In Vitro Targeted Magnetic Delivery and Tracking of Superparamagnetic Iron Oxide Particles Labeled Stem Cells for Articular Cartilage Defect Repair / 华中科技大学学报（医学）（英德文版）

To assess a novel cell manipulation technique of tissue engineering with respect to its ability to augment superparamagnetic iron oxide particles (SPIO) labeled mesenchymal stem cells (MSCs) density at a localized cartilage defect site in an in vitro phantom by applying magnetic force.Meanwhile,non-invasive imaging techniques were use to track SPIO-labeled MSCs by magnetic resonance imaging (MRI).Human bone marrow MSCs were cultured and labeled with SPIO.Fresh degenerated human osteochondral fragments were obtained during total knee arthroplasty and a cartilage defect was created at the center.Then,the osteochondral fragments were attached to the sidewalls of culture flasks filled with phosphate-buffered saline (PBS) to mimic the human joint cavity.The SPIO-labeled MSCs were injected into the culture flasks in the presence of a 0.57 Tesla (T) magnetic force.Before and 90 min after cell targeting,the specimens underwent T2-weighted turbo spin-echo (SET2WI) sequence of 3.0 T MRI.MRI results were compared with histological findings.Macroscopic observation showed that SPIO-labeled MSCs were steered to the target region of cartilage defect.MRI revealed significantchanges in signal intensity (P＜0.01).HE staining exibited that a great number of MSCs formed a three-dimensional (3D) cell "sheet" structure at the chondral defect site.It was concluded that 0.57 T magnetic force permits spatial delivery of magnetically labeled MSCs to the target region in vitro.High-field MRI can serve as an very sensitive non-invasive technique for the visualization of SPIO-labeled MSCs.

Preparation and characterization of hydroxyapatite-coated iron oxide particles by spray-drying technique

Magnetic particles of iron oxide have been increasingly used in medical diagnosis by magnetic resonance imaging and in cancer therapies involving targeted drug delivery and magnetic hyperthermia. In this study we report the preparation and characterization of iron oxide particles coated with bioceramic hydroxyapatite by spray-drying. The iron oxide magnetic particles (IOMP) were coated with hydroxyapatite (HAp) by spray-drying using two IOMP/HAp ratios (0.7 and 3.2). The magnetic particles were characterized by way of scanning electronic microscopy, energy dispersive X-ray, X-ray diffraction, Fourier transformed infrared spectroscopy, flame atomic absorption spectrometry,vibrating sample magnetometry and particle size distribution (laser diffraction). The surface morphology of the coated samples is different from that of the iron oxide due to formation of hydroxyapatite coating. From an EDX analysis, it was verified that the surface of the coated magnetic particles is composed only of HAp, while the interior containsiron oxide and a few layers of HAp as expected. The results showed that spray-drying technique is an efficient and relatively inexpensive method for forming spherical particles with a core/shell structure.

As partículas de óxido de ferro têm sido extensivamente usadas em diagnósticos médicos como agente de contraste para imagem por ressonância magnética e na terapia do câncer, dentre estas, liberação de fármacos em sitos alvos e hipertermia magnética. Neste estudo nós reportamos a preparação e caracterização de partículas magnéticas de óxido de ferro revestidas com a biocerâmica hidroxiapatita. As partículas magnéticasde óxido de ferro (PMOF) foram revestidas com hidroxiapatita por spray-drying usando duas razões PMOF/HAp (0,7 e 3,2). As partículas magnéticas foram caracterizadas por microscopia eletrônica de varredura, energia dispersiva de raios X, difração de raios X, espectroscopia de absorção no infra vermelho com transformada de Fourier, espectrometria de absorção atômica com atomização em chama, magnetometria de amostra vibrante e distribuição do tamanho de partícula (difração a laser). A morfologia da superfície das amostras revestidas é diferente das de óxido de ferro devido à formação do revestimento de hidroxiapatita. A partir da análise de energia dispersiva de raios X foi verificado que a superfície das partículas magnéticas é composta somente por hidroxiapatita, enquanto o interior contém óxido de ferro e uma pequena camada de hidroxiapatita, como esperado. Os resultados mostraram que atécnica de spray-drying é um método eficiente e relativamentede baixo custo para formação de partículas esféricas com estrutura núcleo/casca.

Experimental Study :the Preparing of Targeted-directed Probe (Hab18-SPIO) and Testing of Its Phisichemical Characteristics / 实用放射学杂志

Objective To prepare the Target-directed probe(Hab18-SPIO) and to test its phisichemical characteristics. Methods The McAb Target-directed probe(Hab18-SPIO) was prepared through hepatocellular carcinoma(HCC) McAb(Hab18) conjugated toSPIO using chemical method,while negative McAb probe(SED-SPIO) was also prepared using the same method.These agents weretested by high-performance liquid chromatography(HPLC) and electron microscope. Results The results of HPLC and electronmicroscope proved that Hab18 was conjugated SPIO effectively.The diameter of particles was between 50 and 70 nm.The binding rate of Hab18 was 97.5%. Conclusion The probe targeted to membrane-associated antigen of HCC(Hab18g) has been successfully prepared,which has novel physiochemical property.It is of great value in specific MR diagnosis of early HCCs.