I’ve previously talked up the promise of gene therapy, especially in my posts “Clearing the Ghettos” and “Better Behavior Through Chemistry.” Gene therapy in general uses retroviruses that infect a person’s cells and change their DNA — hopefully to something better! But stem cells provide another avenue for the betterment of man…
Gene Expression: Metamorphosis
In discussions of nature vs. nurture a common assumption is that if it is in the genes then we can’t fix it. Or we can only change it by eugenics or bioengineering babies. I wish to suggest a different approach.
The following links provide background:
- Bioengineered Stem Cells Rejuvenate Muscles In Mice
- Stem Cell Review Series: Aging of the skeletal muscle stem cell niche
- Stem Cell Review Series: Regulating highly potent stem cells in aging: environmental influences on plasticity
- Autism-spectrum disorder reversed in mice
Essentially all tissues turn-over with time. Some tissues such as the gut lining are replaced every three days, other tissues such as bone and fat are replaced over decades. (Proven by tracking green florescent cell markers over time.) In the adult brain, neurons are seldom replaced but new neurons are continually produced and some repair occurs. I believe it will eventually be shown that all tissues contain stem cells that have the potential to rebuild that tissue. Pluripotent hematopoietic stem cells from bone marrow can, with the proper differentiation signals, produce every cell type in the body. Stem cells make up less than 1/10,000 of the cells in tissue. (Adipose tissue may have a higher frequency of stem cells. Satellite cells in muscle tissue may also be relatively common. I welcome correction if I’m wrong about other tissue types.) If scientists could replace that small stem cell fraction and increase the rate of cell turn-over then eventually most of the body cells would become the new type.
Each day a few hundred stem cells in the bone marrow mobilize, circulate in the blood, and either migrate to specific tissue sites, resettle into other bone marrow niches, or die. (This has been observed in mice by florescent labeling of transplanted stem cells.) By injecting a few thousand stem cells each day, a person’s original bone marrow stem cells could be gradually replaced. The process would be accelerated if stem cell mobilizing drugs were used. Or if the old stem cells were selectively targeted for destruction.
By itself, transplants using young stem cells don’t significantly repair damage or rejuvenate tissue. Proper signals are needed to mobilize the stem cells to the desired site, to cause the stem cells to divide, to cause the stem cells to differentiate into the right cells, and to cause those cells to integrate into the existing tissue. This is what happens when our body successfully heals a wound. For rejuvenation scientists also need to kill senescent cells and remodel the extracellular matrix. This isn’t easy but significant progress is being made.
Imagine that in ten years the technology existed to completely replace the stem cells in one mouse with stem cells from a different mouse. And that the tissue turn-over rate was increased so that most of the mouse body cells derived from the second mouse. How much remodeling of body and brain would occur? Some body structures would have been largely fixed during development but much would change due to the new cell DNA. Potentially, a sick or dull mouse could be made healthy or smart by such a full body stem cell makeover.
The great failure of the Progressives is that they were not able to make people better. They wanted to, and tried, but failed. The environmental manipulations they worked through — from more liberal schools, more liberal government institutions, and more liberal tax welfare policies — changed the incentives of people, but did not change human nature. The did not reform the criminals, and the progressive movement in its entirety probably ended up increasing crime.
Imagine if one day we can give a criminal (a murderer, a rapist, a sexual predator, a thug) gene or stem-cell therapy, to make them a better person. Imagine if we can use these techniques to help them see the errors of their ways, they will chose better options.
That’s a future worth creating.