The concept of Happy Cells

My teacher Victor Diaz, in those days at the Max-Planck-Institute always turned on loud Salsa music in the cell culture.

That would make the cells happy.

This attitude together with an excellent cell culture technique let each and every cell line flourish under his hands.

I had to search for a long time till I found such an exact technique in another lab. Who wonders that it was a stem cell lab, one of the trickiest cell types to culture ...

In between I saw a lot of sloppiness, many contaminations and many mistakes in the cell culture. My technique remained clean, as I have learned it. I want to pass on to you this knowledge from 18 years of cell culture experience.


The cell culture is the base of most medical research labs. Why is a clean cell culture technique so uncommon? I dont know.

Everybody thinks ist easy to culture cells. But it is scary what I saw in cell culture labs even at the best universities. So much sloppiness, so many contaminations ...

Although, it IS actually easy to culture cells! Once you know some basic rules ...


If I open the incubator on Monday morning, I see immediately who has experience in the cell culture and who doesnt. The medium should never be yellow! If you starve your cells over the weekend, how should they give you trustable data on Monday? Did you ever get contradicting data after repeating experiments? Why that?

Dont underestimate the status of your cells. They are your currency. You should treat them really well. If your cells are constantly living in good conditions, with sufficient nutrients and sufficient space to grow, then they are happy.

Yes, I purposefully say „Happy“, even if it irritates you. Actually its logic: your cells need to be happy to give you reliable data. There are so many variables in your experiments that you cannot control, try at least to take care of this part, to keep your cells in constantly good conditions.

This will at least increase the probability to get reliable data than if you have cells that suffer from phases of starvation or high dilutions. Each cell line releases their own factors into the medium, which makes them feel cozy. After splitting, cells are very diluted and first have to reestablish their favorite environment.

It needs some years of experience to estimate how to split your cells on Friday that they are not sitting in yellow medium on Monday.


Why are we using antibiotics in cell culture media?

For the single reason that we do not have a clean cell culture technique. Crowded labs, little space under the hood, everybody using same pipet tips and media are the best conditions to get contaminations. So, just throw in antibiotics and things are running again ... No, ist not that easy.

I claim that an antibiotic-free cell culture should not only be possible but the standard in every lab! It shows you how clean you work and your cells might thank it with more reliable data.

Why all this hassle? If antibiotics are available why shouldnt we use them?


Reason 1

Constant sub-infections are supressed by the antibiotics but they are still a stress factor for your cells.



Reason 2

Antibiotics can reduce your transfection efficiency up to 30% !! Did you ever have cells that were tricky to transfect? Where you couldnt achieve a sufficient transfection efficiency? In such critical situations it does make a difference if you have an antibiotic-free culture or not.


Reason 3

Advanced cell culture applications are often antibiotic-free. If you reprogram cells to iPSC and then differentiate them to your cells of interest, you need to be able to culture these cells for weeks without antibiotics. In critical developmental stages, cells just cannot tolerate antibiotics. And if other people can culture tricky cells without antibiotics, you can also do that with any standard cell line!

Just try it out. Other people are also not doing magic, they just learned a proper technique. And you can learn this, too!


Ok, lets get started. Download the PDF under this article, read it carefully and then do a little exercise.

Take your favorite cells and culture them in medium without antibiotics for 2 weeks. If you follow the basic rules, it should work nicely. And if you get a contamination, throw your cells, reflect your work style and try it again ... and again. You will succeed in the end!

And then just write me if it worked or not at



Take part in my challenge:

Download the PDF now and learn the 5 rules how to establish your antibiotic-free cell culture