Department of Pediatrics, University Clinic Carl Gustav Carus, Technische Universität Dresden , Dresden, Germany.
Tissue Eng Part C Methods. 2009 Dec;15(4):687-96. doi: 10.1089/ten.TEC.2008.0556.
Three-dimensional (3D) bone substitute material should not only serve as scaffold in large bone defects but also attract mesenchymal stem cells, a subset of bone marrow stromal cells (BMSCs) that are able to form new bone tissue. An additional crucial step is to attract BMSCs from the surface into deeper structures of 3D porous bone substitute scaffolds. Here we show that transient overexpression of CXCR4 in human BMSCs induced by mRNA transfection enhances stromal cell-derived factor-1alpha (SDF-1alpha)-directed chemotactic capacity to invade internal compartments of porous 3D bone substitute scaffolds in vitro and in vivo. In vitro native BMCSs invaded up to 500 mum into SDF-1alpha-releasing 3D scaffolds, whereas CXCR4-overexpressing BMSCs invaded up to 800 mum within 5 days. In addition, 60% downregulation of endogenous SDF-1 transcription in BMSCs by endoribonuclease-prepared siRNA before CXCR4 mRNA transfection enhanced SDF-1alpha-directed migration of human BMSCs by 50%. Implantation of SDF-1alpha-releasing scaffolds seeded with transiently CXCR4-overexpressing BMSCs resulted in an increase of invasion into internal compartments of the scaffolds in a mouse model. In vivo native BMCS invaded up to 250 mum into SDF-1alpha-releasing 3D scaffolds, whereas CXCR4-overexpressing BMSC invaded up to 500 mum within 5 days. Thus, the SDF-1alpha/CXCR4 chemoattraction system can be used to efficiently recruit BMSCs into SDF-1alpha-releasing 3D scaffolds in vitro and in vivo.
三维（3D）骨替代材料不仅应作为大骨缺损的支架，还应吸引间充质干细胞，间充质干细胞是骨髓基质细胞（BMSCs）的一个亚群，能够形成新的骨组织。另一个关键步骤是将 BMSCs 从表面吸引到 3D 多孔骨替代支架的深层结构中。在这里，我们通过 mRNA 转染证明了人 BMSCs 中 CXCR4 的瞬时过表达增强了基质细胞衍生因子-1α（SDF-1α）定向趋化性，以在体外和体内侵袭多孔 3D 骨替代支架的内部结构。在体外，天然 BMSCs 可以侵入到释放 SDF-1α的 3D 支架中 500 µm，而 CXCR4 过表达的 BMSCs 在 5 天内可以侵入到 800 µm。此外，在 CXCR4 mRNA 转染之前，通过内切核糖核酸酶制备的 siRNA 下调 BMSCs 中内源性 SDF-1 的转录，可使 SDF-1α 定向迁移的人 BMSCs 增加 50%。在小鼠模型中，将 SDF-1α 释放支架植入瞬时 CXCR4 过表达的 BMSCs 中，可导致支架内部结构的侵入增加。在体内，天然 BMSCs 可以侵入到释放 SDF-1α的 3D 支架中 250 µm，而 CXCR4 过表达的 BMSC 则可以在 5 天内侵入到 500 µm。因此，SDF-1α/CXCR4 趋化吸引系统可用于体外和体内有效招募 BMSCs 进入 SDF-1α 释放的 3D 支架中。
