New lab model simulates effects of exercise on muscles

Date:
March 2, 2022
Source:
Tohoku University
Summary:
A team of researchers has developed a simple lab-based system
for growing human muscle cells that are capable of vigorously
contracting.



FULL STORY ==========================================================================
A team of researchers at Tohoku University have developed a simple
lab-based system for growing human muscle cells that are capable of
vigorously contracting. The team used the model, which was described in
the journalScientific Reports, to investigate the properties of muscle
cells from patients with sporadic inclusion body mitosis (sIBM).


==========================================================================
sIBM is a degenerative disease that causes muscles to get progressively
weaker.

It typically affects patients aged over 50, predominantly impacting
muscles in the fingers and knees. Observing how muscle cells from sIBM
patients work during exercise is crucial to understanding more about
this disease.

This can be achieved using 'in vitro exercise models,' which involve
growing elongated muscle cells called myotubes in a petri dish and
applying electrical pulses to them to simulate the effects of muscle contraction. However, these widely used models are limited; the human
myotubes do not contract very well because they are flat in shape and
attach firmly to the material they are grown on. In comparison, myotubes obtained from other species, such as mice, contract much more strongly
under the same conditions.

"We set out to develop a new model that could help not only basic
muscle research, but also the diagnostic use of muscle cells obtained
from patient biopsy samples, which are a very limited resource," said
Dr. Makoto Kanzaki, Associate Professor at the Graduate School of
Biomedical Engineering, Tohoku University.

To aid the growth of human myotubes, the researchers used muscle cells
taken from a mouse cell line to create a population of nourishing
connective tissues.

The mouse cells, known as 'feeder cells,' supply essential proteins to encourage the growth of the human cells. They used this method to nurture
human myotubes grown from muscle stem cells obtained from sIBM patients.

They found that without the mouse feeder cells, the human myotubes showed
very little contraction in response to electrical stimulation. However,
once the mouse cells were added, the human myotubes showed obvious contraction-related activity when electrically stimulated.

The researchers used several different imaging techniques to examine
the properties of the muscle cells from sIBM patients and to compare
them with those from healthy humans. They found that sIBM myotubes have basically the same muscular properties as normal myotubes. Both contracted vigorously upon electrical stimulation, showed the development of muscle
fibre structures called sarcomeres and had raised levels of a skeletal
muscle protein called myokine.

However, they found that myotubes from sIBM patients had raised levels
of a protein called TDP-43 after contraction, while healthy muscle cells
did not.

This suggests that TDP-43 may be involved in the disease.

"The use of feeder cells expands the usefulness of existing lab-based
exercise models, and our system could potentially be used to evaluate
the effects of exercise on patient muscle cells," explains Dr. Kanzaki.

This muscle cell model may help to improve our understanding of muscle
cell conditions, particularly in response to muscle contractions. This
could provide important diagnostic information to aid the development
of customized therapies.

========================================================================== Story Source: Materials provided by Tohoku_University. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Yuqing Li, Weijian Chen, Kazumi Ogawa, Masashi Koide, Tadahisa
Takahashi,
Yoshihiro Hagiwara, Eiji Itoi, Toshimi Aizawa, Masahiro
Tsuchiya, Rumiko Izumi, Naoki Suzuki, Masashi Aoki, Makoto
Kanzaki. Feeder-supported in vitro exercise model using
human satellite cells from patients with sporadic inclusion
body myositis. Scientific Reports, 2022; 12 (1) DOI:
10.1038/s41598-022-05029-w ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220302092710.htm

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