Answering All Of Your Stem Cell Questions: Rapid Fire
For this article, I crowdsourced a bunch of questions around stem cells and then attempted to answer them in as simple as possible. No jargon, no fluff, just explaining topics as simply as possible.
I got quite a few questions so without further ado, let’s get into it!
1. What are stem cells? — Aarna, Frank, Michela
My favourite and simplest way to describe stem cells is by introducing the two criteria they need to fulfill.
❏ They must be able to self-renew/make copies of themselves indefinitely.
❏ They must be able to differentiate.
Being able to differentiate means that stem cells initially don’t have an “identity” and can become nearly any cell type in the entire body. But over time, they differentiate or specialize into more specific cell types like going from a hematopoietic (blood) stem cell to a B cell (a specific immune cell).
2. Where are stem cells found throughout the body? — Steven
There are lots of different types of stem cells and they’re found in many tissues in the adult body, though they don’t share the exact same properties as the stem cells I described above.
The ones I described in the last question are considered pluripotent stem cells while those in the adult body are multipotent; they are only able to differentiate into a small number of other cells. For example, neural stem cells can only differentiate into cells found in the brain but not those in the liver.
More specifically, you can find stem cells in the bone marrow (those are hematopoietic or blood stem cells), in the brain (neural stem cells), in the intestine (intestinal stem cells), and the skin (skin stem cells), just to name a few, all of which are multipotent.
3. Does a stem cell’s environment play a role in regeneration? — Kathy
The answer is yes! There’s something called a stem cell’s niche or microenvironment that greatly affects how the cell decides to differentiate. And this niche is simply the environment around the cell.
This sentence coming from this paper sums things up super well:
The stem cell niche is the […] microenvironment where stem cells both reside and receive stimuli that determine their fate.
4. Why are stem cells important?
I have just 3 phrases for you: disease modelling/drug screening, stem cell therapies/regeneration, and studying human development. Using stem cells, we can model diseases in a lab, without harming humans or using animals.
Disease modelling helps with screening drugs in a fairly accurate but harmless way as well. Stem cells can also help us study the super early stages of development in a controlled environment. As for therapies, we’ll cover that in the next section!
Taking a different approach to the question, we’re all alive thanks to stem cells. Up until the embryo is about 3–6 days old, it’s completely full of stem cells that slowly differentiate and become you. So I guess the simpler answer to the question is we owe our lives to stem cells.
5. How does stem cell therapy work? — Michela
Let’s start by defining what stem cell therapy is or at least what I mean when I say stem cell therapy: it’s any safe and viable health treatment that’s done using stem cells.
Some examples right now include bone marrow transplants for cancer, skin grafts for helping repair the skin of burn patients, and corneal grafts for eye repair.
When it comes to stem cell transplants, there are two different types: autologous and allogeneic.
Autologous means the cells are coming directly from the patient (“auto” for self); in a transplant, this would usually reduce the threat of immune rejection because the cells are coming from the same body they’re going to!
Allogeneic means the cells are coming from another person (“allo” for other); this means the immune system has to be suppressed which comes with its own risks and side effects. There are certainly some benefits like the graft-versus-tumour effect, where the donor cells manage to get rid of any residues of the tumour, while this wouldn’t be possible if the cells were autologous.
6. Why is the unapproved stem cell therapy market dangerous to the public?
There is so much to be said here and if you’re interested in learning about the dangers while hearing an interesting story I recommend listening to the Bad Batch podcast.
To keep it short, it’s because much of the unapproved market is just that: unapproved. To patients who have been waiting years for a treatment or even cure for their disease, these seemingly amazing therapies are just too tempting.
But that’s usually because they are too amazing; it takes a long time to get from basic research to clinical approval and not waiting for the proper testing to be done can lead to a worsening of the patient’s current disease, and even the onset of a new disease. To learn about even more of the dangers, check out this awesome blog post!
7. Have stem cells been used to successfully treat a human disease?
We always hear about the amazing potential of stem cells–curing everything from spinal cord injuries to diabetes, but what’s actually been done?
The most commonly used stem cell treatment would have to be bone marrow transplants, otherwise known as hematopoietic (blood) stem cell transplants, and they’re helping treat diseases like leukemia or lymphoma. Yes, this is happening as I’m writing this!
There are other diseases that are have been worked on quite extensively like Parkinson’s Disease but their treatments aren’t quite ready yet.
8. What are the ethical issues with stem cells? — Rhea
When people talk about stem cells’ ethical issues, they’re usually talking about a specific type of stem cell: embryonic stem cells.
Remember pluripotent stem cells–they can turn into nearly any cell type (except those in the placenta). Well, embryonic stem cells are pluripotent and as the name might suggest, they come from 5–6 day old embryos, hence the controversy.
But a lot of research is now being done using stem cells that aren’t controversial or ethically challenging: induced pluripotent stem cells (or iPSCs for short)! They are also pluripotent even though they are differentiated adult cells at first; they are then reprogrammed back into being pluripotent 🤯
9. Are iPSCs harder to keep alive/use in a lab than embryonic stem cells?
Based on the research I did, induced pluripotent stem cells or iPSCs aren’t necessarily harder to keep alive but they are worse at differentiating (or specializing) than embryonic stem cells in some studies.
For example, this study focused on cardiomyocyte (or heart muscle stem cell) differentiation. When using embryonic stem cells, about 27% of the cell groups differentiated into beating cardiomyocytes. But when using iPSCs, this number was only about 11%.
10. I read somewhere that iPSCs are “not exactly the same as embryonic stem cells” in terms of function. What are these differences in function? It takes more time to differentiate? — Laura
Awesome question and one that I’ve personally researched quite a bit! Based on the research I’ve done, the biggest difference between iPSCs and embryonic stem cells (or ESCs for short) comes down to their epigenetics.
Let’s first tackle what epigenetics means: “Epi” means above and genetics means, well, genetics or the traits you inherit; so epigenetics is above your genetics/DNA. Think about it like this: if your DNA was a recipe, the epigenetics would be the font; the content doesn’t change if the font was changed but the font can make some parts harder to read and some parts easier.
iPSCs basically remember which tissue they came from initially (when they were differentiated adult cells) because of epigenetics and this can lead to them not being as good at differentiation just like we saw with the cardiomyocytes.
If you’re interested, check out my post going in-depth into this!
11. What’s the difference between progenitor cells and stem cells? — Me
This is something I was a bit confused by at first so I decided to throw it in here. Thankfully, it’s actually quite simple. Progenitor cells are just missing one of the criteria they need to be stem cells:
❏ ̶T̶h̶e̶y̶ ̶m̶u̶s̶t̶ ̶b̶e̶ ̶a̶b̶l̶e̶ ̶t̶o̶ ̶s̶e̶l̶f̶-̶r̶e̶n̶e̶w̶/̶m̶a̶k̶e̶ ̶c̶o̶p̶i̶e̶s̶ ̶o̶f̶ ̶t̶h̶e̶m̶s̶e̶l̶v̶e̶s̶ ̶i̶n̶d̶e̶f̶i̶n̶i̶t̶e̶l̶y̶.̶
❏ They must be able to differentiate.
It’s not quite as simple as this, since progenitor cells are often also able to differentiate into fewer cell types than stem cells but self-renewall is the main difference; they can self-renew but just not indefinitely.
That’s it for now, thanks for reading and I hope you learned a thing or two 😄 Check out my references if you’d like right here.
Not too much of my personality shined through here because I was trying to keep things super brief, but here’s a quick intro as to what I do:
I’m Parmin, a 15 y/o student studying stem cells at The Knowledge Society 🧪 Everyday, I aspire to uncover the secrets of biology and learn something new! Make sure to follow me on Medium to hear about every new article I post, connect with me on LinkedIn, or contact me at firstname.lastname@example.org! Also subscribe to my monthly newsletter to learn about every cool, new thing I’m working on ✍️