A cardiac patch is an engineered tissue or biomaterial designed to repair or replace damaged heart muscle. These patches are applied directly to the heart, aiming to improve its function. They represent an advancement in tissue engineering and regenerative medicine, offering a potential solution for various heart conditions.
The Problem They Address
Severe heart damage, often resulting from myocardial infarction, leads to a significant loss of functional heart muscle. During a heart attack, blocked blood flow causes heart muscle cells to die due to lack of oxygen and nutrients. This irreversible injury prompts the body to replace the damaged muscle with stiff scar tissue, which cannot contract or pump blood effectively.
The formation of this non-contractile scar tissue reduces the heart’s pumping ability, eventually leading to heart failure, a condition where the heart cannot pump enough blood to meet the body’s needs. Unlike most other muscles, the adult human heart has a very limited ability to repair itself by regenerating new muscle cells. This is because adult heart muscle cells, or cardiomyocytes, are largely terminally differentiated and do not readily divide. This limited regenerative capacity makes external interventions, such as cardiac patches, a focus for restoring heart function.
Building a Cardiac Patch
Cardiac patches are engineered constructs that combine a structural framework, known as a scaffold, with various cell types and sometimes bioactive molecules. The scaffold mimics the natural extracellular matrix of the heart, primarily composed of collagen and elastin fibers. These scaffolds are porous, promoting cell adhesion, migration, differentiation, and proliferation, and providing mechanical support and electrical conductivity similar to native heart tissue.
Scaffolds use both natural and synthetic polymers. Natural materials like collagen, fibrin, alginate, and decellularized extracellular matrix (ECM) are chosen for their biocompatibility and biodegradability. Synthetic polymers such as poly(lactic acid) (PLA), poly(glycolic acid) (PGA), poly(lactic-co-glycolic acid) (PLGA), and polyurethane offer tunable mechanical properties, controlled degradation rates, and ease of fabrication. Hybrid materials, combining natural and synthetic polymers, are also explored.
To create a functional patch, these scaffolds are seeded with various cell types. Cardiomyocytes, the heart’s contractile cells, are a primary component, often derived from pluripotent stem cells like human embryonic stem cells (hESCs) or induced pluripotent stem cells (iPSCs). Other cell types, including cardiac progenitor cells, mesenchymal stem cells (MSCs), and endothelial cells, are incorporated to promote new blood vessel formation and support the growth and integration of heart muscle cells.
How Cardiac Patches Restore Heart Function
Once implanted, cardiac patches improve heart function through several mechanisms. They provide direct mechanical reinforcement to the weakened heart wall, reducing stress on remaining cardiac tissue and preventing further enlargement of heart chambers, known as ventricular remodeling. This structural support helps maintain the heart’s shape and pumping efficiency.
Beyond mechanical support, these patches promote the regeneration of new heart muscle cells and blood vessels. Cells within the patch, particularly stem or progenitor cells, can differentiate into new cardiomyocytes, directly replacing lost contractile tissue. Patches can also release bioactive molecules and growth factors that stimulate new blood vessel formation (angiogenesis) within the damaged area, improving blood supply and oxygen delivery.
Cardiac patches also improve the heart’s electrical conductivity. The engineered tissue facilitates the propagation of electrical impulses across the damaged region, helping to restore synchronized contraction. This electrical integration is important for efficient pumping and can prevent abnormal heart rhythms that often occur after a heart attack. The combination of structural support, cell regeneration, vascularization, and improved electrical function contributes to comprehensive repair and restoration of the heart’s ability to pump blood effectively.
Where Cardiac Patches Are Being Used and Investigated
Cardiac patches are actively investigated for clinical applications aimed at repairing and regenerating damaged heart tissue. A primary focus is treating myocardial infarction consequences, where patches replace scar tissue and restore contractile function in the damaged left ventricle. These patches hold promise for patients with advanced heart failure, a debilitating condition that severely limits daily activities.
Beyond heart attack recovery, cardiac patches are also explored for repairing congenital heart defects, structural problems present at birth. In pediatric cardiac surgery, engineered patches could offer improved, more biologically integrated solutions. The goal is to provide a long-lasting repair that grows with the patient, minimizing the need for repeat surgeries.
Research and development in this field are progressing. Preclinical studies in animal models have shown promising results, demonstrating improved heart function, reduced scar size, and patch integration with blood vessels. Several clinical trials are currently underway to assess the safety and efficacy of cardiac patches in humans. For example, the BioVAT-HF-DZHK20 study, initiated in Germany, is investigating the implantation of engineered heart muscle derived from induced pluripotent stem cells into patients with severe heart failure. These trials evaluate optimal cell dosage and potential side effects like abnormal heart rhythms or tumor formation, as researchers work towards translating these innovations into widely available treatments.