Just last year, scientists from Duke University successfully grew bioengineered skeletal muscle from rat cells that could not only contract like the real thing when implanted into animals, but was also able to heal itself.
Now, in a world first, researchers from the same institute have grown human skeletal muscle that responds just like native tissue. When the researchers exposed the tissue to various stimuli, such as small electric shocks or drugs, the lab-grown muscle started contracting. Hopefully, this amazing achievement will soon allow researchers to test out new potential treatments and study muscular diseases outside of laboratory animals or the human body.
“The beauty of this work is that it can serve as a test bed for clinical trials in a dish,” lead scientist Nenad Bursac said in a news release. “We are working to test drugs’ efficacy and safety without jeopardizing a patient’s health and also to reproduce the functional and biochemical signals of diseases—especially rare ones and those that make taking muscle biopsies difficult.”
As described in eLife, to grow their muscle tissues, the researchers isolated cells from human muscle biopsies and left them to grow in the lab. These cells had progressed beyond the stem cell stage, but had not yet differentiated into muscle cells. After expanding them by more than 1000-fold, the resulting population was found to contain a significant fraction of muscle precursor cells. These cells were then seeded into a 3D mold filled with a gel and various nutrients to encourage cell growth and differentiation.
Around two weeks later, the cells formed bundles of muscle fibers that began to spontaneously twitch. The muscle had a similar architecture to native tissue and also possessed receptors that are necessary for the communication between muscle cells and nerves. The researchers then subjected these fibers to various different tests to see if they behaved like normal muscle tissue found in the body.
Not only did the bundles strongly contract in response to electrical stimuli, which was a first for human lab-grown muscle, but they also responded to various different pharmaceutical agents. For example, when they applied statins, which are used to lower cholesterol, the researchers observed abnormal fat accumulation at high concentrations, which has been observed in humans. This suggests that the tissue could one day be used by scientists in the development of new drugs, or by doctors so that treatments can be tailored to suit individual patients’ needs.
“One of our goals is to use this method to provide personalized 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.” And it might not be too long before this goal is achieved as the scientists are already attempting to correlate drug efficiency in patients with the observed effects on lab-grown tissues. They are also now attempting to grow muscle tissue from human induced pluripotent stem cells rather than biopsies because some diseases prevent doctors from being able to take decent biopsy samples, such as Duchenne Muscular Dystrophy.