2-3b Listening - Cloning and Stem Cells

Previously, we were looking at the concept of cloning and how this technology can be applied to medical research. Although it has many benefits, you could see that there is a strong debate regarding cloning, as well as the use of stem cells from embryos. The idea of what stem cells are and where they come from was not really focused on enough. So today, we'll look more closely at what stem cells are, as well as how scientists extract them from different sources to get either embryonic or adult stem cells.

Previously, we were looking at the concept of cloning and how this technology can be applied to medical research. Although it has many benefits, you could see that there is a strong debate regarding cloning as well as the use of stem cells from embryos. The idea of what stem cells are and where they come from was not really focused on enough. So today, we'll look more closely at what stem cells are, as well as how scientists extract them from different sources to get either embryonic or adult stem cells.

Okay, what are stem cells? We hear about it all the time and the term just seems so common that few seem to stop and really ask whether or not they truly understand what they are or where they come from. Basically, a stem cell is one which can develop into any type of cell in the body. Each part of the body, your liver, heart, skin, bones, is made up of different types of cells, but these all came from an original cell, a stem cell, which changed into that specialized form of cell. When enough of these cells get together, they form one of those organs. Other cells have specific functions and cannot change to perform a different task. Essentially, stem cells will transform to match the environment they are placed into. This is a process known as differentiation, wherein the stem cells develop to perform different specialized tasks.

You had learned that there were two main types of stem cells, embryonic and adult, which reflect the source of the stem cells being harvested. Let's take a look at each type and stress some of the main differences between them. Embryonic stem cells are, as the name indicates, taken from embryos, which are the early cells of an unborn organism. As was previously discussed, these types of cells are the most versatile and can develop into other specialized cells and tissue better than any other because they are much easier to reprogram. The embryos themselves are not actually fertilized, meaning that they couldn't actually develop into an organism on their own. This in one way avoids some of the controversy about using them that we had discussed. Instead, using a complex process with electricity and various chemicals, which we won't go into today, the embryo is created and begins to grow. Once the embryo is four to five days old, the stem cells are extracted from it and the embryo is no longer used. The harvested stem cells continue to multiply and can be removed for use as they mature, so a limitless series of stem cells can be produced from a single embryo in this way.

Despite the embryos used in this process being unable to develop, debate over their use still persists, so scientists have investigated how to extract usable stem cells from adult tissue. Not every part of the adult body is a good candidate for this procedure, however, it is blood, bone marrow, brain cells, and skin that seem to hold the best possibilities. Even fat in an adult body seems to be a source of stem cells. These cells can also differentiate or transform into other specific cells, but seem more likely limited and so far scientists have only made them change into a few types like liver and brain cells. Research has not yet shown that adult stem cells have the same degree of versatility as embryonic ones. These are also apparently much more difficult to find and seem to occur much less frequently than embryonic stem cells. A third difficulty with these cells is that unlike those harvested from an embryo, adult stem cells are unable to continuously reproduce themselves. This makes working with them much more difficult and labor intensive.

While it's true that both embryonic and adult stem cells have great potential for medical treatments and saving lives, it's obvious that embryonic stem cells have far greater possibilities in this area based on their better differentiation, higher rate of occurrence, and ability to reproduce themselves. Before we finish, let's look a little at how this technology could be used. Most research and application thus far has involved laboratory animals such as monkeys and mice as there is a great deal more research needed before such treatments become standard for humans. If they are, organs can be grown for people with failing livers and hearts from their own cells thus reducing the chance of rejection and saving countless lives. Certain diseases such as leukemia, a form of cancer in the blood and bone marrow, could also be treated using stem cells which would eliminate the need for other more painful and prolonged therapies.

Discussion of the creation and use of stem cells will undoubtedly continue as it focuses on the use of embryonic stem cells and whether or not the cloning of embryos is unethical as it could lead to the cloning of a human being. This is a discussion that we will continue in our next section. Where do you stand on this debate? Should cloning and the subsequent use of stem cells be allowed and research on them continued? Alright, let's get into some groups and get a discussion going.