Question

Distinguish among ES cells, iPS cells, and adult stem cells, and state the pros and cons of working with each to develop a therapy.

Short answer

ES cells, derived from early-stage embryos, are pluripotent but using them raises ethical issues. iPS cells are reprogrammed adult cells with pluripotency bypassing the need for embryos, reducing ethical concerns, but they are still a developing technique with some associated risks. Adult stem cells, found throughout the body, are less controversial but have a more limited ability to differentiate.

Step-by-step solution

Defining ES cells

Embryonic Stem (ES) cells are pluripotent stem cells derived from the inner cell mass of a blastocyst, an early-stage preimplantation embryo. They are capable of dividing without differentiating for a prolonged period and are known to develop into over 200 different cell types of the body. However, the use of ES cells often raises ethical issues as they are harvested from a developing embryo.

Exploring iPS cells

Induced Pluripotent Stem (iPS) cells are a type of pluripotent stem cells that can be generated directly from adult cells. They are reprogrammed to an embryonic stem cell–like state by introducing embryonic genes into a mature cell. This process bypasses the need for embryos and hence, the ethical issues. However, since this a relatively new technique, there may be some unknown factors and potential risks.

Understanding adult stem cells

Adult stem cells are undifferentiated cells, found throughout the body after development, that divide to replenish dying cells and regenerate damaged tissues. They are more limited in their ability to differentiate compared to embryonic or iPS cells, but they are less controversial as they can be obtained with minimal risks. However, they may not be as effective as ES or iPS cells in terms of wide range of therapeutic potential.