A remarkable new biomaterial designed to journey through the bloodstream holds great promise for providing a gentle and innovative solution to quell inflammation and support the healing of injured tissues. Recent studies in animals have shown that this injectable material can significantly enhance recovery from tissue damage caused by heart attacks, benefiting both small and large animals alike. Excitingly, early experiments suggest that this approach may also be effective for various inflammation-related conditions, such as traumatic brain injuries and pulmonary arterial hypertension.

"This biomaterial allows for treating damaged tissue from the inside out," shared Karen Christman, a bioengineering professor at the University of California San Diego and the lead researcher behind this groundbreaking development. "It's a new approach to regenerative engineering."

The findings were published in Nature Biomedical Engineering in 2022 by a talented team of bioengineers and physicians. Christman expressed optimism that human trials to assess the safety and effectiveness of the biomaterial could commence within the next couple of years.

A New Path to Heal Heart Damage

Heart attacks are one of the most pressing medical challenges in the United States, with approximately 785,000 new cases each year. When blood flow to the heart is obstructed, cardiac tissue can suffer or perish. The body's natural response is to form scar tissue; however, this scar lacks the ability to contract like healthy heart muscle. Over time, this can weaken the heart and contribute to heart failure.

Currently, there is no established therapy that directly repairs heart tissue after a heart attack. Existing treatments focus on restoring blood flow, minimizing further injury, and managing future heart issues.

"Coronary artery disease, acute myocardial infarction, and congestive heart failure continue to be the most burdensome public health problems affecting our society today," noted Dr. Ryan R. Reeves, a physician in the UC San Diego Division of Cardiovascular Medicine. "As an interventional cardiologist, who treats patients with coronary artery disease and congestive heart failure on a daily basis, I would love to have another therapy to improve patient outcomes and reduce debilitating symptoms."

From Heart Hydrogel to Bloodstream Infusion

This innovative work builds on Christman's earlier research on a hydrogel derived from the natural scaffolding of cardiac muscle tissue, known as the extracellular matrix (ECM). This gel was initially designed for direct delivery into damaged heart muscle via a catheter. Once in place, it provides a supportive framework that encourages cell growth and tissue repair.

In the fall of 2019, the results of a successful phase 1 human clinical trial of that earlier hydrogel approach were shared. The trial demonstrated that the transendocardial injection of VentriGel, a cardiac extracellular matrix hydrogel, was safe and feasible for post-heart attack patients with left ventricular dysfunction, though larger studies are needed to confirm improved outcomes.

However, the direct injection technique presents limitations. Since it requires a needle-based injection into the heart muscle, it often cannot be utilized immediately after a heart attack, as delivering it too early can pose risks of additional injury.

This challenge sparked researchers to explore a different concept: a biomaterial that could be infused into a blood vessel during procedures like angioplasty or stenting, or even delivered 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," explained Martin Spang, the paper's first author, who earned his Ph.D. in Christman's group.

The Importance of IV Delivery

Utilizing a bloodstream-based approach offers the biomaterial a significant practical advantage. Instead of being confined to a few injection sites, it can distribute more evenly throughout damaged tissue. This could prove especially valuable after a heart attack, when accessing injured areas directly can be challenging and time-sensitive.

The study in Nature Biomedical Engineering described the material as an intravascularly infused extracellular matrix biomaterial made from decellularized, enzymatically digested, and fractionated ventricular myocardium. This innovative material is designed to localize to injured tissue by binding to leaky microvasculature and is largely degraded within about three days.

Crafting the Biomaterial

To create the injectable version, researchers in Christman's lab began with the hydrogel previously developed and tested for compatibility with blood injections. The challenge was particle size, as the original hydrogel contained particles that were too large to effectively target damaged, leaky blood vessels.

Spang addressed this by processing the liquid precursor of the hydrogel in a centrifuge, enabling the team to separate larger particles and retain only the nano-sized ones. The material was then dialyzed, sterile filtered, and freeze-dried. When sterile water is added to this final powder, it transforms into a biomaterial suitable for intravenous delivery or infusion into a coronary artery.

How the Biomaterial Targets Injured Tissue

When researchers tested the biomaterial in a rodent model of heart attack, they anticipated it would move through leaky blood vessels and into damaged tissue. After a heart attack, gaps can form between endothelial cells that line blood vessels.

To their delight, the team observed something even more encouraging. The biomaterial attached to endothelial cells, aided in closing the gaps, and appeared to accelerate blood vessel healing. This process significantly reduced inflammation, a key contributor to tissue damage following injury.

Subsequent tests in a porcine model of heart attack yielded similar positive results. In both rats and pigs with induced acute myocardial infarction treated with intracoronary infusion, the biomaterial was associated with reduced left ventricular volumes, improved wall motion scores, and favorable gene expression changes related to tissue repair and inflammation.

Expanding Possibilities Beyond the Heart

While the primary focus of the research was on heart attack damage, the team also explored whether the same biomaterial could be beneficial for other inflamed tissues. In rat models, they found promising evidence that the approach could be valuable for treating traumatic brain injury and pulmonary arterial hypertension.

This broader potential is truly exciting, as many organs and tissues are not easily accessible, but all are nourished by blood vessels. If a biomaterial can utilize these vessels for delivery, regenerative medicine may reach injuries that are otherwise challenging to treat.

"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," remarked Spang.

What’s Next for This Innovative Research?

Since the original study, ongoing research has continued to explore how extracellular matrix-based biomaterials can influence healing after myocardial infarction. A 2025 study in Nature Communications from researchers including Christman utilized advanced techniques to investigate how injectable extracellular matrix biomaterials affect heart tissue post-myocardial infarction, revealing pro-repair signals related to immune modulation, blood vessel and lymphatic development, and more.

While this subsequent research has added valuable insights about the healing process at the cellular level, clinical testing of the intravascular biomaterial remains essential.

Ventrix Bio, Inc., the startup co-founded by Christman, is actively advancing related cardiac extracellular matrix technologies. A ClinicalTrials.gov listing for VentriGel outlines a phase 1 open-label study in children with hypoplastic left heart syndrome, sponsored by Emory University, to evaluate the safety and feasibility of its application.

Looking Ahead to Human Testing

Christman and Ventrix Bio are now preparing to seek FDA authorization to initiate human studies of the newer intravascular biomaterial for heart conditions. If approved, the therapy will need to demonstrate its safety, practicality for delivery, and effectiveness in enhancing patient outcomes.

For now, the treatment remains in the experimental stage. However, its potential is incredibly promising: rather than necessitating direct injections into heart muscle, it could be delivered through existing blood vessel-based procedures or via IV, allowing for healing from within.

"One major reason we treat severe coronary artery disease and myocardial infarction is to prevent left ventricular dysfunction and progression to congestive heart failure," Dr. Reeves noted. "This easy-to-administer therapy has the potential to play a significant role in our treatment approach."