A new population of stem cells in the Drosophila muscles involved in repair of injured tissue.
OCT 27, 2017 | BY RATNESHWAR THAKUR
Indian researchers are trying to understand the mystery of injured muscles recovery. Stem cell studies are a start of the big quest of understanding muscles related problems like Muscle dystrophy, a progressive muscle disorder where muscles fail to recover after damage. Adult Stem cells repair damaged tissue and are the secret behind why our organs can function without stopping. Stem cells are the hot topic of research with a huge potential for therapeutics.
At the National Center for Biological Sciences-TIFR, Bangalore, the team members (Rajesh Gunage, Dhananjay Chaturvedi, Heinrich Reichert (Biozentrum, Switzerland) and K. VijayRaghavan- have discovered a new population of stem cells in the Drosophila muscles involved in repair of injured tissue.
Previous work from the same group laid the foundation for the project and was continued by Dhananjay Chaturvedi. ‘Excellent team efforts are required to understand complex biology and this study would not have been possible without Dhananjay’s efforts, believes Dr. Gunage.
Exercise such as running and lifting weights causes muscles damage, but they recover and are suitable for work again. How is this achieved? “We thought we can study this in the most easily accessible model i.e. Fly. These are small flying insects, we see hovering on the ripened banana. We were puzzled about how an insect can fly for so long, much like we, humans run and walk throughout our life. It is a simple question with vast implication to understand about muscles in general. Fruit fly came as an easy model,” says Rajesh Gunage (current affiliation-Harvard Medical School), a senior author on this study who also co-authors with Dhananjay Chaturvedi.
In the study done with core support from NCBS, the team designed a simple Pin Prick Assay as an experimental strategy. The ‘pin prick' assay involves a tiny metal pin with dimensions close to an adult’s eyebrow hair. “Using this we could induce non-life threating damage to tiny flight muscles of fly and observe for recovery of flight,” says Dr. Gunage.
Flight muscles as the name suggests are involved in flying, and they are equated to our muscles of leg or arm. Much like the recovery of damaged muscles in case of a runner who recovers from it and starts to run again, researchers were surprised to see fruit fly flying once again after a brief period of recovery. Detailed analysis using best microscope possible- led to the discovery of novel stem cells. Team members observed that pin injury activates stem cells and they multiply in number. These newly formed cells then become part of injured muscles to help them recover from the injury. These results were published in the journal eLife Sciences.
Researchers said, “Just imagine small flying insects with stem cells. Hard to believe, isn’t it? Our reaction was the same and we were skeptical for a very long time. Insect muscles are very small and to confirm the presence of stem cells, we used electron microscopy. Under this microscope, a tiny marble looks like a giant football! Using this we could clearly see these small stem cells next to muscles, much like a number of satellites around the planets.”
“Using the knowledge gained from the current findings, one can understand how in old animals, muscles fail to work or show less recovery following accidental damage. Questions such as how different diet, regular exercise affect muscles or even a possible drug expected to enhance muscle function affect can now be tested. It just makes many difficult experiments easy to perform with much less effort,” said Gunage and Chaturvedi.
Reference:
Identification and functional characterization of muscle satellite cells in Drosophila
