Stem Cells: The Ultimate Panacea?


By Paul O’Lague, Ph.D

Dateline Earth 2176 A.D.
Longevity in most countries is now allowed to reach 250 years with most of those lived in good health. Past major killers - cancer and heart disease as well as many genetic diseases – have been eradicated by gene and organ replacement therapy of modified DNA and RNA viruses, bioengineered repair cells and in vitro grown organs. DNA data banks now allow typecasting individual behavior patterns, inherited talents, susceptibility to diseases, and criminal tendencies. This in turn has allowed more efficient use of public funds in education, medical treatment, and correction facilities. Control of population is now back to snuff with new worldwide termination stations. The future continues to look quite rosy.


Science fiction scenario? Of course. A possible future? Maybe. No one can predict the future with certainty (it violates the second law of thermodynamics). But because of the enormously important biological and genetic revolution now taking place, we are in a good position to consider possible future lifestyles offered by ongoing discoveries in biotechnology. These discoveries are poised to impact significantly on health, aging, longevity, disease eradication, and medicine in general. The sky may be the limit. Of course, whether the fruits of biotech discoveries become commonplace in society depend not only on their effects on our general well being, but also on ethical and economic factors.

Among the recent discoveries that appear to hold great promise in treating human disease and capturing the public’s attention and national debate is the use of stem cells. These esoteric cells, found in a variety of biological sites, offer great promise in repairing or replacing damaged or diseased cells and thus restoring normal function. Some have even viewed them as a possible ‘fountain of youth’. Damaged heart? Squirt in some stem cells capable of differentiating into heart muscle cells and voila, good as new. Results in mice already bear this out.

So what are stem cells, where are they found, how are they used, are there any disadvantages, and what’s all the fuss about using them? This short article touches on these questions.

Like other animals, humans start life as a single fertilized egg cell programmed in part by a mixture of maternal and paternal (i.e. egg and sperm) DNA. This egg divides into two cells then four, and so on, developing as an embryo then fetus and eventually leading to an adult with trillions of cells organized into about two hundred types of differentiated tissues such as skin, muscle, liver, brain, and others. Those who study early animal development have known for some time that cells (called blastomeres) isolated from the two -, four-, or eight - cell stage can, like the intact embryo, each give rise to an adult when reimplanted back into the mother. This spectacular result with isolated blastomeres occurs in a wide variety of animals including humans. Thus blastomeres are said to be totipotent, that is, they contain all the information and materials to produce a complete organism. This important result begged the question of whether there are cells in embryos of all stages even in adults that might retain this ability in one form or another. Today we know there are. These cells are called stem cells (it has been known for over twenty years that bone marrow contains cells that make all the blood cells). These cells, isolated from various sources, range from those found in differentiated tissues and that form only one cell type (termed unipotent) to those forming multiple cell types (multipotent) to those forming most of the differentiated cell types (pluripotent), and finally to stem cells that are totipotent.

Can these stem cells be used to replace a wide variety of damaged or diseased cells? Theoretically, yes, thus the great enthusiasm for stem cell research. In 1998 an important advance in this research was made by James Thompson at the University of Wisconsin-Madison. He and colleagues demonstrated that large numbers of human pluripotent stem cells could be obtained by growing late stage blastomeres in cell culture (essentially in a plastic dish with warm broth). These cells divided and remained undifferentiated for months, but maintained the developmental potential to differentiate into a wide variety of cell types from the three germ layers of the embryo including gut cells (endoderm); cartilage, bone, smooth muscle, and striated muscle (mesoderm); to neural epithelium, embryonic neurons, and epidermis (ectoderm).

Since then many sources of stem cells have been demonstrated including both embryonic (i.e. isolated from 5-7 day embryos and called embryonic stem cells, ES, which are pluripotent), fetal, adult, and teratocarcinomas, germ cell tumors. The hope is that one or more of these types of stem cells can be manipulated to cure human disease. In theory ES-derived brain cells could be used to treat neurodegenerative diseases such as Parkinson’s and Alzheimer’s, muscle cells produced to treat muscular dystrophies and heart disease, haematopoietic stem cells to treat leukaemias and AIDS. Results have been few and all in animal models of diseases or injuries. ES cells have formed stable heart grafts, made sheath cells in rats with myelin disease similar to multiple sclerosis, differentiated into supporting cells in spinal cord injuries and promoted motor function recovery, and enabled partial recovery of diabetic mice by forming insulin-producing cells.

To treat human diseases with stem cells, however, several formidable challenges must be overcome. Human stem cells, which grow slowly in cell culture, will be needed in large quantities; they must be able to differentiate in a controlled manner to form homogeneous populations (uncontrolled growth is a hallmark of cancer); and most importantly, these populations must be histocompatible (i.e. self versus not self) with the recipient (this latter problem is encountered in transplant patients who must take immunosuppressant drugs for life.). Experiments are under way to create such cells.

In spite of the tremendous potential of stem cells, their use, especially those derived from embryos (ES cells) and fetuses, have proven sensitive areas. This has arisen because certain segments of the public (e.g. pro-life movement) are uncomfortable with a technology that destroys human embryos to remove embryonic cells to create stem cell lines or with one that employs therapeutic cloning. The latter is uncomfortably close to reproductive cloning according to those opposed to embryonic stem cell research and thus violates the sanctity of life. One can counter these moral and ethical concerns by pointing out the potential therapies expected to derive from stem cell research. A future middle ground might be the use of one’s own adult stem cells or other sources like umbilical cord blood cells tailored to treat human diseases.

Despite these objections, which are reflected in President Bush’s recent veto of the Stem Cell Bill, many states are ignoring the President’s polarizing stance and establishing a vanguard of stem cell research.

California is at the forefront with its passage of Prop.71 establishing the California Institute of Regenerative Medicine (CIRM). CIRM will spend $3 billion over the next 10 years on stem cell research. The consensus among scientists is that the President’s veto has invigorated stem cell research like nothing thus far. Bush’s administration has misinterpreted and, in some cases, simply made up scientific findings for political purposes.

One may wonder if President Bush would have vetoed the Stem Cell Bill if stem cells were found to produce crude oil.

The author is a Professor of Biology at UCLA and member of the Southern California Federation of Scientists. This is one of a series from the SCFS written for Beachhead readers.

Posted: Sun - October 1, 2006 at 01:29 PM          

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