Read Original Release

Findings from a rat heart study can’t be extrapolated to people

Cardiac stem cells from young hearts could rejuvenate old hearts, new study shows

Our Review Summary

This news release positively spins a study in which researchers observed physical changes in old rats that were injected with cardiac stem cells from newborn rats. Publishing in the European Heart Journal, researchers concluded that cells from baby rats appeared to “rejuvenate” aged rats compared with a placebo. The news release brazenly speculates about potential benefits for humans without cautioning that findings from a rat study can’t be extrapolated to people. It also omits potential harms and costs.

To its credit, the release discloses the fact that Cedars-Sinai and a lead researcher have a financial interest in Capricor Therapeutics, which holds the license for the cardiac stem cell product, known as CAP-1002. It also acknowledges that the study didn’t examine an outcome that the rats — and some humans — would really care about: whether stem cells extend their lifespans.


Why This Matters

Heart failure is a progressive disease that affects millions of Americans. Although therapies exist to reduce symptoms, at least in those suffering from systolic dysfunction, there are no curative treatments. Stem cell therapies have been explored as possible options over the years with mixed results.

Exuberant news releases about stem cell therapies can spark news coverage that attracts investors and fuels enthusiasm for more research. In this case, it seems Capricor Therapeutics could use some positive news. In recent months, it lost key investor Johnson & Johnson after disclosing that a phase 2 clinical trial of its chief product was failing to show efficacy in heart attack patients.

Larry Husten wrote in MedPage Today that Capricor researchers had difficulty acknowledging that the therapy didn’t work: “Stem cells have never been shown to have any clinical benefit in patients with heart disease. But there is mounting anecdotal evidence that they may have serious adverse effects on the reasoning and objectivity of the medical researchers, biotechnology executives and investors who get sucked into their orbit.” Journalists, too, need to resist that gravitational pull. In this instance, at least one news outlet did not. CNN ran this glowing story: “‘Unexpected fountain of youth’ found in cardiac stem cells, says researcher.”


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

There’s no discussion of the potential cost of stem cell infusions generally or of CAP-1002.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The news release says rats injected with stem cells:

  • “Experienced improved heart function
  • Demonstrated longer heart cell telomeres, compound structures located at the ends of chromosomes that shrink with age
  • Improved their exercise capacity by an average of approximately 20 percent
  • Regrew hair faster than rats that didn’t receive the cells.”

It gives no numbers to give readers an idea of how large these benefits were. It doesn’t tell us how many animals were involved in the study and what the comparator was (baseline vs. placebo treated) for the benefits mentioned. Of course, such data isn’t indicative of what might happen in humans, but if it’s worth reporting an outcome, the numbers should be included.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

Potential harms of stem cell therapy are not mentioned, and it’s impossible to know for sure what the risks of this intervention might be. Safety data appears to be limited. The published study states that cardiosphere-derived cells “are already in advanced clinical testing and have proven safe to date,” but it cites just one article that was written by one of the same researchers, Eduardo Marban, who developed and owns a financial interest in the technology.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

To be clear, the study was conducted in a total of 23 rats, 10 of which received the stem cell therapy. The news release acknowledges some limitations of the study:

“This study didn’t measure whether receiving the cardiosphere-derived cells extended lifespans, so we have a lot more work to do,” said Lilian Grigorian-Shamagian, MD, PhD, co-primary investigator and the first author of the study. “We have much to study, including whether CDCs need to come from a young donor to have the same rejuvenating effects and whether the extracellular vesicles are able to reproduce all the rejuvenating effects we detect with CDCs.”

But it omits the most important limitation: data from rats can’t be extrapolated to humans.

Does the news release commit disease-mongering?


There’s no disease mongering here.

Does the news release identify funding sources & disclose conflicts of interest?


The news release states that “general support” for Marban’s lab is provided by the National Institutes of Health, and that Cedars-Sinai along with its heart institute chief Eduardo Marban, a co-author of the study, have financial interests in Capricor, which own the process to grow cardiac-derived stem cells.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

Who’s to say that lifestyle factors such as a good diet and robust exercise wouldn’t do a good job of staving off the harms of aging more reliably than a costly stem cell procedure? That’s not mentioned.

Does the news release establish the availability of the treatment/test/product/procedure?


This was a close call. We rate this criterion Satisfactory since the release includes some cautionary language about the availability and applicability of cardiac stem cells, stating that they “could someday help reverse the aging process in the human heart” and “We have much to study…”

However, the release also mentions that the cardiac cells “have been used in other human clinical trials,” but doesn’t clarify whether it’s been approved by the FDA for use in humans.

Does the news release establish the true novelty of the approach?

Not Satisfactory

There’s no attempt to put this study in the context of numerous stem cell studies that have been performed in recent years. Many studies have attempted to show that stem cells can be used to improve heart function or slow the aging process, including a recent study that concluded stem cells in the hypothalamus control aging.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?

Not Satisfactory

The news release repeatedly uses speculative language:

  • “Cardiac stem cells from young herats could rejuvenate old hearts, new study shows.”
  • Animal study reveals that cardiosphere-derived cells secrete tiny vesicles that could ‘turn back the clock’ for age-related heart conditions
  • Cardiac stem cell infusions could someday help reverse the aging process in the human heart, making older ones behave younger, according to a new study from the Cedars-Sinai Heart Institute.
  • “Now we find that these specialized stem cells could turn out to reverse problems associated with aging of the heart.”

Of course while stem cells could do all of these things, they also could not do them.

Also egregious is a premature statement from lead researcher Eduardo Marban, who is married to the CEO of the company that makes the cells:

“The way the cells work to reverse aging is fascinating,” Marban said. “They secrete tiny vesicles that are chock-full of signaling molecules such as RNA and proteins. The vesicles from young cells appear to contain all the needed instructions to turn back the clock.”

Total Score: 3 of 10 Satisfactory


Please note, comments are no longer published through this website. All previously made comments are still archived and available for viewing through select posts.