大鼠脊髓损伤后不同时期移植异体骨髓间充质干细胞的局部分布

Migration and survival of transplanted allogenic marrow derived mesenchymal stem cells in injured spinal cord of rats

目的观察大鼠脊髓损伤后不同时间点经尾静脉注射移植异体骨髓间充质干细胞（mes．enchymalstemcells，MSCs）后，MSCs在损伤局部的聚集情况。方法取成年雄性大鼠48只，建立脊髓半横断模型，术后即刻、1d、1周、2周、3周、4周、5周、6周，经尾静脉注射移植Hoechst预标记的同种异体MSCs（5×10^6个／只），每个时间点6只。另设立未损伤组（空白对照）及假损伤组（实验对照）作为对照，每组6只。细胞移植后2周，处死实验动物，损伤脊髓部位连续水平纵行切片，在荧光显微镜下观察，计数单张切片平均阳性细胞数，结果行方差分析。结果对照组脊髓内仅见零星标记细胞[未损伤组（14±2）个，假损伤组（11±3）个]，损伤后即刻至损伤4周进行细胞移植组脊髓损伤部位可见大量标记细胞聚集，其中损伤1周组最多达（2197±14）个，损伤5周组标记细胞数明显减少至（259±66）个，损伤6周组标记细胞仅为（43±15）个。标记的移植细胞集中在距离损伤部位0．5cm区域内，主要分布于白质。结论大鼠脊髓损伤后1个月内经静脉移植同种异体骨髓MSCs，移植细胞可向脊髓损伤部位聚集。

Objective To observe migration and survival of marrow derived mesenchymal stem cells （MSCs） in injury site following intravenous transplantation after acute or chronic spinal cord injury in adult rats. Methods Spinal cord semi-transection was made in T10 segment in 48 Wistar male rats, at 0 h, 24 h, 1, 2, 3, 4, 5 and 6 weeks after injury, allogenie MSCs （5×10^6 cells to one animal） stained with Hoeehst were transplanted through coccygeal vein injection, respectively. Two weeks later, animals were killed, the spinal cord including injury epicenters were harvested and sectioned longitudinally at 20 μm. The transplanted cells stained with Hoechst were observed using fluorescent microscope, and the average number of the marked cells in one section was counted. Statistical significance was determined by ANOVA, P〈0.05 was deemed statistically significant. Results There were few transplanted cells in spinal cord in normal group （14±2） or sham injury group （11±3）. When transplanted within 4 weeks following injury, a large quantity of Hoechst marked cells could detected in spinal cord injury site, especially in 1 week group （2197±14）. However, the quantity of the cells decreased remarkablely in 5 weeks group （259±66）, and almost disappear in 6 weeks group （43±15）. The marked cells were mainly assembled about 0.5 cm from site of spinal cord injury. Conclusion Within 1 month after spinal cord injury, intravenous transplanted allogenic MSCs can assemble and survival in injury site, which implies that MSCs transplantation can be used to repair spinal cord injury within a certain time range following injury.