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

(1)骨髓基质细胞移植(BMSCs)(A)脊髓损伤处直接注射骨髓基质细胞(BMSCs)2周后，将BMSCs(5×105)注入脊髓损伤处，观察大鼠移植后4周的变化。大鼠运动恢复到BBB评分的10分左右，控制点为4~5分。大量再生轴突从吻端延伸至远端边缘。电子显微镜显示再生轴突被胶原纤维基质中的雪旺细胞包围。移植后2周内BMSCs消失，提示BMSCs从未整合到脊髓内。(2)经脑脊液移植BMSCs(5×105)于脊髓损伤后1、2、4周注入第4脑室。注射细胞组大鼠的BBB评分恢复到10~13分，而对照组大鼠的运动能力维持在0~4分。在束桥…中延伸的再生轴突更多的病变位于吻部和远端边缘之间。再生轴突穿过胶原纤维基质，并被雪旺细胞包围。这表明再生轴突与周围神经处于相同的环境中。(2)骨髓间充质干细胞条件培养液中所含的影响因子证实条件培养液中含有胰岛素样生长因子-1、肝细胞生长因子、血管内皮生长因子和转化生长因子-β1。培养的海马神经元上有胰岛素样生长因子-1和转化生长因子-β1受体。当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，对细胞存活率和突起伸展的影响程度不如CM。这表明CM可能含有一些未知的营养因子。较少

(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