Embryonic stem cell research
Some scientists and physicians originally celebrated the isolation of human embryonic stem cells because of the pluripotent properties of these cells. A pluripotent stem cell is a cell that can develop into the cells and tissue of all three of the primary germ layers. In layman’s terms this is a cell that can develop into any cell of the body under the appropriate conditions. Embryonic stem cell proponents argued that these pluripotent cells held the key to curing a plethora of grievous human diseases that they incorrectly claimed adult stem cells could not. Without discussing the utility, or lack-thereof, of pluripotent stem cells for treating humans, I ask you to consider this simple question : why the continued insistence on obtaining new embryonic stem cells when we now have pluripotent stem cells called reprogrammed cells (iPS) and pluripotent stem cells isolated from testicular biopsies (SSC)?
If it were merely the pluripotent properties of the embryonic stem cells that were desired, as was once claimed, then iPS and SSC are acceptable pluripotent equivalents. If we want pluripotent stem cells to cure grievous human disease, then don’t we have a imperative to devote all of our efforts and funding to moving iPS and SSC cells into clinical trials? Why the tentative embrace of these acceptable pluripotent stem cells? Why do we still claim that we need embryonic stem cells, and, furthermore, that we need fresh embryonic stem cells?
Some scientists claim that they need embryonic stem cells as a reference for the properties of these other pluripotent stem cells. However, the test for pluripotency does not require embryonic stem cells at any step. The test for pluripotency, which is the quality control test used by companies that sell embryonic stem cells, requires a mouse, a needle, and a waiting period to see if cells injected into the mouse form teratomas (tumors containing cells from all three germ layers; see page 2 and 3 product specification pdf for MEL-1 and MEL-2 human embryonic stem cell lines).
Embryonic stem cells are not required for this test.
Some scientists then argue: we need embryonic stem cells as a comparator for these other cells as to how they behave in a petri dish. That is not the case. Embryonic stem cells become fetal type cells in the petri dish, not adult type cells. Ultimately we need adult cells to treat human disease. Scientists have already taught us that fetal cells don’t work to treat human diseases, because they have used human fetal tissue to treat patients with Parkinson’s and other neurological degenerative diseases with disastrous results. Many people read recently about the young Israeli boy who developed tumors after human fetal tissue treatment. We need to compare pluripotent stem cells such as iPS or SSC cells to adult nerve cells, or adult heart cells, or adult insulin-producing cells, not to embryonic or human fetal stem cells.
Yet some scientists insist that they need fresh embryonic stem cells. What can fresh embryonic stem cells provide that existing embryonic stem cells or reprogrammed cells (iPS) or spermatogonial stem cells (SSC) cannot? Access to human embryos, if nothing else. If we convince ourselves that we need fresh embryonic stem cells then we provide ourselves with access to fresh embryos.
Why might we want fresh embryos? We might, and I grant you subconsciously, want to reproductively clone after all. A very neat trick, to quote a writer for the journal Science, has been learned. Scientists take two embryos and fuse them together and get what is called a tetraploid embryo. This embryo can make the placenta but not the fetus. This has been done and published for embryonic stem cells and for reprogrammed adult stem cells from mice (Cell 2008 v133 page 250, Molecular Reproduction and Development 2005 v71 page 154). Unlike animals such as Dolly the sheep, produced using somatic cell nuclear transfer (SCNT), these tetraploid-produced mice have been ‘normal’ and are exact genetic copies of the pluripotent stem cell used to make them. I don’t know that scientists will really want to take the skin cell from John Doe, reprogram it, inject it into a tetraploid embryo, and make a clone of John Doe, but the point is they could. All we need is access to embryos.
Embryonic stem cell research scientists, funded by tax payers though the NIH, have been busy cloning. They have created babies born with two fathers, or two mothers and one father. Originally done using mice, there are now claims that this has been done with humans. Can you imagine the legal morasse of having three genetic parents, let alone the emotional trauma?
In summary, what can the need for fresh embryonic stem cells provide us that other pluripotent stem cells cannot? We don’t really need fresh embryonic stem cells as comparators for the adult pluripotent stem cells. The quality assurance tests don’t require or call for these. We don’t really want adult pluripotent stem cells to behave like embryonic stem cells in the petri dish. We want pluripotent cells to turn into adult cells in the petri dish. Why then do we insist on fresh embryonic stem cells? A need for fresh embryonic stem cells assures a source of embryos. What neat tricks could we do with embryos? Well, we could, if we wanted to, clone John Doe from a reprogrammed skin cell.
Why do embryonic stem cell scientists persist? As NATURE magazine recently opined, embryonic and other pluripotent stem cells have led to a plethora of patents, and there is a potential monetary gain to be made by these scientists for those patents. The money is made upfront (28 October 2010|VOL467|NATURE|1031). NATURE calls for the NIH to invest even more money in these uneffective embryonic stem cells for income generating purposes. That is not the mandate of the NIH. “NIH’s mission is to seek fundamental knowledge about the nature and behavior of living systems and the application of that knowledge to enhance health, lengthen life, and reduce the burdens of illness and disability” (http://www.nih.gov/about/mission.htm).