Early thinking about embryonic development and differentiation tended to view development as a matter of going from a cell with all kinds of genes on to progeny cells that have a host of these genes turned off and only a small subset of the original cache of genes turned on. If those genes were muscle-specific genes, then the cell became a muscle cell, and if they were nervous system-specific genes, then the cell became a neuron or glial cell.
Several different experiments questioned this conventional wisdom, and in particular, microarray experiments that allowed researchers to examine the gene expression pattern of the entire genome at a time showed that this was not the case. Instead of a host of genes being on in embryonic cells, a particular subset of genes were on, and as the embryo grew and aged, some cells shut one set of genes and turned on others, while a different group of cells turn off yet another set of genes and turned on a completely distinct set of genes.
With embryonic stem (ES) cells, the gene expression pattern depended on the culture system. Therefore, it was always difficult to interpret the results of such experiments.
This problem has now been largely solved, since Austin Smith at the Welcome Trust Stem Cell Institute in Cambridge (UK) has developed a culture system to standardize these conditions for embryonic stem cells. By employing this new methods, Hendrik Marks at the Nijmegen Centre for Molecular Sciences of the Radboud University Nijmegen, the Netherlands, showed that the ground state genes expression of embryonic stem cells is surprising.
There are only a few genes that are activated in embryonic stem cells. However, other genes that are not activated are not actively repressed. Instead that are ready to go and are in a kind of “on hold” status. The protooncogene (a gene that drives cells to divide and grow) c-myc, was thought to be essential for embryonic stem cell growth and division is hardly detectable.
This provides added clues as to how to keep ES cells as ES cells or how to drive them to differentiate into one cell type or another.
According to Marks, formerly researchers thought that “ES cells would subsequently differentiate by turning genes off that are not relevant for a specific specialization, to finally reach the correct combination of active genes for a particular specialization. We now see the opposite: genes are selectively turned on.”
The proteins that bind to DNA and direct gene expression, however, the so-called “epigenome,” are already prepared for action. Thus ES cells are poised to become one thing or another, and the environmental cues that they receive coaxe them into one differentiation pathway or another.
This finding also calls into question the work of Ronald Bailey who thinks that ES cell research is not immoral for the following reason: “So what about the claims that incipient therapies based on human embryonic stem cell research are immoral? That brings us to the question of whether the embryos from which stem cells are derived are persons. The answer: Only if every cell in your body is also a person.” Bailey continues: “Each skin cell, each neuron, each liver cell is potentially a person. All that’s lacking is the will and the application of the appropriate technology. Cloning technology like that which famously produced the Scottish sheep Dolly in 1997 could be applied to each of your cells to potentially produce babies.”
To support his claim, he quotes the Australian bioethicist Julian Savulescu from the 1999 Journal of Medical Ethics: “What happens when a skin cell turns into a totipotent stem cell [a cell capable of developing into a complete organism] is that a few of its genetic switches are turned on and others turned off. To say it doesn’t have the potential to be a human being until its nucleus is placed in the egg cytoplasm [i.e., cloning] is like saying my car does not have the potential to get me from Melbourne to Sydney unless the key is turned in the ignition.”
Savulescu is simply wrong. Many experiments have called this account of development into question, and now Marks’ experiments have placed the nail in the coffin. Furthermore, his analogy that Ta body cell does not have the “potential to be a human being until its nucleus is placed in the egg cytoplasm [i.e., cloning] is like saying my car does not have the potential to get me from Melbourne to Sydney unless the key is turned in the ignition,” is also flawed. The cell of our body are not undergoing development. Development is a process we know a great deal about, and our cells are not undergoing development. Embryos are undergoing development and they are unique human persons. Embryos give rise to our bodies. We are human persons and we began to assume our adult form when the embryo initiated development (i.e., at the termination of fertilization). Development also involves the hierarchical activation and inactivation of various genes. This is not a process that occurs in adult human bodies. Embryos are the beginning of a human person and they are human persons. Savulescu’s analogy would be more accurate if we say that the engine without the car would be unable to get him to Sydney, Australia: It needs a frame, tires and so on. They also all need to be properly connected and integrated with each other to work. His analogy is simply inaccurate and bogus.
Likewise, what Bailey calls “the application of the appropriate technology,” during a cloning experiment is the wholesale creation of a new human being. To say that this new human being is one of your cells is to woefully misunderstand the biological nature has happened during cloning. An egg from a female has its nucleus removed and is fused with a cell from another part of your body. After appropriate manipulation, the egg starts to divide and undergo embryonic development. Even this cell has the same genetic information as the cell from your body, it will not development into an exact duplicate of yourself. There are too many random events that occur during development that cause the individual to become a unique person who may have some similarities with their genetic parent, but will not resemble them completely. Cloning is not a minor manipulation – it is the creation of a new life, and this is a process that our cells are not going through; they are not developing. Therefore, they are not “potential persons.”
Secondly, the embryo is not a potential person, it is a very young human person. It is a potential adult person, but it is a person nonetheless.