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Welcome to Our Lab: Let’s Talk About CFUs

what are CFUs

Today we’re inviting you into our lab here at the clinic so you can learn a little bit about CFUs and what we do with them. CFU means colony-forming units, and you’ve likely seen “CFU” before, either in news articles or while surfing the Web as it makes the rounds fairly often, especially where stem cells are discussed. Broadly speaking, a CFU is one research method that can provide a rough count of the number of living MSCs, or mesenchymal stem cells, in a sample.

You can read about the process all day, but actually observing it can significantly enhance understanding. So today our focus is going to be on the video below of one of our research scientists (Dustin) explaining and demonstrating CFUs. So watch the video (we’ll summarize below it), and welcome to our lab:


The Lab Process for Measuring CFUs

In the video, you will first notice two culture plates, each containing six separate culture areas (called “wells”). Prior to this, these culture plates had been seeded (i.e., samples have been added to the culture areas) with highly diluted (i.e., low density) bone marrow concentrate (BMC). To obtain BMC, bone marrow would have been drawn from the patient and the stem cell fraction isolated from the sample. At this point, the cells were then put into an incubator in their dishes and cultured (i.e., grown) for a period of 10 days.

As the video begins, Dustin has just added a crystal violet dye to the samples. This stains all of the viable cell colonies a vibrant dark purple. After 10 minutes, the plate surfaces are washed with water. Left behind in the dishes will be dots of purple. These dots identify colonies of MSCs that adhere to and grow on the plastic surfaces of the dishes.  Each colony is a CFU, a colony-forming unit. Each colony, it is assumed, represents one healthy MSC from the original sample.

Using image-based software technology, we can calculate the density of the colonies, and this should give us an idea—a very rough idea—of the number of stem cells we started with. In other words, the more CFUs, the greater the original stem cell numbers. So what exactly do we do with CFUs?…

We Use CFUs for Research, Not Dosing

It’s important to note here that we use CFUs for research, not for dosing in our Colorado clinic. Not only would it not be a practical dosing method for our same-day stem cell procedures as it only provides a rough estimate of stem cell counts (and we need a more reliable count for treatment), but more obviously, the samples have to culture for 10 days. So this means it’s not possible to draw, process, and reinject cultured stem cells on the same day they are harvested. For same-day treatment purposes, it is critical that physicians know how to count and dose stem cells. There are a variety of methods, each with pros and cons, and if you want to learn more in-depth information about counting and dosing stem cells, you can read about it at this link.

We hope you’ve enjoyed your visit to our lab and that Dustin’s explanation and demonstration of CFUs helped you visually associate (remember that vibrant dark purple) what you read about CFUs with what actually happens. Come join us in our lab again later this week as Dustin is going to give us a peek at some mesenchymal stem cells.