Biomedicine Making Bioartificial Hearts An ingenious method for making new organs could one day revolutionize medical transplants. by Amanda Schaffer April 22, 2008 Sponsored by A pig’s heart in formaldehyde has been stripped of its cells using a strong chemical detergent. The extracellular matrix left behind will be seeded with cells to produce a new heart. A rat heart in a bioreactor has been chemically stripped of cells and then repopulated with neonatal cardiac myocytes. Suspended in the bioreactor, the new heart receives nutrients; mechanical and electrical cues train it to beat on its own. A close-up of the rat heart in the bioreactor shows that it is attached to two catheters responsible for the inflow and outflow of a nutrient solution. The heart is also hooked to two electrodes that train it to contract and expand.