If successful, FDA approval to test ribozyme therapy in humans would soon follow. Vectors Before gene therapy can be tested in humans, the safety of gene delivery systems must be further tested. In scientific parlance, gene delivery systems are called vectors. Vectors act like a fleet of microscopic delivery trucks transporting genes into retinal cells. Most vectors are derived from viruses.
Viruses are extremely effective at infiltrating the nucleus of a cell where genes reside.
However viruses also contain harmful elements evoke immune responses. Over the past decade researchers have been working to genetically modify viruses to reduce, and hopefully eliminate, their harmful qualities without compromising their delivery capabilities. In addition to concern for immune response, vectors must also be designed to target only the genetically affected cell type. Without careful targeting, the gene or gene product could adversely affect the function of other healthy cell types in the body. Lastly, vectors must also regulate the expression of the gene.