Within stem cells lie the capability to create every part of your body you need to live. From the time you were conceived, these versatile little cells replicated and developed your organs, tissues and functions. Through research, scientists hope to be able to tap into the power of these cells to regenerate damaged organs or even create new organs from scratch.
Identification
All types of multicellular plants and animals contain stem cells. Unlike standard cells, stem cells divide and replicate themselves quickly and can develop into specialized types of cells, such as those that make up your tissues or organs. There are two types of stem cells of interest to researchers. Embryonic stem cells form in the days after a human egg is fertilized, quickly regenerating and specializing into the more than 250 cell types we need to function. You also maintain a limited number of adult stem cells as you develop in your organs and tissues, including your bones, blood, digestive system and brain.
History
Researchers first discovered adult stem cells in bone marrow in the 1950s, according to the U.S. National Institutes of Health. In the 1960s, they found adult stem cells in the brains of rats, though it took another 30 years for researchers to determine that these cells had the potential to produce new brain cells. Embryonic stem cell research is much younger, with scientists first learning how to extract the cells from embryos and grow them in the laboratory in 1998. In the U.S., President Barack Obama in 2009 opened the door to federal funding of embryonic stem cell research for cell cultures created after 2001, which had been blocked by his predecessor, President George W. Bush. During the Bush Administration, the amount of federal funding going toward adult stem cell research dwarfed that going to embryonic stem cell research. From 2001 to 2004, about $180 million in federal funds went to adult stem cell research, compared with $25 million going toward embryonic stem cell research, according to the Sue and Bill Gross Stem Cell Research Center. Embryonic stem cell research has received funding from other sources, such as the California Institute for Regenerative Medicine, which as of 2010 has supplied more than $1 billion in grants since its establishment in 2004.
Significance
Scientists study stem cells to learn how we develop and how our damaged cells repair themselves. Through this research, they've been able to identify causes of birth defects and test the effects of certain drugs. They've also discovered that adult stem cells from certain tissues can be reprogrammed into cells from other tissues, according to Duke University Medical Center cell biology department chair Brigid Hogan. They've been able to convert adult stem cells in mice's blood into muscle, for example. For specific treatments, doctors for decades have used adult bone marrow stem cells to aid in the treatment of cancers such as leukemia, helping the body to repair cells damaged by chemotherapy. More recently, they've been able to use stem cells from umbilical cords for this purpose. In 2009, the U.S. Food and Drug Administration approved testing of embryonic stem cells for use in the repair of spinal cord injuries, though researchers say effective treatment with embryonic stem cells will require a lot more research.
Potential
As scientists better understand stem cell functions, the ability to harness their regenerative ability could yield treatments for a number of conditions. For example, they could create insulin-producing cells to create diabetes or new nerve connections to reverse paralysis after spinal cord injuries. They also could provide treatment for Alzheimer's disease, heart disease, arthritis and severe burns, according to the NIH, and would be much gentler treatment options than surgery. To make effective embryonic stem cell treatments, scientists will have to figure out how to prevent the body from rejecting them, how to keep them alive once in the body and how to stop them from creating tumors, which they are prone to do.
Controversy
Despite the potential for medical advances, stem cell research still raises some ethical questions. While few object to adult stem cell research, most embryonic stem cells for research purposes come from unused embryos created in fertility clinics for couples undergoing in vitro fertilization. Though such embryos generally are destroyed anyway, many people who believe life begins at conception oppose their use in research. U.S. law as of 2010 bans federal funding of research in which scientists create embryos specifically for the purpose of harvesting stem cells, which some scientists say is an obstacle to speedier developments. In addition, embryonic stem cell research opponents argue that it diverts funding from adult stem cell research, which already has produced treatments.
References
- U.S. National Institutes of Health: Stem Cell Basics
- Howard Hughes Medical Institute: Advances in Stem Cell Research
- University of California, San Francisco: Stem Cell Research Advances Cancer Knowledge
- The White House: Removing Barriers to Responsible Scientific Research Involving Human Stem Cells
- CBS News: Obama Ends Stem Cell Research Ban
