Russell H. Morgan Department of Radiology, Division of Magnetic Resonance Research, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Nat Protoc. 2011 Jul 14;6(8):1142-51. doi: 10.1038/nprot.2011.352.
Cell therapy has the potential to treat or cure a wide variety of diseases. Non-invasive cell tracking techniques are, however, necessary to translate this approach to the clinical setting. This protocol details methods to create microcapsules that are visible by X-ray, ultrasound (US) or magnetic resonance (MR) for the encapsulation and immunoisolation of cellular therapeutics. Three steps are generally used to encapsulate cellular therapeutics in an alginate matrix: (i) droplets of cell-containing liquid alginate are extruded, using an electrostatic generator, through a needle tip into a solution containing a dissolved divalent cation salt to form a solid gel; (ii) the resulting gelled spheres are coated with polycations as a cross-linker; and (iii) these complexes are then incubated in a second solution of alginate to form a semipermeable membrane composed of an inner and an outer layer of alginate. The microcapsules can be rendered visible during the first step by adding contrast agents to the primary alginate layer. Such contrast agents include superparamagnetic iron oxide for detection by (1)H MR imaging (MRI); the radiopaque agents barium or bismuth sulfate for detection by X-ray modalities; or perfluorocarbon emulsions for multimodal detection by (19)F MRI, X-ray and US imaging. The entire synthesis can be completed within 2 h.
细胞治疗有可能治疗或治愈多种疾病。然而，需要非侵入性的细胞跟踪技术将这种方法转化为临床环境。本方案详细介绍了用于封装细胞治疗的微胶囊的制备方法，这些微胶囊可通过 X 射线、超声（US）或磁共振（MR）显影，实现细胞治疗的封装和免疫隔离。通常使用三个步骤将细胞治疗物包封在藻酸盐基质中：（i）使用静电发生器将含有细胞的藻酸盐液滴滴出，通过针尖挤出到含有溶解的二价阳离子盐的溶液中，形成固体凝胶；（ii）所得的凝胶球用聚阳离子作为交联剂进行涂层；（iii）然后将这些复合物在藻酸盐的第二溶液中孵育，形成由藻酸盐内外两层组成的半渗透膜。可以通过在初级藻酸盐层中添加造影剂，在第一步中使微胶囊显影。此类造影剂包括超顺磁性氧化铁，用于（1）H MR 成像（MRI）检测；不透射线剂硫酸钡或硫酸铋，用于 X 射线模态检测；或全氟碳乳液，用于（19）F MRI、X 射线和 US 成像的多模态检测。整个合成可以在 2 小时内完成。
