This summer we’re sponsoring high school interns in stem cell labs throughout California. We asked those students to contribute to our Instagram photos and YouTube videos about life in the lab, and write about their experiences.
Erik Owen worked in the lab of Bruce Torbett at teh Scripps Research Institute.
|Erik Owen learning lab techniques. He submitted this photo through Instagram to CIRM’s #CIRMStemCellLab collection.|
Multipotent hematopoietic stem cells (HSCs) develop into all the different types of blood cells (that’s why they named stem cells stem cells, because specialized cells stem from them—how clever!). We figured that out a long time ago. We even know what kind of blood cells are out there. We just don’t know what stimulates HSCs to mature in a certain way. Probability probably plays a part in deciding which HSCs develop into what but it’s also influenced by the epigenetic structure of the cell’s DNA and transcription factors.
Okay, enough with the technical background. Let’s go into specifics. Pu.1 is a transcription factor that causes HSCs to differentiate. My focus is on quantifying certain amounts of Pu.1 to specific types of differentiation. That’s more the big picture than anything though. The point of my project is to test the Pu.1 negative/positive system for leaks. The system is leaky if cell markers for CD11b, part of an integrin that is expressed when a cell is Pu.1 positive, appear in a Pu.1 “null” cell.
Just from asking around the lab about other people’s projects, I’ve realized how extensive (almost) every single project is. Even some of the aspects of my work, a relatively small project, are extensive. For example, isolating stem cells. Wow, who would’ve known that there is about 1 long term hematopoietic stem cell for every other 100,000 cells inside the bone marrow? Yeah, isolating .003% of blood cells in the bone marrow (or in umbilical cord blood which thankfully has a higher HSC concentration) gives a pretty low yield of HSCs.
Obtaining cells is only the start. Culturing cells is a nearly daily process. Although not as time consuming as some lab procedures, it is very important. Cells have to be kept alive and growing (although in the case of stem cells, they have to be kept undifferentiated as well). You have to count cell lines in order to make sure the media in the flask isn’t being too crowded. If too crowded, you have to split the cells (in suspension) by taking out a certain amount of cells, putting it in a new flask, and adding fresh media. It’s not actually as bad as it sounds though. It can be pretty fun to watch your cells grow and fill up the media more and more every single day.
One thing that has really been stressed as I have learned about my project is that a hematopoietic stem cell doesn’t just spontaneously become a neutrophil or eosinophil or basophil or erythrocyte or basically, any fully specialized blood cell. There are many precursor cells that gradually gain more and more characteristics of a specific differentiated cell. For example, a HSC will become a common myeloid progenitor cell, then a granulocyte-macrophage progenitor, then a myeloblast, promyeloblast, myelocyte, metamyelocyte, and finally a neutrophil! That’s seven different progenitor steps before a fully developed cell is created. That’s a lot more complicated than it might seem when a textbook says, “Neutrophils develop from stem cells.”
Overall, even Wikipedia couldn’t fully explain what makes stem cells develop into specific specialized cells. Well, maybe in the not-so-distant future it will, but that’s going to take more research—and that reminds me, I have to go split some K-562 cells now. Time for some more research.
Erik submitted this video about his experience: