A team of scientists at the University of Pittsburgh have hit the mother lode: They’ve grown human heart tissue that can beat on its own (video below). The process, involving decellularized mouse hearts and induced pluripotent stem cells, is equal parts beautiful and insane — and one of the biggest breakthroughs in modern medicine to boot.
Back in 2008, researchers at the University of Minnesota demonstrated that you could remove all of the original rat cells from a rat heart using a process called decellularization. This process, which uses enzymes and detergents to wash away the rat cells, leaves behind a protein-based heart husk — or scaffold, as it’s known in the tissue growth industry. The researchers then introduced rat stem cells, and watched as the husk was slowly regenerated into a working, beating heart.
The University of Pittsburgh scientists have essentially done the same thing, but with a mouse heart — and human stem cells. Excitingly, the researchers use induced pluripotent stem cells (iPSCs) — stem cells that are manually created from normal cells, such as those gathered from a skin biopsy. These iPSCs are then treated to become multipotential cardiovascular progenitor (MCP) cells, which can become the three types of cell found in the human heart (cardiomyocytes, smooth muscle cells, and endothelial cells). These MCPs are introduced to a decellularized mouse heart sitting in a Petri dish, the cells latch onto the heart scaffold, and after 20 days the heart starts beating again at 40 to 50 beats per minute.
Moving forward, it isn’t overly useful to have human-celled mouse hearts — but the same process might work with pig hearts, which are fairly compatible with humans. Another exciting prospect is the creation of heart tissue patches, made from a patient’s own iPSCs, to replace parts of the heart that have been damaged through disease or heart attack. There is always the possibility of a negative immune response to regenerated body parts, but the use of immunosuppressant drugs while the scaffold is replaced by indigenous proteins should be possible. (Read: Carbon nanotubes make it possible to grow human hearts.)
All in all, we are looking at one of the most exciting regenerative medicine breakthroughs yet reported. We are just a small step away from culturing patches of heart tissue, and creeping ever closer to regenerating whole human organs. (Read: Researchers create world’s first 3D-printed bionic organ.) One day, it might even be possible to have your own heart (or liver or kidney) removed, decellularized, and then regenerated using your own stem cells. You might have to lay in bed on bypass for a couple of weeks while your organ is regrown, but that’s a small price to pay for indefinite life extension.
Research paper: doi:10.1038/ncomms3307 – “Repopulation of decellularized mouse heart with human induced pluripotent stem cell-derived cardiovascular progenitor cells”