Serum: FBS, BCS, Human, Horse… What am I supposed to use?

Blog entry

Good day scientist! I trust your cells are doing well and that you are here because your stellar technique affords you a free minute for the guilty pleasure of reading my blog…

Deep breaths, deep breaths… OK, now that you’ve regained your composure, I’ll tell you that today’s topic, serum, is not going to be a tutorial in the sense that I’ll give you all the gory details on how it’s procured. Instead, I thought it might be a good idea to actually discuss which serum to use for various applications.  You know, this stuff isn’t just for your cell culture!

So, let’s start with FBS because it’s easy.   A quick Google search suggests that FBS is only really used for cell culture.  We knew that, so it’s time to move on… But before we do, allow me to take this time to clear something up: FBS = FCS. Fetal Bovine Serum is the same as Fetal Calf Serum. There is no difference and semantics have no place in science, and anyone working with cells should know that.

So as I complete my descent from my uppity soapbox, I’ll bring up Bovine Calf Serum (BCS). This stuff IS different from FBS. It comes from calves already born and typically doesn’t have the levels of growth factors that FBS contains.  It may even have a different complement of growth factors. In any case, it does not provide the trophic support that FBS does. So BCS can be used for super easy-to-grow cells (I’ve used them for feeder cells in the past, as part of a 50:50 mix with FBS). Naturally, I would caution you to test that before you go and commit to that paradigm. But, it worked for me and it saved our lab a few bucks.

Next we move on to horse serum. Being a former ES to neural stem cell guy myself, the first thing that comes to mind is “astrocytes.” Horse serum has been in use for years as a supplement for astrocytes in culture. It also can be used for neuroblastoma cultures and myeloid cancer cell cultures. But it doesn’t stop there folks, horse serum can also be used as a blocking agent in your immunostaining experiments and your western blots. While we all typically block with milk or BSA, or even FBS, if your antibodies are grown in or directed against the right species, horse serum may be a viable option, especially if you’ve been having problems with non-specific binding.  As a matter of fact, it may be worth looking into using donkey or goat serum in your immunostaining and western blot experiments.

We as scientists tend to put much faith in established protocols and handed-down advice from peers and mentors but the truth is, we are experimentalists. We should experiment! From a personal perspective, I would probably not have any publications to show for my postdoctoral work if I didn’t have access to all different types of serum.  You see, I got lucky as a grad student. My local supermarket happened to have my favorite brand of powdered blocking agent that worked well for the limited number of antibodies I was working with.  I wasn’t so lucky when I started my postdoc and my favorite milky multi-tasker wasn’t cutting the mustard.  As it turned out, I used all different kinds of serum as blocking agents and my science started making sense again. So would I have that coveted Cell paper if I had more options as a grad student? Nah. But it’s nice to have an excuse for why my CV doesn’t have one on it!

Have a great day, scientist, and don’t forget to satisfy your curiosity and see what different sera can do to give your experiments that boost you need before your next lab meeting presentation!