Can Stem Cells Seal Carol’s Fate With ‘The Others’? Expert Separates Pluribus’ Science Fact, Fiction

Creative liberties aside, how realistic is the science behind the platform’s all-time greatest hit? We reached out to The Others but, unfortunately, didn’t receive a response. Here in their stead is UC San Diego expert Robert Signer, PhD — stem cell biologist, researcher, associate professor of medicine and deputy director of the Sanford Stem Cell Discovery Center at the Sanford Stem Cell Institute — to answer our pressing questions about stem cells and the plausibility of the show’s plot line.

Sanford Stem Cell Institute (SSCI): Obviously, Pluribus is fantasy. But perhaps the show isn’t so far-fetched, given that its plot line involves some very real cutting-edge science. We’re hoping you can help us separate science fact from science fiction here. In the show, the vast majority of humanity is infected with some kind of lysogenic-like virus that acts as a sort of psychic glue. What are lysogenic viruses?

Signer: Lysogenic viruses like herpes and HIV weave their genetic material into a host’s DNA, become dormant, then replicate passively as a host cell divides.

SSCI: The infamous Carol is immune to the “happy virus,” along with a handful of others scattered across the globe. In episode six, fellow immune Koumba tells Carol that the hivemind can’t “turn” the immune without their consent — and their individual stem cells, which the virus will be tailored to. What are stem cells?

Signer: Stem cells are rare, special cells present in many of our tissues. They are essentially a blank slate that can regenerate any of the specialized cells within that tissue through a process called differentiation. Stem cells also have the unique power to self-renew or make more of themselves. This is what enables us to continue regenerating cells throughout our lives instead of falling apart after a few decades.

SSCI: How could stem cells be used to route immunity to the virus?

Signer: Some viruses, like HIV, primarily target specific blood cells for infection. Due to genetic mutations, some people are immune to such viruses. For instance, some people are immune to HIV because of a mutation in their CCR5 gene. In the case of Pluribus, one possibility is that Carol and The Others are immune to the “happy virus” because of a genetic mutation. Maybe the hivemind thinks it can engineer Carol’s hematopoietic stem cells, and those of other immunes, so that infection can occur.

Another possibility is that there is something special about the immune system of Carol and others that makes them immune. The hivemind might be looking to modify their immune systems by re-engineering their stem cells to eliminate that special quality. It could also modify the virus itself to make it infectious in a way the initial version was not. Judging from events in episode six, that may have been the plan.

SSCI: Back to episode six: Carol informs the hivemind that she does not consent to stem cells being taken from her body. But, plot twist! In the season finale, we learn that The Others are exploiting a loophole: deriving induced pluripotent stem cells from her eggs, which she and her partner froze at some point.

First things first: What are induced pluripotent stem cells?

Signer: Induced pluripotent stem cells are created by reprogramming cells — often skin or blood cells — from a consenting person. In contrast to the stem cells found inside each of us that regenerate only the cells within a specific tissue, pluripotent stem cells can differentiate to form any cell type in the body. It’s the cellular equivalent of convincing an adult to go back to kindergarten to relearn every possible career path.

SSCI: Is it possible to make induced pluripotent stem cells from frozen eggs?

Signer: I’m not aware of it having been done successfully, but, in theory, it should be possible — though doing so could be technically complex, which the show wisely implies through Zosia’s dialogue. It would be much easier to make them from skin or blood cells. Zosia could grab a strand of Carol’s hair with a live follicle, and the hivemind could then use that — though that probably would have made for less compelling television!

SSCI: In the season finale, we see Kuysamyu, who was also immune like Carol, inhaling some kind of vapor before being ushered into union with The Others. How would that work?

Signer: Off camera, they must have modified the virus so that it could infect her. Presumably they collected her stem cells with her consent and used them to identify the necessary changes in the virus. On camera, what she was inhaling had to have been the modified virus.

Alternatively, off screen, they could have performed a stem cell transplant with modified stem cells that make her susceptible to the virus. Then, on camera, she could have simply inhaled the original virus. Either way, some science has to have happened where the camera conveniently isn’t.

SSCI: It’s pretty common to hear about clinics that claim to cure diseases, mend injuries and even reverse aging using stem cells. Then there are the stem cell beauty products — gummies, serums for microneedling, skin creams. What’s legit and what isn’t?

Signer: There are legitimate stem cell treatments, but most of them involve using hematopoietic stem cells and regenerating the blood system of a person who has undergone ablative chemotherapy or radiation. Stem cells can be used to treat other types of conditions as well, and there are many other ongoing clinical trials using different types of stem cells for regenerative medicine purposes.

Most of the time, if you’re seeing an ad for a stem cell clinic, it’s unclear what they’re doing exactly because many of their so-called “treatments” are unapproved. If it sounds too good to be true — especially if it’s being sold on Instagram — it probably is. These services are often unregulated, untested and have the potential to do harm.

If you’re interested in stem cell therapy, you want to be sure what you’re getting is as safe as possible and genuinely effective. Talk to your primary care physician or specialist if you’re interested, and stick to treatments and trials through systems you trust. For example, at UC San Diego Health, our Sanford Stem Cell Institute California Institute of Regenerative Medicine (CIRM) Alpha Clinic has tens of clinical trials available, including stem cell therapies for conditions like Parkinson’s disease and epilepsy. These trials — approved by the U.S. Food and Drug Administration — often lead to new approved therapies made widely available to those who need them.

SSCI: Thanks, Rob, for your time and expertise. And Carol, if you’re reading this, call us. Seriously. We have ideas!