In a path-breaking research, researchers at Duke University have grown human skeletal muscle in the lab that contracts and responds just like native tissue to external stimuli such as electrical pulses, biochemical signals and pharmaceuticals.
The lab-grown tissue should soon allow researchers to test new drugs and study diseases in functioning human muscle outside of the human body.
"We are working to test drugs' efficacy and safety without jeopardising a patient's health and also to reproduce the functional and biochemical signals of diseases including rare ones," explained Nenad Bursac, associate professor of biomedical engineering at Duke University.
Bursac and Lauran Madden, a post-doctoral researcher in Bursac's lab, started with a small sample of human cells that had already progressed beyond stem cells but had not yet become muscle tissue.
They expanded these "myogenic precursors" by more than a 1000-fold and then put them into a supportive, 3D scaffolding filled with a nourishing gel that allowed them to form aligned and functioning muscle fibres.
Madden subjected the new muscle to a barrage of tests to determine how closely it resembled native tissue inside a human body.
She found that the muscles robustly contracted in response to electrical stimuli - a first for human muscle grown in a laboratory.
She also showed that the signalling pathways allowing nerves to activate the muscle were intact and functional.
To see if the muscle could be used as a proxy for medical tests, the duo studied its response to a variety of drugs, including statins used to lower cholesterol.
The effects of the drugs matched those seen in human patients.
"One of our goals is to use this method to provide personalised medicine to patients," said Bursac.
"We can take a biopsy from each patient, grow many new muscles to use as test samples and experiment to see which drugs would work best for each person."
The study appeared in the open-access journal eLife.
