Biosynthetic Heart SymbioHeart: Pig Heart Cells Regenerated Into a Complete Heart Inside the Human Body

SymbioHeart, jointly released by Massachusetts General Hospital's cardiac surgery department and biotech company BioNova Therapeutics, is a technology that uses gene-edited pig heart scaffolds and a patient's own stem cells to grow a complete biosynthetic heart. This technology gives end-stage heart failure patients the possibility of receiving a new heart grown from their own cells that will not trigger immune rejection, fundamentally relieving the global shortage of donor hearts for transplantation.

The project grew out of the convergence of two fields: xenotransplantation and regenerative medicine. Traditional heart transplantation is heavily reliant on brain-dead donors, with only about 8,000 surgeries performed globally each year, far below demand. The BioNova team's strategy is to first use gene editing to remove the immunogenicity of pig hearts, then refill the entire organ with the patient's own stem cells to create a personalized new heart.

The technology core has two steps. The first step is to prepare the pig heart scaffold. BioNova uses CRISPR gene editing to make 13 key modifications to pig hearts, including knocking out three sugar antigen genes that cause immune rejection, knocking out one gene that causes blood clotting, and inserting five human anticoagulation genes. The processed pig heart is then stripped of all living cells, leaving only the natural three-dimensional scaffold structure composed of collagen and elastin. This process is called decellularization.

The second step is to refill the scaffold with the patient's stem cells. The doctor extracts about 5 milliliters of bone marrow from the patient, isolates mesenchymal stem cells and cardiac progenitor cells, and cultures them in a bioreactor for six weeks until they proliferate to about 20 billion. The cell suspension is then injected into the decellularized scaffold, and through a mechanical environment that simulates fetal heart development (pulsatile flow, shear force, electrical stimulation), the stem cells are guided to differentiate into mature cardiomyocytes, endothelial cells, and fibroblasts, eventually forming a fully functional heart.

In animal experiments, the BioNova team performed orthotopic SymbioHeart transplant surgery in 48 pigs. After transplantation, SymbioHeart resumed normal pumping function in pigs, with a three-month survival rate exceeding 85 percent. More importantly, the cell composition of the transplanted heart was entirely from the recipient, with no observed hyperacute immune rejection. Matthias Klibanov, who heads cardiac surgery at Massachusetts General Hospital and is a professor at Harvard Medical School, said this is the culmination of twenty years of research in xenotransplantation and regenerative medicine.

For applications, BioNova plans to submit an Investigational New Drug application to the US FDA in the second half of 2026, with the first human trial expected to start in 2027. The first indication for SymbioHeart is end-stage dilated cardiomyopathy, a patient group with a five-year survival rate currently below 30 percent. If the SymbioHeart human trial succeeds, it will bring new hope to more than 26 million heart failure patients worldwide.

On the commercialization path, SymbioHeart's pricing is still under discussion. As a one-time treatment for heart transplantation, the pricing model differs from drugs. With the current US heart transplant cost of about 1.6 million dollars as a reference, BioNova expects SymbioHeart to be priced between 1.8 million and 2.5 million dollars. BioNova has secured 340 million dollars in Series C funding from Flagship Pioneering, valuing the company at 2.8 billion dollars.

On the ethical front, SymbioHeart uses pigs as the scaffold source, and some religious and cultural groups may have reservations about a human heart grown from a pig organ. BioNova responded that the company has held two years of dialogue with multiple religious organizations and has obtained approval from major ethics committees. Professor Klibanov said the company is also exploring the use of a wider range of mammalian scaffolds, including cattle and sheep, to accommodate patients from different cultural backgrounds.