Recent progress in polymeric gene vectors: Delivery mechanisms, molecular designs, and applications.

Gene therapy and gene delivery have drawn extensive attention in recent years especially when the COVID-19 mRNA vaccines were developed to prevent severe symptoms caused by the corona virus. Delivering genes, such as DNA and RNA into cells, is the crucial step for successful gene therapy and remains a bottleneck. To address this issue, vehicles (vectors) that can load and deliver genes into cells are developed, including viral and non-viral vectors. Although viral gene vectors have considerable transfection efficiency and lipid-based gene vectors become popular since the application of COVID-19 vaccines, their potential issues including immunologic and biological safety concerns limited their applications. Alternatively, polymeric gene vectors are safer, cheaper, and more versatile compared to viral and lipid-based vectors. In recent years, various polymeric gene vectors with well-designed molecules were developed, achieving either high transfection efficiency or showing advantages in certain applications. In this review, we summarize the recent progress in polymeric gene vectors including the transfection mechanisms, molecular designs, and biomedical applications. Commercially available polymeric gene vectors/reagents are also introduced. Researchers in this field have never stopped seeking safe and efficient polymeric gene vectors via rational molecular designs and biomedical evaluations. The achievements in recent years have significantly accelerated the progress of polymeric gene vectors toward clinical applications.