July 10, 2008
Adult Stem Cells Treat Muscular Dystrophy In Mice

Mice see themselves as more important than humans because we always develop cures for mice first.

By injecting purified stem cells isolated from adult skeletal muscle, researchers have shown they can restore healthy muscle and improve muscle function in mice with a form of muscular dystrophy. Those muscle-building stem cells were derived from a larger pool of so-called satellite cells that normally associate with mature muscle fibers and play a role in muscle growth and repair.

In addition to their contributions to mature muscle, the injected cells also replenished the pool of regenerative cells normally found in muscle. Those stem cells allowed the treated muscle to undergo subsequent rounds of injury repair, they found.

"Our work shows proof-of-concept that purified muscle stem cells can be used in therapy," said Amy Wagers of Harvard University, noting that in some cases the stem cells replaced more than 90 percent of the muscle fibers. Such an advance would require isolation of stem cells equivalent to those in the mouse from human muscle, something Wagers said her team is now working on.

Suppose this team manages to isolate muscle stem cells from human muscles and manages to get to replicate outside of the body. Add in a gene therapy to fix a mutation that causes muscular dystropy and it should be possible to inject these stem cells back into muscles and cause a gradual improvement in symptoms.

What I'd really like to see: Apply this approach to old folks who have old shriveled muscles. Imagine the development of a technique to separate the stem cells that have the most DNA damage from those stem cells that are still in good shape. Then grow up the stem cells that are still fairly young and inject them back into a person. The result might be a partial rejuvenation of aged muscles.

Share |      Randall Parker, 2008 July 10 11:14 PM  Biotech Stem Cells


Comments
Fly said at July 11, 2008 10:00 AM:

"Imagine the development of a technique to separate the stem cells that have the most DNA damage from those stem cells that are still in good shape. Then grow up the stem cells that are still fairly young and inject them back into a person."

Why mess around with an old, inferior stem cell line with lots of accumulated damage?

Develop healthy, young, exceptional genotype, pluripotent donor stem cell lines that would be immune compatible with matched patients. Monitor the cell culture for genetic quality and grow as many cells as desired to supply the aging populace. Differentiate the cells into the desired tissue specific stem cell types. Your tissue not only becomes younger but also better. It should also be much cheaper than fixing each person's own stem cells.

There is still the problem of getting rid of the old stem cells and getting the new stem cells into the vacant niches. And getting the new stem cells to repair and replace the old tissue. (Fixing muscular dystrophy may be easier than regenerating old muscle.)

Ray said at July 11, 2008 4:28 PM:

The potential for treating heart disease could be tremendous..

Kralizec said at July 11, 2008 9:34 PM:

Fly said,

Your tissue not only becomes younger but also better.

My tissue becomes better for whom, and from the standpoint of what end? Here's a modest proposal: I'll use my stem cells, while you, on the other hand, will use my stem cells. I'll slowly rejuvenate, while you'll slowly become my clone. Everybody wins!

Dave said at July 12, 2008 8:45 AM:

Well said Kralizec.
I have commented similar regard 'improving' peoples children with genetic engineering. If its to remove a severe disability then yes, if its to alter things such as behaviour by altering the workings of the brain then its an attack on that persons very identity. Its like a rape, genetically implanting your own prefered genetic profile inplace of someone elses. Fair enough the person might agree to the 'treatement' but do they really understand the implications of what is going on?

Another point, once the procedure becomes commonplace wont it basically ruin police genetic profiling at crime scenes? if many people share common stem cell lines?

Fly said at July 12, 2008 10:46 AM:

Kralizec: "I'll slowly rejuvenate, while you'll slowly become my clone."

Only in the biological sense of shared DNA. Not in the sense of sharing memories, experiences, connection, or identity.

You can't become a different person. You can only change the person you are. I'm not the person I was at age four. I'm not the person I was at age 24. If I suffer a massive stroke I won't be the same person. However the interior "me" continues.

I try to improve "me". I exercise and eat a nutritious diet to improve "me". I study certain topics because I want that knowledge to become part of "me". When drugs become available that improve memory or intelligence, I will take them. I'd happily accept stem cell transplants that increased my intelligence or athletic ability.

Good traits are unfairly distributed. I'm 6'2", a decent athlete, and have an IQ over 160. I could have been born retarded or crippled. Whether a genius or retarded there would be a "me" looking out of my eyes and feeling my joys and my pains. I believe that the retarded, crippled "me" should have had the chance to experience being smart and athletic. The world would also benefit more from the genius "me" than the retarded "me". Such transplants would be good for the individual and good for society.

Randall Parker said at July 12, 2008 11:27 AM:

Fly,

Any starting cell could have genetic damage (actually will have genetic damage). We need ways to sort thru an assortment of potential starter cells (taken from different places in the body) to choose some that do not have any damage that matters for the purpose(s) in mind.

As for starting with pluripotent cells: Riskier and harder in some respects. If you start with stem cells that already want to become muscle cells they are closer to what you want to accomplish.

As for those adult stem cells being worn out: We will be able to identify cells that have little damage, fix a few genes with gene therapy, then build back up some telomere caps, and get a pretty good cell line.

Fly said at July 12, 2008 1:39 PM:

Randall: "Any starting cell could have genetic damage"

Yes. However, the germ cell line is well protected. Spermatogonial stem cells have extra DNA protective mechanisms and are usually quiescent with relatively few cell divisions. By fully sequencing cells from several tissue samples taken from the donor the original donor genome could be determined. The spermatogonial stem cells could then be used as a starting point with minor damage repaired by genetic engineering. The production stem cultures would be monitored against the donor reference genome and cultures that developed significant deviation would be discarded. If desired there could be less variation than occurs during normal embryonic development.

Over time, the stem cell line would be improved with well tested genetic modifications.

This would be far easier to do with mass production stem cell lines than with a person's own unique stem cells.

Randall: "As for starting with pluripotent cells: Riskier and harder in some respects. If you start with stem cells that already want to become muscle cells they are closer to what you want to accomplish."

Yes, if I needed a stem cell transplant today tissue specific stem cells and progenitor cells would be my best bet.

Pluripotent embryonic stem cells will fill vacant niches in adult tissues. Usually the local niche environment programs the ESC so that it becomes a fully functional tissue specific stem cell. (Proven by using ESC's cell to repopulate mouse testical tissue which could then produce sperm.) Occasionally the niche reprogramming fails and a tetranoma forms.

There are pluripotent adult bone marrow cells. I believe they are safe for transplants as I've never read of a bone marrow transplant causing a tetranoma. These cells don't have the full regenerative capacity of ESC's. (Repopulating mouse testis with BM stem cells caused tissue generation but didn't restore sperm production.)

By the time rejuvenation by stem cell tranplants is a practical procedure I expect scientists will be able to fully control cell differentiation. At that point it would be simpler to have one quality source of immune compatible pluripotent stem cells which would be used to produce cells of the desired type.

Reality Czech said at July 16, 2008 7:32 AM:
This would be far easier to do with mass production stem cell lines than with a person's own unique stem cells.
And huge masses of people would, over time, lose their individual resistances and become susceptible to the same strains of disease.

Just because something is easier does not mean it is desirable.

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