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How is transfection critical to the success of a cell or gene therapy?

Not all, but many cell and gene therapies implicitly involve transfection in their manufacture. For example, consider therapeutic viral vectors such as Luxturna, which consists of AAV2 packaged with the gene RPE65. To manufacture this AAV vector, cells are transfected with plasmids that contain instructions to assemble and package the therapeutic gene into the viral particle. Over one hundred billion of these viral vectors are injected into the eye to restore vision through expression of RPE65 protein.1 Some gene therapies may require as many as 1016 viral vectors per dose which would require transfection of MANY liters of cells! Efficient, consistent and scalable transfection is critical to producing affordable viral vector-based therapies.

Genome engineering of cells ex vivo, such as with CRISPR methodology, also requires transfection. In order to alter genes for therapeutic benefit, nucleic acids that guide or template the edit must be transfected into the cells. Once modified, the genetically engineered cell stock can be expanded before infusion into patients. As with viral vector-based therapies, transfection is a key first step in the manufacture of cell-based therapies.

How about those cell and gene therapies that do not directly use transfection in their manufacture? Consider Spinraza, the first FDA-approved drug to treat spinal muscular atrophy.2 Spinraza is an 18-base antisense oligonucleotide that is completely chemically synthesized. It is injected near the spine and works by binding to a complementary region on the mRNA of the ‘survival of motor neuron 2’ (SMN2) gene, which causes the production of functional SMN protein, which in turn ultimately leads to improved muscle function. Decades before this gene therapy was introduced into the clinic, the groundwork was set at the bench to understand the underlying genetic factors of the disease and conceive of and test potential therapeutics. Countless transfections were undoubtedly performed to characterize the SMN genes and to probe the mechanism of action of antisense oligonucleotide candidates. Though transfection is not always directly involved with their manufacture, transfection is an essential technique that is prominently featured during research, development and assessment of cell and gene therapies.

Have you applied transfection to develop a gene or cell therapy? Send a comment to techsupport@mirusbio.com. We’d love to hear from you!


  1. FDA. “LUXTURNA.” Accessed 08 March 2023.
    Link: fda.gov/vaccines-blood-biologics/cellular-gene-therapy-products/luxturna
  2. FDA. “Drug Trials Snapshots: SPINRAZA.” Accessed 08 March 2023.
    Link: fda.gov/drugs/drug-approvals-and-databases/drug-trials-snapshots-spinraza

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