September 11, 2011 | David F. Coppedge

Are Embryonic Stem Cells Obsolete?

Adult stem cells can apparently do everything embryonic stem cells can – and they are moving regenerative medicine forward faster, with more results.  Since the use of human embryos for research is ethically repugnant to many people, what motivations remain to continue the practice?  Here is a rapid-fire list of stem cell news this month:

  1. Are embryonic and adult stem cells equal?:  “Ever since human induced pluripotent stem cells were first derived in 2007, scientists have wondered whether they were functionally equivalent to embryonic stem cells, which are sourced in early-stage embryos.”  The answer is: yes, they are.  Science Daily reported that a study published today at the University of Wisconsin-Madison showed that the protein products produced by the two sources of stem cells are 99% identical.  Repeated runs show the statistics are extremely robust; in fact, some of the products from embryonic stem cells more closely resembled those from induced pluripotent stem cells than they did from other embryonics, so any differences in that last 1% may be statistical noise.
  2. Endless supply:  Understanding the self-renewal process of adult stem cells was explained on PhysOrg.  “The promise of stem cells is two-fold: On one hand, they can differentiate into all the specialised cells in the tissues of the body and thereby guarantee tissue repair; on the other hand, they can self-renew and form new stem cells ensuring -at least in theory- an inexhaustible supply of cells in demand.”  The new finding is that “Scientists from the Friedrich Miescher Institute for Biomedical Research (FMI) are the first to establish a direct link between a conserved stem cell factor and the cell cycle regulation in adult stem cells.”
  3. Exercise:  Stem cell science is not just academic or about invalids.  You can steer your internal stem cells, PhysOrg said.  Research at McMaster University showed, “Exercise boosts health by influencing stem cells to become bone, not fat, researchers find.”
  4. Fountain of youth:  “Adult stem cells can be rejuvenated, simply by growing them in a youthful environment – at least in mice,” Linda Geddes reported on New Scientist.  “The discovery boosts hopes that adult human stem cells could be used to grow replacement tissue without the need for embryonic stem cells or complicated cell reprogramming.”
  5. Colon therapy:  Stem cells from the colon have been grown in a lab plate for the first time, reported Medical Xpress.  “This achievement opens up an exciting new area of research with the potential to bring about a huge breakthrough in regenerative medicine,” one of the researchers said, his thoughts turning to treatments for colon cancer and Crohn’s disease.
  6. Blood therapy assisted by sound:  Transplantation of hematopoietic stem cells is already an effective treatment for malignant blood diseases, Medical Xpress reported, but now researchers in Sweden have found the process can be enhanced using ultrasound.
  7. Neck vertebra restored:  In another exciting breakthrough, scientists at UC Davis found that stem cells can be used to re-grow damaged cervical disks between vertebrae in the neck.  Story on Medical Xpress.
  8. Preventing premature births:  An artificial amniotic membrane with human amniotic stem cells shows promise for helping women keep preemies at risk, said Medical Xpress.  “For pregnant women with a ruptured fetal membrane, the artificial AM can be used to replace the damaged area to allow her to carry the baby to term.”
  9. Tooth regeneration:  Two pockets of stem cells were identified in certain teeth of mice that grow continuously.  In PLoS ONE, researchers described how “the progeny move out of the stem cell niche and migrate toward the distal tip of the tooth.” Understanding the role of stem cells in teeth might help humans regrow damaged teeth, but first, the science.  “These studies point to miRNAs [micro-RNAs] that likely play a role in the renewal and differentiation of adult stem cells during stem cell-fueled incisor growth,” the team of California scientists reported.        
  10. Cell fate:  Understanding what causes stem cells to “decide” what tissue to become was discussed on PhysOrg.  Communication between cells is critical.  “When it comes to speaking out, cells wait their turn,” the headline reads.  A researcher at CalTech found a “mechanism that allows cells to switch from sender to receiver mode or vice versa, inhibiting their own signals while allowing them to receive information from other cells — controlling their development like a well-run business meeting.”
  11. Regulating the adult stem cell pool:  Another article on PhysOrg discussed the tight regulation of adult stem cells so that they do not develop into cancer.  “A study from Children’s Hospital Boston finds that a network of genes crucial in embryonic development may also keep tight [sic] rein on adult stem cells in the lung and other tissues, particularly as these cells rally to repair tissue damage.”
  12. Simplified freshnessScience Daily told how researchers at RIKEN have reduced down to one the number of factors required to keep induced pluripotent stem cell populations fresh.  “Key Protein Reveals Secret of Stem Cell Pluripotency,” the headline read.

So what are embryonic stem cells good for?  Medical Xpress talked about research to repair damaged retinas from bandages infused with retinal cells derived from embryonic stem cells, but it was not clear that adult stem cells or induced pluripotent stem cells (iPSC) couldn’t work just as well.  In another article on PhysOrg, researchers were said to have overcome a major obstacle for purifying stem cells; they worked on both embryonic and iPSCs, but again, it was not clear that embryonic stem cells offered any advantage. 

The BBC News reported on the first clinical trials of fetal stem cells injected to repair brain damage from stroke, but the only news so far is that the doctors have not noticed any ill effects (yet) – not that brain tissue is getting healed.  A veiled apology was apparent in the article: “Critics object as brain cells from a foetus were originally used to create the cell treatment,” reporter Pallab Ghosh wrote.  “Michael Hunt, Chief Executive Officer of the company that produced the stem cells, Renuron, said that the technology used to grow the cells is such that no further foetal tissue will be required.

As the first article quoted above stated, “the newer form, called IPS cells, have two advantages. They face less ethical constraint, as they do not require embryos. And they could be more useful in cell replacement therapies: growing them from the patient’s own cells would avoid immune rejection.”  Now that adult stem cells and IPS cells have taken the lead on actual treatments in the booming field of regenerative medicine, it seems the burden is now on embryonic stem cell researchers to explain why they need to tinker with human embryos at all.

The wonderful news from adult stem cells discussed above needs to be seen against a disturbing historical backdrop.  Not so many years ago, not long after 9/11, the scientific institutions were screaming for federal funding for embryonic stem cells, ridiculing anybody who stood in their way (like President George Bush) as ignorant obstructionists who would leave America in the dust of other nations in the quest for a Nobel Prize, all because of a few questionable worries about ethics.  Tear-jerking commercials tugged on the heartstrings of Americans, pleading for access to human embryos so that Christopher Reeve might walk again (he didn’t), or Michael J. Fox might be cured of Parkinson’s Disease.  My, how times have changed.  The Hwang scandal, followed by the discovery of iPSCs, and the rapid growth of adult stem cell therapy, has made stem cell research a new ball game.

But the game isn’t over.  Researchers are still using taxpayer dollars to experiment on human embryos, and the current administration and the courts are still giving them all they want.  Citizens need to realize they have a responsibility to keep scientists under control.  Scientists need a certain amount of autonomy, since one never knows where a fundamental breakthrough will emerge, but no scientist should get carte blanche to do anything.  The history of the 20th century showed that horrible atrocities can be committed under the guise of scientific research.  Ethics is to publicly-funded science what a bridle is to a horse.  A good workhorse needs its head, if it is well-trained and already knows where the owner wants it to go, but sometimes the rider (an informed public) needs to yank the reins when the horse gets ornery.  This would be a good time to yank the public funding from the snorting, out-of-control stem cell science snobs.  Bad Charlie!

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