Tuesday’s Part 1 related the discovery of stem cells and recognition of their life-saving potential. Today’s Part 2 tells how political restrictions, rather than stifling research, have instead caused a burst of productive creative work.
As described in Part 1 of this post, stem cells come in a wide variety of types. The most flexible stem cells of all are those are the totipotent cells found in human embryos. The quest for healing damaged or diseased adults thus ran headlong into the desire to protect human life in its earliest stages.
Several developments created tremendous momentum for political restrictions on stem cell research:
– 1973: The Roe v. Wade Supreme Court decision legalizing abortion in the U.S.
– 1978: The birth of Louise Joy Brown, the first “test-tube baby”
– 1981: The isolation of stem cells from mouse embryos by two research groups
– 1996: Dolly the Sheep was born, the first mammal cloned from an adult cell
– 1998: Stem cells were extracted from fetuses whose mothers had elected abortion, and the cells were successfully maintained in a cell culture
These results made headlines and raised a storm of controversy:
– Religious Concerns: Deriving stem cells from human embryos could encourage the creation of embryos purely to supply research needs; taking cells from those embryos would in most cases destroy the embryo, amounting to murder of a human life;
– Ethical Concerns: The destruction of human embryos and the possibility of human cloning raise moral questions concerning the sanctity of life and the potential misuse of these technologies.
These concerns could not be easily dismissed. Religious faith is a personal and passionate commitment whose sense of right and wrong will not be swayed by economic or social arguments. Ethical systems are socially dependent and they present dilemmas (such as having to place monetary value on human lives when allocating government resources) that cannot be resolved within the ethical system itself. Thus these deeply held and inherently unresolvable questions migrated into the political world.
Political Restrictions on Stem Cells
U.S. legal restrictions on research using human embryos were imposed by a wide-ranging and rapidly changing mosaic of laws and government regulations beginning in 1995. In parallel, many other countries adopted similar restrictions while still other countries did not.
Response of the Research Community
Some researchers continued to work on embryonic stem cells within the new regulations. This was a difficult path to follow, since rules could and did change without warning from year to year. Others sought private rather than government funding for their work, since privately-funded work was much less controlled.
However, the most interesting result of the government restrictions was to unleash a great burst of creativity among stem cell research scientists. After all, plenty of work had been done to identify the tremendous gains in medical treatment that might result; stem cells of various types were being found in tiny concentrations all over the human body; and since every cell in the human body had arisen from a stem cell, perhaps it could be persuaded to step back in time and become a stem cell once again.
Thus by closing off the “easy” approach, the most obvious means to obtain and cultivate stem cells, scientists were inspired to try a much wider range of ideas than they might have otherwise. This work led to a number of impressive advances in the field, both in the creation of highly adaptable stem cells without disturbing any embryos, and in applying the resulting cells to treat various diseases and injuries.
Recent Results NOT Using Embryo Tissue
– 2005-2006: Cord Cells. Following birth, the placenta and severed umbilical cord have no use and are traditionally incinerated or buried. Researchers in the U.K. and the U.S. found that multipotent (highly differentiable) stem cells could be derived from “cord blood” that was extracted before disposal of the placenta. The stem cells were successfully used to cure induced diabetes in mice, suggesting their potential to treat human diabetes.
– 2005: Nerve Regeneration. Human neural stem cells from adults were shown to repair damaged spinal nerves when injected into paralyzed rats, again as a step toward developing nerve-restoring treatments for humans.
– 2006: Making Liver Cells. Using umbilical stem cells, scientists created clumps of liver cells. One long term goal is to develop a fully functioning organ for replacement in humans. However, even at this early stage the liver cells can be used to test experimental drugs for safety before embarking on potentially risky human tests.
– 2007: Amniotic Stem Cells. Researchers extracted amniotic fluid, which cushions the baby in the womb, from pregnant women volunteers, without harming mother or fetus. From the fluid, they extracted stem cells which they were able to maintain in a cell culture, and which they were able to differentiate into brain, liver and bone cell types. [See news story or full article]
– 2007: Stem Cells from Skin, Mouse Version. Three independent research groups re-programmed normal skin cells from mice to produce stem cells that behave like embryonic stem cells. This set off a race to see who could achieve a similar result in humans.
– 2007: Stem Cells from Skin, Human Version. The race was simultaneously won just a few months later by researchers in the U.S. and Japan, who showed that by treating human skin cells with four specific proteins (“transcription factors“) the skin cells turned into pluripotent stem cells showing the essential characteristics of embryonic stem cells.
– 2008: Cartilage Replacement. Bone marrow cells were taken from a volunteer suffering from knee degeneration. Stem cells were isolated, cultured and then injected into the same person’s knee, where they grew into new cartilage. The patient had reduced pain and improved joint motion.
– 2008: Stem Cells from Hair. Human hair was shown to be a particularly rich source of induced embryo-like stem cells.
– 2012: Human Diabetes Treatment. The blood of diabetic patients was circulated through a device that added small amounts of umbilical stem cells. The stem cells appeared to “educate” the beta cells in the pancreas, causing increased production of insulin and reduced need for insulin therapy.
– 2013: Lab Grown Meat. Stem cells isolated from adult cows were cultivated to produce artificial beef muscle. The lab grown meat was chopped, mixed with fat, made into hamburger patties, cooked and eaten.
– 2014: Easy Creation of Stem Cells. Research teams in the U.S. and Japan showed that adult cells can be re-programmed into stem cells by treating the cells with a 30-minute acid bath – enough to stress them, but not enough to kill them. These STAP (Stimulus-Triggered Acquisition of Pluripotency) cells were first produced from mouse cells, then a week later from human cells.
The Golden Age A-Dawning
I won’t call this rosy forecast “speculation” because I think it’s much more real than that.
Today, it’s clear that you can create stem cells from a wide variety of human cell types, by treating them so that they de-differentiate, approaching their original embryonic state. In this flexible form they can be persuaded to create new tissue to repair nerves, organs, and tissues of all kinds. As tissue scaffolds are developed, we can create more and more complex structures for implantation, hopefully leading to full organ replacement in the foreseeable future. Moreover, these medical treatments can probably be achieved using the patient’s own cells, reducing the risk of transplant rejection as well as avoiding the ethical issues that arise when working with embryos.
Stem cells can potentially replace almost any tissue or organ. Which treatments do you think would have the most social and medical value?
Drawing Credit: aidaivars, on openclipart.org