Researchers at UC San Diego have developed a liquid biomaterial that travels through the bloodstream to repair heart tissue damaged by heart attacks, sidestepping the need for invasive surgical injection into the organ itself.
The injectable material works by delivering fragments of heart tissue scaffolding directly to damaged areas through the circulatory system. Once there, it reduces inflammation and triggers the body's own repair mechanisms. Animal studies showed the approach improved tissue damage in both rodents and larger animals, with early results also suggesting potential for treating traumatic brain injury and pulmonary arterial hypertension.
"This biomaterial allows for treating damaged tissue from the inside out," said Karen Christman, the bioengineering professor who led the research team. "It's a new approach to regenerative engineering." The findings were published in Nature Biomedical Engineering in 2022, and the team indicated at the time that human safety testing could begin within one to two years.
Heart attacks kill or damage cardiac muscle tissue, which the body then replaces with scar material. Unlike healthy heart tissue, scar cannot contract effectively, gradually weakening the organ and potentially leading to heart failure. Currently, doctors can restore blood flow to the heart or manage symptoms, but no established therapy directly repairs the damaged tissue itself.
The work builds on earlier research from Christman's team involving a gel made from heart tissue scaffolding, called extracellular matrix. That gel was designed to be injected directly into the heart through a catheter. A phase 1 human trial in 2019 found the approach safe and feasible, though larger studies were needed to prove it improved outcomes.
Direct injection has a critical drawback, though. Because it requires a needle pushed into the heart muscle itself, it cannot be used immediately after a heart attack when the tissue is most vulnerable to further damage. That limitation pushed researchers toward a completely different delivery method.
"We sought to design a biomaterial therapy that could be delivered to difficult-to-access organs and tissues, and we came up with the method to take advantage of the bloodstream," said Martin Spang, the paper's first author. The new injectable version could be delivered through standard IV administration or infused into a coronary artery during procedures like angioplasty or stenting.
Creating the injectable form required solving a particle size problem. The original gel contained particles too large to effectively target the leaky blood vessels that appear after heart injury. Researchers used centrifugal processing to separate out larger particles and keep only nano-sized ones. The material was then treated with specialized processing steps, freeze-dried into powder form, and reconstituted with sterile water when ready for use.
In animal tests, something unexpected happened. Rather than simply passing through leaky blood vessels into damaged tissue as expected, the biomaterial actually attached to the cells lining the vessels and appeared to help seal the gaps. This process reduced inflammation, one of the primary drivers of tissue damage following heart attack. Tests in rats and pigs with induced heart attacks showed the treatment reduced abnormal heart enlargement, improved heart wall motion, and triggered gene expression patterns associated with tissue repair.
The potential reaches beyond cardiology. Researchers demonstrated proof of concept in animal models that the same approach could target inflammation in the brain and lungs. Because virtually all organs receive blood supply, using the circulatory system as a delivery route could open regenerative medicine to tissues that are otherwise nearly impossible to access surgically.
Since the original 2022 study, related research has continued. A 2025 Nature Communications study examined how these injectable biomaterials affect heart tissue at the cellular level, finding they trigger immune system changes, promote new blood vessel formation, activate tissue-building cells, and even stimulate nerve regeneration in rat models. This work provided deeper insight into the mechanisms driving healing without replacing the need for human clinical trials.
Ventrix Bio, the company Christman cofounded, continues advancing the cardiac biomaterial technology. The company has plans to seek FDA authorization to test the newer intravascular version in humans with heart disease. A clinical trial sponsored by Emory University is listed for studying the biomaterial in children with a severe congenital heart condition, though recruitment had not yet begun at last check.
For now, the treatment remains experimental. The therapy's main advantage over existing approaches is straightforward: it can be administered through routine vascular procedures or a simple IV line, potentially reaching injured tissue without the risks associated with surgical intervention into the beating heart.
Author Jessica Williams: "If this clears human trials, it could reshape how cardiologists approach heart attack recovery, replacing a technically demanding surgical procedure with something as simple as an IV infusion."
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