Restoring Muscle Strength in Aging Muscle


Unfortunately, muscle tone and strength decrease as we age. You can work out at the gym all you want. Eventually the relentless march and deterioration of age catches up with even the most avid athlete. However, a Stanford University group believes that they might have discovered why this happens and new cell targets to help reverse it.

According to Helen Blau (the doyen of muscle research), over time, stem cells that help repair damaged muscle cells after injury are less able to do so. This explains why regaining strength and recovering from a muscle injury gets more difficult with age. Blau and her team published their results in the journal Nature Medicine.

Fortunately, Blau’s study also suggests a way to make older muscle stem cells function more like younger ones. The caveat is that research in mice often doesn’t translate to humans. Therefore more work is necessary in order to determine if this technique could ever be used in people.

“In the past, it’s been thought that muscle stem cells themselves don’t change with age, and that any loss of function is primarily due to external factors in the cells’ environment,” study senior author Helen Blau, director of Stanford’s Baxter Laboratory for Stem Cell Biology, said in a university news release.

“However, when we isolated stem cells from older mice, we found that they exhibit profound changes with age,” said Blau, a professor of microbiology and immunology at the university. “Two-thirds of the cells are dysfunctional when compared to those from younger mice, and the defect persists even when transplanted into young muscles.”

The research also revealed, however, that there is a defect specific to old muscle stem cells that can be corrected, which allowed scientists to rejuvenate these stem cells.

“Most exciting is that we also discovered a way to overcome the defect,” Blau said. “As a result, we have a new therapeutic target that could one day be used to help elderly human patients repair muscle damage.”

The muscle stem cells in 2-year-old mice are the equivalent of those found in 80-years-old humans. In the course of their study, Blau and her team found that many muscle stem cells from these mice had increased activity in a certain biological pathway (p38α and p38β mitogen-activated kinase pathways, for those who are interested) that inhibits the production of the stem cells.

Drugs that block this pathway in old stem cells, however, allowed the aged stem cells to make a larger number of new cells that could effectively repair muscle damage.

According to Blau: “In mice, we can take cells from an old animal, treat them for seven days — during which time their numbers expand as much as 60-fold — and then return them to injured muscles in old animals to facilitate their repair.”

Once the mice received their rejuvenated muscle stem cells, the researchers tested their muscle strength with assistance from co-author Scott Delp, a professor in the School of Engineering, who has developed a way to measure muscle strength in animals that underwent stem cell therapy for muscle injuries.

Study lead author Benjamin Cosgrove, a postdoctoral scholar at the university, said: “We were able to show that transplantation of the old, treated muscle stem cell population repaired the damage and restored strength to injured muscles of old mice. Two months after transplantation, these muscles exhibited forces equivalent to young, uninjured muscles. This was the most encouraging finding of all.”

The study’s authors said they plan to continue their research to determine if people could benefit from this technique.

“If we could isolate the stem cells from an elderly person, expose them in culture to the proper conditions to rejuvenate them and transfer them back into a site of muscle injury, we may be able to use the person’s own cells to aid recovery from trauma or to prevent localized muscle atrophy and weakness due to broken bones,” Blau said.

“This really opens a whole new avenue to enhance the repair of specific muscles in the elderly, especially after an injury,” she said. “Our data pave the way for such a stem cell therapy.”

Ending the Reliance on Feeder Cells for Stem Cell Growth


A new study, published today in the journal Applied Materials & Interfaces reports the discovery of a new method for growing human embryonic stem cells that does not depend on feeder cells from human or animal cells.

Traditionally, embryonic stem cells are cultivated with the help of feeder cells derived from animals. Feeder cells secrete a host of growth factors and other signaling molecules that prevent the embryonic stem cells from differentiating and maintain their pluripotency. However, the use of animal products in the production of human cells lines rules out their use in the treatment of humans, since they can become contaminated with animal proteins that will cause rejection by the immune system or animal viruses that can infect the patient and cause significant disease.

The team of scientists led by the University of Surrey and in collaboration with Professor Peter Donovan at the University of California have developed a scaffold of carbon nanotubes upon which human stem cells can be grown into a variety of tissues. These nanotube networks mimic the surface of the body’s natural support cells and act as scaffolding for stem cells to grow on. Even cultured cells that have previously relied on feeder cells can now be grown safely in the laboratory, which paves the way for revolutionary steps in replacing tissue after injury or disease.

Dr Alan Dalton, senior lecturer from the Department of Physics at the University of Surrey said: “While carbon nanotubes have been used in the field of biomedicine for some time, their use in human stem cell research has not previously been explored successfully.”

“Synthetic stem cell scaffolding has the potential to change the lives of thousands of people, suffering from diseases such as Parkinson’s, diabetes and heart disease, as well as vision and hearing loss. It could lead to cheaper transplant treatments and could potentially one day allow us to produce whole human organs without the need for donors.”