Viral vector research in human gene therapy: Basic principles, alternative evaluation models, and clinical applications

Gene therapy holds a great potential for treating a variety of human disorders by introducing foreign therapeutic genetic material into target cells using gene carriers (vectors). Most particularly, viral vectors show a notable effectiveness in newly available assays and alternative evaluation models developed to reduce the use of mammalian models in gene therapy research and across a broad spectrum of disease indications, showcasing encouraging results both in preclinical investigations and in clinical trials. This overview work aims at thoroughly exploring the pivotal role of viral vectors in gene therapy, comparing their efficacy across various alternative evaluation models and therapeutic applications that we investigate in our own research, with the exception of vaccination strategies. Challenges that need to be overcome to use viral vectors safely and across different fields are also discussed, as well as the advancements in viral vector technology, focusing on improving their stability and safety. Understanding the nuances of viral vector-mediated gene delivery is crucial to optimize the current gene therapy strategies and to establish effective clinical procedures. Incorporating the alternative evaluation models discussed in this review could advance the broader use of viral vectors in gene therapy by addressing current challenges while also reducing the reliance on experimental animals to adhere to the 3Rs principle (reduction, refinement, replacement).