Most patients with an inherited heart condition known as arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) don't know they have a problem until they're in their early 20s. The lack of symptoms at younger ages makes it very difficult for researchers to study how ARVD/C evolves or to develop treatments. A new stem cell-based technology created by 2012 Nobel Prize winner Shinya Yamanaka, M.D., Ph.D., helps solve this problem. With this technology, researchers can generate heart muscle cells from a patient's own skin cells. However, these newly made heart cells are mostly immature. That raises questions about whether or not they can be used to mimic a disease that occurs in adulthood. In a paper published January 27 in Nature, researchers at Sanford-Burnham Medical Research Institute and Johns Hopkins University unveil the first maturation-based "disease in a dish" model for ARVD/C. The model was created using Yamanaka's technology and a new method to mimic maturity by making the cells' metabolism more like that in adult hearts. For that reason, this model is likely more relevant to human ARVD/C than other models and therefore better suited for studying the disease and testing new treatments.
"It's tough to demonstrate that a disease-in-a-dish model is clinically relevant for an adult-onset disease. But we made a key finding here-we can recapitulate the defects in this disease only when we induce adult-like metabolism. This is an important breakthrough considering that ARVD/C symptoms usually don't arise until young adulthood. Yet the stem cells we're working with are embryonic in nature," said Huei-Sheng Vincent Chen, M.D., Ph.D., associate professor at Sanford-Burnham and senior author of the study.
To establish this model, Chen teamed up with expert ARVD/C cardiologists Daniel Judge, M.D., Joseph Marine, M.D., and Hugh Calkins, M.D., at Johns Hopkins University. Johns Hopkins is home to one of the largest ARVD/C patient registries in the world.
"There is currently no treatment to prevent progression of ARVD/C, a rare disorder that preferentially affects athletes. With this new model, we hope we are now on a path to develop better therapies for this life-threatening disease," said Judge, associate professor and medical director of the Center for Inherited Heart Disease at the Johns Hopkins University School of Medicine.
Disease in a dish
To recreate a person's own unique ARVD/C in the lab, the team first obtained skin samples from ARVD/C patients with certain mutations believed to be involved in the disease. Next they performed Yamanaka's technique: adding a few molecules that dial back the developmental clock on these adult skin cells, producing embryonic-like induced pluripotent stem cells (iPSCs). The researchers then coaxed the iPSCs into producing an unlimited supply of patient-specific heart muscle cells. These heart cells were largely embryonic in nature, but carried along the original patient's genetic mutations.
However, for nearly a year, no matter what they tried, the team couldn't get their ARVD/C heart muscle cells to show any signs of the disease. Without actual signs of adult-onset ARVD/C, these young, patient-specific heart muscle cells were no use for studying the disease or testing new therapeutic drugs.
Speeding up time