Final answer:
Stem cells' capacity to divide and differentiate into specialized cells makes cell-based delivery possible for viral vectors.
Step-by-step explanation:
The property of stem cells that makes cell-based delivery possible for viral vectors is their capacity to divide and differentiate into specialized cells. Stem cells can be induced to differentiate into the specific cell type that the viral vector is designed to target.
For example, if the viral vector is carrying a gene therapy treatment for heart disease, stem cells can be induced to differentiate into heart cells and then injected into the patient to repair damaged or destroyed heart cells.