By Eduardo Grunvald, M.D.
Michael J. Fox‘s successful acting career might soon be upstaged by his success as a lobbyist his stumping for stem cell research in last month’s election turned the tide in favor of the controversial legislation in several states across America.
Fox, who suffers from Parkinson’s disease, is putting hope for a cure in medical research using embryonic stem cells.
But the issue is laden in debate.
Proponents laud its potential for reversing diseases and injuries currently considered chronic and incurable. Opponents argue against it because of ethical concerns related to questions about tampering with human embryos. No matter what side of this moral fence you sit on, in order to formulate an educated opinion it is important to have a basic understanding of stem cell research.
The nine-month process whereby a single fertilized cell develops into a beautiful baby is nothing short of marvelous and mind-blowing. Your body is composed of millions and millions of cells that make up the different tissues, like your heart, muscle and skin. But how does one cell know how to become all that? This question is really at the crux of embryonic stem cell research.
After the egg cell is fertilized in the womb, it begins to divide. One becomes two, two become four, four become eight and so forth. After three to five days of this process, a ball of cells called a blastocyst - is created. In this mass, one cell will become the parent of all the cells that compose the skin; another will be the parent of cells of the heart, and so on for all organs, tissues, and structures that make up the human body. The different types of cells that will eventually make up a certain tissue stem from a single “mother cell”, hence the term “embryonic stem cells.”
Organs in the adult body also contain similar types of cells, termed “adult stem cells.” The best example lies in the bone marrow, where these parent cells make the different types of white cells in the blood. These have been used therapeutically for over 30 years in bone marrow transplants to treat a variety of cancers, such as leukemia or lymphoma. The problem is that only a limited number of organs in the body contain cells that can be “turned on” to regenerate injured tissue.
But what if scientists could figure out what controls an embryonic stem cell to differentiate into a brain cell and not a heart cell, and why it occurs at precisely the right time compared to the other cells, and what turns them off so that they don’t develop into a large tumor instead of a heart? And once this entire process is better understood, what if those stem cells could be manipulated in a laboratory to become skin if they are fed certain nutrients, but turn into certain types of brain cells if they are given other ingredients?
Potentially they could be used to make new skin, new brain cells, insulin producing cells in the pancreas, or repair nerve tissue in the spinal cord. Medical researchers think this technology holds hope for treating conditions such as Park-inson’s Disease, diabetes, muscular dystrophy, damaged heart muscle after a heart attack, blindness, and other conditions. Perhaps burn victims could be treated with new skin derived from stem cells. Many spinal cord injury victims are hopeful that this could lead to regeneration of nerve cells that were severed in an accident. And perhaps new organs could be created to complement, or even substitute, the current organ transplant process.
To create these cell lines in the laboratory, cells have to be taken from the blastocyst stage of the human embryo. This is done during the process of invitro fertilization, from extra embryos that will not be used and are destined to be destroyed. Human embryonic stem cells were first isolated and grown in 1998. Within the timeframe of biomedical research, this field is considered to be in its infancy, and real clinical benefits to patients are many years away. These are some of the issues that opponents of stem cell research raise in concern.
In 2004, California voters sent the message that embryonic stem cell research was a worthy endeavor with viable prospects for curing disease. Proposition 71 approved three billion dollars of state funds, over ten years, to support research for this purpose, and potentially making California a leader in this young field of medical research. All this in the context of the federal government placing limitations on financing this type of investigation.
Many technological advances in human history have given birth to more questions, both moral and otherwise, that parallel the answers they achieve. This quest is no exception.
Dr. Grunvald is Assistant Clinical Professor, Department of Medicine at the Perlman Internal Medicine Group, UCSD Medical Center.