A new technique developed by researchers at the University of California San Diego School of Medicine in collaboration with a few others enables them to accelerate or decelerate the growth of human heart cells in-lab by simply shining a light with varying intensity on it. The cells themselves are grown on graphene, which has proven to be a much more realistic environment than lab dishes as it has the ability to convert light into electricity. 

There are a number of different applications in which this method could be used in both research and clinical settings. It could be used to create better medical devices or to develop more precision drugs that have fewer side effects or to test therapeutic drugs in systems that are more biologically relevant. But none of it would be possible without the wondrous semimetal, graphene.

Graphene is made up of a tiny network of carbon atoms. And while this is the exact same element that makes up everything else living in this world, it’s properties are quite unique. One of the things that makes graphene so special is the fact that it can convert light into electricity. This makes it good to use in lab settings as Petri dishes and glass plates aren’t very conductive, whereas the human body is. The researchers noted that cells grown on graphene behave much more like cells in the human body than those grown in Petri dishes.

As part of the study, researchers developed heart cells from skin cells that had been donated via an induced pluripotent stem cell (iPSC) and grew them on a graphene surface. It took a while for them to pinpoint the best graphene-based formulation as they also had to find the best light source for the job and a way of delivering it to the cell. But when they did, they were able to control just how much electricity was generated by the graphene by varying the light’s intensity.

“We were surprised at the degree of flexibility that graphene allows you to pace cells literally at will,” says first author on the study, Alex Savchenko, Ph.D., and research scientist in the Department of Pediatrics at UC San Diego School of Medicine and Sanford Consortium for Regenerative Medicine. The researchers found that by using light and dispersed graphene they were able to control the heart activity of zebrafish embryos. 

It’s an exciting time for Savchenko and colleagues as they look forward to the number of possible applications this graphene-based system can be used in. One such application is drug screening. At the moment, robots are used to test drug samples, screening them for their abilities to alter the way a cell behaves. Those drugs that are found to have the effect they’re after are studied in more detail. The problem is that many drugs could be being missed because their effects aren’t quite as apparent when using cells that are grown in plastic or glass Petri dishes.

Heart cells grown in a standard plastic petri dish contract at their own pace and therefore do not model the same conditions as someone might display just before they have a heart attack. Drugs tested on those cells may appear to do nothing if they are use-dependent. In order to test this theory, the team added mexiletine to the cells. Mexiletine is a drug that’s used to treat arrhythmias and is known for being use-dependent, meaning it is only effective when there’s a rise in the heart rate. 

When illuminating the heart cells on graphene using the light of different intensities, the researchers found that the faster the cells beat, the more the mexiletine inhibited them. While the team is currently focusing on just heart cells and neurons, eventually they wish to apply this graphene-based light system to search for drugs that are able to eradicate cancer cells while leaving healthy cells unharmed. They are also hoping to see graphene being used to find alternatives to opioids.

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