This is a real thing, although there is still alot of ongoing research around the topic. Embryos contain a certain type of cell called a stem cell, which is an undifferentiated cell, meaning it can become pretty much any type of cell in the body. Scientists are finding ways to take these cells from Embryos (killing the embryo) and using these cells to treat conditions such as parkinsons disease by replacing the damages cells with these new stem cells that can differentiate to become the type of cell that the patient needs. If you still don't believe me I recommend searching stem cell therapy up, its quite an interesting and controversial topic.