Growing Hearts for Transplants

Many people are on waiting lists for organ transplants. Unfortunately, many people will not receive the organ they desperately need. For example, there are about 4,000 people in the U.S. awaiting heart transplants and only 2,500 of these will receive a new heart within a year. Additionally, a serious problem with transplants is the possibility of organ rejection (when the body's immune system doesn't recognize the new organ and instead fights the foreign cells).

Now imagine if human hearts could actually be grown, not taken from an organ donor, but actually grown by scientists in a lab. This would potentially provide many sick patients with the heart they need to survive and wouldn't otherwise receive. This concept is not science fiction. Scientists have been working on growing organs (ears, lungs, bladders, windpipes etc.) that are specifically designed for their recipient. The process works by using a scaffold of the particular organ (like a template) and seeding the scaffold with stem cells derived from the patient (building upon the template). This means that the organ will not be rejected by the patient's immune system since it was formed from his or her own cells. 

Recently, scientists from Massachusetts General Hospital and Harvard Medical School have grown full-sized, beating human hearts using stem cells. First, they take skin cells from the adult patient and genetically reprogram them to make them into stem cells (called Induced Pluripotent Stem Cells or IPS cells). Then, a donor heart that is deemed unfit for transplantation is washed with a detergent and many of its cells are stripped away, leaving the heart scaffold. At this point, the patient's reprogrammed stem cells are applied to the scaffold where they take hold, grow, and divide. After about 2 weeks in a nutrient-rich solution, the heart looks like a developing human heart and even beats when given an electrical signal! 

While not quite ready for transplantation into patients, this research provides much hope to those that need a heart transplant. Researchers are now trying to increase the number of IPS cells they can create, as well as speed-up the cell maturation process. 

http://www.popsci.com/scientists-grow-transplantable-hearts-with-stem-cells

Images: Stripped human heart (left) and heart grown using a scaffold and IPS cells (right)