Low-frequency electromagnetic fields enhance the recovery of spinal cord injured rats undergoing bone mesenchymal stem cell transplantation

doi:10.3969/j.issn.2095-4344.2013.32.012

Abstract

Abstract:

BACKGROUND: Bone marrow mesenchymal stem cell transplantation is considered as a promising therapy for spinal cord injury. How to more effectively promote the survival of bone marrow mesenchymal stem cells in the area of spinal cord injury and to accelerate the recovery of motor function after spinal cord injury is a current study focus. Previous studies have found that low-frequency electromagnetic fields can promote bone marrow mesenchymal stem cell proliferation and differentiation, but whether the low-frequency electromagnetic fields can be applied to bone marrow mesenchymal stem cell transplantation for treatment of spinal cord injury requires further studies.
OBJECTIVE: To discuss the effects of low-frequency electromagnetic fields on motor function of spinal cord injury rats after transplantation of bone mesenchymal stem cells.
METHODS: Sixty-four rat models of incomplete spinal cord injury at T10 were established by compression method and then randomized into control group, transplantation group (bone mesenchymal stem cell transplantation), electromagnetic field group and combination group (electromagnetic field+bone mesenchymal stem cell transplantation). After successful modeling, bone mesenchymal stem cells labeled with 5-bromo-2'-deoxyuridine were injected into the original injured site in the transplantation group and combination group, which were isolated and purified with the fast adherence method; while alpha-minimum essential medium was injected into the electromagnetic field group and control group for instead. At 24 hours post-operation, the electromagnetic field group and combination group were explored to low-frequency electromagnetic fields (frequency 50 Hz, magnetic indaction intensity 5 mT) for 60 minutes per day.
RESULTS AND CONCLUSION: After cell transplantation for 21 days, the Basso, Beattie, and Bresnahan scores in the combination group was higher than the other groups (P < 0.05). 5-Bromo-2'-deoxyuridine positive cells grew well, and integrated into the normal spine; syringomyelia was reduced, and the number of spinal neural cells was increased in the combination group. In addition, glial fibrillary acidic protein expression was decreased in the combination group, while matrix metalloproteinase 2 expression was increased. It indicates that low-frequency electromagnetic fields could promote recovery of motor function in the spinal cord injury rats transplanted with bone mesenchymal stem cells, which could be associated that low-frequency electromagnetic fields facilitate the survival of transplanted bone mesenchymal stem cells, up-regulate the expression of matrix metalloproteinase 2, and reduce glial scar formation in the spinal cord injured site.

Key words: stem cells, stem cell transplantation, low-frequency electromagnetic fields, spinal cord injury, bone mesenchymal stem cells, cell transplantation, provincial grants-supported paper, stem cell photographs-containing paper

CLC Number:

R394.2

Feng Yu, Bai Wen-fang, Xu Wei-cheng, Li Xin-ping, Bai Li-ming, Liang Ling, Wang Xin, Zhang Ming-sheng . Low-frequency electromagnetic fields enhance the recovery of spinal cord injured rats undergoing bone mesenchymal stem cell transplantation[J]. Chinese Journal of Tissue Engineering Research, 2013, 17(32): 5819-5826.

Figures/Tables 5

第7天，对照组和电磁场组脊髓组织结构破坏严重，损伤区有较多坏死液化吸收后形成的囊性空洞，神经细胞明显减少且变性、肿胀较重，周围有炎性细胞浸润，组织进一步肿胀，血流减少；骨髓间充质干细胞组和电磁场+骨髓间充质干细胞组损伤区囊性空洞面积较小、肿胀稍减轻，可见肥大的巨噬细胞和胶质细胞等，组织结构仍比较模糊。随着时间变化，如图3A-H所示，各组脊髓组织结构逐渐改善，第14天，除了对照组外，其他3组囊性空洞几乎闭合，被其它细胞组织所代替填充，骨髓间充质干细胞组组织水肿消失，仅有少量炎细胞浸润，电磁场+骨髓间充质干细胞组脊髓损伤结构已大部分修复，细胞排列有序，炎细胞基本消失。造模后第21天，除对照组外，其他各组损伤脊髓组织结构基本修复。 2.5 电磁场促进骨髓间充质干细胞移植治疗大鼠损伤脊髓中BrdU阳性细胞的生长及基质金属蛋白2的表达免疫组化染色显示，对照组在脊髓损伤14 d和21 d脊髓损伤区见大量的胶质纤维酸性蛋白的表达；电磁场组和骨髓间充质干细胞组大鼠损伤脊髓中可见中等量胶质纤维酸性蛋白表达分布于损伤区周围；电磁场+骨髓间充质干细胞组大鼠损伤脊髓中胶质纤维酸性蛋白的表达最少，表明损伤局部胶质瘢痕组织最少，见图4A-D。骨髓间充质干细胞组和电磁场+骨髓间充质干细胞组在脊髓损伤后7 d，大鼠损伤脊髓局部组织基质金属蛋白2的表达量开始升高，14 d 最明显，见图4E-H。脊髓损伤后3-21 d，骨髓间充质干细胞组和电磁场+骨髓间充质干细胞组大鼠损伤脊髓组织中都可观察到BrdU阳性细胞，并与组织融合生长，电磁场+骨髓间充质干细胞组大鼠损伤脊髓中BrdU阳性细胞生长情况较好，对照组和电磁场组脊髓损伤部位未发现BrdU阳性细胞。"

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