Figure 3. Ex Vivo vs. In Vivo Editing Therapy.

In ex vivo editing therapy cells are removed from a patient, edited and then re-engrafted (top panel). For this mode of therapy to be successful, target cells must be capable of survival outside the body and homing back to target tissues post-transplantation. In vivo therapy involves genome editing of cells in situ (bottom panels). For in vivo systemic therapy, delivery agents that are relatively agnostic to cell identity or state would be used to effect editing in a wide range of tissue types. For example systemic delivery of AAV serotype 8 vectors has been used in preclinical models to target liver tissue with high efficiency. Alternatively, in vivo therapy, may also be achieved through local injection of viral vectors to the affected tissue, such as the eye, brain, or muscle.