干细胞治疗是脑卒中等神经系统疾病的研究热点，常用的光学成像、MRI成像和核医学分子显像多用于监测移植干细胞体内的分布、迁移和存活状态，对其神经元分化的监测尚无有效的方法。神经元烯醇化酶（NSE）是神经元分化的重要标志物，酪氨酸酶（TYR）则是一种可以同时用于光声成像（PAI）、磁共振成像（MRI）和核医学分子显像的新型多模态报告基因，以NSE特异性启动子引导的TYR有望实现对移植干细胞神经元分化的活体监测。本研究拟构建NSE特异性启动子引导的TYR基因慢病毒表达载体，稳定转染骨髓间充质干细胞，将转基因干细胞引入脑卒中模型，利用PAI/MRI/microPET多模态成像对移植干细胞进行无创、动态监测，分析多模态成像与干细胞神经元分化组织学检测结果的相关性，以期为脑卒中模型中移植干细胞神经元分化的监测寻找一种简单、有效、无创的活体监测方法。

The stem cell therapy for neural diseases, such as stroke, is the research hotspot at present. Although optical imaging, MRI imaging and molecular imaging of nuclear medicine have been widely used in tracking the transplanted stem cell, it is still beset by the difficulty of monitoring the neuronal differentiation of stem cells in vivo. Neuron-specific enolase (NSE) is an important marker of neuronal differentiation. Tyrosinase (TYR) as a new type of multimodality reporter gene, which could be applied for photoacoustic imaging (PAI), magnetic resonance imaging (MRI) and nuclear medicine imaging respectively. Therefore, NSE promoter-driven TYR is expected to achieve monitoring the neuronal differentiation of transplanted stem cell in vivo. This study intends to construct the lentiviral vector expressing TYR reporter gene under the control of NSE promoter, and to obtain the bone marrow mesenchymal stem cells (MSCs) transfected with the vector stablely. The transfected MSCs are transplanted into the rats model of middle cerebral artery occlusion (MCAO). The method of PAI/MRI/microPET multimodality imaging is introduced to monitor the MSCs non-invasively and dynamically. Furthermore, the neural differentiation of transplanted stem cells is evaluated with the nerual specific markers, and analyzed the relationship with the result of multimodality imaging. It is expected to develop a simple, effective and non-invasive method to monitoring the neuronal differentiation of the tranplanted stem cell in the model of stroke.