I discovered "Axis Power Hetalia" yesterday, both the webcomic and the anime. The anime (the first episode at least) is hysterical in a "wow I can't believe they did that" kind of way (and occasionally the caricature will even ring true). The anime is based off of the comic, which is hugely irreverent and disturbing and amazing. I pondered what would've happened if I'd discovered this during the year in high school when I had world history. It is possible I would've been traumatized, though how something can be so soul-destroying-ly cynical yet cute at the same time is a mystery.
(In case the name didn't make it obvious, it's about the anthropomorphic personifications of world powers, mostly during WWI and WWII.)
Now: onward to something totally unrelated.
We recently had a Stem Cell Awareness day on campus, the discovery of which led me to go up to our post-doc who is working on the (murine; read: mouse) stem cell project and ask, "Are you Aware of stem cells?", to which she replied that yes, she was and so we were all good.
That wasn't the point though. The point of that day was to raise public awareness about the sort of research we do and why it's important. There was a seminar with panels to answer questions from the public. Although I didn't attend and am by no means an expert in the field of stem cell research, I do know there are a few points of stem cell biology that tend to be confusing for people encountering it for the first time:
1) Not all stem cells come from embryos.
True stem cells that we work with are either embryonic stem cells, which does derive from a fertilized egg (when it's starting to divide and is on its way to the "ball of cells" stage), or they are adult stem cells, which can come from a fully grown organism.
2) Not all progenitor cells are stem cells.
To be considered a stem cell, it must fulfill two criteria:
a) self-renewal - the stem cell must be able to divide and grow as a stem cell
b) differentiation - under certain conditions the cell must be able to change into another cell type, and stay that way.
3) The most important aspect is potency.
A stem cell is special because it can become many different types of cells, and so for disease that results from defect and/or death of one particular cell type, we like to dream about a therapeutic procedure where you fix the disease by replacing the dead / defective cells with new, working cells. However, not all stem cells are created equal -- meaning they can't all differentiate into all types of cells, and in this case they are classified by potency:
a) Omnipotent (does anyone even still use the term "totipotent"?) cells - can become anything.
b) Pluripotent cells - can become anything but the placenta, so still very useful.
c) Multipotent cells - can only become one lineage of cells, e.g. only neuronal cells, or only blood cells. Adult stem cells are multipotent.
4) ipSC is supposed to be pluripotent.
Researchers have found a way to take certain cells in the body and reprogram them to become Induced Pluripotent Stem Cells. Which is excellent, except...
5) It's unknown whether ipSC is a true stem cell.
Sure it looks like a duck and it'll quack like a duck, but until you know how to ask the right question -- for instance, "does it have feathers? does it move autonomously?" -- how can you tell apart a very good mechanical wind-up toy from the real duck? My understanding of the ipSC right now is that for the general tests that people can think of testing, they look and behave like true stem cells. But whether the tests we've done are the right, key, tests or whether ipSC is a different animal altogether and we've just didn't test for the right things -- no one knows.
In therapeutic considerations, this brings up additional problems, because ipSC is made by reprogramming a cell. Usually with virus. Virus can change the expression of genes in the cell, which is what the "reprogramming" is all about. Changing the expression of genes is what gives you the stem cell like behavior, but you know what else changing the expression of genes can result? Cancer. (This has been shown to occur, though I should add that one of the ways we test for the stem-cell-ness of stem cells is by seeing if they form the right kind of tumors, because the types of cells the tumor contains give us an idea of the potency of the cell -- but you can imagine the problems if the cell likes forming tumors too much and then metastasized.) We are, essentially, taking a genetic program Nature has perfected through eons of evolution and random sticking in codes that we think regulates certain cell behavior. So yeah: so much we don't know, it's a little scary.
So there you go, five main points people should know about stem cells. From vicarious observation in lab I can tell you that trying to get cells to change cell type is really hard, and often a multistep process. (I had to work with a neural precursor cell line once and I kept getting the cells stuck one step before the final stage and my god, that was frustrating.) I don't think I need to mention this but my labmates seem to think there might be cause for concern, but stem cells don't glow. They are special, but not that special. Unless we infect them with a virus that codes for a glowing protein or stain them with something that glows and then, you know, they glow. But so will any other cell type. (Glowy pulsating heart muscle cells is, frankly, kind of creepy.)
No comments:
Post a Comment