US agency ARPA-H and other funders award Boston Children's Hospital up to $29,6 million to develop living heart valves, blood vessels and heart muscle patches designed to grow with children and be assembled into a whole heart

US agency ARPA-H and other funders award Boston Children's Hospital up to $29,6 million to develop living heart valves, blood vessels and heart muscle patches designed to grow with children and be assembled into a whole heart

On October 21, 2026, Boston Children's Hospital, the Harvard John A. Paulson School of Engineering and Applied Sciences, the Mass General Brigham health system and NTT Research, whose computational models support the treatment of cardiovascular disease, announced the THUMPIN' consortium. The contract runs for up to five years. Bioengineer Kevin Kit Parker leads the project.

About 40 thousand babies are born with a heart defect in the United States each year. Roughly one in four of these defects is critical: according to the US Centers for Disease Control and Prevention, these children usually need surgery or another procedure within their first year of life. Implants deteriorate over time and need to be replaced, the hospital writes. Parker says, “The baby keeps growing. The repair stays the same size.” Children with the most severe defects may undergo repeated operations, adds Pedro del Nido, the hospital's chief of cardiac surgery, and some run out of treatment options.

Over five years, the consortium is tasked with developing the cells, tissues, manufacturing methods and computational tools needed to make heart valves, vascular grafts, heart muscle patches, components of the conduction system (which sets the heart's rhythm), ventricles and a whole heart. These components could be implanted individually, with the ultimate goal of assembling them into a heart for transplantation. The hospital expects these components to function without blood-thinning medication and reduce the need for repeat procedures.

The tissues will be tested in the laboratory and then in large animals. In parallel, the consortium is preparing the regulatory groundwork for a future FDA application to begin human trials, with Landmark Bio as its manufacturing partner. Parker says, “Building a heart is only part of the task. We need to establish the clinical and manufacturing infrastructure to turn the results of THUMPIN' into treatment options for patients.”

Parker's laboratory has studied how the heart's structure determines its function since 2003. In 2012, Parker and his colleagues built a jellyfish from silicone and rat heart cells, arranging its muscle to resemble that of a real jellyfish. Electrical pulses made it swim. In 2018, the laboratory grew a model of the left ventricle from human heart cells on a nanofiber scaffold that served as a template. It functioned consistently for six months. In 2022, the laboratory reported in Science that ventricular models with cells arranged in a spiral, as in real heart muscle, ejected more blood per contraction than models with cells arranged circumferentially. According to ARPA-H's description, the THUMPIN plan combines heart cells with scaffold printing.

THUMPIN is part of PRINT, an ARPA-H program for 3D-printing organs from a patient's own cells or cells from a cell bank. These organs are intended to function without immunosuppressive medication. The five teams announced in January 2026 are developing livers and kidney tissue; none was working on a heart. ARPA-H identifies two obstacles to printing a heart: heart cells are in short supply, and extracellular matrix proteins, such as collagen, are expensive. The project relies on a “universal cell source,” and the team includes specialists in hypoimmune engineering, which involves creating cells that the recipient's immune system does not recognize as foreign.

Another living vascular graft is being tested in children. At Nationwide Children's Hospital, researchers make it from a biodegradable scaffold and the child's own bone marrow cells. The scaffold breaks down, leaving a blood vessel made from the child's own cells. According to its developers, the vessel grows with the patient.