September 24, 2012 | David F. Coppedge

Why Exercise Builds Muscle

You have stem cells alongside your muscles that provide a ready pool of new muscle cells.

In special “niches” alongside muscle cells, muscle progenitor stem cells are at the ready.  When called upon, they can differentiate into new muscle cells.  This is the finding of a German team announcing it in a press release from the Max-Delbrück-Center for Molecular Medicine.

A signaling pathway called Notch ensures that the progenitor cells occupy their niche.  How, though, do they stay stem cells?  Notch has a second function: suppressing their differentiation until the called upon.  Consequently, as the headline implies, Notch ensures these stem cells are “at the right place at the right time.

Update  9/27/2012:  Accompanied by a photo of a strong bicep, Science Daily reported that there may be a way to make old muscles feel young again – by replenishing the pool of muscle precursor stem cells to their original state.

In other stem cell news:

  • Medical researchers are finding ways to use carbon nanotubes to coax adult stem cells into repairing damaged hearts. (PhysOrg)
  • Scientists at UC San Francisco are figuring out how chromatin modifications during development transform an embryo’s stem cells into heart tissue (Science Daily).
  • Programming of induced pluripotent stem cells (iPSC) is becoming more efficient. (PhysOrg)
  • Scientists are probing the epigenetic signatures of iPSCs to see if they retain signatures of their progenitors (PNAS).  This will undoubtedly become an active area of research in light of the ENCODE project findings.
  • “Stop worrying about human embryonic stem cells – they may not be needed any more,” an article on Gizmag shouted.  Adult stem cells are making them obsolete.

Speaking of human cells, the BBC News happily announced improvement to hearing in gerbils with use of human embryonic stem cells.  The rest of the article, though, indicated that the improvement was incomplete (45%), and then stressed that treatment on humans is unlikely.  “While there is excitement at the prospect of using stem cells to restore nerves in the ear this exact technique will not help the vast, vast majority of people with hearing loss,” the article said, adding, “There are also questions around the safety and ethics of stem cell treatments which would need to be addressed.”

If there is no need to use human embryonic stem cells, then stop.  Adult stem cells do not have any ethical problems.  Why use ESCs?  A human being is a continuum from zygote to adult.  If it is unthinkable to dissect unborn babies for medical research, then where is the dividing line between growing blastula and newborn?  The last remaining hangouts for ESC research need to cease and desist.  All they need to do can be done with adult stem cells and iPSCs.


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