MRI活体示踪超顺磁性氧化铁标记兔骨髓间充质干细胞的自体皮下移植

背景：高磁场MRI已被成功应用于示踪移植超顺磁性氧化铁标记骨髓基质干细胞的研究，但目前还有应用低磁场MRI示踪移植干细胞的报道。 目的：探讨用0.2 T MRI活体示踪自体皮下移植磁化标记骨髓基质干细胞的分布和迁移的可行性。 方法：从兔骨髓中分离培养骨髓基质干细胞，采用超顺磁性氧化铁和BrdU双重标记后，与壳聚糖复合植入兔自体大腿皮下。自体皮下移植未标记骨髓基质干细胞和皮下单纯注射超顺磁性氧化铁为对照。 结果与结论：超顺磁性氧化铁标记骨髓基质干细胞经普鲁士蓝染色和电镜检查证实细胞胞浆含致密铁颗粒。超顺磁性氧化铁标记后自体皮下移植的兔骨髓基质干细胞在GRET2*WI序列成像时产生特征性的低信号改变至少维持8周，且信号逐渐从移植部位进入组织深处。但普鲁士蓝染色和BrdU免疫组化显示大部分的移植细胞仍停留在原移植部位。提示体外超顺磁性氧化铁能有效地标记骨髓基质干细胞，利用0.2 T MRI活体示踪自体皮下移植的超顺磁性氧化铁标记兔骨髓基质干细胞分布和迁移是可行的。

In vivo magnetic resonance imaging tracking of superparamagnetic iron oxide labeled rabbit bone marrow mesenchymal stem cells after subcutaneoustransplantation

BACKGROUND:Magnetic resonance imaging with high field units has been successfully used in tracking the superparamagnetic iron oxide labeled bone marrow mesenchymal stem cells. However, the validity of a low-field magnetic resonance imaging unit for detecting labeled cells has not been thoroughly investigated. OBJECTIVE:To explore the feasibility of 0.2-T magnetic resonance imaging for in vivo tracking the distribution and migration of magnetically labeled bone marrow mesenchymal stem cells after subcutaneous transplantation. METHODS:Bone mesenchymal stem cells were isolated from rabbit bone marrow. Before implantation, bone marrow mesenchymal stem cells were double labeled in vitro with superparamagnetic iron oxide and BrdU, then the cells were composited with chitosan and subcutaneously implanted in the thigh. Thighs subcutaneously implanted with unlabeled bone marrow mesenchymal stem cells and simply superparamagnetic iron oxides were used as control. RESULTS AND CONCLUSION:The dense iron particles could be seen in the cytoplasm of the superparamagnetic iron oxide labeled bone marrow mesenchymal stem cells through Prussian blue staining and electron microscopy detection. Subcutaneously transplanted superparamagnetic iron oxide labeled autologous rabbit bone marrow mesenchymal stem cells showed low signal changes and maintained at least 8 weeks during T2*-weighted gradient-echo sequence imaging, and the signal gradually entered into the tissue from the graft site. Prussian blue staining and BrdU immunohistochemistry showed that most of the transplanted cells remained in the original transplantation site. It indicated that bone marrow stromal stem cells could be effectively labeled with superparamagnetic iron oxide in vitro, and it was possible to in vivo track the subcutaneously transplanted superparamagnetic iron oxide labeled autologous rabbit bone marrow mesenchymal stem cells with 0.2-T magnetic resonance imaging.