基因疗法旨在增加,替换或关闭基因以帮助治疗疾病。迄今为止,美国食品和药物管理局(FDA)已经批准了14种基因治疗产品。随着人们对基因治疗的兴趣日益浓厚,可行的基因传递载体对于将新基因插入细胞是必要的。有不同种类的基因传递载体,包括病毒载体,如慢病毒,腺病毒,逆转录病毒,腺相关病毒等,和非病毒载体如裸DNA,脂质载体,聚合物纳米颗粒,外泌体等人,病毒是最常用的。其中,最受关注的载体是腺相关病毒(AAV),因为它的安全性,有效地将基因传递到细胞中并在多个组织中持续转基因表达的自然能力。此外,例如,AAV基因组可以被工程化以产生含有感兴趣的转基因序列的重组AAV(rAAV),并且已经被证明是安全的基因载体。最近,rAAV载体已被批准用于治疗各种罕见疾病。尽管有这些批准,rAAV的一些主要限制仍然存在,即非特异性组织靶向和宿主免疫反应。其他问题包括阻断转基因递送的中和抗体,有限的转基因包装能力,高病毒滴度用于每剂量和高成本。为了应对这些挑战,已经开发了几种技术。基于工程方法的差异,本文提出了三种策略:基于基因工程的衣壳修饰(capsidmodification),衣壳表面通过化学共轭连接(表面连接),和装载有AAV的其他制剂(病毒载量)。此外,总结了rAAV工程策略中遇到的主要优点和局限性。
Gene therapy aims to add, replace or turn off genes to help treat disease. To date, the US Food and Drug Administration (FDA) has approved 14 gene therapy products. With the increasing interest in gene therapy, feasible gene delivery vectors are necessary for inserting new genes into cells. There are different kinds of gene delivery vectors including viral vectors like lentivirus, adenovirus, retrovirus, adeno-associated virus et al, and non-viral vectors like naked DNA, lipid vectors, polymer nanoparticles, exosomes et al, with viruses being the most commonly used. Among them, the most concerned vector is adeno-associated virus (AAV) because of its safety, natural ability to efficiently deliver gene into cells and sustained transgene expression in multiple tissues. In addition, the AAV genome can be engineered to generate recombinant AAV (rAAV) containing transgene sequences of interest and has been proven to be a safe gene vector. Recently, rAAV vectors have been approved for the treatment of various rare diseases. Despite these approvals, some major limitations of rAAV remain, namely nonspecific tissue targeting and host immune response. Additional problems include neutralizing antibodies that block transgene delivery, a finite transgene packaging capacity, high viral titer used for per dose and high cost. To deal with these challenges, several techniques have been developed. Based on differences in engineering methods, this review proposes three strategies: gene engineering-based capsid modification (capsid modification), capsid surface tethering through chemical conjugation (surface tethering), and other formulations loaded with AAV (virus load). In addition, the major advantages and limitations encountered in rAAV engineering strategies are summarized.