Video Transcript
Stem cells are unspecialized cells that can differentiate into a variety of different cell types found in a human body. This makes them incredibly useful in medicine to treat disease. However, the use of stem cells faces a lot of opposition. Which of the following would be a correct scientific objection to using stem cells in medicine? (A) Stem cells could mutate in the host body and lead to diseases like cancer. (B) Stem cells can be used to create large amounts of tissue or even new organs. (C) Stem cells can only be used to treat genetic disorders, not injuries or acquired diseases. (D) Embryos are created solely for the purpose of taking embryonic stem cells. (E) Stem cells cannot be taken from consenting adult volunteers.
Let’s first remove our answer choices to think together about this question.
Stem cells offer great promises in medicine. But they are also the object of controversy amongst the general population and scientists. Let’s lay out the basic concepts of stem cell biology to understand their potential in medicine.
Stem cells come in different types, depending on their potency. The first stem cells that were successfully used in medicine were hematopoietic stem cells. These adult stem cells were isolated from the bone marrow of healthy adult donors. Because hematopoietic stem cells are multipotent, they can become many types of blood cells. They can help curing patients who suffer from leukemia or some cancers.
Although hematopoietic stem cells are very useful, they cannot become any other type of body cell, like muscle cells or skin cells. In fact, the cells produced by the fertilization of the egg by a sperm cell can become absolutely any type of cell of the human body. These cells forming the zygote are said to be totipotent. Then, when the zygote starts to differentiate into an embryo, the cells become a bit more specialized. However, there is still an amazing number of cell types into which they can possibly differentiate. These embryonic stem cells are said to be pluripotent. These embryonic stem cells could be isolated and grown in cell cultures. With some chemical signals, these cells can differentiate into almost any desired cell type, for example, skin cells. The skin tissue that would be obtained could then be transplanted onto someone whose skin has been badly burnt.
In theory, there are many examples of genetic or acquired disorders or injuries that could be treated with embryonic stem cells. Embryonic stem cells could be taken from extra embryos that are not going to be implanted in a process of in vitro fertilization, called IVF. However, destroying embryos to produce embryonic stem cells pose ethical issues and is extremely controversial.
In 2006, scientists discovered a different way to produce pluripotent stem cells that did not involve the use of embryos. These stem cells were called induced pluripotent stem cells, or iPSC. To produce iPSC, scientists just needed a sample of skin cells from a patient. Using chemicals that can reprogram the DNA, these skin cells can become pluripotent stem cells. Then, these cells can be grown in culture to differentiate into any desired type of cells, for example, skin cells that can treat the patient’s burn.
The advantage of iPS cells is that they enable personalized medicine. Since the stem cells come from the patient themselves, there is no immune rejection of the transplanted tissue. There is still intensive research on the safety of using iPS cells for treatment. In particular, scientists need to make sure the transplanted cells will not mutate or cause cancers.
We can now bring our choices back on screen to decide which one is the correct scientific objection to using stem cells in medicine. As we just mentioned with the development of induced pluripotent stem cells, the correct answer is (A). Stem cells could mutate in the host body and lead to diseases like cancer.
