Imagine for a moment that one of your siblings needs a new kidney. If you don't have any siblings, pretend you do, or use your imaginary friend Drop Dead Fred. Often, when something like this happens, people end up waiting for months or even years for a kidney to become available. Many even die before an organ donor is found. Wouldn’t it be wonderful if doctors could simply take a few of your sibling’s healthy kidney cells and grow a whole new kidney in the lab?
In the past few decades, biologists have been trying to figure out how to do this very thing. One solution they have found is a process called therapeutic cloning, where a nucleus from a patient’s somatic cell, or any cell in the body that is not an egg or sperm cell, is inserted into a special fertilized egg cell. This egg cell is special because all of its DNA, including its nucleus, has been removed before fertilization, meaning that only DNA from the patient is present after somatic cell nucleus insertion. At this point, the combined cells are allowed to grow and divide until they form a small mass of cells called a blastocyst, which contains stem cells.
The blastocyst, in all its glory:
Biologists can remove these stem cells and grow them into almost any tissue in the body, including, potentially, a kidney. Even though this seems like the perfect solution to a very worrisome problem, it’s not all peaches and blastocysts. Many people strongly object to therapeutic cloning because they believe that life begins at the moment an egg cell is fertilized. To them, the blastocyst from which stem cells are taken is a form of human life and should not be harmed. Even for those who do not believe that life begins at conception, there are major concerns about how available such a procedure would be to the general public, or even if there might be serious problems that would appear years after a cloned organ had been transplanted.
Because of these concerns, research on therapeutic cloning has not proceeded very far, and most of the benefits it might provide for humans are only theoretical at this point. However, interesting studies on mice and other organisms have shown that therapeutic cloning in humans, if allowed, would most likely be quite beneficial.11 If you have an opinion on this important ethical issue in cell biology, we at Shmoop would love to hear it.