A new injectable biomaterial is showing promise as a way to treat damaged tissue through the bloodstream, rather than by injecting directly into the injured organ.
In animal studies, the material improved damage caused by heart attacks in rodents and large animals. Early proof of concept experiments also suggested it could one day help treat traumatic brain injury and pulmonary arterial hypertension.
“This biomaterial allows for treating damaged tissue from the inside out,” said Karen Christman, a professor of bioengineering at the University of California San Diego, and the lead researcher on the team that developed the material. “It’s a new approach to regenerative engineering.”
The findings were reported in Nature Biomedical Engineering in 2022 by a team of bioengineers and physicians.
The work builds on earlier research from Christman’s team on a hydrogel made from the extracellular matrix of cardiac muscle tissue. That gel was designed to be delivered directly into damaged heart muscle through a catheter, where it forms a supportive structure that encourages cell growth and tissue repair.
Results from a phase 1 human clinical trial of that earlier approach were reported in 2019. The trial found that transendocardial injection of VentriGel, a cardiac extracellular matrix hydrogel, was safe and feasible in post-heart attack patients with left ventricular dysfunction, though larger randomized studies would be needed to test outcomes.
The newer method was designed to avoid the main limit of direct heart injection. Because needle-based injection into heart muscle generally cannot be used immediately after a heart attack, researchers looked for a way to deliver a biomaterial through blood vessels during procedures such as angioplasty or stenting, or through an IV.
“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 , the vessels that already supply blood to these organs and tissues,” said Martin Spang, the paper’s first author, who earned his Ph.D. in Christman’s group in the Shu Chien-Gene Lay Department of Bioengineering.
The study described the material as an intravascularly infused extracellular matrix biomaterial made from decellularized, enzymatically digested, and fractionated ventricular myocardium. It was designed to localize to injured tissue by binding to leaky microvasculature and was largely degraded within about three days.
To make the injectable version, researchers started with the hydrogel they had already developed, then processed the liquid precursor in a centrifuge to remove larger particles. They kept nano-sized particles, then dialyzed, sterile filtered and freeze dried the material. When sterile water is added to the final powder, it becomes a biomaterial that can be delivered intravenously or infused into a coronary artery in the heart.
In a rodent model of heart attack, researchers expected the biomaterial to move through leaky blood vessels and into damaged tissue. Instead, they found it attached to endothelial cells, helped close gaps between them and appeared to speed up blood vessel healing. That process reduced inflammation, one of the major drivers of tissue damage after injury.
The team then tested the treatment in a porcine model of heart attack and saw similar results. In rats and pigs with induced acute myocardial infarction followed by intracoronary infusion, the biomaterial was linked with reduced left ventricular volumes, improved wall motion scores, and gene expression changes associated with tissue repair and inflammation.
The researchers also tested the biomaterial in rat models of traumatic brain injury and pulmonary arterial hypertension, where they found proof of concept that the same approach could target other inflamed tissues.
“While the majority of work in this study involved the heart, the possibilities of treating other difficult-to-access organs and tissues can open up the field of biomaterials/tissue engineering into treating new diseases,” Spang said.
Since the 2022 study, related work has continued. A 2025 Nature Communications study from researchers including Christman used spatial transcriptomics and single nucleus RNA sequencing to examine how injectable extracellular matrix biomaterials affect heart tissue after myocardial infarction. In rat models, that study found pro-repair signals involving immune modulation, blood vessel and lymphatic development, fibroblast activation, myocardial salvage, smooth muscle cell proliferation and neurogenesis.
Christman and Ventrix Bio have planned to seek FDA authorization to study the newer intravascular biomaterial for heart conditions in humans. For now, the treatment remains experimental.
“One major reason we treat severe coronary artery disease and myocardial infarction is to prevent left ventricular dysfunction and progression to congestive heart failure,” said Dr. Ryan R. Reeves. “This easy-to-administer therapy has the potential to play a significant role in our treatment approach.”
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