The last two decades have seen significant growth in the field of stem cell research, as its potential for the development of powerful therapeutics and disease treatments is huge. However, even as the field sees success as a whole, conflict and controversy arise when you mention the use of embryonic stem cells. The medical implications are huge, but it is important to consider the moral implications of the research and if potential alternatives exist.
Stem cells are cells that have not yet differentiated, or become a specific cell type, and can renew themselves relatively limitlessly through mitotic division. Because they are precursors to all kinds of cells, they are highly sought after to develop treatments to repair damaged tissues. There are many kinds of stem cells. Those isolated from bone marrow or umbilical cords are fairly versatile and show great promise in therapeutics. Recent research has been able to reprogram skin cells and other differentiated adult cells so that they can function as stem cells.
The controversy appears, however, when you begin to consider and work with embryonic stem cells. These stem cells are the precursors of life and can form any kind of cell. They are the most versatile and clearly show the greatest promise. Unfortunately, they involve the cloning of human embryos and the destruction of these embryos to harvest cells.
Many critics, especially pro-life advocates, find issue with the destruction of embryos as a form of abortion. Beyond just this, critics see the destruction of embryos as the first step towards growing and breeding humans for organ and tissue harvesting, creating medical "farms" to assist with the donation of vital tissues. The issue facing scientists is where to draw the line between what is considered life and what is not. Also, we need to maintain a standard to prevent the situation where some humans are simply tools or farms for the research and medical needs of others.
Pro-life advocates see no alternatives, as the destruction or manipulation of any embryos is simply wrong. For the critics of medical farming potential, standards must be created and any practice of allowing the embryos to grow to differentiation as an entire embryo must be outlawed.
Beyond the destruction of embryos comes the repercussions of embryonic cloning and its potential misuse. A strong, very vocal portion of the scientific community sees great danger in further developing cloning technology in order to create more embryonic stem cells and stem cell lines. This is related to the medical farms mentioned above. One can imagine a situation where a rogue group clones embryos and even allows them to grow to differentiation. Soon you have cloned humans and the implications of such an event are huge and the slope is slippery at best.
A solution often given for preventing this development of cloning technology is to seek embryonic stem cell lines from fertility clinics. These clinics often require multiple fertilized eggs for in vitro fertilization, yet only use a small number of them for implantation. These extra embryos could be potential stem cell lines, without any cloning necessary.
The current trend in the biological research community is to find alternative means to develop stem cell lines that do not require embryonic stem cells, bypassing the controversy behind embryonic stem cells entirely. Scientists have been using bone marrows cells, which can differentiate into different blood cells, for some time now as a source of adult stem cells. Reprogramming fully differentiated tissues, such as skin cells, shows great promise for creating lines of stem cells that are just as powerful as embryonic stem cells without the ethical implications.