'Artificial muscles' repair damaged tissue and muscle diseases are expected to usher in new treatments

In a study published in the journal Cell Stem Cell, a research team led by the Johns Hopkins University School of Medicine grew self-renewing human muscle stem cells in vitro and used the cells to grow them in mice.

To make the self-renewing stem cells, the research team started with lab-grown human skin cells and used gene editing to turn these cells into more primitive induced pluripotent stem cells (iPS cells), which have the ability to evolve into any cell in the body.

In fact, scientists have long been able to turn iPS cells into skin cells, brain cells, and many other types of cells in the lab

To achieve this, in the latest study, the authors induced iPS cells to become muscle stem cells using a medium rich in nutrients and standard cell growth factors

The team then tested how the newly cultured cells migrated in living animals and whether they could repair damaged tissue in experiments in mice

When they injected the newly cultured muscle stem cells into the muscles of mice, the stem cells moved into the muscle's stem cell niche, the same area where the mice's own muscle stem cells gathered

▲ Image of mouse muscle: green is a muscle stem cell protein; red is human-specific laminin A/C (Image source: Sunny Sun)

Could these stem cells work to repair damaged tissue? The authors used two different means to verify this question

First, the authors injected muscle stem cells into gene-edited mice that lacked a normal immune system and thus avoided immune rejection of the transplanted cells

The researchers found that at sites of toxin and radiation damage in muscle tissue, the transplanted muscle stem cells developed into myoblasts, which fused and developed into microfibrils in normal muscle, thereby successfully repairing muscle damage

▲Schematic diagram of the experimental design of the latest research (Image source: Reference [1])

In a second validation experiment, the researchers transplanted muscle stem cells into another gene-edited mouse

The research team found that the transplanted muscle stem cells migrated to the stem cell niche area of ​​the muscle

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References:

[1] Congshan Sun et al, Human pluripotent stem cell-derived myogenic progenitors undergo maturation to quiescent satellite cells upon engraftment, Cell Stem Cell (2022).

[2] Lab grown, self-sustainable muscle cells repair muscle injury and disease, mouse study shows.