The Stem of the Issue

Last night after writing my previous post I was doing my laundry and all the while thinking about Stem Cells, a topic I brought up as an example. Well, even though the issue hasn't been in the media or most peoples minds as much, I figured this very important issue deserved a post of its own.

A stem cell is a type of cell that isn't specialized. In other words, through the usage of special signals a stem cell can, in some cases, turn into any of the 220 "normal" cells in a human body. It can also, just like normal cells, make 2 copies of itself through mitosis. Now what is so great about this?

Imagine one of your friends has recently been involved in a car crash. He has suffered a spinal injury that killed most of the nerve cells in his spine leaving him paralyzed from the waist down. With current technology chances are he will never heal, due to the fact that healthy nerve cells in an adult don't multiply to replace damaged ones. However, if doctors created a line of stem cells that contained your friends DNA and exposed them to the proper signals they could "grow" him new nerve cells that they could repair his spine with. This has other applications as well, such as possibly curing/preventing Alzheimer's Disease, repairing other organs such as the heart, and even producing new white blood cells for someone with HIV.

However, many people are against researching and utilizing stem cells. Today, the only place we can harvest stem cells is from a blastocyst, an early stage of an embryo. The way medical researchers go about doing this might surprise you. By taking an unfertilized egg from a woman and removing its nucleus, the place the DNA is stored, and inserting the nucleus from a normal cell, such as a skin cell, we can create an egg that contains all of the instructions needed to create an embryo. The stem cells that can be harvested from this embryo will have the same DNA, and thus be identical to, the stem cells of the embryo that formed the person who donated the nucleus that was transplanted into the egg. This process is called therapeutic cloning if the stem cells are harvested, and reproductive cloning if the embryo grows to be an individual. However, there is a huge roadblock that stops researchers from practicing this.

A Blastocyst (http://www.advancedfertility.com/pics/blastocyst.jpg)

By now I'm sure many of you are sick of the biology lesson and want some politics, well here you go. In 1995 President Clinton signed the Dickey Amendment which prohibited federal money to be used in research that created or destroyed and embryo (Thanks wikipedia). Considering the fact that the vast majority of research funding is attributed to federal spending, this really brought therapeutic cloning to a near stand-still. This law was passed due to many factors. Some people believe the act of killing these embryos to be similar to killing an individual, much like abortion. Others think therapeutic cloning will lead to reproductive cloning of humans. These fears, with help from the media, have put the issue of stem cells usage into a very negative light in public opinion. Well, allow me to put these fears to rest.

When gametes, egg and sperm cells, are formed through a process called meiosis, they go through a process called Imprinting. Every cell in your body contains 2 of each of the 23 types of chromosomes, which make up your DNA. These chromosomes code for the production of proteins, which basically means they code for what makes you you , and what makes me CandiedYams. Since you have 2 of each type of chromosome, you have 2 of every type of gene, which causes 2 dosages of every type of protein you body produces. However, during development, an embryo only needs 1 dosage of about 50 different genes. If they have the normal 2, they will either be severely deformed, or will spontaneously abort.

This is where Imprinting comes into play. There are about 25 male and 25 female imprints. This means that in the egg, 25 different genes are "turned off," and the same goes for a different 25 in a male. Together this turns all 50 of the extra genes that an embryo does need. After some time, these imprints wear out, and both pairs of these genes are expressed, but by that time the person is fully developed and can handle them.

In normal adult cells some, if not all, of the imprints are gone. This means that when you take the nucleus out of an adult cell and transplant it into an egg without a nucleus, it will more than likely lack the imprints as well. This is why reproductive cloning is so ineffective. Dolley, the famous cloned sheep, took over 800 attempts before the embryo grew to become a normal individual. Because of this, an embryo that is used for therapeutic cloning has less than a 0.125% chance of becoming an adult with todays techniques. I hardly consider killing these embryos the prevention of life or murder. If the stem cells are grown and used to save the life of the DNA donor you just traded in 1/800th of a life for a whole life. Seems like a good trade to me.

So the next time you hear that stem cells are harvested from aborted babies, remind yourself that they aren't. Stem cells are made from an unfertilized egg and the nucleus of a normal cell that you can get from your skin. To a medical researcher, stem cells are the like clay an artist molds to make art or the hot iron a blacksmith uses to forge his creations, they are the tools a surgeon and doctor can use to cure dozens of disease and restore life to someone who might not have any left.

I would like to give credit to Dr. Sam Rhine, from whom I learned most of this information from.