Target distribution of magnetic nano C3- transferase carrier under external magnetic field in injured spinal cord in rats

English Keywords:Spinal cord injury  Drug carrier  Targeting  Rat

English Abstract:

  【Abstract】 Objectives: To observe the target distribution of magnetic nano C3- transferase carrier under external magnetic field in injured spinal cord and explore this time-related effect. Methods: Drug carrier microsphere was constructed; the particle size, zeta potential, magnetic properties, drug release wｅｒｅ　assessed; the morphology was observed by transmission electron microscopy; the in vitro cytotoxicity was tested either; ａｎｄ　the cellular uptake was analyzed using ｆｌuorescence microscopy. Eight-two SCI rats were divided into 5 groups randomly: Ｇroup A (n=20), fluorescein isothiocyanate group (FITC)　administered by caudal vein, 20 rats; Group B (n=20), drug carrier microsphere administered by caudal vein; Group C(n=20), drug carrier microsphere administered by caudal vein and external magnetic 15min; Group D(n=12), drug carrier microsphere administered by caudal vein and external magnetic 30min; Group E (n=10), drug carrier microsphere administered by caudal vein and external magnetic 1h. 10 rats in Ｇroup A, B and C respectively were selected, and the tissueｓ including liver, kindey, spleen and T10 spinal cord wｅｒｅ harvested 1h after administration by caudal vein, then the liposome distribution in these tissues was observed under ｆｌuorescence microscopy. 10 rats in Ｇroup A, B, C, D and E respectively were sacrificed and the T10 spinal cord was harvested 1h after administration by caudal vein, and ｔｈｅ　ｉｒｏｎ　ｃｏｎｔｅｎｔｓ　were assayed by flame atomic absorption spectrophotometry. 2 rats in Ｇroup D sacrificed and the T10 spinal cord wａｓ harvested　1h after administration by caudal vein, and the distribution of drug carrier microsphere was observed under electron microscope. Results: Drug carrier microspheres showed good dispersion, with the saturation value of magnetization of 63.5emu/g, and the carrier could maintain drug realease in vitro until day 9; when co-culturing with MCF-7 cells, the average cell survival rate was 78.10%; FITC fluorescence density of Ｇroup C in injured center wａｓ more than group A and B. The iron contentｓ in spinal cord of Group C showed significant difference than Group A and B (P<0.05), and those in group E were more than group C (P<0.05), while those in group D showed no difference than group C. The carriers were noted gathering in the center of injury and into neurocyte under electron microscopy. Conclusions: Magnetic nano C3- transferase drug carriers can accumulate into injured site of spine cord and enter neurocyte; adding external magnetic field of 30min after SCI can achieve optimal effect for aggregation.