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Adult vs. Embryonic Stem Cells


Making the distinction

 

           It is unfortunate, and I believe deliberate, that the biotech industry, the media, and many lawmakers do not distinguish between embryonic and adult stem cells.  They most often refer simply to stem cell research, removing the moral implications of the word “embryonic.”  There is a difference.  Embryonic stem cells (ESC) comes from a human embryo that, as of this writing, has to be destroyed to retrieve those cells.  The adult stem cell (ASC) comes from tissue other than embryonic.  ASCs are found in adults, but also in umbilical cords, placentas, and even lost baby teeth.1

 

            Many stem cell research advocates insist that ESCs hold the most promise for curing disease because they are pluripotent, which means they can become most or all of the differentiated cells in the human body, while ASCs cannot.  They insist that they need federal funding, your tax dollars, because cures are just around the corner.  Unfortunately cures from ESCs are not just around the corner; they are not even close.  David Prentice, in his book, Stem Cells and Cloning, writes, “Thus far, there is only scant evidence that embryonic stem cells can actually work in the body to successfully treat degenerative diseases.  There are no current treatments available for human patients.”2  What many researchers, lawmakers, and, especially, the media will not talk about are all the ESC pitfalls that need to be overcome before ESCs can become a viable, scientific treatment.

 

 

Are treatments from ECSs feasible?

 

            Setting aside the ethical implications of destroying human life to harvest ESCs, one of the major obstacles is that ESCs may be too undifferentiated.  Stem cells take cues from surrounding cells and differentiate accordingly.  ESCs belong in an embryo; they are meant for rapid generation of a human being, not for repairing damaged tissues.  When they are removed from the embryo, they tend to get confused.  Prentice explains, “…when taken out of that normal environment and placed into a lab culture dish, the ESCs do not behave as expected….  The cells usually form a mixture of several different specialized cell types, along with some cells that just continue to grow.  And it is these cells that continue to grow and divide that are potentially another big problem—if injected into a patient, they might form a tumor.”3  In animal studies, injected ESCs tend to form tumors and a mixture of cell types, not just the ones that are needed.  In a study with rats, a little over half of them died from tumors resulting from injecting ESCs into their brains.4  The fact that ESCs tend to form tumors is a huge problem to overcome.  It requires the knowledge of how and which genes are turned on and off, at the right time, to produce the desired cell type.  Researchers are far from understanding those processes.

 

            Even if scientists could resove the tumor problem, ESCs do not prove to be that effective at treating disease. In mice and rats, researchers had modest success at treating Parkinson’s disease, spinal cord injury, and diabetes.  In one study with diabetic mice, the ESCs could not be induced to produce enough insulin to prevent death.5

 

The major issue with ECSs is rejection of the cells by the patient.  A treatment with stem cells would be exactly like receiving an organ transplant.  A compatible genetic match in organ donation is required, otherwise the organ is rejected by the patient’s immune system, and the transplantation will not work. Even with a suitable match, patients have to take strong drugs that suppress their immune response to keep the body from rejecting the organ.  Stem cells are no different.  They are cells that come from another human being, an embryo, with a different genetic make-up than the patient.

 

Currently, lawmakers like Senator Bill Frist (R-TN) and embryonic stem cell researchers want to use the approximately 400,000 “leftover” IVF embryos, sitting in American deep freezes, to harvest stem cells.  Michael West of Advanced Cell Technologies estimates that, at a minimum, “we would need a library of a hundred thousand cells in the future to be able to ensure that every patient in need …could have even a close match.”6  Even if all those IVF couples donated all of the 400,000 frozen embryos, not all would result in viable stem cell lines.  Prentice estimates that only 1 in 10 embryos would create a viable stem cell line.7  That means that only 40,000 stem cell lines would result from all of the leftover IVF embryos, less than half of what West estimates is needed to provide even a minimal stem cell library. 

 

 

The slippery slope to cloning

 

In reality, using leftover IVF embryos for embryonic stem cell research is a red herring.  Once we get comfortable with destroying existing human life to harvest desirable biological material, we can then start creating human life for that same purpose.  What ESC researchers really want is federal funding to engage in therapeutic cloning or somatic cell nuclear transfer (SCNT).  In SCNT, the donated eggs, normally used in IVF, would instead be emptied of their donor’s DNA, and the DNA from a patient’s skin or muscle cell would be injected, creating a “delayed twin” of that patient, a clone. (For more in-depth information on SCNT, see the Cloning topic.)  This clone (as much a human being as the original) would be allowed to develop to a certain stage and then destroyed to harvest ESCs that researchers say will be a genetic match for the original patient.

 

No need to wait for the donation of left-over IVF embryos, cloning researchers will create a customized twin just for you, providing ESCs that will not be rejected.  Because cloning or SCNT is not banned in the United States, companies like Advance Cell Technologies are already cloning humans and trying to harvest their embryonic stem cells. But private investment is hard to find for ethically-suspect research with no real evidence that cures will result any time soon.  Such biotech companies want federally funded, state-sponsored cloning, and the first step is to fund embryonic stem cell research using all of those left-over IVF embryos.  Michael Cook, editor of BioEdge, an email newsletter on bioethics, warns us about embryonic stem cell research: “The appetite of stem cell scientists for tinkering with human life is insatiable.  It must be resisted.”8

 

Adult stem cells: the ethical alternative

 

            While ESCs are fraught with ethical and technical problems, adult stem cells are showing amazing promise minus the moral dilemmas.  First, ASCs are harvested without destroying human life and appear to exist in many kinds of tissues.  ASCs have been found in blood, bone marrow, brain, fat, skeletal muscle, esophagus, stomach, pancreas, liver, hair follicles, and nasal tissues, among others.9

 

            The major objection to ASCs was that researchers believed they were not pluirpotent like ESCs, but that seems not to be the case.  Many studies are showing that ASCs from adult bone marrow and brain tissue can form virtually any body tissue.  Prentice writes, “The adult stems cells seem to look at what tissue they’re in and simply become that tissue type.”10  And it may be because ASCs are already programmed to be the body’s damage repair and regenerative cells that they do not have problems with tumor generation, as do ESCs.

 

            With ESCs, there is the problem of having a close enough match so that the patient’s immune system will not reject the stem cells.  Because ASCs come from the patient, the problem of rejection by the immune system is eliminated, without having to create and destroy more embryos or clone the patient to get a match.

 

            The most compelling reason to further explore ASCs is that they show great promise in curing disease.  In fact, ASCs are already showing the ability to cure or ameliorate many diseases in animal and human studies.  Wesley J. Smith, lawyer and author, complied a list of advances in ASC research in his book, Consumer’s Guide to the Brave New World.  An excerpt:

 

·        Five Parkinson’s disease patients…experienced significant improvement in their ability to perform daily activities.  Three of the patients regained their sense of taste and smell.

·        Adult neural stem cells grafted into the brains of newborn mice resulted in “extensive myelin production,” which could lead scientists to a future ASC treatment for multiple sclerosis.

·        Stem cells from bone marrow have been found to repair damaged muscle…the results are promising for a future use of ASCs in the treatment of neuromuscular diseases such as muscular dystrophy.

·        Scientists in Canada have turned adult skin cells into the building blocks of brain cells….

·        Bone marrow stem cells were induced in vitro to differentiate into islet cells—i.e., pancreatic cells that produce insulin.  The researchers claimed their findings “show that human bone marrow-derived stem cells may serve as a potential source for cell therapy in the treatment of type 1 diabetes.”  Meanwhile, juvenile diabetes was cured in mice using human spleen cells.11

 

Prentice reports that, “Using bone marrow and muscle stem cells, as well as umbilical cord stem cells, scientists have repaired damage in experimental animals due to heart attack, stroke, liver disease, diabetes, Parkinson’s disease, and spinal cord injury.”12

 

            The point is that ASCs are much closer to providing cures than ESCs, without the need for cloning or leftover IVF embryos.  So, why are so many scientists and reporters confusing the issue?  Why are they pushing for the creation and destruction of embryos for embryonic stem cells?  I believe that, once we no longer recognized the sanctity of human life from its beginning, we entered a culture where human embryos have become, not a precious gift, but a commodity that many researchers cannot wait to exploit, regardless of whether cures will result or not.  They want to divert precious research dollars toward the manipulation of human life, not toward research that actually shows real promise.  It is crucial that, as a society, we remain informed.  There is a distinction between adult and embryonic stem cells.  There are alternatives to the “creation and destruction of human life” to cure devastating disease.

 

 

© 2005 MaryMeetsDolly.com.  All rights are reserved.

 



1 Wesley J. Smith, Consumer’s Guide to the Brave New World, San Francisco, Encounter Books, 2004, pp. 6,7

2 David A. Prentice, Stem Cells and Cloning, Pearson Education, Inc., San Francisco, 2003, p. 10

3 Ibid., p. 9

4 Ibid., p. 10

5 Ibid.

6 Michael D. West, The Immortal Cell: One Scientist’s Quest to Solve the Mystery of Aging, Doubleday, 2003, p. 192

7 David Prentice, Stem Cells and Cloning, p. 9

8 Michael Cook, "Promise of miracles a false one," The Australian, May 23, 2005

9 Wesley J. Smith, Consumer’s Guide to the Brave New World, pp. 6,7

10 David Prentice, Stem Cells and Cloning, pp. 11, 18

11 Wesley J. Smith, Consumer’s Guide to the Brave New World, pp 159-160

12 David Prentice, Stem Cells and Cloning, p. 15