β地中海贫血(β-地贫）是常见的遗传性血液病，也是基因治疗的最佳候选疾病之一，而慢病毒载体（LVV）则是基因治疗中被运用最多的载体之一。近年来，以LVV介导的对β-地贫的基因治疗虽然取得了效果，但同时也引发了细胞的克隆化扩增现象，从而存在着潜在的安全性隐患。因此，如何组织实施既安全又有效的β-地贫基因治疗的方案是该研究成功与否的关键。本课题拟将近年来我们在改进LVV的安全性研究方面所取得的科研成果，即在LVV整合入染色体后，进一步自删除其慢病毒元件，以及降低LVV转录通读率的科研成果，与本所多年来在β-地贫基因治疗研究的成功经验相结合，用经安全性改进的LVV介导β-珠蛋白基因等在β-地贫的细胞和模型小鼠中进行基因治疗的研究。从外源基因的表达、贫血症状的改善程度以及载体的位点整合信息等多方位、多角度地进行安全性和有效性的深入评估，从而为β-地贫基因治疗的临床应用提供理论和应用依据。

β-thalassemia is a common inherited blood disorder. It is also the disease best fit for gene therapy. Lentiviral vector is recently one of the most often used vectors in gene therapy. Though the clinical trial for treating severe β-thalassemia mediated by lentiviral vector has been successfully conducted, it was simultaneously raised a problem for the formation of the transduced cell clones after the cell amplification, which poses a potential bio-safety risk. Thus, how to organize a bio-safe and effective β-thalassemia gene therapy protocol is the key for the success of the trial. In this proposal, we aim to apply our recent achievements on improving lentiviral vector bio-safety by introducing self-deletion viral backbone mechanism in chromosome at the meantime of reducing its transcriptional read-through in our β-thalassemia gene therapy study, using patient cells and model mice. Upon the assessment of bio-safety and treating efficacy by analyzing the transgene expression efficiency, the improvement of β-thalassemia phenotypes, the potential risk for the vector flanking sites, and their read-through rates in situ, etc, we wish the outcomes would pave a way for a safe and effective clinical application.