Scientists create mature heart muscle cells from stem cells

Jan. 26 (UPI) -- Researchers at Johns Hopkins University School of Medicine have successfully generated mature heart muscle cells using stem cells.

The mature heart muscle cells were created by implanting stem cells from a healthy adult or one with a type of heart disease into newborn rat hearts. The host hearts then give biological signals and chemistry necessary for the implanted immature heart muscle cells to overcome a developmental blockage that usually stops growth.

"Our concept of using a live animal host to enable maturation of cardiomyocytes can be expanded to other areas of stem cell research and really opens up a new avenue to getting stem cells to mature," Chulan Kwon, Ph.D., associate professor of medicine, member of the Johns Hopkins University School of Medicine's Institute for Cell Engineering and lead author of the study, said in a press release.

Up to this point, cell biologists have been unable to induce heart muscle cells to move past the point in development shown in newborns when allowed to mature in petri dishes for a year.

Researchers found that heart muscle cells grown in lab dishes were not activating the proper genes needed for cells to mature. So they focused their research on overcoming the developmental roadblock by creating a cell line of immature heart cells from mouse embryonic stem cells and tagging the cells with a fluorescent protein.

The team then injected roughly 200,000 of the cells into the ventricle of newborn nude rats with deficient immune systems, so they would not be attacked or rejected.

After a month, the cells began to look like adult heart muscle cells, which are elongated with striped patterns.

When researchers compared 312 genes in individual mouse cells grown in rat hearts with the genes in both immature and adult heart muscle cells, they found the cells in the rat hearts more closely resembled genetics of adult heart muscle cells. The new heart-grown cells were able to contract and beat like normal adult heart muscle cells.

Further studies showed that stem cells taken from a person with arrhythmogenic right ventricular cardiomyopathy, or ARVC, and grown in the heart ventricles of rats showed the cells demonstrated properties of heart tissue with the disease.

"The hope is that our work advances precision medicine by giving us the ability to make adult cardiomyocytes from any patient's own stem cells," Kwon said.

The study was published in Cell Reports.