Gene therapy is a technique that modifies a patient’s gene(s) to prevent, treat or cure disease. One type of gene therapy is cell modified gene therapy, which involves removing cells from the patient, genetically modifying the cells using a gene delivery/modification vehicle, and returning the modified cells back to the patient.

Viral vector is currently the most common vehicle for gene therapy due to its high gene delivery efficiency. However, use of viral vectors are associated with several disadvantages including: (1) virus-associated safety risks, (2) high manufacturing costs, and (3) limited payload capacity of viral vectors, which severely restrict the repertoire of genes that can be encoded.

A virus-free vector obviates these shortcomings. It is safer than viral vectors due to lower immunogenicity and lower risk of genome toxicity. Moreover, virus-free vector has the capacity to carry larger fragments of genetic material compared to conventional viral vectors. The manufacturing costs of virus-free vectors are also markedly lower than those required for viral vector production.

Despite the advantages of virus-free vectors, it remains a challenge to efficiently modify, expand, and deliver persistent therapeutic cells with stable gene expression. Electroporation is the most efficient method for delivery of virus-free vectors into therapeutic cells, but following electroporation these cells become fragile with markedly reduced viability and expansion capacity.