ABSTRACT
Objective To study the biodistribution of 131 I-2'-deoxy-1-β-D-arabinofuranosy1-5-iodouracil (FIAU) in the rat middle cerebral artery occlusion model and the expression of thymidine kinase (TK) gene in brain tissue after gene-modified stem cell transplantation,and thus evaluate the possibility of further noninvasive monitoring of stem cell transplantation therapy in cerebral infarction.Methods Adenovirus recombinant Ad5-TK-intemal ribosome entry site-brain derived heurotrophic factor-enhanced green florecent protein(IRES-BDNF-EGFP) carrying TK-IRES-BDNF gene was prepared.Cerebral infarction model was established in rats by intraluminal middle cerebral artery occlusion with nylon monofilament.Gene modified bone marrow mesenchymal stem cells were transplanted via intraparenchymal route,lateral ventricle,carotid artery and tail vein,respectively.The normal rats were used as controls.131 I- FAU was prepared to be the tracer for biodistribution study and the ％ ID/g was calculated based on measurement of the tissue radioactivity counts.The expression of TK gene was evaluated by quantitative real-time PCR (QR-PCR) and Western blot analysis.Data were analyzed with independent-samples t-test,one-way analysis of variance (ANOVA) test,and Pearson linear correlation test.Results The ％ ID/g of infarcted brain tissue in the intraparenchymal group was 0.124 ± 0.013,which was significantly higher than that in lateral ventricle group (0.052 ±0.004),carotid artery group (0.061 ±0.002),tail vein group (0.059 ±0.005) and control group (0.005 ±0.001) (t =2.913 - 5.652,all P＜0.05),while there were no statistically significant differences among the other route transplanted groups ( t =0.694 - 1.448,all P ＞ 0.05 ).The differences of ％ ID/g between the infarcted and contralateral sides of brain tissue in all transplanted groups were statistically significant (t =9.004 - 15.734,all P ＜ 0.05 ),while there was no statistically significant difference of this parameter between both sides of brain tissue in control group (t =1.511,P =0.182).The expression of TK gene in intraparenchymal group was significantly higher than other groups (t =7.482 -12.371,all P ＜0.05).The expression levels ofTK gene on QR-PCR showed a positive correlation with ％ID/g of the brain tissue ( r =0.971,P ＜ 0.001 ).Similarly,the ratio of TK/β-actin by the Western blot analysis correlated with the ％ ID/g ( r =0.899,P =0.002 ).Conclusion Intraparenchymal route may be the way of choice for cell transplantation therapy of cerebral infarction.If suitable radionuclide tracer is available,PET or SPECT may be potentially used for noninvasive monitoring of stem cell transplantation in cerebral infarction in vivo.