MR示踪观察面神经损伤大鼠脑内移植超顺磁性氧化铁标记神经干细胞

MR tracking of transplanted neural stem cells labeled with SPIO nanoparticles in rats brain after facial nerve injury

目的探讨大鼠面神经损伤后脑内移植超顺磁性氧化铁(SPIO)标记的绿色荧光蛋白(GFP)转基因胎鼠NSCs的迁移情况及MRI对移植NSCS示踪的可行性。方法24只SD大鼠随机分为4组,A、B和C组均行面神经切断,D组为正常大鼠。造模后1周,A、D组移植SPIO标记的GFP转基因胎鼠NSCs,B组移植未标记的GFP转基因胎鼠NSCs;C组移植含SPIO的NSCs培养液。分别于移植后第3天及第2、3、4周行MR,并于第4周处死大鼠,取材后观察GFP和SPIO双标的NSCs的迁移,并将该结果与MRI相比较。结果损伤侧面神经核区域:MRI:移植后第3天及第2周所有大鼠均无低信号改变,移植后第3、4周A组3只(3/6)见低信号,余所有大鼠均无低信号改变;普鲁士蓝染色:仅A组见多少不等的蓝染,且与MRI低信号区相符;GFP荧光检测:A、B组均见多少不等的GFP阳性细胞,其中A组与普鲁士蓝蓝染区对应。结论SPIO和GFP双标记的NSCs移植入面神经损伤大鼠脑内后可向损伤侧面神经核周围迁移;1.5TMR可对其迁移进行示踪。

Objective To explore the migration of transplanted NSCs of GFP transgenic mice labeled with SPIO in rat brain after facial nerve injury and feasibility of magnetic resonance tracking of this migration.Methods Twenty-four adult SD rats were randomly divided into 4 groups.A,B and C groups underwent right facial nerve cuting off,D group were normal rats.One week after model induction,NSCs stereotaxis transplantation was performed.SPIO labeled NSCs suspension was infused into group A and D.Unlabeled NSCs suspension was infused into group B.NSCs mediam contained SPIO was infused into group C.MR scanning was performed after implantation in 3 days and 2,3,4 weeks,respectively.Frozen sections of brain tissues were prepared 4 weeks later.The migration of GFP and SPIO co-labeled NSCs was observed and the results were compared with MRI.Results In the area around facial nucleus of injured side facial nerve,3 days to 2 weeks after transplantation,MRI showed that there was no area of low signal intensity in all groups.Three to 4 weeks after transplantation,there was low signal intensity presented on 3 animals（3/6）of group A,but no low signal intensity was observed on the rest 3 animals.Prussian blue staining found blue staining area which was matched with the low signal intensity area on MRI only on 3 animals in group A.In groups A and B,GFP-positive cells were observed migration to this area.In groups A,GFP-positive cells were matched with blue staining area on Prussian blue staining.Conclusion NSCs co-labeled with SPIO and GFP can migrate into area around nucleus of injured side facial nerve after transplanted into rats＇ brains,and 1.5 T MR is able to track this migration.