Can Stem Cells be Used to Create People?
We’ve known about stem cells for half a century. They are
cells that not only make copies of themselves but can also become other types
of cells and tissues. This kind of biological feat is unique in science and has
the potential to cure disease. So why haven’t we seen more scientific success
and stem cell therapies? Where’s the beef?
Jewels Within Jewels
Like good wine, good science takes time to mature and have
its potential fully realized. This is exactly the case with stem cell science.
Take reproduction. Ten years ago, we
published that human sperm precursors, termed spermatogonial stem
cells, can create not only sperm, but also other organs in the body. We call
this “multipotency” or “pluripotency,” and it suggests that the adult human
testicle contains some nifty
and powerful stem cells. But neither human sperm nor other organs have
been made from these cells over the last decade.
What takes so long is trying to understand how stem cells
reproduce themselves or turn into other tissues. This all has to do with
getting to know where they live, termed their “niche,” what signals they get,
and how they respond to these signals. The science has progressed very quickly in
rodents and other mammals, but as you know, humans are…well…different. And
figuring out exactly how rodents and men differ has been the Achilles heel of
stem cell research.
A Shining Jewel
So, it was nice to see some serious progress in reproductive
stem cell science recently published by a large team of researchers. To simulate
a potential method of fertility preservation in boys receiving sterilizing
cancer treatment, the researchers took testicular spermatogonial stem cells
from prepubertal monkeys and then froze them. The monkeys then received
sterilizing chemotherapy and recovered. After the monkeys passed through
puberty, the researchers thawed the frozen stem cells and implanted them under
the skin of the monkeys from which they were taken. The testis tissue grafts
made mature sperm which was then harvested and used with IVF-ICSI to
make a healthy baby monkey. Years of preparation, four universities, one baby
monkey. That’s hard work.
Using stem cells to make sperm outside the testicle. Another
advance in stem cell science. Granted, the natural fertility of these monkeys
was not restored, monkeys are not humans, and the steps used aren’t that easy
to translate into the clinic. But this proof-of-concept study is a cellular
leap in right direction.
This article first appeared on Dr.