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Earlier this week, we welcomed you into our onsite lab so we could explain and demonstrate colony-forming units (CFUs) and how we use these to provide a rough count of mesenchymal stem cells (MSCs) in a cultured sample. Today, as promised in our CFU post, we’re inviting you back to the lab so we can focus in closer on MSCs. Specifically, we’re going to walk you from the incubation phase through how cultured MSCs appear on inversion microscopy. Start by watching the brief video below, where our research scientist Dustin will now introduce you to mesenchymal stem cells, and then we’ll summarize.


CFU Review

If you remember from our CFU video, the culture plates are first seeded with low-density (meaning high dilution) bone marrow concentrate (BMC), where the mesenchymal stem cells reside. The plates are put inside an incubator, and the cells cultured, or grown, for a period of ten days.

MSCs in the Incubator

In today’s MSC video, we begin with cultured MSCs in an incubator. You see two pieces of equipment, or vessels, in the incubator that we can use for cell culturing: a monolayer flask and a culture plate. The monolayer flask is the flask-shaped vessel in which cells are culturing in the video. The culture plate, which you also saw in the CFU video, is the vessel that contains those six “well” areas, each of which contains culturing cells.

Mesenchymal Stem Cells Under the Microscope

In the video, you we’ll then get to take a look at the MSCs under a microscope, but it’s important to note that this isn’t just your typical compound microscope you used in high-school biology; we’re using inversion microscopy to view our cultured cells. What’s the difference?

Using a standard microscope, cells typically need to be stained in order to visualize them. However, this technique can harm or even destroy the cells, so it doesn’t work if you want to see living cells. An inversion microscope doesn’t require staining to visualize the cells, so they can be seen while they are alive. Our microscope also has fluorescence software, which allows even more advanced functionality, such as viewing cell parts and measuring any changes. This comes in very handy for some of the research we perform here. One, for example, was on how stem cells react to certain local anesthetics. During this study, we were also able to measure the calcium that was stored in the endoplasmic reticulum, an organelle that resides within the cells.

One of the main identifiers (according to the Foundation for the Accreditation of Cellular Therapy [FACT]) for the presence of specifically mesenchymal stem cells is their adherence to the bottom of the plastic wells. This adherence demonstrates CFUs have formed in culture. Under the microscope (as seen in the video), you can clearly see what these culturing, or growing, MSCs look like.

MSCs are shaped like a spindle. The nucleus is located in the fatter segment of the
“spindle,” and from here, the cell tapers one way or the other into what looks like the spindle shaft. If you are interested in scientific cellular descriptions, you will hear Dustin describe MSCs as elongated and linear with a fibroblastic morphology.

How Our Clinic Uses Cultured MSCs

In the U.S., treatments using your stem cells that require isolation of the stem cells from your bone marrow, for example, must be performed during the same procedure. This means harvesting of the stem cells and reinjecting of the stem cells must occur on the same day. Culturing mesenchymal stem cells takes much longer than a few hours. The cells typically incubate for anywhere from 12 to 21 days. While we are able to use cultured cells for research and experimental purposes in the U.S., they cannot be used for therapeutic purposes. Why? The FDA classifies them, even when it’s your own cells, as a drug. In other words, it is currently illegal to use cultured cells in the U.S. for therapeutic purposes.

For patients who do need a more advanced level of therapy that requires cultured stem cells, we can treat them at our licensed Grand Cayman site and have done so for many years. We hope the visits this week to our onsite state-of-the-art lab have helped enhance your understanding of CFUs and MSCs.