Skip to Content

Injecting Stem Cells into the Heart Could Stop Chronic Chest Pain

Early research suggests that the treatment works by promoting blood vessel growth.

Patients with hard-to-treat chest pain reported feeling better, and could exercise longer, after doctors injected stem cells taken from their bone marrow into their heart, according to a new study in Circulation Research.

Stemming pain: Douglas Losordo of Northwestern University hopes that CD34+ stem cells, like this one shown here, can help treat patients with chest pain.

The early-stage research suggests that the cells were able to help heal tiny, damaged blood vessels that are often untouched by procedures like stents and angioplasty, says lead researcher Douglas Losordo of Northwestern University.

Losordo has been searching for more than a decade for ways to repair the heart using a patient’s own stem cells. He is by no means the only scientist on this quest, but Losordo is the only one using a particular stem cell, called CD34+, which is believed to promote blood vessel growth.

Richard Lee, a cardiologist at Brigham and Women’s Hospital in Boston and head of the cardiovascular program at the Harvard Stem Cell Institute, says Losordo’s research is novel because of his use of these cells, and because he is aiming his treatments at a group of people who have not been well helped by medicine so far.

The American Heart Association estimates that 850,000 Americans have lingering bouts of chest pain, a condition called refractory angina, which is not relieved by medication, angioplasty, or stenting. At the beginning of Losordo’s study, the 167 participants had 20 or more episodes of pain a week so severe that they had to stop what they were doing. Six months into the research, patients who received a low dose of the stem cells reported roughly seven attacks a week on average, while those who received a placebo treatment had 11.

The low-dose patients also were able to tolerate exercise for more than two minutes longer at the end of the study compared to the beginning, while those in the placebo arm could last just over a minute longer.

By harvesting a patient’s CD34+ cells from bone marrow, amplifying them, and injecting them directly into the damaged portion of the heart, Losordo says, he is circumventing natural steps that these people’s bodies might not be equipped to perform anymore. In animal studies, he found that the cells were naturally recruited to the heart after an injury to help repair damaged tissue. His research suggests that they secrete growth factors and immune molecules.

“These cells seem to represent one of the natural mechanisms for helping to repair damaged tissue,” he says. “We’re taking a preprogrammed repair mechanism and simply trying to leverage that in patients who have been damaged over the course of many years or decades.”

Lee compliments the thorough nature of Losordo’s work. “I think that this is a promising study, because it was so carefully done and because this patient population can be very incapacitated,” Lee says.

However, he offers three reasons for caution. First, patients in the placebo arm of the study also showed dramatic improvements. Second, although the procedure seemed generally safe, the patients’ hearts released an enzyme that is typically discharged when damage occurs. And third, patients receiving a lower dose of the stem cells fared as well or better than those receiving a higher dose.

“That really implies that we really don’t know what’s going on,” Lee says. “You like to see dose-dependence. If it’s the low-dose [that’s most effective], then you wonder, can we go lower and get the same effect? Have we missed the real benefit?” Other cell therapies for the heart suffer from similar shortcomings, Lee notes.

Losordo expects to start the final phase of clinical trials in a larger group of patients at the end of this year. Trials have already begun using CD34+ cells to help restore blood vessels in people at risk for amputation and in patients with artery blockages in their legs. 

Keep Reading

Most Popular

DeepMind’s cofounder: Generative AI is just a phase. What’s next is interactive AI.

“This is a profound moment in the history of technology,” says Mustafa Suleyman.

What to know about this autumn’s covid vaccines

New variants will pose a challenge, but early signs suggest the shots will still boost antibody responses.

Human-plus-AI solutions mitigate security threats

With the right human oversight, emerging technologies like artificial intelligence can help keep business and customer data secure

Next slide, please: A brief history of the corporate presentation

From million-dollar slide shows to Steve Jobs’s introduction of the iPhone, a bit of show business never hurt plain old business.

Stay connected

Illustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at with a list of newsletters you’d like to receive.