Two researchers from the Stanford School of Medicine have made breakthrough discoveries about heart cells that could aid scientists hoping to test drugs on lab-grown human heart cells. They have found that heart cells grown from stem cells require tension to develop properly and that cells grown in a long, thin shape will contract more strongly.

These lab-grown cells have the potential to replace the traditionally used animal cells in drug testing, which have proven in recent years to produce questionable results.

“It gives us the potential to test drugs almost on an individual level,” said Beth Pruitt, a mechanical engineering processor and senior author on the study, to the Stanford Report.

The Stanford School of Medicine began its expedition to develop lab-grown adult heart cells in 2010. In the past, labs attempted to grow heart cells from stem cells but found that they didn’t look like adult heart cells.

Stanford postdoctoral research fellow in mechanical engineering Alexandre Ribeiro attempted to manipulate the shapes of the stem cells as they matured into heart cells. Starting with induced pluripotent stem cells (iPS cells), those derived from skin, he worked to shape the cells into everything from squares to very narrow rectangles. Upon testing the tension produced, he realized that the narrowest rectangles began to look more like normal heart cells.

Going a step further, Ribeiro manipulated the biomaterial used to grow the cells in order to simulate different degrees of tension exerted upon the cell. The testing conditions ranged from the loose stress of a developing heart to the stiffness expected in diseased hearts. In further testing, it became clear that based on the structure of these heart cells, the cells couldn’t operate in pressures that were too high or too low.

“We keep seeing in more studies that there is a certain blood pressure range in people where the heart is healthiest for longest,” Pruitt said to the Stanford Report. “I think we’re seeing that mirrored at the cell scale.”

Contact Ribhav Gupta at rgupta97 ‘at’ stanford.edu.