Reprogramming stem cells to make muscle

Induced pluripotent stem cells - or iPS cells for short - are one of the hottest topics in biology right now, and have the potential to transform medicine...

This month, researchers led by Nenad Bursac at Duke University in the US have announced that they’ve managed to grow the first functioning human skeletal muscle from iPS cells, providing an exciting path towards new treatments for muscle wasting diseases.

Publishing in the journal Nature Communications, the scientists are building on their previous work growing functional muscle tissue from stem cells extracted from small samples of fully-grown muscle tissue, transplanting the cells onto a supportive three-dimensional scaffold that allowed them to grow into fully-formed muscle fibres. But the number of these stem cells is limited, and can only be obtained by taking an invasive muscle biopsy.

This time the team started with iPS cells, which can be made from cells obtained less invasively such as skin or blood, and turned them into muscle stem cells with the help of a protein known as Pax7 - a key transcription factor involved in muscle development.

Impressively, the lab-grown muscle fibres could contract and respond to electrical or chemical signals - just like real muscles in the body. And when they were transplanted into mice, the lab grown muscles soon settled down and started to grow a blood supply, surviving for at least three weeks.

There’s still a lot more work to be done to build up this body-building technology - the lab-grown muscles from iPS cells aren’t as strong as ones grown from muscle-derived stem cells, but the scientists are still hopeful that the technique could be used to develop and test treatments for rare but devastating muscle-wasting diseases and maybe one day even provide new muscle tissue for transplantation.