Cell transplantation for the treatment of spinal cord injury in rats-morphological study and search for humoral effective factors-

(1)骨髓基质细胞（bone marrow stromal cells, BMSCs）移植(a)脊髓损伤后直接注射骨髓基质细胞（5×10^5）于损伤后2周注射骨髓基质细胞于脊髓损伤后4周观察。大鼠运动能力恢复至BBB评分10点左右，控制点4-5点。大量的再生轴突从吻侧延伸到远端边缘。电镜观察显示，再生轴突被胶原原纤维基质中的雪旺细胞包围。骨髓间充质干细胞在移植后2周内消失，表明它们从未融入脊髓。(b)脊髓损伤1、2和4周后，通过脑脊液（CSF）将骨髓间充质干细胞（5×10^5）注射到4^< >脑室。细胞注射大鼠运动恢复至BBB评分10-13分，对照组运动恢复为0-4分。再生轴突呈束状桥状延伸…更多的是在吻侧和远端边缘之间的病变。再生轴突穿过胶原原纤维基质并被雪旺细胞包围。这表明再生的轴突与周围神经处于相同的环境中。注射后2周骨髓间充质干细胞从脊髓中消失，表明骨髓间充质干细胞不是通过整合到脊髓中发挥作用，而可能通过向CSF分泌一些营养因子来发挥作用。(2)骨髓间充质干细胞条件培养基中所含的有效因子研究表明，条件培养基（CM）中含有IGF-1、HGF、VEGF和TGF-β1。培养海马神经元具有IGF-1和TGF-β1受体。经CM处理后，它们的密度没有变化。这些营养因子单独或与2、3、4因子联合作用于体外培养的海马神经元时，对细胞活力和神经突延伸的影响程度均不及CM。这提示CM可能含有一些未知的营养因子。少

(1) Transplantation of bone marrow stromal cells (BMSCs)(a) Direct injection of BMSCs into the spinal cord lesion BMSCs (5×10^5) were injected into the spinal cord lesion 2 weeks after injury, and rats were observed for 4 weeks post-transplantation. Locomotion of rats was recovered up to about 10 points of BBB scale, with the control points of 4-5. Numerous regenerating axons extended through the lesion from the rostral to distal border. Electron microscopy showed that regenerating axons were surrounded by Schwann cells in the collagen fibril matrices. BMSCs disappeared within 2 weeks post transplantation, indicating that they were never incorporated into the spinal cord.(b) Transplantation through the cerebrospinal fluid (CSF)BMSCs (5×10^5) were injected into the 4^<th> ventricle 1, 2, and 4 weeks after spinal cord injury. Locomotion of cell-injected rats was recovered up to 10-13 points of BBB scale, while those of control remained at 0-4. Regenerating axons extended in bundles bridg … More ing the lesion between the rostral and distal margin. Regenerating axons extended through the collagen fibril matrices and were surrounded by Schwann cells. This shows that regenerating axons are in the same environment as peripheral nerves. Injected BMSCs disappeared from the spinal cord 2 weeks after injection, indicating that BMSCs exert their effects not by integration into the spinal cord, but probably by secreting some trophic factors in to the CSF.(2) Effective factors contained in the conditioned medium of BMSCs It was demonstrated that the conditioned medium (CM) contained IGF-1, HGF, VEGF, and TGF-β1. Cultured hippocampal neurons had receptors of IGF-1 and TGF-β1. They showed no changes in density by the treatment of CM. These trophic factors, when they were used single or in combination of 2, 3 and 4 factors to treat cultured hippocampal neurons in vitro, did not show the same effect level of cell viability and neurite extension as the case of CM. This suggests that the CM may contain some unidentified trophic factors. Less