron microscopy examination.Signal intensity (SI) of ROIs in the wall of rectum or colon,muscles of the pelvis near the rectum and background were measured and corresponding relative SIs were calculated.Relative SI values between the two groups and pre- and post- infusion were compared with pared t test.Results Dimension of the Gd-CPs was about 500 nm,and content rate was about 30%. Values of relative SI of the rectum for pre- and post- infusion in the Gd-CPs group were 0.84±0.06 and 0.98±0.09(t=4.327,P＜0.01),respectively,while those in CPs group were 0.83±0.04 and 0.84±0.05(t=0.658.P＞0.05). The medial value of signal increase rate for CPs group was 19.0%.Gd-CPs particles were found inside the mucosal cells under the electron microscopy.Conclusion MR imaging in-vivo can reveal the phenomenon of adhesion and absorption of mucosa targeted chitosan particle carriers. Clinical MR imaging based on small animal coil is a good method to monitor colon mucosa targeted particle vectors in-vivo.